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

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

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

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

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

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

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

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.