Archive for the ‘GCxGC’ Category

Testing for pesticides in tobacco… QuEChERS makes it easy!!

Whenever it is time to analyze pesticides in complex matrices I always hope that we can use the QuEChERS sample preparation approach and not something more laborious!  The Quick-Easy-Cheap-Effective-Rugged-Safe method was developed for multiresidue pesticides in fruits and vegetables, however we have been using this approach outside of the typical fruit and vegetable matrices with success.   When compared to more traditional sample prep techniques (liquid-liquid and solid phase extraction) QuEChERS significantly decreases the time spent and solvent used.

Tobacco can be a very complex sample, but with a few modifications to the EN QuEChERS method we were able to get good spike recoveries (92%)  for  a wide range of pesticides.   Some of the modifications that we made were to use a 2 g sample and add 10 mL of water to hydrate the sample, then after the addition of 10 mL of acetonitrile we vortexed the sample for 30 min, instead of the typical 1 min shake.  We also used the power of GCxGC-TOFMS to separate some of the matrix interferences away from our analytes of interest (Figure below).  In a 1D GC-MS analysis we would have needed to perform cartridge SPE instead of the dispersive SPE to further remove matrix interferences.

If you want all of the details check out the full application note that was recently published! Evaluation of Dispersive and Cartridge Solid Phase Extraction (SPE) Cleanups for Multiresidue Pesticides in QuEChERS Extracts of Finished Tobacco Using GCxGC-TOFMS


GCxGC separation of matrix components from the incurred pesticide piperonyl butoxide in the second dimension that would have coeluted in a one-dimensional analysis.

GCxGC separation of matrix components from the incurred pesticide piperonyl butoxide in the second dimension that would have coeluted in a one-dimensional analysis.


Dilution and cleanup strategies for QuEChERS extracts of food prior to LC-MS/MS… and Tarballs!

If you missed the newly published tour de force piece from Julie Kowalski, check it out here: “Mitigating Matrix Effects: Examination of Dilution, QuEChERS, and Calibration Strategies for LC-MS/MS Analysis of Pesticide Residues in Diverse Food Types.”

Same thing for another excellent article just published by Michelle Misselwitz, “Fingerprinting Crude Oils and Tarballs using Biomarkers and Comprehensive Two-Dimensional Gas Chromatography.”

You can view the latest titles from the Restek News page and, if you dive a bit deeper, by clicking on the view all posts link,  you’ll, well, view all posts, and get additional valuable reading material.



P.S.  I know at least one person immediately clicked on this blog post after seeing the word “tarballs”, our own Chris English, the Innovations Lab Manager at Restek, who is an extreme tarball aficionado.

Eastern Canada Trace Organic Workshop

Last month, I attended two trace environmental workshops at the National Water Research Institute (CCIW) in Burlington, Ontario; the Workshop on LC-MS/MS Applications in Environmental Analysis and Food Safety and the Eastern Canada Trace Organic Workshop (ECTOW). The full program can be found here.

This was my first exposure to work done on Thermo’s Orbitrap, which appears to be a very powerful tool for non-targeted analysis when combined with UHPLC. An underlying theme of the trace analysis workshop (and Orbitrap talks) was the persistence of pharmaceuticals and pesticides wastewater effluents. This is a theme common to the conferences I attend, and I find myself wondering more and more what we can do as individuals to minimize our contribution to this developing problem.

This summer, I’ve set up raised garden beds for the first time, and I was amazed by how quickly weeds took over. The photo below was taken less than three weeks after the planter was set up. There is a sweet potato vine near the center, some carrots at the top left, and broccoli at the bottom right, but the majority of the seedlings in the open space are weed sprouts.


Walk through the garden section of your local home improvement store, or even Walmart, and you will find whole sections dedicated to Roundup and its generic variants. After spending a couple hours weeding three 4′ x 8′ vegetable beds with my wife, it is easy to see the allure of a weed killing spray.


Still, while I don’t shop for organic produce at the grocery store, it is nice to have some control over the food growing in my yard. For now, at least, I’m willing to trade an hour or two of work every couple weeks for near organic produce.

Dr George Frame speaks at Restek on Comprehensive Quantitative Congener Specific (CQCS) polychlorinated biphenyl (PCB) analysis

We were lucky to have Dr George Frame, PCB Analyst Emeritus as I call him, speak at Restek on the GC of PCBs prior to his plenary lecture at the International Network of Environmental Forensics meeting at The Pennsylvania State University last week.  While working as Chief of PCB Analytical R&D at GE Central Research Labs in Schenectady, NY, George created and implemented the landmark study on Comprehensive Quantitative Congener Specific (CQCS) PCB analysis in the early 90s that involved a collaborative of researchers and column vendors to profile elution orders on 20 different GC stationary phases for all 209 PCB congeners.  I was honored to contribute to this study and speak in George’s organized PittCon session on congener-specific PCB analysis in 1996, which George notes is one of the highlights of his career (chairing that session, not my talk!).  George and I formed a fast friendship at PittCon and soon after we published the definitive characterization for PCBs in Aroclors with Soren Böwadt, as well as a review paper on PCB analysis.

George’s talk at Restek included PCB structure and nomenclature, Aroclor production, early analytical efforts (e.g. packed column GC work, EPA methods, congener-specific methods based on Aroclor mixes), non-Aroclor analysis challenges (including atropisomers), GCxGC, and anecdotes from years of doing PCBs.  One of the most interesting stories was how he discovered a late production lot of Aroclor 1254 representing only 1% of total Aroclor 1254 production had higher amounts of toxic mono-ortho and coplanar congeners.  This Aroclor was created by chlorinating to 54% the still bottoms remaining from the production of Aroclor 1016.  The reason this is so important is that many toxicological studies on Aroclor 1254 employed this disproportionately produced Aroclor.

George’s talk reminded us too that chromatography is so important for congener-specific work, as mass spectrometry cannot typically distinguish isomers.  He also noted that even with the mass spectrometry advantage, there is still no “Holy Grail” GC column that can separate all 209 PCBs, or even the ~140 Aroclor congeners.  Sounds like a good challenge for a chromatography company like Restek!  


This isn’t your average CSI, the International Network of Environmental Forensics (INEF)

Next week (June 10-12) at the Pennsylvania State University (PSU) the International Network of Environmental Forensics conference is being held.  This isn’t your typical crime scene investigation but, as defined by the INEF, “environmental forensics is the use of scientific techniques to identify the source, age, and timing of a contaminant into the environment.”  We may not be learning how to catch the killer, but maybe the contaminator! This conference is essentially next door to Restek (10 min drive) so it is a great opportunity to attend presentations from some of the international leaders in the field.  I know that I am looking forward to learning more about environmental forensics.  A few Restek scientists will also be presenting at the conference.  Chris English will be presenting work that he did using purge and trap to analyze BTEX in crude oils.  He did a blog on the topic if you are interested.   I will be presenting some work that I did using GCxGC-TOFMS to fingerprint crude oils and tarballs using petroleum biomarkers.  We used the NORDTEST oil spill identification system to determine if some of the tarballs we received from Florida matched the oil from the Deepwater Horizon Oil Spill.  The full application note was just published if you are interested in more detail. Last, but certainly not least, Jack Cochran will present about true peak capacity increase using GCxGC for environmental forensic applications.  Jack also blogged about true peak capacity increase for GCxGC in the past.  The list of speakers, topics and visiting my alma mater has me excited for a great week next week!

Here is the INEF program if you are interested.

No Prescription Needed: Pharmaceuticals in Your Supplements

vintage photoThere are many fake products out there including foods like “virgin” olive oil, honey and branded liquor. I hear a lot about these because my work focuses on food and food safety. Food fraud seems to be on the rise…at the very least governments and researchers are devoting more resources to finding and tracking incidents. Sometimes adulteration of foods can be dangerous, but often, fraud takes the form of mislabeling or misbranding, dilution or substituting lower quality, less expensive ingredients. One recent example is the presence of horse meat in food sold as beef.

But other types of products like dietary supplements can prove more dangerous, particularly items like weight loss supplements. The US FDA monitors these products and sometimes finds some interesting compounds, including controlled pharmaceuticals.  

A few years ago I got a notice that one such product had been pulled from the market because it contained drugs that were considered

Throwing caution to the wind, I found a website still offering the product and ordered it immediately. My colleague Jack Cochran and I took a look using GC-TOFMS and GCxGC-TOFMS to see if we could find the same compounds as the FDA reported as well as anything else that looked interesting.

We found fenfluramine, sibutramine, propranolol and ephedrine, which were reported by the FDA. Fenfluramine was part of the weight loss drug Fen-Phen that was pulled from the market in 1997 because it is a stimulant that caused heart valve problems. Sibutramine has a similar story; it was prescribed as a weight loss drug until being withdrawn from the market in 2010 due to heart health concerns. Ephedrine is a CNS stimulant with a well-documented history of producing weight loss as well as recreational use. It has been linked to a host of adverse effects resulting in partial bans, restricted levels or requiring a prescription. Propranolol is a beta-blocker used to treat disorders like anxiety and panic as well as heart-related problems like hypertension and myocardial infarction.

We also found niacinamide which is part of vitamin B and a popular supplement often found in energy drinks. We detected caffeine as well as phenolphthalein. As a chemist, I immediately associated phenolphthalein with acid/base titrations and that pretty pink color. I found out that it is also a laxative that has been used for many years but has lost favor because it may be carcinogenic. Sounds like you would be full of energy, have to stay near a bathroom and be relaxed all at the same time while taking this product!

You can read the product instructions here…seems to me like it calls for a lot of this cocktail.


Mining through complex data and non-target analysis is made easier with GCxGC-TOFMS

I am currently working on a project looking for pesticides in herbal tea.  At this point, I am using the contents of one tea bag (~1.5g) and 10mL of freshly boiled water with a QuEChERS extraction.  I am still working through the details on the impact of the hot water and what type of cleanup will be necessary for pesticide determination, so that will be a blog for another day. I first decided to do some split injections of the raw extract to see what type of natural products are in some of the herbal teas I picked up at the grocery store.

Using GCxGC-TOFMS with a 30m x 0.25mm x 0.25µm Rxi-5Sil MS in the first dimension and a 1m x 0.25mm x 0.25µm Rtx-200 in the second, I processed the data by doing a “peak find” and library search for anything with a S/N of at least 100.  I then get my peak list and sort according to the NIST library similarity number, so that the highest matches are at the top of the list.  I start scanning through the list and see what names sound either like a pesticide or something else interesting.  For example, I came across the name niacinamide with a similarity of 912, and a spectra that seemed fairly unique.  I did a quick google search on the name and (according to Wikipedia) it is a main ingredient in an acne medication and has shown to have anti-anxiety properties among other potential medicinal uses.  This type of peak find is made possible by the spectral deconvolution of the time-of-flight mass spectrometer.

I also mine through the data by taking advantage of the ordered chromatograms produced by GCxGC.  This means that compounds with a similar structure, or a homologous series, will elute in a band across the chromatogram.  I found another compound, lupeol, which is a triterpenoid that has been noted to have several medicinal properties.  By looking at peaks that are eluting near lupeol, I found sitosterol which is a phytosterol that may reduce cholesterol.

While I don’t have standards to positively confirm peak identity, a high NIST match similarity with a spectra that contains abundant high m/z ions increases my confidence in the peak assignments.  I really enjoy digging through the data and seeing if anything interesting pops up.  Using GCxGC-TOFMS can give you A LOT of data to mine through, but with spectral deconvolution and ordered chromatograms, it makes it much easier.

The NIST library spectra, the peak true (spectral deconvoluted) and caliper spectra all show a high match similarity for Niacinamide

The NIST library spectra, the peak true (spectral deconvoluted) and caliper spectra all show a high match similarity for Niacinamide

 Sitosterol and Lupeol have a similar structure and elute in a band in the GCxGC-TOFMS chromatogram

Sitosterol and Lupeol have a similar structure and elute in a band in the GCxGC-TOFMS chromatogram

I ain’t feelin’ the blues today…St Louis Metabolomics Symposium

I just returned from the St Louis Metabolomics Symposium that was held earlier this week. The event was sponsored by LECO, AB SCIEX, Gerstel, Monsanto and Restek. Metabolomics is the study of the small molecules or metabolites resulting from specific cellular processes. The idea is that metabolite profiles can help reveal biological processes including disease mechanisms. The presentations were interesting and covered different aspects related to the analytical chemistry of metabolomics…ranging from ion mobility separations to database informatics. The speakers have graciously allowed me to post their presentations on ChromaBLOGraphy. See the links below.
I spend most of my time working on food safety projects…sometimes delving into an environmental project. It is a logical move because both test for compounds like pesticides and PAHs. Every once in a while I get to help on something a little more exotic and unfamiliar like helping my colleague Jack Cochran with a GCxGC metabolomics project last year. It was fun because I got to do something totally different. I did a lot of reading and asked plenty of questions. While reviewing a GCxGC chromatogram, I asked “why is it so skinny?”. This piqued (no pun intended!) my interest and resulted in a simple idea…using general chemistry and selectivity to use more of the GCxGC space, “fatten” the chromatogram, for metabolomics relevant compounds…the goal was to take advantage of this technique…like Jack and Mark Merrick of LECO have done with their true peak capacity increase studies.

You can see the results for yourself in my presentation…and be sure and check out the other presentations, too.



High Resolution GC-MS for Metabolomics Applications

Vladimir V. Tolstikov; Lilly Research Laboratories


Analysis of Lipids using SelexION Technology

Fadi Abdi, AB SCIEX


Metabolomics in agricultural research: Expanded applications and database capabilities for volatile compound capture and tracking  –

Kirsten Skogerson, Monsanto


Investigating GCxGC Separations Using Selective Column Chemistry and Compound Derivitization Pairings for Common Metabolomics Compound Classes –

Julie Kowalski, Restek


Comprehensive GCxGC-MS for Eukaryotic Metabolomic Studies –

Dr. Mark Styczynski, Georgia Institute of Technology



First GCxGC Separation of PAHs Triphenylene and Chrysene, and Benzo [b], [k], and [j] fluoranthenes Using the New Rxi-PAH GC Column

Polycyclic aromatic hydrocarbons (PAHS) are carcinogenic, mutagenic, and teratogenic environmental contaminants.  But not all PAHs are created equal, so the European Food Safety Authority (EFSA) suggests analysis of the PAH4, benz[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene, to represent the majority of the toxicity in any food sample.  Unfortunately, some of these PAHs coelute with other isobaric PAHs on typical “5% phenyl-type” and other GC columns leading to erroneous quantification and overestimated toxicity.  Two of the most common coelutions are triphenylene and chrysene (m/z 228) and benzo[b] and benzo[j]fluoranthenes (m/z 252).  This led Restek to develop the Rxi-PAH GC column, which separates the EFSA PAH4 and other important PAHs.

While the “5% phenyl-type” is the most common GC column for environmental priority pollutant-type analysis, including for the 16 PAHs suggested for analysis by the US EPA, for those studies that require a different selectivity and higher efficiency, the 60m x 0.25mm x 0.10µm Rxi-PAH GC column may be an option.  Don’t expect ultra-fast analysis times, but the separations are excellent for comprehensive congener-specific PAH analysis (CCSPAHA).

In fact, they are so good in one-dimensional GC that I can report here the first simultaneous GCxGC separation for triphenylene and chrysene, and benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[j]fluoranthene.  I even threw in benzo[a]fluoranthene as a bonus.  The triphenylene and chrysene separation, especially, isn’t trivial here, but with a True Peak Capacity Increase GCxGC approach, i.e. a longer first dimension GC column, optimum flow rate in the first dimension, optimal GC oven program rate, a relatively short second dimension column, and fast modulation times, I’m able to pull it off!

To illustrate the point about quantitative error on PAHs, I use a Spring Creek soil extract that contains PAHs (kindly provided by my colleague Frank Dorman at Penn State University) and contrast the results using an Rxi-5Sil MS and those from the Rxi-PAH GCxGC analysis.  The Rxi-5Sil MS, like all 5% phenyl-type columns has a triphenylene/chrysene coelution and a benzo[b]fluoranthene/benzo[j]fluoranthene coelution, leading to high bias for chrysene and benzo[b]fluoranthene.  The Rxi-PAH, in contrast, provides accurate numbers because it separates the isobaric interfering PAHs.

Next up: one dimensional Rxi-PAH work on environmental samples.

PAH 01 PAH 02 PAH 03 PAH 05

GCxGC is the Star at 4th Multidimensional Chromatography Workshop!

My colleagues and I made the road trip to the Ontario Ministry of the Environment in Toronto for the 4th Multidimensional Chromatography Workshop.  This workshop organized by Eric Reiner at the MOE is a veritable who’s who in the world of GCxGC.  I personally love going to this workshop because of the wide variety of topics covered by not only excellent scientists, but engaging speakers as well (and it’s free).  The topics covered fundamentals of multidimensional chromatography, including alternative modulators, GCxGC (or as suggested GC×GC) nomenclature, and retention markers for two-dimensional chromatograms.   The program then switched gears towards applications of multidimensional chromatography, with a focus on comprehensive two-dimensional gas chromatography (GCxGC).  The first day included fire debris analysis, forensics, chlorinated dioxins and furans, and my personal favorite of GCxGC going to Mars! The second day started with a few talks on metabolomics, characterizing the odor of human decomposition (yum!), and novel halogenated contaminants in the environment.  The program is listed below, including links to some of the presentations (note how far many of these speakers traveled to Toronto in January!).

This workshop attended by over 160 people this year just keeps growing.  There seems to be a strong desire to continue to grow this workshop, which will require moving to a larger auditorium and possibly adding a third day of presentations.  It really shows that GCxGC is gaining familiarity across a broad range of possible applications.   If you are interested in learning more about comprehensive two-dimensional gas chromatography, or are just getting started, check out our GCxGC brochure (GCxGC Columns, Your One Source for 2D Chromatography).  The brochure has a handy column combination guide and some of the applications that we have done here in the lab.  We also have numerous posts about GCxGC here on ChromaBLOGraphy that you can view by either searching or clicking the GCxGC link under Categories on the sidebar. 

The 4th Multidimensional Chromatography Workshop  Jan 8 & 9 2013

Tuesday January 8, 2012:

Multidimensional Chromatography – past, present, future Philip Marriott, Monash University, Victoria Australia

Optimization Aspects of Comprehensive Two-Dimensional Gas Chromatography Tadeusz  Gorecki, University of Waterloo, Waterloo, ON

Study of complex VOC mixtures by GCxGC-TOFMS  Jef Focant, University of Liege, Liege Belgium

The Use of GCxGC TOFMS for Forensic Applications   Frank L. Dorman, K Organtini, J. Westland, E. Ly, A. Brockman, J. Stubleski, Penn State, State College PA, USA

Bidimensional Retention Normalization in GCxGC: Advances and Perspectives. Jean-Marie Dimandja, Spelman College, Atlanta GA, USA

High Speed Deans Switch for GCxGC Separations: Principles and Applications John Seeley, A, Ghosh, S. Seeley Oakland University, Rochester MI, USA

How soft ionization, high mass resolution and a comprehensive data analysis could further enhance the significance of GCxGC-TOFMS.  Thomas Gröger, M. Schäffer, M.Saraji, M. Sklorz, M. Eschner, J. Wendt, R. Zimmermann, Helmholtz Zentrum,  Munich Germany

GCxGC-TOFMS for Chlorinated Dioxin and Furan Analysis in South Africa, Jack Cochran, EJ Reiner, T. Kolic, K. MacPherson, L. Quinn, M. Brits, C. Swiegelaar, J. de Vos, P. Gorst-Allman, Restek, Bellefonte PA, USA

Time controlled Cryogenic Zone Compression (t-CZC) GC-HRMS – can we detect attogram amounts of TCDD?   Dirk Krumweide, Thermo Fisher, Bremen Germany

  Identification of New Markers of Wood Smoke Exposures in Firefighters using GCxGC-TOF-MS- Sujan Fernando and Brian McCarry, McMaster University, Hamilton ON

Analysis of blubber extracts of Peponocephala Electra by GC x GC-high resolution TOF-MS.  Teruyo Ieda, Gerstel Japan

GCxGC for Space Science – Opportunities and Challenges for Deep Space Organic Analysis.   Mark Libardoni, Southwest Research Institute, San Antonio TX, USA


Wednesday January 9, 2012:

Using GCxGC-TOF/MS to elucidate metabolome differences in complex biological matrices.  Catherine Rawlinson, Joel P. A. Gummer, Robert D Trengove,  Murdoch University, Perth Australia

Identifying biomarkers of P. aeruginosa antibiotic susceptibility using GCxGC-TOF and Statistical Compare.  Heather Bean, JM Dimandja, J.E. Hill University of Vermont, Burlington, VT, USA

Investigating GCxGC separations using selective column chemistry and compound derivatization pairings for common metabolomics chemical compounds Julie Kowalski, Michelle Misselwitz, Jack Cochran, Restek, Bellefonte PA, USA

Benefits of GCxGC-TOFMS approach for chemical characterization of environmental risk factors in the Sudden Infant Death Syndrome (SIDS) and Sudden Intrauterine Unexplained Death (SIUD)  Daniela Cavagnino, A. Siviero, A. Mantegazza,V.Termopoli, P. Palma, G. Famiglini, A. Cappiello, Dani Instruments, Italy

Multidimensional LC for shotgun proteomicsor Proteomics. Herman Lam, Ivan Chu, Ricky Ng, Ricky Kong, S.O. Siu, Maggie Lam, Yuen Zhao and Edward Lau. CVG, Toronto, ON

Planar Microfluidics in Multidimensional Chromatography, H.J. Cortes, R. Shellie, J.Luong, K. Parlevliet. H. J. Cortes Consulting, LLC., Midland, MI. USA

Further exploration in the quest of orthogonally  PH Stefanuto, JM Dimandja, JF Focant,  University of Liege, Liege Belgium

Characterizing human decomposition odour: an application of Thermal Desorption-GCxGC-TOFMS, Sonja Stadler, PH Stefanuto, M Brokl, JF Focant, S Forbes University of Ontario Institute of Technology, Oshawa, ON

Making sense of the fume: GCxGC TOFMS analysis of mainstream tobacco smoke, M Brokl, L Bishop, C Wright, C Liu, K McAdam, JF Focant, : University of Liege, Liege Belgium

GCxGC Analyses of Naphthenic Acid Esters in Oil Sands Composite Tailings, Dave Bowman, B. E. McCarry, McMaster University, Hamilton ON

The Analysis of Mixed Bromo/Chloro Planar Compounds Produced as Combustion Byproducts  Kari Organtini, Frank L. Dorman and Mark Merrick, Penn State, State College PA, USA

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