Analysis of the State of the Art: Gas Chromatography Instrumentation

Aug 01, 2012

In honor of LCGC's celebration of 30 years covering the latest developments in separation science, we asked a panel of experts (listed in the sidebar) to assess the current state of the art of gas chromatography (GC) instrumentation and to try to predict how the technology will develop in the future. This article is part of a special group of articles covering the state of the art in sample preparation, GC columns, GC instrumentation, liquid chromatography (LC) columns, and LC instrumentation.

The Future of Fast GC

GC Instrumentation Expert Panel
We started by asking our expert panel about some of the latest methods, including fast GC. All our experts agree that the future for fast GC is bright. Naturally, chromatographers would like to get their results faster with lower consumption of carrier and detector gas. Also, fast GC is synergistic with the shift from helium to hydrogen carrier gas, and it can increase overall sample throughput. This speed is particularly valuable in applications like high-throughput screening.

The main route toward faster GC analysis, note Paola Dugo, Luigi Mondello, and Peter Q. Tranchida of the University of Messina, is to use microbore capillaries. Such an approach is readily accessible, because most commercially available GC systems can provide the required instrument performance needed when using such columns. Also, microbore capillaries with a 0.1-mm internal diameter are now available with a wide variety of stationary phases. "All this means that it is now possible to shorten analyses times by a factor of 4–5 times, with no price to pay in terms of resolution," they say.

But there are challenges with fast GC, notes John Hinshaw, a senior scientist at BPL Global and a longtime columnist for LCGC. For example, the instrumentation must present the column with fast enough injection speeds and rapid column oven program rates while capturing the resulting fast peaks. Also, existing methods must be translated to preserve peak order, and they still may require revalidation. Lastly, he says, narrow-bore thinner-film columns may have reduced sample capacities and injection-volume limits that require adjusted sample concentrations and volumes.

Fast GC can also get bogged down by slow sample preparation or delays in cooling the oven at the end of the run. "There's no point in a 2-min fast GC run if it is accompanied by a 6-min oven cool down," says Alastair Lewis of the University of York. This points the way, he says, toward resistively heated columns, but with really low thermal masses. "The annual energy savings for labs could turn out to be the clincher here, rather than better analytical capability."

Nor will fast GC solve problems of poor resolution, notes Frank Dorman of Penn State University. "Fast GC really needs to be coupled with the optimization of the other GC parameters, most notably the selectivity of the stationary phase," he says. "This is especially true for targeted separations, which is where more of the fast GC applications have been directed." So he predicts that fast GC will remain a niche technique for the short term. "But that could change if we move away from 30-m fused-silica columns," he adds.

Hans-Gerd Janssen of Unilever Research and Development argues that there is not that much need for fast GC. A standard GC run including cooling, reconditioning, and cleaning the syringe, rarely takes more than 45 min, he points out, which means at least 30 unattended runs can be done in one day. "For most laboratories, that is enough and more than the analyst can handle in sample preparation and interpretation," he says. "Also, there are not many laboratories that need a short time between arrival of the sample in the laboratory and the results being available."