Presentations Announced for AOAC 2012

The AOAC annual meeting is fast approaching. Beginning this Sunday, September 30th and running through next Wednesday, October 3rd, the 2012 AOAC meeting in Las Vegas, Nevada promises to be another exciting conference. The final program has been announced and Restek chemists will be participating in meeting events and giving several technical presentations. Visit us at Booth 209 or stop by one of the posters listed below to learn more about our latest innovations and applications.


Poster Session: “Analysis of Non-Foodborne Contaminants and Residues”


A New Capillary GC Column for Highly Efficient Separation of Polycyclic Aromatic Hydrocarbons, Including the EFSA PAH4

Poster Number: P-M-070

Julie Kowalski, Amanda Rigdon, Jack Cochran, Shawn Reese, and Roy Lautamo

Abstract: Polycyclic aromatic hydrocarbons (PAHs) are toxic (carcinogenic, mutagenic, teratogenic, etc.) compounds sometimes found in food and require monitoring by capillary gas chromatograph with mass spectrometry (MS), often at very low levels. Some of these PAHs are isobaric so MS will not be sufficient to quantify them in an unbiased fashion, which means they must be separated by GC prior to detection. Some are more toxic than others, including the PAH4 noted by EFSA, benz[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene. Possible GC coelutions that would lead to qualitative and quantitative bias include triphenylene and chrysene (m/z 228), benzo[b]- and benzo[k]fluoranthene (m/z 252), and benzo[e]- and benzo[a]pyrene (m/z 252). The triphenylene and chrysene coelution can be particularly difficult to resolve.

A new GC stationary phase has been developed that separates the PAH4, the PAH8, and many more PAHs that can be present in food samples. Chromatograms that detail these separations will be shown, and column ruggedness will be explored with QuEChERS oyster and smoked paprika spice extracts.


Feasibility of Dilute-and-Shoot LC-MS/MS, Solvent-Only Calibration and Multiple Food Types for Multiresidue Pesticide Analysis: Lazy Chemists and Old Instruments

Poster Number: P-M-068

Julie Kowalski, Sharon Lupo and Jack Cochran

Abstract: Increased selectivity and better sensitivity of LC-MS/MS have impacted how multiresidue methods are performed, sometimes by decreasing the need for rigorous sample preparation. However, this technique is susceptible to matrix effects causing poor data quality and quantification to be difficult. Often instrument manufactures tout the dilute-and-shoot technique which greatly decreases processing time as no sample cleanup is performed, but it also often requires the sensitivity of the newest instrumentation. Using a robust, but older LC-MS/MS with sensitivity limitations, we investigated two aspects of multiresidue methods, sample preparation and calibration strategies, to determine the best procedures considering both data quality and time/cost. A variety of food types and two sample preparation methods, dilute-and-shoot and QuEChERS methods were performed and experimentally determined matrix effects were compared. Calibration methods were evaluated by determining recovery values using both solvent-only calibration and matrix-matched calibration. This allows assessment of sample preparation/calibration method combinations. We determined that with the easiest commodities, the dilute-and-shoot method and solvent-only calibration gave acceptable recovery values.  However, for other commodities either a matrix-matched curve or cleanup was needed to obtain good recovery values. The high carbohydrate and citrus commodities proved to be too difficult. In almost every case, matrix-matched calibration provided improvement.


The QuEChERS Sample Preparation Approach with Dispersive and Cartridge SPE Cleanup, GCxGC-TOFMS, and LC-MS/MS for the Analysis of Pesticides in Tobacco

Poster Number: P-M-067

Julie Kowalski, Michelle Misselwitz, Sharon Lupo, Jack Cochran

Abstract: The production of tobacco, a high-value crop for the United States, is increased by the use of pesticides that are specifically approved for use on tobacco by the Environmental Protection Agency (EPA).  Even after the processing of tobacco, some pesticide residues remain on the product and under its pesticide registration program EPA is charged with assessing risks to smokers from exposure to these residues.  Because tobacco is such a complex matrix, the challenges associated with determining pesticides at trace levels are substantial.  This includes pesticide extraction from tobacco and the instrumental analysis step, which can be complicated by matrix interferences.

We used the Quick – Easy – Cheap – Effective – Rugged – Safe (QuEChERS) sample preparation approach to isolate pesticide residues from tobacco leaf, ranging from such small, polar pesticides, such as methamidophos, to relatively nonvolatile, nonpolar, large pesticides, like deltamethrin.  We also explored two extract cleanup methods, dispersive solid phase extraction (dSPE) and cartridge SPE (cSPE), monitoring their efficiency at pesticide recovery and matrix reduction.  Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-TOFMS) and liquid chromatography with tandem mass spectrometry (LC-MS/MS) were compared and contrasted for their ability to determine pesticide residues in the resulting extracts.


The Holy Grail: Comprehensive Polycyclic Aromatic Hydrocarbon Analysis by Serial Combination of HPLC Columns with Different Selectivities and UV and Fluorescence Detection

Poster Number: P-M-069

Julie Kowalski, Sharon Lupo, Ty Kahler, Jack Cochran

Abstract: Polycyclic aromatic hydrocarbon analyses are performed regularly throughout the world for both food safety and environmental testing. Many organizations test for PAH residues in food products, but the analyte lists vary from organization and country. For example, domestically, the EPA, FDA, AOAC, and NOAA all test for PAHs, but do not share the same target compound lists. Internationally, the EU and individual countries test for different PAH compounds. Chromatographic methods are typically tailored to specific target compounds and are not transferable when target compounds change. A further complication is the need to separate interfering compounds that are not considered target compounds, but that do occur in samples, like triphenylene, perylene, and benzo[e]pyrene.

In this work, we developed a chromatographic solution that allows the separation of 29 PAH compounds including interfering compounds. This was accomplished by combining two HPLC columns in series: a PAH-specific phase and an aromatic bond selective phase. Separate column selectivities were tested and then combined based on a predicted ratio of the column lengths that would results in no coelutions. Temperature was also determined to play a critical role in the elution order and resolution of the PAHs tested. Time programmed fluorescence detection was optimized to yield the best sensitivity possible, ppb range, with closely eluting compounds.

Restek Chromatographers Lend Their Expertise to NEMC 2012

As in years past, Restek sent a contingent of environmental and air chromatography experts to the National Environmental Monitoring Conference (NEMC). This year’s event took place in Washington, DC, and featured talks from our own Michelle Misselwitz, Jason Herrington, and Chris Rattray. See below to review their abstracts and presentations.

Restek was also involved with NEMC from an organizational standpoint—Joe Konschnik supported Earl Hansen, NEMC’s Technical Program Chair, by serving as Co-Chair of the Air Methods & Monitoring Session. In this role, Joe helped plan, coordinate, and moderate oral presentations by some of the industry’s brightest minds. The session received such unprecedented interest that it was split into three sections!

We are also proud to announce that Joe has been invited to join the steering committee for NEMC 2013. We hope you consider making the trip to San Antonio, TX, on August 5–9 for what is sure to be an enlightening conference.

For more information on NEMC, visit their website at

Technical Presentations

Characterization of Crude Oils and Tar Balls Using Biomarkers and Comprehensive Two-Dimensional Gas Chromatography

Michelle Misselwitz (presenter), Jack Cochran, Chris English, Barry Burger

Abstract: The analysis of petroleum biomarkers is commonly used to determine the origin of crude oil samples. These biomarkers are “molecular fossils” that are complex hydrocarbon molecules from formerly living organisms in the source rock. Utilizing biomarkers to fingerprint crude oils is advantageous because they are resistant to weathering or degradation and provide a unique profile for oil-to-oil correlations. This information can be used by environmental forensic chemists to pinpoint source oil from spills, or in this case, tar balls washed along the shore of the Gulf of Mexico.

Gas chromatography mass spectrometry (GC-MS) is typically used to monitor the ratios of hopane and sterane isomers. This work will focus on characterizing crude oil samples, including from the broken riser pipe collected via an underwater robot during the Deepwater Horizon oil spill of 2010, by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS). GCxGC is a two-dimensional separation using two columns of different selectivity with thermal modulation. Utilizing a retention plane provides a structured chromatogram that aids in fingerprinting complex oil samples. The hopane/sterane profile of these oils will then be compared to extracts of tar balls that washed ashore on the Gulf of Mexico beaches months after the spill occurred. 

Concerns Regarding 24-Hour Sampling for Formaldehyde, Acetaldehyde, and Acrolein Using 2,4-Dinitrophenylhydrazine (DNPH)-Coated Solid Sorbents

Jason Herrington
For more information, email Jason Herrington.

Abstract: There is high demand for accurate and reliable airborne carbonyl measurement methods due to the human health and environmental impacts of carbonyls and their effects on atmospheric chemistry. Carbonyl sampling methodologies based on derivatization with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents are the current standard. However, these methods present multiple challenges that detract from an accurate understanding of carbonyl-related exposure, health effects, and atmospheric chemistry. Since their original development in the late 1970s, these methods have been extensively evaluated and developed. However, studies have demonstrated formaldehyde interferences from 2,4-dinitrophenylazide (DNPA) and 2,2-dinitrochlorobenze (DNCB); low acetaldehyde collection efficiencies for 24-hour sampling; and numerous acrolein sampling interferences. This presentation will discuss the sampling issues associated with DNPH-coated solid sorbents, the potential for remedies, and will provide recommendations and areas for future research. The presentation of this information is important because it seems clear that carbonyl data produced utilizing DNPH-based methods are being reported without acknowledgment of the method short-comings or how to best address them.

Click here to download a PDF of the full presentation.

Lowering Detection Limits for 1,4-Dioxane in Drinking Water using EPA 522 with Concurrent Solvent Recondensation – Large Volume Splitless Injection

Christopher Rattray (presenter), Jack Cochran, Scott Grossman, Chris English
For more information, email Christopher Rattray.

Abstract: The third Unregulated Contaminant Monitoring Regulation (UCMR 3) is scheduled to begin next year and includes a requirement for 1,4-dioxane analysis using EPA Method 522. EPA Method 522 was originally written to be performed using a standard gas chromatograph (GC) equipped with a single quadrupole mass spectrometer (MS). However, a recent reevaluation of 1,4-dioxane’s carcinogenic risk resulted in the EPA lowering the suggested minimum reporting limit from 0.3 to 0.07 µg/L, and even when operating in selected ion monitoring (SIM) mode, most GC-MS instruments would be hard pressed to meet this lower 0.07 µg/L limit. One way to lower detection limits is to inject more sample, but large volume splitless injection (LVSI) for gas chromatography typically requires a special injection port such as a programmable temperature vaporizer (PTV). The technique described here for the analysis of 1,4-dioxane in drinking water uses an unmodified split/splitless inlet with LVSI to lower reporting limits without concentrating extract. With an injection volume of 10 µL, we achieved a linear calibration range exceeding 3 orders of magnitude, with levels ranging from 5 to 10,000 pg on column. We saw 89% recovery when 1 L of bottled water fortified at 0.005 µg/L was extracted using coconut charcoal SPE tubes and analyzed according to EPA Method 522 with LVSI, matching the method performance data published by the EPA. This LVSI technique requires absolutely no changes to standard laboratory instrumentation.

Click here to download a PDF of the full presentation.

Air Methods/Monitoring Sessions

• Data Interpretation and Policy Development

• Developments in Analytical Methods

• Sorbent Based Sampling Methods

Session Chairs & Moderators: Joe Konschnik1, George Lucier2, Deb Gaynor3, Michael Flournoy4, Nicola Watson5
1. Restek Corporation, 2. Battelle Memorial Institute, 3. Phoenix Chemistry Services, 4. SGS-Analytical Perspectives, 5. Markes International

For more information, visit