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 www.nemc.us


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 www.nemc.us/meeting/2012/nemc-program.php