Technology Forum: GC

This month, Chromatography Online's Technology Forum looks at the topic of GC and the trends and issues surrounding it. Joining us for this discussion is Sky Countryman of Phenomenex, Nicholas H. Snow of Seton Hall University, John Hinshaw of Severon Corp., and Meredith Conoley, Jason Cole, Eric Phillips, Joergen Olsson, and Flavio Bedini from Thermo Fisher Scientific, Inc.

What trends do you see emerging in GC?

Countryman: The major trends in GC are faster analysis and better resolution of complex mixtures. In some ways, they go hand in hand. Because the primary goal of GC is separation, you can only go as fast as you can achieve adequate resolution. But everyone is looking to save time.The system manufacturers have focused on giving people faster temperature ramp and higher pressure capabilities that are needed when using fast GC columns. Using columns with internal diameters less than 0.25 mm such as 0.18 mm and 0.10 mm offer significant gains in efficiency and can often lead to shorter analysis, while maintaining the same resolution.When it comes to shortening GC analysis, MS is a very useful tool. Working with complex samples leads to co-elutions between target analytes and matrix interferences, which can limit optimization. In such cases, the MS gives positive confirmation for your target compounds even if there are many co-eluting peaks. This problem is common in food testing and we have been doing work with the US FDA where we are resolving more than 350 pesticides in one analysis. We use SIM mode to achieve detection limits similar to ECD, but the MS gives us the positive confirmation. Of course, this type of analysis requires the right combination of GC column technologies and fast scanning instrumentation, but it gives labs the opportunity to really increase their productivity.

Snow: Today's trends in GC have been developing over the past several years and mirror those of analytical chemistry at large. The main trends are toward analyses that are faster, easier to perform, have lower detection limits, and more reproducible quantitation.The need to examine increasing numbers of impurities and contaminants at increasingly lower levels will drive quality assurance and environmental analysis in the coming years. GC has a continuing and strong role to play as it provides the best combination of cost, separation power, and resolution of any chemical analysis technique on the market today.

Hinshaw: Two major trends in gas chromatography today are comprehensive GCxGC and instrument miniaturization. Comprehensive GCxGC subjects an entire sample to serial two-dimensional analysis on two columns which have complementary separation characteristics, usually one nonpolar and one polar. This tremendously increases the total peak capacity relative to either column taken separately, so that many previously unresolved substances can be separated effectively. Even so, the sheer number of peaks in, for example, a complex petroleum sample, can be so large that interpretation of GCxGC results becomes quite complicated; analysts often are forced to group peaks into typed classes such as linear alkanes, aliphatics, aromatics, polycyclics, and so on. Advances in the instrumentation and applications of GCxGC continue to be made, and this technique will hold the attention of chromatographers for some time to come.Miniaturized GC instruments are making rapid progress, in the form of micromachined GCs as well as portable units that are larger in size but still considerably smaller than classical lab systems. The very small analyzers tend to be application specific, in large part because they owe a great deal of their small proportions to the removal of common lab instrument features that support a multiplicity of configurations. It's also difficult to change columns or detectors on an instrument where the entire separation and detection package is the size of a credit card. Portable GCs - about the size of a modern digital oscilloscope - support two or more separation modules that are fairly simple to change, although many users simply set them up for a single application with no intention of re-purposing them later. The attractiveness of miniaturized GC instruments lies both in their more efficient use of lab space and in the ability to take the analyzer to a site instead of taking a sample back to the lab.

Thermo Group: Today's laboratories, regardless of application area, remain under enormous pressure to perform productive work. Lowering the cost per sample is critical and can be achieved by a number of avenues. Accessories that automate sample preparation can reduce the amount of time required to make a sample ready for analysis, and can dramatically cut back on the time that laboratory staff need to spend on the extractions and preparations. Increasing the speed of analysis and reducing the need for intensive sample preparation can also drive down cost per sample. Finally, improving software to reduce the time requirements of moving from data to reporting can enhance productivity by reducing the time required to review data and generate reports.In addition to driving toward improved productivity, advances in multidimensional separations offer improved detection in complex matrices and provide a more complete view of sample components than can standard gas chromatography. Continued development of GCxGC techniques stands to provide information-rich chromatographic data.

Are you expecting any new developments at Pittcon 2008?

Countryman: I'm not expecting to see any major developments on the system side, but I am expecting to see many more application specific testing devices. More and more people are looking for "turn-key" systems for things such as biodiesel.The advances this year will most likely be from the consumable manufacturers in the way of new GC columns that offer better resolution for problematic analytes.

Snow:At Pittcon 2008 I will be looking for even more new developments than we have seen over the past few years.I expect to see all of the manufacturers introducing new and improved technologies that take advantage of the separation power of capillary columns. It is important to remember that fused silica capillary columns were invented less than 30 years ago, a relatively short time in the life cycle of instrumentation development. Only in the last 10 years or so have instruments that take full advantage of capillary columns been routinely available.In instrumentation, I will be looking for advances in flow control, rapid oven heating and cooling and pneumatic options that allow greater access to short, fast capillary columns, and multi-dimensional separations. GCxGC and LCxGC are becoming more main stream. I will also be looking for simplified instruments that bring advanced capabilities such as PTV injection, on-line and automated sampling, and multidimensional separations to users at lower costs and learning curves.I will also be looking for further simplified GC-MS systems at lower cost. GC-MS is underutilized in the market. One GC-MS can often replace the throughput of several GC's with the added advantages of MS as the detector.

Hinshaw:No, not really. GC in general is a mature technique that continues to experience technology increments such as comprehensive GCxGC and micromachining techniques. Last year saw the introduction of a number of new or upgraded classical lab-size instruments from the large instrument companies, so I don't expect much in this regard in 2008. However, there have been a number of preliminary announcements of incremental developments that will be very interesting to watch.

Thermo Group:We would expect to see little in terms of the technology itself, except in terms of continued incremental development. However, new advances and innovations in software and in GC accessories should be visible at Pittcon and other events in 2008 as companies evolve with the market.

What is the GC application area that you see growing the fastest?

Countryman: The food testing area is by far the fast growing area right now. With the recent problems with food contamination, countries have to do a lot more testing to prove their food is safe.I am also seeing a growth in the pharmaceutical market as the implementation date for the new USP revised Chapter approaches. As of July 1st, 2008 all companies selling drugs into the US will have to demonstrate that their products are compliant with the new requirements. Many of the smaller companies and especially the biotech companies may not even have GC systems, so they are rushing to get things set up.

Snow:GC is probably considered too mature a technique by most to expect phenomenal growth in any of its application areas. However, there seems to be increasing demand for product testing, environmental analysis and quality assurance analyses that directly relate to consumer and public safety. I see all of these as potential growth areas. The main challenge is that reliable analytical methods are often already in place, resulting in new instrument sales only as the old ones stop working, and many of the GC's that have been marketed over the past two decades have proven extremely reliable!

Hinshaw:Environmental analysis is undergoing a resurgence. Two major instrument companies have chosen to emphasize the environmental sector this year, and I would expect the trend to continue.

Thermo Group: Petrochemical applications, particularly in areas of biodiesel and biofuel characterization and analysis are a growing area for gas chromatography. As the energy demands in a global economy place increasing pressure on finding, developing, and commercializing biofuels and biodiesel, the need to analyze these products is increasing as well. Also, the last year has seen numerous news stories highlighting food safety and food analysis, including flavor and fragrance characterization. Gas chromatography has always played a key role in these application areas, and as public awareness grows, so too will the demand for accurate testing.

What obstacles stand in the way of GC development?

Countryman: The main limitation right now is sensitivity for GC-MS. More and more applications are moving to LC-MS-MS because they are able to analyze at much lower levels and without the need for derivatization. GC can achieve these detection limits, but only with analyte specific detectors such as ECD and NPD. Labs want the positive confirmation that the MS gives you. To stay competitive, MS sensitivity needs to be improved.

Snow:Packed column thinking. I think the biggest obstacle in the way of GC development is more perception than capability. Most chemists are trained to think of GC as only used for highly volatile analytes such as solvents, which was pretty much the case with packed columns.In seminars, I often ask the audience to name volatile compounds that they would analyze by GC and answers such as, "methanol, hexane, xylene" and the like. There are usually some shocked responses when I remind them that common drugs such as caffeine, estradiol and aspirin are also easily analyzed by GC.The capability of short thin film capillary columns, when coupled to an advanced inlet such as PTV or on-column, to separate and analyze labile, polar or high molecular weight compounds is underestimated by nearly the entire GC marketplace and thus also by the developers of instruments.

Hinshaw:Perhaps the largest obstacle for GC is competition with other analytical techniques for limited R&D funding. It's difficult to justify spending precious research funds on a technique that's viewed as "mature," even though significant developments continue to manifest.

Thermo Group: The remaining frontiers of development for GC in terms of innovation are incremental in value for the customer, as GC is seen as a mature technology. One limitation for new technology is seen in terms of inadequate data handling capabilities which stall the market uptake of GCxGC multidimensional technology.

What was the biggest accomplishment or news in 2007 for GC?

Countryman: I'm biased, but I think the biggest accomplishment in GC was the release of the ZB-Inferno columns, which are the first nonmetal GC columns able to withstand temperatures up to 430C! In fact, these columns were recognized as one of R&D 100's most significant innovations of the year, the first GC columns ever to win such an award.

Snow:In 2007, the introduction of the 7890 series GC by Agilent Technologies was probably the biggest news. For the past decade or so, since the introductions of electronic control of the pneumatics, developments in GC have tended to be incremental, with few big splashes, but still significant improvements. These have tended to evolve over several years. The 7890 appears to be a product of just such an evolution as many of the improvements incorporated into previous GC's as options or aftermarket products were incorporated.

Hinshaw:It's difficult to choose any one of the many incremental advances last year. Perhaps most significant was the attention garnished on GC by the instrument companies as evidenced by the fourteen new instrument and eight major accessories that were introduced to the market in 2007.

Thermo Group: Continued incremental development and new product releases for mainstream GC indicate that gas chromatography as a technique remains vital for today's laboratories.