The Pickeringlabs.com Blog

Antioxidants Are No Accident

2011-11-28T13:09:00.000-08:00

Recently we learned about a paper published by a team in Poland describing their work on the analysis of anti-oxidants. We wanted to share this work with the AHPA community.

Barbara Kusznierewicz and her colleagues from Gdansk University of Technology have developed a method to analyze antioxidants in complex mixtures by HPLC with post-column derivatization and UV/Vis detection. The authors studied three well-known reagents routinely used in colorimetric assays to measure antioxidant activity. They determined that Diammonium 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and Folin-Ciocalteu reagent (FCR) were best suited for post-column derivatization of antioxidants after they were separated on reversed-phase HPLC column.

Photo from FoodProductDesign.com

Researches optimized HPLC conditions as well as post-column parameters such as concentration of post-column reagent, duration of derivatization reaction and reaction temperature. Trolox and 20 other phenolic compounds were investigated and scientists were able to demonstrate good correlation between Trolox equivalent antioxidant capacity (TEAC) determined by HPLC with post-column derivatization and standard colorimetic assay. This method was successfully applied to analysis of extracts from sloe fruits and mirabelle plums and allowed to calculate concentration of individual antioxidants as well as TE antioxidant capacity.

Pickering Laboratories strives to provide new post-column applications, and the instruments and chemistry to support these applications. It is our philosophy to provide a complete solution and customer support. We plan to follow-up this interesting research with some development of our own to see if we can optimize the post-column technique further.

The full version of the paper can be found in the Wiley online library:

http://onlinelibrary.wiley.com/doi/10.1002/pca.1294/abstract

REFERENCE:

Kusznierewicz, B., Piasek, A., Bartoszek, A., Namiesnik, J., “The Optimisation of Analytical Parameters for Routine Profiling of Antioxidants in Complex Mixtures by HPLC Coupled Post-column Derivatization,” Phytochemical Analysis, 22, 392-402 (2011)

New! FREESTYLE Series Instrumentation

2011-11-23T12:50:00.000-08:00

Pickering Laboratories introduced the Freestyle™ Sample Clean-up workstation from LCTech at this year's AOAC International meeting in New Orleans. Building on the success of the GPC Ultra product line of Gel Permeation Chromatography systems, the FREESTYLE™Series is an innovative design adding new time saving features to the automated sample clean-up work flow.

The Freestyle™ begins with:

FREESTYLE™ Basic, which has an XYZ robotic arm for automated liquid handling; dilutions, additions, mixing, extraction, dispensing, and other operations.
Add the GPC module for GPC processing of up to 4 GPC columns.
Add to this the SPE module to enable SPE processing.
Add the EVA module for programmable evaporation and solvent exchange for a completely automated in-line evaporation instrument.

Flexibility of the system starts with the suspended rack design. The system can handle multiple vial shapes from 1mL to 1000mL.

The FREESTYLE™software is drag and drop to program multiple sample parameters and able to handle exceptions to insert into the workflow. Graphical reporting and full audit logs round out the robust software.

The FREESTYLE™ automation of sample clean-up saves time, improves consistency and protects your staff from potentially harmful chemical exposure.

Send us an email or give us a call to find out how FREESTYLE™ can solve your sample clean-up challenges.

Email: sales@pickeringlabs.com
Phone: Toll-free: 800-654-3330, Direct: 650-694-6700

Pickering Participates in BCEIA 2011 in Beijing, China

2011-11-23T12:49:00.000-08:00

By David Mazawa

Beijing, outside of Exhibition Center

The Beijing Conference and Exhibition on Instrumental Analysis was held on October 12-15, 2011 at the Beijing Exhibition Center. This biennial exhibition is sponsored by the China Association for Instrumental Analysis and supported by the Ministry of Science and Technology of China. The BCEIA is 3 days long, because it will take you a full three days to cover all 17,000m² of exhibition space.

The Beijing Exhibition Center became a bustling city of exhibitors and guests from all over the world showcasing instruments from the fields of Electron Microscopy & Material Sciences, Mass Spectrometry, Optical Spectroscopy, Chromatography, Magnetic Resonance, Electroanalytical Chemistry, Analytical Techniques in Life Science and Environmental Analysis.

BCEIA Exhibition Hall

David and Ameritech in Tianjin City

David and Tegent

I traveled to China to support our distributors that represented Pickering Laboratories at the BCEIA. I gave training to Ameritech in their Tianjin office and to Tegent in their Shanghai office.
Both distributors have been working with Pickering Laboratories for many years and are completely capable of supporting our post-column instruments and applications. Their hospitality was incredible and I look forward to visiting them again in the near future.

Feel free to contact either Ameritech or Tegent for sale inquiries in China.

http://www.ameritechsc.com/index.html

http://www.tegent.com.cn/en/index.asp

The Great Wall of China

David Mazawa

Technical Support Chemist

Pickering Laboratories, Inc.

1280 Space Park Way

Mountain View, CA 94043 USA

Phone: 650-694-6700 ext 710

Fax: 650-968-0749

Email: david.mazawa@pickeringlabs.com

Chromatography Quiz

2011-11-23T11:06:00.000-08:00

Chromatography Quiz #7 Results

We would like to congratulate the grand prize winner of our last newsletter’s Amino Acid Analysis Chromatography Quiz: Jaime Lee Palmer from Underwriters Laboratories!!!

She has won, and will shortly be receiving: a gift card for Barnes and Noble! Additionally, for this quiz all our participants will each be receiving a Smiley Face Sampler Box courtesy of The Popcorn Factory! Again, we would like to thank all of you for your submissions.

The correct answer for the modified Amino Acids chromatogram: the Trione reagent is oxidized. Either the reagent has been improperly stored (not under Nitrogen), or has been in extended contact with air.

Thank you!
Pickering Labs

Chromatography Quiz #8:

Identify the error made when running the Carbamates chromatogram below and win a prize! Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by January 31st in order to win. You will receive email confirmation that your submission has been received. The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Carbamate Analysis for US EPA Method 531.1

Pickering Column: 1846250 Carbamate Column, C18, 4.6 x 250 mm

Sample: Actual customer's 531.1 standard at 10ppb

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 42 °C

Flow rate: 1 mL/min

Eluant Gradient:

TIME	WATER	MeOH %
0	85	15
1	85	15
44	25	75
44.1	0	100
49	0	100
49.1	85	15
57	85	15

Post-column conditions:
Reagent 1: Hydrolysis reagent CB130
Reagent 2: 100 mg of OPA, 2 g Thiofluor™ in 950 mL of CB910

Reactor 1: 100 °C, 0.5 mL
Reactor 2: ambient. 0.1 mL

Reagent flow rates: 0.3 mL/min

Detection: Fluorometer ex 330 nm, em 465 nm

Full Chromatogram:

Enlarged View:

Further Enlarged View:

For an example of a Good Carbamate Chromatogram, click here

SupplySide West Expo 2011

2011-11-18T12:34:00.001-08:00

By Mike Gottschalk

Laszlo Torma inside the Venetian Hotel & Casino

The Supplyside West Conference is a very important Herbal Supplement Industry event. It provides important educational and networking opportunities to this $29 billion market. Since the FDA set out required current good manufacturing practices (cGMP) in 2007, the Herbal Supplement producers are working to meet the new requirements before the FDA audits. These regulations are intended to insure the quality, purity and safety of the Herbal Supplement products available today.

The show is held in Las Vegas, Nevada, October 19-23. Pickering Laboratories exhibited at the show. We introduced our instruments, and methods to the industry. Of primary concern are Mycotoxins and Amino Acids, but also pesticides. Our GPC Clean-up and post-column instruments are well-suited to these applications.

In addition to the literature and instruments in the booth, we presented two posters:

“Immunoaffinity Clean-up and Analysis of Aflatoxins and Ochratoxin A in Herbs & Spices using HPLC with Post-column Photochemical Derivatization”

The production of herbal supplements and spices is a fast growing industry. There are numerous reports on the presence of Mycotoxins in commercially available herbs and spices such as chamomile, black and white tea leaves, ginkgo leaves, paprika and cumin. We developed a simple, sensitive and robust HPLC-Post Column Derivatization method for analyzing Aflatoxins B1, B2, G1, G2 and Ochratoxin A in herbs and spices. AflaOTAClean Immunoaffinity columns contain antibodies specific for both classes of Mycotoxins and allow for fast and efficient sample clean-up. We used the AcceClean automated workstation, which processes three samples simultaneously.

"Accelerated Amino Acids using HPLC with Post-Column Derivatization"

We developed an accelerated amino acids analysis method for Physiological and Protein Hydrolysate samples that utilizes temperature and eluant gradients. Protein Hydrolysates can be analyzed in 48min (inject-to-inject). Amino Acid Analysis is an important step in the Quality Control and R&D of dietary supplements, sports drinks, pharmaceuticals and in any type of sample where the amino acid content is of importance. The objective of the study was to reduce the total run time of Amino Acid Analysis by implementing both a column temperature gradient and a linear buffer gradient using HPLC with Post-column derivatization.

If you would like a copy of either or both of these posters or any additional information about our products, please feel free to send us an email or give us a call:

Email: sales@pickeringlabs.com

Phone: Toll-free: 800-654-3330 Direct: 650-694-6700

Dinner on the canal in "Venice"

AOAC International 2011

2011-11-18T12:33:00.001-08:00

By Mike Gottschalk

Any trip to New Orleans requires a visit to
Cafe du Monde for coffee and beignets

The annual meeting of the AOAC International in New Orleans, Louisiana on September 18-21, had a strong emphasis on Herbal Supplements testing. The AOAC organization is central to FDA efforts to provide analytical structure to testing methods for this newly regulated industry.

Pickering Laboratories participated in the AOAC sponsored Single Laboratory Validation of Multi-residue Mycotoxin Analysis in Feeds and Grains. For this work, Pickering Laboratories was awarded the “Single Lab Validation of the Year”. This pivotal work in the analysis of Mycotoxins continues in Herbal Supplements as well as agricultural products.

We presented our new instrumentation and a poster titled “Analysis of Paralytic Shellfish Toxins in Bivalve Mollusks using HPLC with Post-column Derivatization and Fluorescence Detection”

In support of our new instrumentation, the incredibly versatile FREESTYLE series, we presented the highlights and capabilities in our Vendor session on Tuesday afternoon. You can find more details about Freestyle in a separate blog post and on the LCTech website: http://www.lctech.de/english/FREESTYLE-GPC.html

The post-column method for Paralytic Shellfish Toxins presented in our poster is now a official AOAC Method: OMA 2011.02. Earlier in 2011, we attended the 2nd Joint Symposium & AOAC Task Force Meeting on Marine & Freshwater Toxins meeting in Spain in support of the work done by Mr. Jeffery van der Riet to complete method 2011.02. You can read about the meeting and the method in an earlier blog post.

If you would like a copy of the poster or any additional information about our products, please feel free to send us an email or give us a call:

Email: sales@pickeringlabs.com

Phone: Toll-free: 800-654-3330 Direct: 650-694-6700

Good Toys Stimulate Imagination

2011-11-18T10:41:00.000-08:00

By Michael Pickering

A sandbox is a reasonably scaled and so infinitely variable a toy that it should be an important consideration for any family with children and the use of about 20 square feet of ground. The basic design is simple: 1) Make a collar of the depth you want out of rot-resistant material (i.e. heart redwood, cedar, et. al.) and 2) fill to desired level with sand.

That is the most obvious design consideration but not the most important factor by far. Sand management is the important issue. Sand is predominantly silica (aka quartz) and as purchased is fine grained and fairly uniform in size. Thus it packs densely. The most critical property is the extremely hydrophilic nature of silica. It can sustain a great deal of water just by surface tension. So, if you put sand in a blind hole on dirt, once it gets wet it can readily puddle and take weeks or months to dry, depending on where you live. It rains sometime where most people live. And to maximize the “toy-ness,” the sandbox must quickly drain so the children can add a dribbling hose to the party.

A design that worked for our four children:
Our sandbox is 6’ x 6’ x 1’ and is filled to 8” deep. About 25 cubic feet of sand in all. Although it is simple arithmetic, I’m going to give you the small numbers to inspire you. Its position on the ground is controlled by gravity. The mount is three layers:

Gravel, also called drain rock, minimum one inch deep – 3 cubic feet
Galvanized fencing, ¼ inch mesh, 36 square feet
Aluminum screen, 36 square feet
When not in use, protect your sandbox with a screen to keep the local cats out

Play Time:
You can also add a degree of nonsense. I added marbles, surf tumbled beach glass and stainless flatware from the local Goodwill. Our children would squirt water droplets into the air and the humming birds would come to collect them. It was a four-act play that had a long run.

Secondary Metabolites

2011-06-28T12:58:00.002-07:00

Secondary Metabolites

By Michael Pickering

Peyote Plants (1)

This name encompasses the category of chemicals that living organisms make which are not used in their normal growth, development, or reproduction. They are a staggering array of chemical structures and properties. Antibiotics are largely produced by bacteria, and a large variety of mammalian toxins are of fungal origin. Pigments are produced by both botanicals and insects. The peyote cactus, Lophophora williamsii, produces the hallucinogenic alkaloid mescaline. Fugu, the Chinese puffer fish, harbor symbiotically produced tetrodotoxin.

Puffer Fish at Japanese Market (2)

The producers of these exotic structures usually must isolate them to keep them out of the traffic of their living processes. They can interfere with everyday life, or more often are toxic for the producer. Dalea emoryi (aka dyebush) makes an intense red pigment that it stores in blister-like vesicles on its bark. Coyotillo shrubs, Karwinskia humboldtiana, make deadly neurotoxins which they store in the seeds, discouraging browsing animals such as cattle, deer, and sheep from eating them. (You can read more about this plant in a previous newsletter: Coyotillo in Del Rio, Texas)

Lotus scoparius, or deer weed, makes a water-soluble flavinoid, which is a biodegradable germination inhibitor, and stores in its seeds. Upon first rain, this compound sterilizes the surrounding ground so that no seeds can germinate. The result is that competitive weed seeds rot. When the second rain comes, the deer weed seeds germinate with nothing but clear sky surrounding them.

Sometimes, we can see a competitive advantage of the presence of these chemicals: attracting pollinators, protective insects, or mates, or discouraging predators, competitors, or tramplers. But often not. Today’s musings are about two species (an insect and a botanical): Daclylopius coccus and Citrus sinensis.

"Gusano Rojo", Dactylopius coccus

Red dyes produced by insects have been and remain among the most important dyestuffs in human commerce. Before the Americas were exploited, the most abundant source of red pigments was the Asian scale insects and their excretions. This broad class of quinoid dyes bind permanently to proteinaceous substrates (in dye talk they are ‘fast’) such as wool and silk. Historically, they have also been used as art pigments.

Early in the 16^th century, the Spanish introduced the world to the American cochineal, and the Asian scale insects were doomed to a mere historical reference.

Cacti with Cochineal (3)

Cochineal Cluster (3)

The females of this American species that feeds on cactus provide the popular Latino name “red worm.” Interestingly, Dactylopius coccus is not actually a worm, but is part of the cochineal family. By dry weight, the females can produce an astounding double digit percentage of pigment. The pigments have great variation of color and intensity (Carminic Acid extinction coefficient 6800, Laccaic Acid A extinction coefficient 43700). The commercial growers of the pigment use the cactus Indian Fig Opuntia (Opuntia ficus-indica) to feed the caterpillars, whose fruit and tender young shoots are also popular in Latino diets. The same insects in a blue agave farm are considered a pest.

Because of the significance of these insect-derived pigments in human history, they are the subject of anthropological study in ancient art. In 2004, we were invited into the study by the Department of Conservation and Scientific Research of the Smithsonian Institute. Although the pigments have long wavelength chromophores (little or no interference) and large extinction coefficients, the sample size is only 2-5 ng to minimize damage. As the pigments are only a small component of the sample, adequate detection requires a post-column reaction to make the pigments fluorescent. We made them an inert system as the reagent AlCl₃ is a powerful reducing agent, which translates as very corrosive to hardware. During the reaction, the Al³⁺ reduces the quinone to a hydroquinone, which chelates the spent Al³⁺ and makes the entire complex fluorescent.

Oranges, Citrus sinensis

Valencia oranges produces two main bitter principles, Limonin, a terpenoid, and Naringin, a flavenoid, which it mainly stores in its seeds. The seeds are easily removed when the fruit is harvested for juice. Lacking seeds, the navel orange must develop a different storage strategy.

The navel orange stores the Limonin and Naringin as tasteless precursors (at neutral pH) in the peel, concentrated in the vestigial seed, the navel end. When the orange is juiced, the membranes are torn and spill their contents into the acidic juice. The acidity catalyzes the hydrolytic elimination of a sugar from a tertiary alcohol and facilitates a ring-closure to form a lactone, the bitter Limonin.

The tasteless Naringin precursor reacts similarly.

California, and I am sure other commercial orange-producing areas, has strict standards for exportability of the whole fruit, size being paramount. Thus, the most important commercial value in un-exportable fruit is the juice. One hundred percent navel orange juice is unpalatably bitter.

It is my opinion, and I encourage you to compare, that non-specific blended frozen orange juice concentrates contain a noticeable amount of navel orange juice. Pure Valencia concentrate is available, so do the experiment and voice your opinion. We will post opinions (with your bylines, or make up a cool avatar name) in the next newsletter.

2nd Joint Symposium and AOAC Task Force Meeting on Marine and Freshwater Toxins Analysis

2011-06-28T12:58:00.001-07:00

Held in Baiona, Spain, May 1-5, 2011

By David Mazawa

.

Pickering Laboratories was proud to sponsor the Second Joint Symposium and AOAC Task Force Meeting of Marine and Freshwater Toxins Analysis. This growing symposium addressed new developments, method validation efforts, and method implementation in the analysis of marine and freshwater toxins. A variety of methods needs for detecting saxitoxins, domoic acids, okadaic acids, azaspiracids, other seafood toxins and the cyanobacterial toxins were addressed. Presentations and discussions addressed special needs of the community ranging from emerging toxins to the ongoing replacement of the mouse bioassay with modern and fully validated chemical methods. Principle sponsor of the symposium was the University of Vigo, Spain, Department of Analytical and Food Chemistry.

New methods have been recently validated in an effort to replace the Mouse Bioassay. Due to the hard work of Jeff van de Riet et al. in his single laboratory validated study, the HPLC post-column oxidation method for analysis of paralytic shellfish toxins (saxitoxins) in shellfish, is now an official AOAC method (AOAC OMA 2011.02). Pickering Laboratories was there to support this occasion and to show the symposium that we have instrumentation perfectly suited for this method. For details on the method, please visit our website or contact Pickering Laboratories Technical Support.

To view the official method, members should log onto AOAC's website: www.aoac.org

Pickering Laboratories' Mycotoxin Workshop held at MidWest AOAC in Lincoln, NE

2011-06-28T12:58:00.000-07:00

Sculpture on U of NE-Lincoln campus

By Maria Ofitserova, PhD

At the Midwest AOAC meeting (Held from June 6-9, 2011 in Lincoln, Nebraska) Pickering Laboratories presented a workshop on analysis of Aflatoxins in different matrices such as animal feeds, corn and peanut butter. The workshop generated a lot of interest with representatives from several State Departments of Agriculture, State Universities, as well as companies like Silliker and General Mills attending the two sessions of the workshop. The participants were able to learn about new analytical equipment and have a discussion about different aspects of Mycotoxins analysis.

During the workshop the samples extracts were cleaned with AflaClean™ Immunoaffinity columns and analyzed using an HPLC method with post-column photochemical derivatization by UVE™ and fluorescence detection. We also demonstrated how AcceClean™ workstation automates the labor-intensive column clean up step. The participants were impressed with versatility of the AcceClean workstation capable of handling multi-step procedures with both Immunoaffinity and SPE columns.

To learn more about Pickering products for Mycotoxins Analysis please visit our website http://www.pickeringlabs.com/catalog/Mycotoxin_Analysis.asp or call (800)-654-3330

Third Latin American Pesticide Residue Workshop

2011-06-28T12:57:00.002-07:00

Held in Montevideo, Uruguay, May 8-11, 2011

By David Mazawa

Laszlo Torma at LAPRW

The Latin American Pesticide Residue Workshop (LAPRW) is a biannual open forum for discussion on current concepts and future developments in the field of pesticide residues in food and the environment. Pickering Laboratories was proud to support this workshop by sponsoring and also presenting a poster titled "Glyphosate in soy beans, corn and sunflower seeds by HPLC with post-column Derivatization and fluorescence detection"

Downtown Montevideo

If you would like a copy of the poster, please email support@pickeringlabs.com

Famous sculpture on the beach at Punta del Este, Uruguay

Southern Section AOAC Meeting

2011-06-28T12:57:00.001-07:00

By Wendy Rasmussen

From April 11-12, Pickering attended the Southern Section AOAC Meeting in Atlanta, Georgia.

The meeting was well attended, and we enjoyed some good talks with current and future customers as well as long-time friends in the industry.

In preparation for our Vendor Seminar (see below), I did some research about the southern states, and Georgia in particular. In the process, I learned a couple of interesting facts about Georgia. For example, even though Georgia is nicknamed the Peach State, they're only the 3rd largest producer of peaches. Turns out the state is known for its Quality rather than the quantity of the fruit. According to the internet, Georgia produces A LOT of poultry & eggs (Georgia is ranked 1st in the US for production of broilers*), but also peanuts as well as cotton and tobacco.

We presented a Vendor Seminar at the meeting about our Aflatoxin Analysis products. We opted for a "show & tell" approach in which we brought in the key components to the method:

UVE Photochemical Reactor

AflaClean Immunoaffinity Columns

and the AcceCLEAN Automated Sample Handling Workstation

The combination of these products was later demonstrated at the Mid West AOAC Workshop in Lincoln, NE

More about Georgia:
http://georgiainfo.galileo.usg.edu/gaecon.htm
http://en.wikipedia.org/wiki/Georgia_%28U.S._state%29

*Broiler: A young chicken bred for meat

Western Canada Trace Organic Workshop

2011-06-28T12:57:00.000-07:00

By Wendy Rasmussen

Held in Edmonton, Alberta, from May 9-11. Rebecca Smith and I attended the 46th Annual WCTOW. The meeting is a place where scientists can meet and present their work, and to learn about new challenges, applications, and methods.

We have attended this workshop in the last couple of years so that we could support our distributor in Canada, Chromatographic Specialties, but also to meet and get to know our current and future customers in western Canada.

Some highlights included the measurement of antibiotics excreted by cattle and how antibiotics in manure spread on the ground as fertilizer can ultimately run off into the drinking water. Another interesting topic, especially for Alberta, is the question of identification of napthenic acids in water and soil to determine whether is naturally occurring or whether it is due to environmental contamination by oil refineries.

After the meeting, we had to good fortune to visit a few laboratories in Edmonton and Calgary.

Chromatography Quiz No. 7

2011-06-28T12:56:00.000-07:00

Chromatography Quiz #6 Results

We would like to congratulate the grand prize winners of our last newsletter’s Aflatoxins Analysis Chromatography Quiz: Matthew Hartz and Keena Njoroge from Underwriters Laboratories, Steven Moser from the Oklahoma Dept of Agriculture, Food & Forestry, and Holger Franz from Dionex Germany!

They have won, and will shortly be receiving: a gift basket stuffed with Starbucks coffee, tea, and treats! Additionally, for this quiz all of our participants will each be receiving a $20 gift card from Starbucks! Again, we would like to thank you all for your submissions.

The correct answer for the modified Aflatoxins chromatogram: The Aflatoxins G1 and B1 must be derivatized in order to achieve maximum sensitivity. The derivatization is achieved either by reaction with Iodine, or with a photochemical reactor. In this case, we achieved the modified chromatogram by turning off the UVE prior to injection. The same chromatogram would be noticed if the Iodine reagent was not pumping.

Thank you!

Pickering Labs

Chromatography Quiz #7:

Identify the error made when running the Amino Acids chromatogram below and win a prize! Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by August 31^st in order to win. You will receive email confirmation that your submission has been received. The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Amino Acid Analysis of Protein Hydrolysate

Pickering Standard: 012506H, 10 μL injected of 0.25 μmole/mL standard in both chromatograms

Pickering Analytical Column: 1154150 High-Efficiency Sodium Cation-Exchange Column (4.0 x 150 mm)

Pickering GARD^TM Column Protection System: 1700-3102

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 48 °C

Flow rate: 0.40 mL/min

Eluent Gradient:

TIME	1700-0112 %	Na740 %	RG011 %
0	100	0	0
12	100	0	0
34	0	100	0
53	0	100	0
53.1	0	0	100
55	0	0	100
55.1	100	0	0
67	100	0	0

Post-column conditions for amino acid analysis:

Reagent 1: Trione

Reactor 1: 130 °C, 0.5 mL

Reagent flow rate: 0.3 mL/min

Detection: UV-Vis Detector, 570 nm for primary amino acids, 440 nm for secondary amino acids

Amino Acids Chromatogram to Troubleshoot:

Amino Acids Reference Chromatogram:

Chromatography Quiz No. 6

2011-02-11T16:21:00.000-08:00

Chromatography Quiz #5 Results

We would like to congratulate the grand prize winner of our last newsletter’s Carbamate Chromatography Quiz: June Black from the Pennsylvania Department of Environmental Protection!

She has won, and will shortly be receiving, an extensive California Wines Gift Basket! Additionally, for this quiz all of our participants will each be receiving a $25 gift card from Bevmo! Again, we would like to thank you all for your submissions.

The correct answer for the modified Carbamate chromatogram: The system was improperly equilibrated at a higher percentage of methanol (50:50 Water:Methanol) prior to injection. After injection, the gradient program began with normal starting conditions (85:15 Water:Methanol). For the less retained compounds, the improper conditions on the column at the time of injection will push them through faster, causing coelutions. Longer retained compounds are less affected by starting conditions of the column, and impacted more by the gradient (which was correct) so you see less of an effect on the later part of the chromatogram.

Thank you!

Pickering Labs

Chromatography Quiz #6:

Identify the error made when running the Aflatoxins chromatogram below and win a prize! Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by March 31^st in order to win. You will receive email confirmation that your submission has been received. The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Aflatoxins Analysis by AOAC Official Method 2005.08

LCTech Standard: 0.25 ng B2, G2 and 1.0 ng B1, G1 injected on-column in both chromatograms

LCTech Analytical Column: 150 x 4.6 mm; RP C18 (P/N 10522)

LCTech Guard Column: 8 x 4 mm (P/N 10523; holder P/N 10750)

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 36 °C

Mobile Phase: Water/methanol/acetonitrile 55/30/15

Isocratic Flow rate: 1.3 mL/min

Post-column conditions:

Photochemical Derivatization: 254nm UV low pressure lamp (LCTech UVE derivatizer, Pickering P/N 1100-3347)

Detection: Fluorometer: ex 365 nm, em 460 nm

Pinnacle Preventative Maintenance

2011-02-11T16:00:00.000-08:00

Keep your Pinnacle in good condition and minimize downtime by performing annual maintenance. Performing Preventative Maintenance on your Pinnacle PCX is easy to accomplish with the Kits and Instruction we provide. Refer to the Maintenance Section of the Pinnacle Manual for details on performing the maintenance. Contact Pickering Laboratories Technical Support with any questions. 800-654-3330, 650-694-6700, or email support@pickeringlabs.com

Below you can find a general maintenance schedule. Your maintenance schedule will depend on usage. If you use the Pinnacle PCX 24x7, you may want to perform the Preventative Maintenance more often.

Maintenance Schedule

Routine Maintenance

- Check for leaks every day

- Replace Flush and Piston Wash reservoirs every week

- Record operating pressures in a daily log book

Preventative Maintenance

- Replace Valve and Pump Seals every 12 months

- Replace the 10um Reagent Frits every 3 months

- Change the tubing every 24 months

Part Numbers

1000-1003 Kit, PM Service, Pinnacle Single Pump (Pump seals, Valve seals, and replacement filter)

1000-1004 Kit, PM Service, Pinnacle Dual Pump (Pump seals, Valve seals, and replacement filter)

1100-0500 Tubing Kit, Pinnacle Dual Pump

1100-0501 Tubing Kit, Pinnacle Single Pump

1452-0122 Pump Seal Kit, Pinnacle

1452-0200 Valve Seal Tool, Pinnacle (Tool only)

1452-0201 Valve Seals kit, Pinnacle (Seals only)

1452-0202 Valve Maintenance Kit, Pinnacle (seals and tool)

3102-9040 Replacement Reagent 10um Filter

1452-0200 Valve Seal Tool

Parts Lookup

Please try our Parts Lookup on our website if you ever need to find a part number. The Parts Lookup is located on our website. Start at http://www.pickeringlabs.com/

Select Parts Lookup under the Service & Support menu

Or, you can also find the Parts Lookup under the Products menu.

Select the Parts Lookup from the Replacement Components menu on the left side of the page.

Next, choose which instrument you are using.

Once you are in the Parts Lookup, simply click on a part or drag you mouse over the part of interest to see the part numbers.

Sincerely,

David Mazawa

Technical Support Chemist

Pickering Laboratories, Inc.

1280 Space Park Way

Mountain View, California 94043 USA

Phone: 650-694-6700, ext. 710

Fax: 650-968-0749

david.mazawa@pickeringlabs.com

Herbal Remedy

2011-02-11T15:15:00.000-08:00

By Michael Pickering

Echinacea purpurea, often called a coneflower, has long been used to ameliorate the symptoms of upper respiratory problems caused by viruses and allergies. The most common form available in the San Francisco Bay Area is in a tablet called Airborne®. My wife and daughters always have it on hand. However, if I ingest a tablet, it worsens my symptoms. I reasoned that the effect was due to the residual incorporated plant material aggravating my hay fever. So I decided to test the theory by making a tincture wherein the plant material could be categorically removed.

When water is the extraction solvent, the product is called an infusion and is taken as a hot “tea.” My solvent of choice for herbaceous tinctures is potable ethanol (190 proof), although as low as 60 proof may be used. The Everclear® available in California is only 150 proof. The same brand in Oregon and Nevada is 190 proof, so I had my Oregonian daughter get me some. That allowed me to filter out the plant residue. The experiment provided a useable form of Echinacea that is free of allergic side-effects. My recommended dose is one teaspoon. I share the extract with my coworkers, friends, and relatives, who all acclaim its efficacy. One friend actually claims to be allergy-symptom free.

The flower is an annual which my wife and I cultivate in our garden. Our two plants provide enough cones per season to make 2 liters of solution. At Pickering Labs, we recently purchased some Echinacea from an herbal supply vendor as a sample for a multi-mycotoxin study, and rather than cones it was supplied as the plant root, called Black Sampson Root.

Herbal Tincture Preparation:

- Put 100 g dried herbs into a sufficiently sized jar.

- Add 500 mL of 190 proof alcohol.

- Seal, and place on shaker for three days.

o Note: Longer contact time is recommended for lower proof alcohol. Two weeks is recommended for 60 proof, for example.

- Filter using a 0.45 μm filter.

Echinacea purpurea

Silk Stockings

2011-02-11T15:00:00.000-08:00

By Michael Pickering

Silk stockings were originally made of a single thread formed into a cylindrical tube. They were handmade by a process then called tatting and now known as crocheting. Unlike knitting, which uses two threads and two needles, crocheting only requires one tool, called a hook. The hook size is scaled to the thread diameter. In its simplest execution, the process produces a chain-like, continuous series of interlocking loops. Lace, circular doilies, and rectangular antimacassars were made by creatively interconnecting the chain to form symmetrical patterns. In the “men’s work – women’s work” divide, tatting fell under the women’s craft and so the products were always useful at home.

Grandma Pickering taught me to tat chains as a preschooler which kept me non-kinetic and silent as I marveled at the ever longer creations while I tried to out-do myself day after day.

To make a tube, a mandrill or tool is used with the hook. The tool consists of a tube with projection pins at one end. The diameter of the stocking (hose and the frequency of pins controls the symmetry and mesh size. For each pair of stockings an appropriate length was cut off and knotted to prevent unraveling. The toe was neatly tied off and a garter, i.e. non-stretchable holder, was sewn or tatted to the top.

By grammar school, I made my own tube tool with a wooden thread spool and headless brads. I don’t remember the hook, but I suspect it was made from a piece of wire hanger.

The larger ID reactors that Pickering Laboratories offers are made like stockings. The mandrill has four pins. The misnomer is that our literature calls them “knitted” because that is the most common description in print and conversation in our industry. Describing them properly would only create a lot of idle questions. The necessity for the crocheting is to minimize band spreading. The post-column reaction occurs after the separation is complete, so when the peaks enter the reactor they are as far apart as they are going to be. The torturous path eliminates the band spreading of longitudinal mixing by replacing it with radial mixing.

Pickering Laboratories to introduce new and updated products and applications at PITTCON

2011-02-11T14:00:00.000-08:00

By Mike Gottschalk

PITTCON 2011 - Atlanta, Georgia:

Pickering Laboratories is building on the success of the LCTech product line with the introduction of the new GPC VARIO III, a fast and flexible instrument for Gel permeation chromatography (GPC) and upgradeable for automated sample preparation using SPE.

The GPC VARIO III is completely re-designed to optimize every component of XYZ Robot arm technology for faster processing and feature-rich flexibility. Highlighted is the innovative arm technology that handles the processing of samples.

The integrated software allows for easy setup with drag and drop icons for even complex multi-step processes for volumes of 1mL to 1Liter . The modular design enables processing scalability and flexibility to standard columns, bottle and vial sizes.

Another GPC instrument, GPC Quattro will be shown. This popular 4 column GPC is designed for concurrent operation of 4 columns providing the faster throughput and flexible programming.

For Post-Column applications the new Pinnacle PCX Sigma series instrument featuring faster Amino Acid Analysis and new software features is being introduced as an update to our line of derivatization instruments. The small yet powerful UVE photochemical reactor for Aflatoxin analysis will also be shown.

Pickering Laboratories will be introducing new post-column methods for Hexavalent Chromium (Chrom-6), Aflatoxin in herbal products. As part of the AFFCO and AOAC lab committee collaboration Pickering Labs developed our new method for the effective analysis of Sugars in feeds with existing and additive sugars.

With increasing interest in Chromium 6 in drinking water this year, Pickering Laboratories is publishing an updated Chromium 6 method demonstrating definitive yet easy analysis.

Pickering Lab’s technical liaison director Laszlo Torma is a member of the American Herbal Products Association (AHPA) laboratory committee. The work of the committee and collaborating with AOAC has resulted in new methods for analysis of Mycotoxins in many herbal products including ginger, ginseng, Echinacea.

Come to Booth 1767 at Pittcon to see and hear about the exciting work going on at Pickering Laboratories.

Pickering Laboratories Introduces Key Products to Herbal Supplements Market

2010-11-08T15:37:00.000-08:00

By Mike Gottschalk

The Supplyside West Conference in Las Vegas, Nevada October 19-23, is a very important Herbal Supplement Industry event. It provides important educational and networking opportunities to this $29 billion market. Since the FDA sent out required current good manufacturing practices (cGMP) in 2007, the Herbal Supplement producers are working to meet the new requirements before the FDA audits. These regulations are intended to insure the quality, purity and safety of the Herbal Supplement products available today. Pickering Laboratories had a booth at the show to assist the producers and laboratories with the instrumentation, chemistry, methods, and support for the analysis and clean-up of samples for Amino Acids, Aflatoxins, Carbamate pesticides, Glyphosate Herbicides, and 23 other methods.

Click on the links to see our Latest Method Abstracts, introduced at the show:
1) MA 215: Clean-up and Determination of Alfatoxins in Peanuts and Peanut Butter

2) MA 218: Clean-up and Analysis of Aflatoxins and Ochratoxin A in Herbs and Spices

The annual meeting of the AOAC International in Orlando, Florida on September 20-25, also had a strong emphasis on Herbal Supplements testing. The AOAC organization is central to FDA efforts to provide analytical structure to testing methods for this newly regulated industry. Pickering Laboratories participated in the AOAC sponsored Single Laboratory Validation of Multi-residue Mycotoxin Analysis in Corn. For this work, Pickering Laboratories was awarded the “Single Lab Validation of the Year”. This pivotal work in the analysis of Mycotoxins continues in Herbal Supplements as well as agricultural products.

Send us an email to support@pickeringlabs.com to request a copy of our poster: “Clean-up and Determination of Alfatoxins in Peanuts and Peanut” from the AOAC show.

Our next show is Pittcon 2011 on March 13-18 in Atlanta, Georgia.

See you there!

ACIL Annual Meeting, San Diego, California

2010-11-05T14:00:00.000-07:00

The American Council of Independent Laboratories (ACIL) show in San Diego, California on October 9-12, was a new opportunity for Pickering Laboratories to introduce ourselves to the principals of these independent laboratories during their annual networking meeting.

The meeting was a great opportunity to visit with existing customers, but also to make new contacts in the Environmental testing industry. At the meeting we had information on our mainstay applications and also presented our new GPC Cleanup Instruments and other new products to prospective customers.

Rebecca Smith reports that the meeting was a success in terms of networking, scientific and educational talks.

Our new Gel Permeation Chromatography (GPC) line continues to perform well. We have both automated and manual GPC cleanup systems and we also have systems that include concentration & solvent exchange. Sample cleanup using GPC is especially useful for fatty matrices, but also perfect for vegetable matter and spices, as well as soil & waste water.

Our next show is Pittcon 2011 on March 13-18 in Atlanta, Georgia.

You can read more about the ACIL at their website: www.acil.org

NIST/NIH Dietary Supplements Quality Assurance Program Workshop

2010-11-05T13:00:00.000-07:00

By Wendy Rasmussen

Natural products industry is under increasing pressure to increase analytical testing of raw materials and finished products. This not only includes contaminants (such as heavy metals, pesticides, and mycotoxins), but also identification and nutrition labeling.

The DSHEA (Dietary Supplement Health & Education Act) created the Office of Dietary Supplements in 2002. The Dietary Supplement Quality Assurance Program, is a collaboration between the NIH's ODS and the NIST. The program consists of Exercises in which several samples are sent out to participating labs throughout the year, and the results are then analyzed in a report. This is a completely voluntary exercise, and it gives a laboratory a great opportunity to check their results against a certified value and also against those of their peers. Even though participation is not part of a regulatory certification, the choice to participate greatly increases confidence and credibility.

And since the NIST are working closely with the NIH's Office of Dietary Supplements, I asked the ODS if they could describe the relationship:

"The DSQAP is part of the ODS Analytical Methods and Reference Materials Program. We’ve been funding them to produce supplement matrix reference materials since about 2002. A few years ago, we discovered that NIST had QA programs for other commodities, and we thought that a dietary supplement program would complement the reference materials already being produced and added funding to the inter agency agreement we already had in place with them. While we are a funder for the NIST program, it could be described as more of a collaboration than a strict funding relationship. NIST pretty much matches our funding with internal funding. "

The NIST website http://www.nist.gov/mml/analytical/dsqaprogram.cfm also does a good job of describing the program in more detail. If you would like to participate in the DSLQAP, they would love to have more participants, just send them an email to the address on the above webpage.

This past September, the NIST hosted a workshop in Bethesda, MD which brought together participants from several sample exercises. This was a great opportunity for labs and companies to come together to discuss and learn. Pickering Laboratories participated in the most recent Exercises by analyzing Aflatoxin in peanut samples.

We used our Photochemical reactor (UVE) and our AflaCLEAN Immunoaffinity columns for the sample cleanup. The results can be found on our new application note and in a presentation given to the group at the workshop.

We gave a quick presentation to the group on Thursday morning, detailing our method and results. We would love to share our talk titled simply "Aflatoxin Analysis". Just send us an email to support@pickeringlabs.com and we'll send you a copy!

The Photochemical derivatization of Aflatoxins has been shown to be a very rugged and sensitive method for analyzing low-levels of the toxins. And the Immunoaffinity columns can be used to cleanup a very wide variety of sample matrices. Indeed, there have been several publications showing the results using Photochemical Derivatization.

We are now distributing Mycotoxin Immunoaffinity products for Ochratoxin and Aflatoxin. The performance and batch-to-batch reproducibility of the columns is exceptional and far exceeds that of other manufacturers. The columns can be used for any matrix, from wine and juice, to nuts and grains, to herbs and spices. Contact Sales for more information.

Definition of Acronyms:
NIH - National Institutes of Health
ODS - Office of Dietary Supplements, part of NIH
NIST - National Institute of Standards and Technology
DSLQAP - Dietary Supplement Laboratory Quality Assurance Program, formed by the ODS in collaboration with NIST
AHPA - American Herbal Products Association
AOAC - Association of Analytical Chemists

Laszlo Torma has also contributed a very nice piece about our Membership in the AHPA on our blog.

Special Alert: American Ale Takes 1st Place

2010-11-05T12:00:00.000-07:00

In keeping with our company’s motto “Guaranteed Chemistry” our resident Technical Support Chemist, David Mazawa, brewed an American Pale Ale which won him the 1st place in the 2010 Reddit Homebrew competition. His beer was described as a nicely hopped beer that went well with a hot day.
So if you're calling in with questions and you talk to David, be sure to Congratulate him. Who knows? If he's feeling generous, he may share a bottle...

Photo of the 1st Place Trophy

Notice of Backwards Compatible Board for Pinnacle Users

2010-11-05T11:00:00.000-07:00

The new Sigma Series Pinnacle PCX has rolled out with a lot of new features. A new Electronic Control Board is included to support many of these features. You will notice that the new boards are blue in color and have a USB connection replacing the RS-232 connection.

Customers with the older Delta Series Pinnacle PCX will have to purchase a backwards compatible board if they experience a board failure.

The backwards compatible board will have a slightly different relay connector to fit properly in the old chassis. The backwards compatible boards will have the most recent firmware, software, and also include a USB cable. Make sure to have your Pinnacle PCX Serial Number handy when ordering a replacement board.

Part Number	Description	Serial Numbers
1500-1507	Replacement board for Delta Series Pinnacle PCX	before 0510308
1500-1508	Replacement board for the Sigma Series Pinnacle PCX	after 0610300

David Mazawa

Technical Support Chemist
David.mazawa@pickeringlabs.com
(650)694-6700 x710

Polymers: To Eat Or Not To Eat

2010-11-05T10:00:00.000-07:00

By Michael Pickering

The stationary phase in our amino acid columns is a polymer made of two monomers: styrene (vinyl benzene) and 1,4-divinylbenzene. If only styrene were used, the result is a thermoplastic substance, which is solid (glassy state) at room temperature, but flows if heated above its melting point. The divinylbenzene acts as a cross-linker by covalently connecting the linear polymer strands. The result is a spherical bead described as macro reticular, or big and tangled. Imagine a ball of string with some small strings knotted between two proximal intervals: polyethylene with one benzene moiety per unit. The mass ratio of cross-linker can be varied depending on the ultimate use of the bead. In our case, 8-12% is ideal.

At this stage, the bead is very hydrophobic. The final synthetic step to create a cation-exchange resin is to completely sulfonate the available phenyl rings. This provides the cationic-exchange functionality and allows for water to swell the bead, resulting in an accessible interior.

Mass transfer is osmotically controlled so the (w/w%) water in the interior is dependent on the cation in the mobile phase, i.e. Na (45%), Li (50%). For the same reason, higher normalities in the mobile phase also shrink the resin. The same hydrophobic polymer can be functionalized to create an anion-exchange phase (P-NR3X), a heavy metal scavenger (P-SH), et. al.

With a different set of synthons, chefs and mixologists worldwide are creating exciting and fun palate sensations. These edible experiments and discoveries are grouped under the umbrella of “Molecular Gastromy.”

One popular and successful idea produces hollow beads where the interior can capture and hold savory or sweet flavors and alcoholic beverages. The polymer employed is a common food thickener called sodium alginate, which is extracted from brown kelp and is water soluble. It is a linear polysaccharide with one carboxylate per unit. A bead spontaneously gathers on the surface when the sodium alginate solution is dripped into a solution of CaCl2.

.

The divalent Ca++ ion acts as the cross-linker. Since it is not a covalent bond, merely ionicly linked by the Calcium, a skin forms as a flexible bubble rather than as a solid bead.

The captured ingredients, either as a slurry or as a solution, are added to the gelatinous sodium alginate solution. The bead size is determined by drop size. The most popular size now being served is usually described as caviar in appearance, but I have seen pictures of beads larger than a softball. The harvested beads are robust and so may be washed, dried, and stored. People who have experienced them describe it as a thrilling sensation when the flavor beads burst in their mouth.

The most recent news I’ve heard about edible structures was in the New York Times (September 7, 2010, page D3). Not spheres, but clear nano-crystalline cubes are made by cross-linking a cyclic polysaccharide, a monovalent metal cation, and ethanol. The nano-cubes cluster to form millimeter-scale cubes. Unlike the beads, however, the cubes require one week to harvest. The good news is that they require no attention during the wait. Similarly to the beads, all ingredients are readily available in food grade quality. The N.Y. Times article was reporting on the work of Professor J. Fraser Stoddart of Northwestern University. The paper is to be published in the journal Angewandte Chemie this November.

The nano-crystals fall under a class of structures called metal-organic frameworks (MOFs) which are porous but rigid. The holding capacity is greater than half the volume. And as with the beads, the cubes can capture the solution they are formed in. Although in this particular case, the cubes do not form in acidic solutions.

Materials and Methods

Beads, sweet:
Mix:
1 cup pure water (tap water contains too much calcium)
¾ tsp sodium alginate
¼ cup any syrup, stir in last

Note: The polysaccharide dissolves slowly. It can be hastened by blending but then must be left to stand several hours for the bubbles to evanesce.

In the bead size desired, drop this solution into the following one.
Mix:
2 ¼ cups water
¾ tsp CaCl2

Cubes:
The following is adapted from the N.Y. Times article taken from the abstract about the Angewandte Chemie article.

A: 1 cup 190 proof ethanol

B: 2 ½ cups water
1 tsp gamma-cyclodextrin
1 tsp potassium benzoate
the flavor ingredient (Note: no alcohol or acids)
C: Sealable, airtight container, to scale

Assemble and set aside for at least one week. The cubes will form in the B solution and may be harvested and crunched.

Photos Credits:
Dessert and Cocktails photos taken by Amanda Lucier, of The Virginian-Pilot. Taken from HamptonRoads.com website

Sodium Calcinate "Caviar" photo taken from an article by Martin Lersch for Khymos

Chromatography Quiz No. 5 and Results from Quiz 4

2010-11-05T09:00:00.000-07:00

Chromatography Quiz #4 Results
Congratulations to the grand prize winner of our last newsletter’s Amino Acid Chromatography Quiz: Matthew Hartz from Underwriters Laboratories!

He has won, and will shortly be receiving, a $150 gift card to Dick’s Sporting Goods! Additionally, for this quiz our other participants will each be receiving a $20 gift card from Amazon.com. Thank you all for your submissions!

The correct answer for the modified Amino Acid chromatogram: the guard column has been contaminated with proteins. The dirty guard causes poor peak shape and loss of resolution on key pairs of amino acids. Replacing the guard will restore the chromatography.

Thank you!
Pickering Labs

Chromatography Quiz #5:

Identify the error made when running the Carbamates chromatogram below and win a prize! Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by December 15th in order to win. You will receive email confirmation that your submission has been received. The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Carbamate Analysis for US EPA Method 531.1

Pickering Standard: 1700-0063 Carbamate Test Mixture, 2.5 µg/mL, 10 µL injection

Pickering Column: 1846250 Carbamate Column, C18, 4.6 x 250 mm

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 42 °C

Flow rate: 1 mL/min

Eluent Gradient:

TIME	WATER	MeOH %
0	85	15
1	85	15
44	25	75
44.1	0	100
49	0	100
49.1	85	15
57	85	15

Post-column conditions:
Reagent 1: Hydrolysis reagent CB130

Reagent 2: 100 mg of OPA, 2 g Thiofluor™ in 950 mL of CB910

Reactor 1: 100 °C, 0.5 mL

Reactor 2: ambient. 0.1 mL

Reagent flow rates: 0.3 mL/min

Detection: Fluorometer ex 330 nm, em 465 nm

For an example of a Good Carbamate Chromatogram, Click Here

Mouse Out! Chemistry In. Updates in Paralytic Shellfish Toxins

2010-08-11T17:30:00.000-07:00

By Saji George

The paralytic shellfish toxins are a group of 18 secondary metabolites deposited in bivalve mollusks by dinoflagelates. Dinoflagelates blooms are seasonal, occurring during warm months. Since it is unpredictable whether an infestation will occur, the shellfish population should be regularly monitored for toxins. Ingestion of contaminated shellfish can lead to paralytic shellfish poisoning; a life-threatening illness.

Mouse bioassay is the official method of AOAC International, but the drawbacks associated with this method have led to exploration of chemical methods. The most common HPLC post-column method is to oxidize the separated toxins under alkaline conditions to a fluorescent compound. Sullivan et al. used this method to determine the gonyautoxins 1-6 (GTX1-6), saxitoxin (STX) and neosaxitoxin (neoSTX) but not the N-sulfocarbamoyl-11-hydroxysulfate toxins (C1-C4). Oshima et al. modified this method to determine the 3 toxin groups separately using isocratic elution with 3 different mobile phases. Further improvement by Jeffery van de Riet of the Canadian Food inspection Agency (CFIA) in collaboration with National Research Council Canada (CNRC) has led to a shorter analysis time to determine the 3 groups of toxins using step gradient and a switching valve.

Marine Biotoxins were a hot topic at the recent Pacific Northwest AOAC meeting in Tacoma, WA. According to Jeff, this method is also the topic of an AOAC interlaboratory study (currently underway) and has already been approved by the Shellfish Sanitation Program (NSSP) at the single laboratory validation (SLV) stage for use in the United States as a screening (type IV) method in shellfish monitoring. If approved by AOAC following the interlaboratory study as an official method of analysis (OMA) for shellfish, the method will then be eligible for consideration as a type II reference method by Codex Alimentarius This will also effectively end the use of mouse bioassays in shellfish monitoring within Canada.

This method was presented at the Annual Meeting of the Pacific NW Section, held at the University of Puget Sound (UPS) in Tacoma, which offered extensive laboratory training workshops this past June.

NEW Amino Acid method: Oxidized Feeds in 30 minutes

2010-08-11T17:00:00.000-07:00

Dear Valued Customer,
We are pleased to announce the new 30 minutes Oxidized Feed method. This method uses the new fast sodium column 1154110T and utilizes the column temperature gradient with the Pinnacle PCX. Because this method uses a column temperature gradient, it is important to note that the method is not compatible for Vector or PCX5200 users.

Peak Identification
1. Cysteic Acid
2. Methionine Sulfone
3. Aspartic Acid
4. Threonine
5. Serine
6. Glutamic Acid
7. Proline
8. Glycine
9. Alanine
10. Valine
11. Isoleucine
12. Leucine
13. Phenylalanine
14. Lysine
15. Histidine
16. Ammonia
17. Arginine

Kits are available and include the following:

0352-0020 30 minute Oxidized Feed Kit – T100C
1154110T Qty 1 Column, Fast Sodium 4.6x110mm (includes 1700-070 Test Mix)
1700-3102 Qty 1 Kit, GARD Holder and 2 Cation GARD
1700-0155 Qty 1 Cal Standard, Feed Hydrolysate
Na220 Qty 1 Sodium Diluent, pH 2.20 4x250mL
Na270 Qty 1 Sodium Eluent, pH 2.80 4x950mL
Na740 Qty 1 Sodium Eluent, pH 7.40 4x950mL
RG011 Qty 1 Sodium Column Regenerant 4x950mL
T100C Qty 1 TRIONE, Ninhydrin Reagent 4x950mL

0352-0021 30 minute Oxidized Feed Kit – T200
1154110T Qty 1 Column, Fast Sodium 4.6x110mm (includes 1700-070 Test Mix)
1700-3102 Qty 1 Kit, GARD Holder and 2 Cation GARD
1700-0155 Qty 1 Cal Standard, Feed Hydrolysate
Na220 Qty 1 Sodium Diluent, pH 2.20 4x250mL
Na270 Qty 1 Sodium Eluent, pH 2.80 4x950mL
Na740 Qty 1 Sodium Eluent, pH 7.40 4x950mL
RG011 Qty 1 Sodium Column Regenerant 4x950mL
T200 Qty 1 TRIONE, Ninhydrin Reagent 2 part

0352-0022 30 minute Oxidized Feed Kit – O120
1154110T Qty 1 Column, Fast Sodium 4.6x110mm (includes 1700-070 Test Mix)
1700-3102 Qty 1 Kit, GARD Holder and 2 Cation GARD
1700-0155 Qty 1 Cal Standard, Feed Hydrolysate
Na220 Qty 1 Sodium Diluent, pH 2.20 4x250mL
Na270 Qty 1 Sodium Eluent, pH 2.80 4x950mL
Na740 Qty 1 Sodium Eluent, pH 7.40 4x950mL
RG011 Qty 1 Sodium Column Regenerant 4x950mL
O120 Qty 1 OPA, 5g
OD104 Qty 1 OPA Diluent 4x950mL
3700-2000 Qty 2 Thiofluor, 10g

Sincerely,

David Mazawa
Technical Support Chemist
Pickering Laboratories, Inc.
1280 Space Park Way
Mountain View, California 94043 USA
Phone: 650-694-6700, ext. 710
Toll Free: 800-654-3330, ext. 710
http://pickeringlabs.blogspot.com/

A Brief Report on the European Pesticide Residue Workshop in Strasbourg, France

2010-08-11T16:00:00.000-07:00

By Laszlo Torma
The 8th European Pesticide Residue Workshop (EPRW 2010) was held in Strasbourg, FR on June 20-24, 2010. As usual, EPRW 2010 was a great success and it was a productive and worthwhile meeting.

First, I would like to share a little information about Strasbourg. The city is the capital of region which was part of the Holy Roman Empire and later annexed by France. In more recent history, Alsace changed hands four times between France and Germany in 75 years. Although the historical language of Alsace is Alsatian, a Germanic language, today most Alsatians speak French and only about 40% of the adult population is fluent in Alsatians. Strasbourg is the seat of several European Institution such as the European Parliament, the Council of Europe (with its European Court of Human Rights) and others.

Back to the meeting; EPRW meets every 2 years and in my opinion, it gets better and larger each time. In spite of the global economic down turn, there were about 500 participant and 30 exhibitors representing all the continents. The Scientific Organizing Committee has assembled a great program, including 29 oral presentations, more than 200 posters and a number of vendor sessions. Scientists from all over the world were represented and participated in various discussions to exchange new ideas in the area of pesticide regulations, residue monitoring, new analytical techniques and methodology. I enjoyed the high quality posters that have been presented. These posters demonstrated the desire of many scientists to share their practical and fundamental know how with the participant during the workshop. And last but certainly not least, I had the opportunity to work with our European distributor, LCTech from Germany and to visit with our mutual customers.

Pickering Laboratories at the Florida Pesticide Residue Workshop

2010-08-11T15:00:00.000-07:00

By Wendy Rasmussen

Last month we participated in the Florida Pesticide Residue Workshop, held in St. Pete's Beach in Florida from July 18-21. It was a very interesting meeting from many aspects: talks, posters, mix of attendees and exhibitors, current topics. There were talks on mycotoxins and veterinary drugs as well as policy and risk assessment.

Pickering presented a Vendor breakfast session on Wednesday July 21, titled "Keys to an Analytical Method: Focus on Mycotoxins" We decided to highlight our Mycotoxin analysis product line which we are distributing from our German partners, LCTech GmbH.

The weather was unusually cool for Florida in July, hovering in the mid-90s (35°C). The water temperature in the Gulf was surprisingly refreshing at "only" 89°F (32°C). The usual thunderstorms were present, although fewer in number. Mother Nature provided us with some very impressive lightning storms just off shore in the evenings.

The meeting was much larger this year, both in terms of attendance and exhibitors. Not only were there more attendees, but there was a very large number of First-time attendees, as well as a greater contingency of international attendees from Europe, Asia, Australia, and South America. There were 226 attendees and 25 exhibiting companies.

One of the hot topics of discussion at the meeting was the Deepwater Horizon spill in the Gulf. No oil has reached that part of the Florida coast, and so the beaches were open, but inside there was much debate about the testing of the seafood for PAHs, the cleanup of the spill, and the environmental impact, both on marine human life. There was a great deal of discussion about using the NOAA method for PAHs (which involves GPC Cleanup), as well as testing for the alkyl homologs present in the oil and potential screening methods to speed up the analysis time.

GPC cleanup remains very effective at cleaning up fatty and complex matrices, and it's still part of the official methods. GPC Quattro would be an excellent choice for this. With 4 individual channels, each with their own pump and lines, and with rugged, easily repackable columns, a lab would get 4 times the productivity of a single column system: GPC Quattro

Links for info on the Gulf:
There is an abundance of websites, news, and general information about the oil spill. Here are a few links I found to be interesting:

The FDA has approved an HPLC-FLD screening method for the PAHs, which will still need confirmatory testing, but this will decrease the initial testing time down from 4-5 days to 48hrs.
For FDA's latest updates: http://www.fda.gov/Food/ucm210970.htm

It's been proposed that we should be looking at Alkyl Homologs of PAHs. Ed Overton gives a pretty good overview of these compounds and the composition of oil spills in general: Overton perspective

Restek recently analyzed some of the oil via GCxGC-TOFMS: ChromaBLOGraphy

(This is not meant to be a comprehensive list, nor is there any endorsement intended or implied)

Del Rio, Texas

2010-08-11T14:00:00.000-07:00

By Michael Pickering

While in graduate school at the Oregon Graduate Center, a private technical school with no undergraduate program, my advisor, G. Doyle Daves was awarded a grant to elucidate plant toxins. The plant, Karwinskia humboldtiana, known by Texas ranchers as “coyotillo,” has toxins in its ball-bearing like seed that cause rising paralysis
from the hind quarters to eventual death. Although human poisoning is extremely rare, the oldest documented poisoning is a conquistador soldier who was hungry and had strong jaws to crush the seeds.

Since I was already into plant secondary metabolites due to my M.S. research, I eagerly volunteered to go to Del Rio for the first harvest. Del Rio is a small town on the Rio Grande about an hour car drive southwest of the San Antonio airport. A bridge walk across the river gets you into the thriving village (as in mostly well-maintained dirt roads) of Ciudad Acuña, Mexico. It was attractive and friendly. Each morning I would walk over to get a pan dulce for my morning coffee; I then had lunch in Del Rio and then back to Mexico for dinner. The most striking feature of Acuña is a thin, Eiffel-like 300-foot metal broadcasting antenna stand. This is XERB’s continent-spanning 250,000 watt broadcasting transmitter - illegal a few feet from where it stands, made famous by Wolfman Jack. (¿Te acuerdas de una época en que se pensaba que los Americanos eran ingeniosos solucionarios de problemas?)

The regional climate is semi-arid. The topography is the largest area of flat ground I have ever seen. The surface appeared to be very small gravel or coarse sand. Flora is sparse. The largest visible plant is the coyotillo at 4-6 feet, which evenly dotted the available view. The only other noticeable plant was a 2-inch very sparse dry grass.

Permission to collect plant material was arranged by the USDA soil conservationists who had an office in town. Each day they would introduce me to the host ranch owners where I was going to collect. Much friendly teasing about this young Oregonian’s coon-like behavior, taking poison berries home, was endured during introductions. The ranches were 100,000+ acres of cattle and sheep. The ranchers’ grandfathers had been shepherds; their fathers became cattlemen when synthetics undermined the market for wool and cotton. The source of livestock was Mexico via rail. The cattle looked like starving animals when they arrived to be put to graze and become normal looking animals when they were wholesaled to feed lots in the northern states. That sparse grass has to be high in protein – not only do the livestock prosper, the land teems with deer and other vegetarian wildlife. Because of the size of the ranches, an important part of their revenue is selling hunting packages to corporations in Louisiana and Texas. After all, they have well-maintained bunkhouses and appropriately sized kitchens and dining areas. The locals don’t hunt deer; they all have a pen of small ‘Mexican” goats at home for the table.

Still in the field but back to the berry: it is the color of a small dark blueberry, with a thin coating of flesh over a spherical seed. The ring-tailed raccoon knows not to crush the seeds when feeding and thus is the planter that adorns the landscape with seeds and appropriate fertilizer. The leaves and stems are non-toxic and as such are reliable and bountiful resources for browsers.

Unfortunately my visit there followed a major drought. The plants were suffering since rain is the only habitat irrigation. Visually, they sorted into two categories: 1) bushes with sparse berries and almost no leaves, and 2) lush, green bushes with no berries. We knew that the toxin was only in the hard seed, which was most of the mass of the berry, so we wanted to maximize the collection of the berries.

The collection period was five days. The plan was to collect berries three to four days, and to collect leaves otherwise. In anticipation of leaf collection, I went to a local coffee roaster and bought some burlap bean shipping bags. Also on hand were a curved upholstery needle, appropriate twine, and proper shipping tags for rail cargo.

Each morning I would start harvesting berries until the territory got so big, i.e. distance from the car, that I would then begin stuffing leaves into bags, i.e. very little walking. Many stomped bags of leaves were shipped by rail, and the drought-impacted, meager berry harvest was no more than a carry-on for the flight home.

Epilogue:
When the ranchers brought in 100 head of cattle from Mexico, they lost one to two steers to the toxin. When they brought in 100 sheep, they lost two to four. The toxins are a group of four red, closely related compounds. For more information, see Doyle’s paper in the Journal of the American Chemical Society: “Toxins Causing Noninflammatory Paralytic Neuronopathy, Isolation and Structure Elucidation,” August 1975, pages 4985-4990.

Editor's Note:
I was curious as to the location and look of Del Rio and Ciudad Acuña. For anybody interested in Geography, check out these links:

Photos from the Universidad Autonoma de Ciudad Juarez:
http://www.mexicoenfotos.com/?seccion=2&menu=ft&cat=Coahuila&subcat=Ciudad%20Acu%F1a&len=en

And also from the TX Dept of Transportation: http://www.txdot.gov/project_information/projects/border_crossing/delrio.htm

Karwinskiana photo: http://www.swsbm.com/Images/New2005/Karwinskia_humboldtiana-2.jpg

Sigma Series Pinnacle Control Software

2010-08-11T13:00:00.000-07:00

By David Mazawa

You may have noticed something different about the Pinnacle. That is because the new Pinnacle Sigma series started shipping out mid June. Some improvements include fully ROHS compliant components, power cooling, USB connection, log file expansion, PEEK front end for reagent pumps, and lighter parts. It is important to note that new Pinnacle Control Software has been updated to support some of the new features.

Before installing the new software, make sure to export your Methods and Sequences. This will create a back up of all your Methods and Sequences. It is possible that your old Methods and Sequences will not transfer after installation of the new software. If this is the case, import your backup file.

You will notice that you need to install drivers with the new Pinnacle Control Software. The drivers are required to communicate with the USB port of the Sigma Series Pinnacle. We have replaced the RS-232 connection with USB. Make sure you follow the instructions included with the Pinnacle Control Software Installation CD.

After you have installed the new Pinnacle Control Software, make sure you double check the instrument configuration. It is possible that the default configuration of “No Connection to HPLC” will be loaded. After your methods and sequences are imported and your configuration is correct, you are ready to use the new Pinnacle Control Software.

The new Pinnacle Control Software includes pressure tests. These pressure tests should be used after a PM or when pump or valve seals have been replaced. You can pressure test individual pumps or pressure test the entire system. Make sure to follow the instructions presented by the Pinnacle Control Software. These tests can be found under Instrument then Maintenance.

The Pinnacle Control Software has expanded the log files. An extra day of data is collected and more detail is collected per log file. This will greatly help Pickering Laboratories Technical Support troubleshoot any problems you may have in the future.

Please email or call Pickering Laboratories Support with any questions.

support@pickeringlabs.com / (650) 694-7700 / (800) 654-3330

David Mazawa

Technical Support Chemist

david.mazawa@pickeringlabs.com

(650) 694-6700 x 710

Pickering Expands into the OEM Pump Market!

2010-08-11T12:00:00.000-07:00

By Mike Gottschalk

Pickering Laboratories has made available the Pinnacle PCX syringe pump for OEM applications. The pump is the heart of the successful Pinnacle PCX instrument. “This syringe pump’s service record and performance are truly remarkable. We designed it for long life and exacting specifications; now six years later and a thousand working units in the field we are very confident this pump will be successful in other applications”, said Michael Pickering.

When the Pinnacle PCX was designed a suitable pump could not be found so the design of a perfect syringe pump was begun. The results are a very precise, pulse free, and inert pump rugged and reliable enough for our analytical chemical instrument. The current specifications are an alumina ceramic cylinder with PEEK for inert flow path, a 70 ml volume cylinder, low flow rates range of 30µL/min - 1500µL/min, at pressures of 300 – 500 psi.

Of all the syringe pumps available today our pump is unique in its pressure range and absolute inert materials. These features will be useful in industrial fluid delivery applications and we will begin marketing to the large industrial equipment market. We have engaged with Globalspec to help us introduce this product. Globalspec is the leading specialized vertical search company serving the engineering, manufacturing and related scientific and technical market segments.

For more information on the OEM Syringe pump:
www.pickeringlabs.com/OEM_Pump.pdf

Chromatography Quiz No. 4

2010-08-11T11:00:00.000-07:00

Chromatography Quiz #3 Results
Congratulations to the grand prize winners of our last newsletter’s Glyphosate Chromatography Quiz: Jim Balk from Nebraska DHHS Public Health Environmental Laboratory, Matthew Hartz and Keena Njoroge from Underwriters Laboratories, and Narjes Ghafoori from the County of Los Angeles Environmental Toxicology Laboratory! They have won, and will shortly be receiving from Apple.com, a new iPod Shuffle! Additionally, for this third quiz all of our participants will be receiving a $10 gift card from iTunes. Thank you all for your submissions!

The correct answer for the modified Glyphosate chromatogram: the Glyphosate ‘doublet’ is caused by injecting a sample at basic pH. An improperly buffered sample extract at a large injection volume will not mix with the mobile phase sufficiently to create the acidic pH necessary for Glyphosate to be at the proper single charge state, impacting the interaction between Glyphosate and the active sites on the column resin. Adding a couple drops of Restore ^TM(pH 1.3) to the sample before injection will eliminate the ‘doublet’ and return proper peak shape.
Thank you!
Pickering Labs

Chromatography Quiz #4:
Identify the error made when running the Amino Acids chromatogram below and win a prize! Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by September 30th in order to win. You will receive email confirmation when your submission is received, and the troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Amino Acid Analysis of Physiological Fluids
Pickering Standard: 011006P Native Sample Standard 0.25 µmole/mL, 10 µL injection
Pickering Column: 0354100T High Efficiency Lithium Cation-exchange Column, 4.0 x 100 mm
Pickering Guard Column: 0352020, 2.0 X 20 mm

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 37 °C
Flow rate: 0.35 mL/min

Eluent Gradient:

TIME....Li275%.......Li750%.......RG003%
0............100...............0..................0
12..........100...............0..................0
48...........65................35................0
90...........0..................100..............0
95...........0..................100..............0
120.........0...................94...............6
122.........0...................94...............6
122.1.....100...............0..................0
140........100...............0..................0

Post-column conditions for amino acid analysis:
Reagent 1: Trione

Reactor 1: 130 °C, 0.5 mL
Reagent flow rate: 0.3 mL/min
Detection: UV-Vis Detector: 570 nm for primary amino acids, 440 nm for secondary amino acids

You can find an example of a good chromatogram on our website. Either click on the link, or go to www.pickeringlabs.com

RESULTS: Chromatography Quiz Number 2 (Amino Acids)

2010-06-29T13:49:00.000-07:00

Congratulations to the Grand Prize Winner of our Newsletter's Amino Acid Chromatography Quiz: Mary Barnes from Marin General Hospital!

She has won, and will shortly be receiving from Amazon.com, a new Kindle Wireless Reading Device and leather book cover!

The correct answer for the modified Amino Acid chromatogram: we did not allow the instrument proper equilibration. The column was equilibrated using a mixture of Li275 and Li750 buffers, and the higher starting pH caused peaks in the beginning of the chromatogram to come too early and co-elute. A similar chromatogram can also be caused by a higher pH of the sample or first buffer or an insufficient equilibration time between runs.

Also, we are extending our deadline for the Chromatography Quiz Number 3 (Glyphosate) until July 15th - so please get your entries in! Rebecca will accept submissions to rlsmith@pickeringlabs.com and confirm via email that she has received your answer.

Thank you and Good Luck!
The Pickering Labs Team

(Kindle image copyright Amazon.com)

Chromatography Quiz Number 3

2010-05-24T14:41:00.000-07:00

Reminder: Please resubmit your answers to last quarter’s Amino Acid Chromatography Quiz by June 1st to be eligible for a prize. You can find that quiz located on our Blog: http://pickeringlabs.blogspot.com/2010/01/chromatography-quiz-no-2.html

Chromatography Quiz #3
Identify the error made when running the Glyphosate chromatogram below and win a prize! Simply email your answer and your full contact information to Rebecca at rlsmith@pickeringlabs.com by July 1st in order to win. You will receive email confirmation when your submission is received, and the troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Glyphosate Analysis for US EPA Method 547
Normal Operating Conditions: (for reference only, changes may be reflected in chromatogram)

Customer’s Glyphosate Standard: 25 ppb, 100 µL injection

Pickering Column: 1954150 Cation-exchange Column for Glyphosate Analysis, 4 x 150 mm

Column Temperature: 55 °C
Flow rate: 0.4 mL/min

Eluent Gradient:

Post-column conditions for pesticide analysis:
Reagent 1: Oxidizing reagent – 100uL of 5% Sodium Hypochlorite in 950mL of GA116
Reagent 2: 100 mg of OPA, 2 g Thiofluor™ in 950 mL of GA104

Reactor 1: 36 °C, 0.5 mL

Reactor 2: ambient. 0.1 mL
Reagent flow rates: 0.3 mL/min

Detection: Fluorometer ex 330 nm, em 465 nm

Please Re-submit Your Answers to Amino Acid Quiz (No. 2)

2010-05-24T14:38:00.000-07:00

Due to an unfortunate set of circumstances, all submitted answers to the previous Chromatography Quiz on Amino Acid Analysis have been lost. We sincerely apologize for the inconvenience to everyone who submitted an answer, and ask for all entries to be resubmitted. As we genuinely regret our technical difficulties, Rebecca will be sending prizes to all submissions, and grand prizes to everyone with the correct answer. Please resend your email, or resubmit your answer to rlsmith@pickeringlabs.com. Rebecca will send you confirmation via email that she has received your submission. All entries will be reviewed on June 11^th, and prizes will be sent at that time. You can review the quiz at: http://pickeringlabs.blogspot.com/2010/01/chromatography-quiz-no-2.html. Again, our apologies, and if you have any questions please contact Wendy or Rebecca at 650-694-6700.

Persistent Food Myth No. 2: Wood Bad, Plastic Good, by Michael Pickering

2010-04-27T14:17:00.001-07:00

In the early 1970’s, the USDA recommended that meat handlers such as butchers and restaurants replace wood cutting boards with plastic. The recommendation was heard as a categorical “MUST”. The assumption was that plastic cutting surfaces were less likely to transfer pathogens. No scientific evidence existed to support their opinion. Years later, researches decided to eliminate the information void by challenging the plastic and wood surfaces with E. coli O157:77, Salmonella, et al. Results indicated that new plastic and wood surfaces were comparable in cleaning and disinfecting properties.

It was discovered that bacteria were not recoverable from wood surfaces a short time after application. Bacteria did migrate into the interior of the wood, however they 1) did no multiply, 2) were not transferable, and 3) eventually died. The same bacterial concentrations on the plastic were transferable, but both surfaces were easily cleaned. Blade damaged plastic surfaces are very different.

Here is the rub: Blade damaged plastic surfaces are very different. First, plastic suffers much greater damage than wood under similar use. More importantly, damaged plastic surfaces proved difficult or impossible to decontaminate while the marred wood behaved much like new wood.

The plastic smoothness factor has reach the street according to my friend Brad Daley, Partner and General Manager at one of my favorite haunts, Cascal, a popular tapas restaurant and bar in Mountain View. He said the Health Department inspectors tell him when the plastic cutting surfaces need sanding. If the surface is visually scarred or discolored, they are told to replace or sand them; no other specifications. I’ll bet there’s an assumption hiding there. Another dangling end is that plastic surfaces vary greatly in chemical properties compared to close-grained wood, and only a few polymers have been tested.

In 1999, the USDA Meat & Poultry inspection manual (official regulations) and the US FDA Food Code (recommendations for restaurants, etc.) permitted the use of close-grained hardwoods, like maple, for cutting boards. Neither has a recommendation for the type of polymer that is acceptable nor do they specify how the plastic surfaces must be maintained. That’s a Gilda Radner “Never mind” to me.

Persistent Food Myths Part 1: MSG, The Last Sentence, by Michael Pickering

2010-04-27T14:15:00.000-07:00

The amino acids important to our well-being are a small set divided into two groups: essential and non-essential. The essential amino acids typically must be supplied in the diet. The normal body makes the non-essential amino acids from molecules harvested from the diet. Glutamic acid can be synthesized in the body and so falls into the non-essential group. It has two carboxylate groups and under physiological conditions travels as the half salt, aka, glutamate and hence the mono- in monosodium glutamate (MSG). Besides its key role in protein and energy metabolism, Glutamate serves as a neurotransmitter in the brain.

One would be hard pressed to find anything edible containing no MSG. It is so ubiquitous that it is one of the most intensely studied food ingredients. Human breast milk contains 10x more MSG than cow’s milk and nursing infants recognize its taste.

MSG has been valued in world cuisine for more than 2000 years. The unique taste was first described in print in 1866 and proposed as a distinct taste in 1908. In 2000, the L-Glutamate taste receptor was identified: taste mGluR4. This fifth taste receptor is named “umami.” When stimulated, the umami signal to the brain is extremely positive. It is variously translated from the Japanese as “yummy,” “delicious” and “wow.” Of the long list of translations, I prefer “savory.” The list of positives regarding MSG in one’s diet would be wearisome to enumerate.

So why in 1968, when Robert Ho Man Kwok, M.D. coined the phrase “Chinese restaurant syndrome” (CSR), did the rap get hung on MSG? The answer is that tough, leathery cuts of meat are often tenderized with blends containing the digestive enzyme papain. These blends do usually include MSG as a flavor enhancer. Since the tenderizing effect is shallow, it is usually only used with thinly sliced meat which is typical in a Chinese kitchen. Catabolic enzymes like papain facilitate hydrolysis of peptide bonds. The reactive stew also brews side reactions, among which is the possible conversion of the amino acid L-Histidine into histamine, which is well-known to allergy sufferers.

Can you eat parmesan cheese, peas, corn, tomatoes or spinach? MSG is everywhere, even if you don’t eat. Do you think you’re allergic to MSG? Check again, perhaps there is something else…

The Art of Noise, by Maria Ofitserova, Senior Research Chemist

2010-04-27T14:14:00.000-07:00

Baseline noise is a common and often frustrating problem in HPLC analysis. It makes integration difficult and adversely affects reproducibility and sensitivity of analysis. The most common sources of baseline noise are from pumps and bubbles in the lines or detectors. Not all noisy baselines can be easily explained but understanding common noise patterns will help you to determine what part of your system has a problem.

The Sine Wave
To observe the noise pattern you need to find a portion of the chromatogram that does not have any peaks and zoom in to look at about 5-10 min of the baseline. Baseline noise caused by reciprocating HPLC or post-column pump looks like a fairly regular sine wave. This kind of noise is usually due to old/poorly installed seals or bad piston. Ups and downs in the baseline follow flow/pressure variations as the piston moves. The period of the sine wave is different for different pumps. Measure the interval (in seconds) between the maximums of two waves to determine which pump is causing the noise. Most HPLC pumps have an interval of 6 -13 seconds. Pickering PCX5200 and Vector PCX reagent pumps have 2 sec and 4 sec intervals respectively. Pinnacle PCX contains a syringe pump which moves the piston in a single stroke hence it does not produce sine wave noise.

Most HPLC software programs record the column pressure during the analysis. It is very helpful to look at the trace to check if pressure variations have a similar pattern to your baseline noise. Pinnacle PCX users can also take advantage of log files collected by the Pickering software. Reagent pump pressure recorded in the log file helps Pickering technical support to evaluate the performance of the post-column system and determine if the syringe pump needs maintenance.

Bubbles
Baseline noise caused by bubbles consists of random spikes of varying amplitudes. Bubbles can occur in solvent lines or in the detector flow cell and are often caused by solutions outgassing. To prevent this from happening use a properly working degasser and install a backpressure regulator on the detector waste line to prevent boiling and outgassing in the heated reactor.

Detector Noise
Detector noise is always present and can be visible even on a “good” baseline if you zoom in deep enough. It is random and looks about the same throughout the chromatogram. An old detector lamp, dirt in a flow cell or problems with electronics can greatly increase noise level. If detector noise is suspected make sure the flow cell is clean and check the lamp hours. Built-in detector tests are also useful in assessing detector performance.

Shooting in the Dark
A common mistake people make when troubleshooting baseline noise in post-column applications is turning off the post-column reagent pump. Noise in the baseline is essentially variations in signal so it is proportional to background signal. Common eluants don’t fluoresce or absorb light in the visible range so when eluants alone go through the detector there is no signal and hence no noise. Post-column reagents, on the other hand, are often either colored or have background fluorescence so elevated noise caused by any part of HPLC system becomes visible. Turning off the reagent pump is akin to turning off the detector lamp and taking a shot in the dark – the noise is still there but we just can’t see it.

Let Us Help
When contacting Pickering support about elevated baseline noise please be ready to fax or e-mail your chromatogram and zoomed in portion of the baseline. For Pinnacle PCX users sending the log files will also help us to find the problem. You can email support@pickeringlabs.com or send a fax to 650-968-0749.

Pickering Laboratories rolls out up-grade to Pinnacle PCX: New Sigma Series, by Mike Gottschalk

2010-04-27T14:13:00.000-07:00

The Pinnacle PCX Delta Series post-column derivatization instrument was first introduced in January 2005 to replace the PCX 5200 instrument. The Pinnacle PCX introduction brought new technologies to post-column systems including programmable temperature gradient column oven, inert flow path, reactor coil cartridge switching system, computer controlled software among others.

With the inclusion of the column temperature gradient feature, our amino acid analysis time for hydrolysates was reduced by half from 60 minutes to 30 minutes. In addition to improved analysis speed the ability to change reactor volumes easily made the Pinnacle PCX ideal for method development and application switching.

The development team at Pickering has been working behind the scenes to improve and expand the advantages of the Pinnacle PCX. Now with the confluence of several new features and improvements a complete series up-grade is occurring to the Sigma Series.

Notable improvement highlights:

Fully ROHS compliant – the European Union directive to eliminate toxic compounds in electronic equipment.
Power cooling – additional fans and air ducts have been developed to speed airflow in the column oven for faster cooling.
USB connection to PC – in addition to the Ethernet and relay connections USB has been added.
Pinnacle PCX Software version 1.0.0.7 includes 4 day log files for over the weekend log files, timer algorithm that runs independent of the system clock in the PC.
PEEK Front end on the pumps to prevent corrosion.
Injected composite parts – Column oven door and instrument base are 50 % lighter – saving on shipping costs.

Best of all the work flow of all methods are unaffected and migration of existing methods to the new Sigma series is seamless.

Pickering continually improves the components and manufacturability of all our products to provide the best analytical tools in the industry.

PICKERING LABORATORIES IS AHPA MEMBER, by Laszlo Torma

2010-04-27T14:12:00.000-07:00

This year we joined the American Herbal Products Association (AHPA) and I was appointed to the joint Botanical Raw Materials, Standards and Analytical Labs committee. AHPA is a national trade organization and it is focusing on promoting the responsible commerce of herbal products.

AHPA is also involved with key scientists and organizations that conduct research on herbs and maintain an active role with the various standards –setting organizations.

AHPA and AOACI are working together to establish and validate analytical methods for herbal products.

I attended the AHPA meeting in California for the first time in March. They are a very active and interesting association. They promote self-regulation, crisis management, education and other areas. They usually meet jointly with Natural Products Expo (East and West) which is a private, very large trade show.

AHPA also encourages member and contract laboratories to participate in the National Institute of Standards and Technology (NIST) Dietary Supplement Laboratory Quality Assurance Program. This program allows laboratories to perform specific analyses and to see their results against known values. Pickering Laboratories is participating in this

Quality Assurance Program in the area of analysis of aflatoxins in peanut products.

International Connections, by Laszlo Torma

2010-04-27T14:11:00.000-07:00

The “Pickering Brand” is well known all over the world. Thanks to our customers and our dedicated distributers, Pickering Laboratories instruments and methods are utilized in more and more countries. In order for us to offer better service and communication we have been expanding our participation at international meetings.

Pickering Laboratories is regularly represented at the Latin American Pesticide Residue Workshop (LAPRW). The first LAPRW was held in Brazil (2007) and Wendy Rasmussen and I were representing our company. We worked with Roberto de Souza Cruz of Cromatec. The second LAPRW (2009) was in Argentina and David Mazawa and I were representing Pickering Laboratories. We visited our distributer Victorio Bogunovich of Analytical Technologies. We had great cooperation from Analytical Technologies; sharing booth space during the meeting and were able to visit their facility. In Argentina the level of interest and knowledge of participants was much better than the first workshop. At both meetings we had the pleasure to meet lots of interesting people. In Latin America, like other parts of the world many Laboratories are struggling to purchase high performance and high cost instruments. In Argentina during a general discussion, many people expressed their anger about the very high cost of instruments like LC/MS/MS and requested reliable methods with affordable instruments. Latin American countries are using large amounts of glyphosate and are interested in reliable analytical methods in crop and environmental samples. It seems to me that glyphosate is an emotional and political issue in Argentina. The next LAPRW meeting is in Montevideo, Uruguay in 2011.

In 2009, David Mazawa attended BCEIA, China’s largest conference on analytical instruments. David worked with our distributer Ameritech and enjoyed meeting potential customers and as well as their hospitality. You can read more about this trip in our January 2010 Newsletter.

Recently Wendy Rasmussen and David Mazawa represented Pickering Laboratories at Analytica in Germany. Analytica is similar to PITTCON but they meet every second year and it has become larger than PITTCON in recent years. Wendy and David were assisting our distributer and business partner LCTech GmbH during the show. They also received training on LCTech’s new products that we are marketing in the USA.

Wendy, David, and the LCTech team at Analytica

In April, Wendy and I attended the Western Canada Trace Organic Workshop in Vancouver, Canada. We are presented 2 posters; and Wendy gave a presentation on “Sample Clean-Up with Immunoaffinity columns and Gel Permeation Chromatogphy”. We had a great time and we especially were glad to meet with our distributor, Chromatographic Specialties as well as some current and (hopefully!) future customers. Chromatographic Specialties have a great product range and offer wonderful support all accross Canada.

In June, I will attend the European Pesticide Residue Workshop (EPRW2010) in France. This will be my fourth EPRW meeting. EPRW meets every two years alternating with LAPRW. I will work with our distributor LCTech and visit with our customers. Scientists and pesticide regulators from all over the world will attend this meeting because it is considered by many to be the best pesticide residue workshop. In addition to the Europeans, the attendees are from Africa, Asia, Latin America and North America. This meeting allows me an opportunity to visit with laboratory personnel with different scientific backgrounds, from different parts of the world.

And last but not least, we are regularly participating as exhibiters and presenters at PITTCON and AOAC International. Even though these meetings are in the USA there are lots of foreign scientists attending and this gives us additional opportunity to cultivate our relationship with them.

Ion Pair

2010-04-13T12:23:00.001-07:00

We have two new additions to our Pickering Family, Oso and Valentino, our new unofficial company mascots.

The "Ion Pair" born Feb 14, 2010:

Gloria Garcia, the Executive Assistant to the Vice President, Operations here at Pickering adopted these two MaltiPoo (part Maltese, part Poodle) puppies last month and brought them into our office.

"Oso" is Spanish for "bear", because he was the largest of the litter and looks a little bit like a little bear.

"Valentino" is named for the day on which they were born: Valentine's Day.

New Products and Applications Unveiled at Pittcon

2010-01-18T16:22:00.000-08:00

By Mike Gottschalk

This year's Pittcon in Orlando, Florida (Feb 28 - March 5) will be an exciting event for Pickering Laboratories when new instruments and applications will be rolled out.

Pickering Laboratories continues to bring new products and improvements to the analytical market with the new line of Gel Permeation Chromatography (GPC), Mycotoxin, and Classic post-column derivatization products.

A new addition to the GPC line is the GPC Quattro; a manual GPC clean-up system that has 4 columns for simultaneous operations of 4 different applications or high throughput of the same applications.

Immunoaffinity column processing gets some help with the introduction of AcceCLEAN™; an automated system for Immunoaffinity columns holding 30 columns for unattended operation.

For the detection of Aflatoxin by photochemical reaction the UVE™ reactor is the best designed product available. Recognized for exceptional design and ease of use the UVE™ is fast becoming the leading product in this area.

A new Column protection system for Cation-exchange HPLC applications will be unveiled exclusively at Pittcon this year.

The new GARD™ manufactured by Pickering Laboratories is a substantial improvement over the standard packed guards. The new GARD™ adds little pressure, is invisible to the chromatography, and has substantially more capacity for strongly retained compounds that can foul the analytical column.

Photo: GARD and Holder

Amino Acid Analysis is faster than ever with 2 new columns for the Pinnacle PCX. The 30 minute sodium run and 70 minute lithium run provide exceptional separation and selectivity at faster run times.

New Post-column derivatization applications include Voglibose and Alendronic Acid to the family of Pickering Laboratories' validated methods. If Pickering Labs validates a method it is guaranteed to work!

Visit us in booth 2368 at Pittcon for full details.

SAFFRON - Crocus sativus

2010-01-18T16:15:00.000-08:00

By Michael Pickering

Until the late 15th Century, selling inferior or adulterating authentic saffron was a punishable crime. Times have changed. In my neighborhood today, the price of saffron ranges from $1.50/oz (a Chinese medicinal, which is a mixture of saffron and safflower) to $1000.00/oz (certified organic, unit size 0.007oz, sold as a food commodity). At organic prices, moisture would be a significant adulterant. Buyers beware: I have also seen pure Safflower (Carthamus tinctorius) pistils sold as saffron at $12.45/oz. The pure pistils are variously referred to as Mexican saffron, Portuguese saffron, or bastard saffron. Though safflower will produce the desired color, it is lacking the distinctive taste and smell of true saffron. Such egregious behavior surely would have warranted the death penalty in the Middle Age.

The North African Crocus is a lovely, lavender bloom in the fall. Each flower bears three outrageously large stamens which must be harvested by hand immediately upon blossoming. The stamens are bright red-orange when plucked and deep red to brown when dried. In trade, they are referred to as threads. Although saffron is cited as a medicinal in the Chinese Pharmacopeia, most peoples of the world prize the threads for their characteristic color and heady, aromatic spice qualities. The spice is considered the costliest in the world due to the laborious harvest and paltry yield (estimated at 13,000 stamens per ounce).

The following are singular dishes that cannot be prepared without saffron: Bouillabaise, Harira, Risotto Milanese, and Seafood Paella.

Since saffron has no ritual significance to me, nor am I royalty, the bulk Chinese variety suits my palate. I just use more to create the effect I want. My favorite personal recipe, using the bulk Chinese saffron, is as follows:

Poached White Fish with Saffron Infused Lime Sauce

White fish filletsThree peppercorns per filletCourt Bouillon:

- about 4 cups water
- one-forth cup Mirin (Japanese sweet cooking wine)
- one lime, juice and zest
- three green onions, chopped
- one stalk celery, thinly sliced including the leaves if possible

Sauce:

- Cointreau and lime juice, 1:1 ratio (if you want stronger lime flavor, add the zest too)
- Saffron 1/8 tsp. per fillet, ground in a mortar (if using certified organic saffron,
add three threads per four fillets)

Garnish:
- chopped green onions
- toasted pumpkin seeds

Using a heavy iron skillet large enough to accommodate the fish without touching, warm the peppercorns until aromatic. Add water and other bouillon ingredients. Simmer 15-20 minutes. Push aside solids and lay fish fillets flat on bottom of skillet - bouillon level in skillet should be even with tops of fillets. Bring back to simmer, cover skillet and turn off heat. Set aside for 15-20 minutes. Remove fillets and set on serving platter, pour sauce over fish, garnish and serve. Enjoy!

Photo (l to r): organic Saffron, Safflower, and Herbal mix containing Safflower and trace amounts of Saffron

New! GARD: Column Protection System

2010-01-18T16:00:00.000-08:00

A new Column protection system for Cation-exchange HPLC applications will be unveiled exclusively at Pittcon this year.

The new GARD™ manufactured by Pickering Laboratories is a substantial improvement over the standard packed guards. The new GARD™ adds little pressure, is invisible to the chromatography, and has substantially more capacity for strongly retained compounds that can foul the analytical column.

The new GARD Column Protection System significantly prolongs column life without band spreading or added pressure. We will have a poster at Pittcon demonstrating, by means of a performance comparison for Amino Acid Analysis, that the use of a GARD will protect the analytical column more effectively than traditional guard cartridges, is more cost-effective for the laboratory, is easy to change, and most importantly has zero band spreading.

Chromatography Quiz No. 2

2010-01-18T14:45:00.000-08:00

Congratulations to the winners of our last newsletter's Chromatography Quiz: Matthew Hartz, Jamie Palmer, and Keena Njoroge from Underwriters Laboratories, Sudheer Reddy from Chemtex, and Becky Canela from Environmental Laboratory Services!

They've each won, and will shortly be receiving from Gifttree.com, two dozen irresistible cookies in five flavors: White Chocolate Hazelnut, Snickerdoodle, Peanut Butter, Oatmeal Raisin, and Chocolate Chip.

The correct answer for the modified Carbamates chromatogram: we reversed the two reagents. The OPA reagent was pumped in the Reagent One position, and the Hydrolysis reagent was pumped in the Reagent Two position. Thus 1-Naphthol, which is naturally fluorescent, appears full-sized. The other Carbamate peaks have different sizes due to their varying rate of hydrolysis - the high pH of the OPA reagent will allow for some but not complete hydrolysis prior to detection.

Chromatography Quiz: Amino Acid Analysis

Identify the error made when running the Amino Acids chromatogram below and win a prize! Simply email your answer and your full contact information to Rebecca at rlsmith@pickeringlabs.com by March 1st in order to win. The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Amino Acid Analysis of Physiological Fluids:

Pickering Standard: 011006P Native Sample Standard 0.25 µmole/mL, 10 µL injection

Pickering Column: 0354100T High Efficiency Lithium Cation-exchange Column, 4.0 x 100 mm

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 36 °C

Flow rate: 0.35 mL/min

Eluent Gradient:

Post-column conditions for amino acid analysis:
Reagent 1: Trione
Reactor 1: 130 °C, 0.5 mL
Reagent flow rate: 0.3 mL/min

Detection: UV-Vis Detector, 570nm for primary amino acids, 440nm for secondary amino acids
Hint: Assume in this case that both Guard and Analytical column are good. To see a standard Amino Acid chromatogram, click here

Pickering at AOAC International in Philadelphia

2009-10-21T15:00:00.000-07:00

By Mike Gottschalk, Marketing Manager

It was the 125th Anniversary of the AOAC in Philadelphia, Pennsylvania and this annual meeting was especially exciting with the anniversary celebrations.

At the Vendor exhibition we highlighted our Mycotoxin and GPC Sample-Cleanup products lines to expand our offering of the post-column derivatization products we are most known for.

The Scientific sessions also reflected growing interest in the analysis of Mycotoxins as well as Paralytic Shell Fish Toxins and a broad range of analytical instrumentation and techniques.

We brought a large contingency of personnel including Dr. Pickering, Dr. Ofitserova, Dr. Nerkar, Dr. Torma to accept the AOAC's Single Laboratory Validation of the Year Award for our Multi-residue Mycotoxin Analysis. The paper, titled "Multi-residue Mycotoxin Analysis in Corn Grain by Column High-Performance Liquid Chromatography with Post-column Photochemical and Chemical Derivatization: Single-Laboratory Validation" was also published in the Journal of AOAC International Vol. 92, No. 1, 2009.

Photo: Michael, Maria, and Sareeta at AOAC

New Product Lines from Pickering, October 2009

2009-10-21T14:45:00.000-07:00

Mycotoxin product line
We are now distributing Mycotoxin Immunoaffinity products for Ochratoxin and Aflatoxin. The performance and batch-to-batch reproducibility of the columns is exceptional and far exceeds that of other manufacturers. The columns can be used for any matrix, from wine and juice, to nuts and grains, to herbs and spices. Contact Sales for more information.

GPC Sample Clean up line
We have a new GPC Sample Clean-up product line! We have both automated and manual GPC cleanup systems and we also have systems that include concentration & solvent exchange, or just GPC. Sample cleanup using GPC is especially useful for fatty matrices, but also perfect for vegetable matter and spices, as well as soil & waste water.

New faster AAA columns
We now have a Lithium amino acid run which will separate 45 amino acids in 70 minutes for Physiologic fluids, an a new 30-min Sodium amino acid run which will separate the 20 amino acids commonly found in protein hydrolysate samples. These columns are for use with our Pinnacle PCX.

Histamine Product Line
Our newly launched Histamine product line consists of Dip-sticks and Elisa kits as well as Post-column derivatization for fast and in-situ testing as well as quick, reproducible, and sensitive methods for follow-up confirmation. Contact Pickering Laboratories at 1-800-654-3330 or sales@pickeringlabs.com for more information!

Ask Technical Support! October 2009

2009-10-21T14:30:00.000-07:00

By David Mazawa, Technical Support Chemist

Parts Lookup for Pickering Instruments Now on the Internet:

Looking for a part number? Try out our new Parts Lookup for the Pinnacle, Vector, and 5200 models. It can be found on our website http://www.pickeringlabs.com/

Click on "Service and Support" tab and then choose the Parts Lookup from the pull-down menu. Just choose the model of your instrument, then click on the parts of interest and the part number will be displayed.

You can also use the following link: http://www.pickeringlabs.com/partslookup/default.asp

Make sure your web browser can support Flash applications before selecting your instrument. Place your mouse over the part you are looking for and the part number will be displayed. The Parts Lookup was designed to provide part numbers of commonly replaced parts. If what you are looking for is not available on the Parts Lookup, call Technical Support at (800) 654-3330 or (650) 694-6700 or email support@pickeringlabs.com.

Soap Opera

2009-10-21T14:15:00.000-07:00

by Michael Pickering

In the process of washing laundry the cleaning agent is the water, the “universal solvent.” The surfactant (soap/detergent) facilitates the removal of strongly adsorbed and hydrophobic soil from the clothes. Foam, however, is a contaminant. Suds stabilizers added to the surfactant create persistent foam. Unfortunately, most consumers believe foaming to be evidence of a good surfactant; that it is desirable. The truth is quite the opposite. Foam residues are difficult to remove. Notice, after all, that the foam is excluded from the solution/emulsion phase: it floats. Thus the rinse cycle is inadequate to the task of removing it. It is the residue of these suds stabilizers on laundered swim suits that necessitate the frequent exchanging of spa water. Contaminated hot tubs, when set to the ‘jets’ cycle, quickly build up foam on the surface of the water. The foam becomes thicker and more persistent with each subsequent use. Eliminating the use of swim suits, or rinsing the suits with water alone, will greatly increase the life of your spa water.

Community Corner, October 2009

2009-10-21T14:00:00.000-07:00

This section is devoted to our customers: for sharing customer experiences and feedback, up-coming changes in products, upcoming surveys, etc. This is also our Chromatography Quiz section, where each issue will contain a new chromatogram and a question associated with it. Each winner will receive a prize, and will be listed in the next issue.
We encourage all of our customers to submit stories, feedback, experiences, and we’ll pick one or two to share with the community.

Upcoming Events

Customer Satisfaction Survey – keep an eye out for a survey coming by email in late November. It will be a short questionnaire designed to gauge our customer satisfaction and how we can improve.

Chromatography Quiz
Chromatography Quiz No. 1: Carbamate Analysis for US EPA 531.1

Special Note: This is the first Quiz included with our newsletter. For each issue, we’ll choose a chromatogram from a different application or industry. So if Carbamates don’t apply to your lab this round, stay tuned! The quizzes and newsletter will be published Quarterly

To Win:

Simply email your answer and your full contact information by December 1st to: Rebecca at rlsmith@pickeringlabs.com

The troubleshooting answer and winner congratulations will be published in the next issue.

Identify the error made when running the Carbamate chromatogram below and win a prize!

Pickering Standard: 1700-0063 Carbamate Test Mix, 2.5 µg/mL, inject 10 µL

Pickering Column: 1846150 Carbamate Column, C18, 4.6 x 150 mm

Normal Operating Conditions (for reference only, condition changes may be reflected in chromatogram):

Column Temperature: 42 °CFlow rate: 1 mL/min
Eluent Gradient:

TIME.......WATER......MeOH %
0.................85.............15
0.5..............85.............15
28.5............30.............70
28.6..............0.............100
33.5..............0.............100
33.6.............85............15
41.................85............15

Post-column conditions for pesticide analysis:
Reagent 1: Hydrolysis reagent CB130
Reagent 2: 100 mg of OPA, 2 g Thiofluor™ in 950 mL of CB910
Reactor 1: 100 °C, 0.5 mL
Reactor 2: ambient. 0.1 mL
Reagent flow rates: 0.3 mL/minDetection: Fluorometer ex 330 nm, em 465 nm

Chromatography Quiz No. 1: Carbamate Analysis for US EPA 531.1

2009-10-21T13:30:00.000-07:00

Special Note: This is the first Quiz included with our newsletter. For each issue, we’ll choose a chromatogram from a different application or industry. So if Carbamates don’t apply to your lab this round, stay tuned!

To Win:
Simply email your answer and your full contact information by December 1st to: Rebecca at rlsmith@pickeringlabs.com

The troubleshooting answer and winner congratulations will be published in the next issue.

Chromatography Quiz
Identify the error made when running the Carbamate chromatogram below and win a prize!

Pickering Standard: 1700-0063 Carbamate Test Mix, 2.5 µg/mL, inject 10 µL
Pickering Column: 1846150 Carbamate Column, C18, 4.6 x 150 mm

Normal Operating Conditions (for reference only, condition changes may be reflected in chromatogram):

Column Temperature: 42 °C
Flow rate: 1 mL/min
Eluent Gradient:

Post-column conditions for pesticide analysis:
Reagent 1: Hydrolysis reagent CB130
Reagent 2: 100 mg of OPA, 2 g Thiofluor™ in 950 mL of CB910Reactor 1: 100 °C, 0.5 mL
Reactor 2: ambient. 0.1 mL
Reagent flow rates: 0.3 mL/min
Detection: Fluorometer ex 330 nm, em 465 nm

About Post-Column derivatization analysis for HPLC - Part Three

2009-05-04T13:00:00.000-07:00

Detector Considerations

Refractive Index Sensitivity

RI sensitivity applies only to UV-vis detectors. There are two sources of RI noise in post-column applications:

- RI discontinuities due to imperfect mixing.
- RI discontinuities due to temperature gradients in the eluant/reagent stream as it leaves a heated reactor.

In either case, when such inhomogeneities enter the flowcell, they bend light into the wall or off the photomultiplier tube, causing detector noise. The noise usually correlates with the piston cycles of the pumps, thus limiting the detector to low-sensitivity applications.
Most flowcells in modern UV-vis detectors are designed to minimize the effects of RI.

In order to minimize the temperature-related RI effects mentioned above, some manufacturers have a capillary heat exchanger at the flowcell entrance. In some instances this heat exchanger has an internal diameter of 0.12 mm (0.005 inches), which can result in post-column pressures in excess of 42 bar (600 psi). Since this can exceed the pressure rating of a heated reactor made with fluorocarbon tubing, this small-diameter heat-exchanger tube may need to be replaced with a 0.25 mm (0.010 inch) i.d. tube.

Detector Pressure Ratings

When the eluant-reagent stream from the heated reactor reaches the detector, it can release dissolved gas as it cools. The Pickering Laboratories derivatization instruments place a back-pressure of 7 bar (100 psi) on the detector flowcell in order to prevent the formation of bubbles.

- suppress boiling in the reactor
- prevent outgassing in the detector flowcell.

The back-pressure regulator can be factory-adjusted to accommodate flowcells with a lower back-pressure rating, depending upon the reactor temperature. but a setting lower than 3.2 5 bar (70 psi) is not recommended for reactor temperatures over 100° C.

Operating an HPLC system with a post-column derivatization system can be as routine as regular LC. The benefits from this LC/post-column combination include minimal sample pre-treatment, greatly improved sensitivity, and enhanced selectivity for compounds that would normally be much more difficult to detect.

About Post-Column derivatization analysis for HPLC - Part Two

2009-05-04T12:00:00.001-07:00

Chemical Requirements

The chemical requirements for post-column derivatization are generic.

Stability of Reagent: The minimum reagent stability sufficient for routine work is one day. This means that the yield and signal-to-noise ratio for a given sample must remain constant for at least 8 hours.
Completeness of Reaction: The analytical separation is complete when the reagent is mixed with the column effluent. Therefore, in order to minimize band spreading, it is important to keep the volume small between the mixing tee and the detector. If the reaction is slow (in excess of one minute), an elevated temperature can be used to decrease the reaction time.
Reproducibility: Unless the system consistently produces the same signal for the same sample, quantitation is impossible. Because the reaction is occurring ³on the fly² as the combined column and reagent stream flows toward the detector, the reproducibility is linked to the flow-rate precision of the pumps and to the temperature. Accordingly, even an incomplete reaction will be as repeatable as the retention time for any given species. The completeness of the reaction, then, is not strictly necessary for reproducibility, but it is important for maximum sensitivity.
Minimal Detector Response of Reagents: The color or background fluorescence of the reagent (or its by-products) represents a continuous noise source. Because the reagent is present in excess relative to the analyte, the analyte's signal could be obliterated by the reagent's strong background signal. Pickering's Chromatographic Grade® eluants and reagents are guaranteed to produce the absolute minimum possible detector background signal in post-column applications.
Solubility: All species must remain in solution, including the combined components of the eluants and the reagent(s), as well as the newly formed derivative(s). Precipitates can block capillary tubes, burst reactors and foul detector flowcells.

Ninhydrin chemistry provides a good example of multiple solubility considerations. Ninhydrin reagents contain a lithium acetate buffer, ninhydrin, hydrindantin, and a water-miscible organic solvent. The organic solvent is necessary to maintain both the hydrindantin and the new purple chromophore (derivative) in solution. Also the presence of lithium ion in the formula precludes the use of eluants containing phosphate, because lithium phosphate is insoluble and would precipitate at the point of mixing.

About Post-Column derivatization analysis for HPLC - Part One

2009-04-27T11:00:00.000-07:00

Chromatography is a science of separations. High Performance Liquid Chromatography (HPLC) like other forms of chromatography, is used to separate complex mixtures into their components. There are many flavors of HPLC, but what they have in common is that the separation takes place in solution. Having separated a mixture, you need to see the components. The most popular detectors use either UV/VIS light absorption, or fluorescence. Unfortunately, many substances are difficult to detect. Moreover, you want to see the components of interest without distraction from the background.

Post-column derivatization, also known as post-column reaction, renders visible certain compounds that are normally invisible. This trick is accomplished after the separation by performing a chemical reaction on the substances that gives them an easily-detectable physical property. Typically you use a reaction that produces a strong color or makes a fluorescent product. You can increase the sensitivity of detection by several orders of magnitude in favorable cases. Most reagents are selective for a particular class of substances, so analytes of that class are more easily seen against a complex background. So, post-column derivatization is used to increase sensitivity and selectivity in HPLC analysis.

The post-column reaction system mixes the stream of eluant from the HPLC column with a stream of reagent solution. The mixture usually flows through a reactor to allow enough time for the chemical reactions to complete. If the reaction is slow, the reactor may be heated to speed things up. Some reactions need two or more reagents added in sequence. Finally the mixed streams pass into the detector, typically UV/VIS absorbance or fluorescence. Of course a practical system requires metering pumps, pulse-dampeners, thermostats, and safety systems to give reliable results.

Examples of the chemistry and hardware are given in the catalog and user's manuals.