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MEETING NEWS News from the 25th International Symposium —Cheryl M. Harris reports from Riva del Garda, Italy
2-D GC: Lots of might or just all hype? Heated discussion over whether twodimensional (2-D) GC is as powerful as its backers say dominated the ISCC conference. Leon Blumberg, a theoretician who once worked for Hewlett-Packard and is now a consultant in Maryland, questioned claims about the method’s strengths, such as sensitivity and optimization. In most cases, researchers are misrepresenting its potential, he says. Blumberg’s comments had researchers, who were ready to challenge him, shifting restlessly in their seats during his lecture. At a separate seminar, some scientists left the conference room early. Others said they were frustrated because they didn’t spend more time talking about the subject. The technique, invented by the late John Phillips at Southern Illinois University in the early 1990s, uses two separations columns in series. Advocates say its major advantages over single-column GC are its very high separation power, enhanced sensitivity, and structured chromatograms.
on Capillary Chromatography (ISCC)
Australian chromatographer Philip Marriott says he and many others are confident that the method is much stronger than conventional GC. For example, he says, he and his colleagues have run samples through normal GC and noted that some peaks are almost lost in the baseline. When they repeat the same injection with the same concentration of sample using 2-D GC, they get peaks 15, 20, or 30 times more intense. “Now, for us, that means [there’s] more sensitive detection,” he says. One issue Blumberg raises is that researchers have deliberately made 1-D GC look inferior. He saw examples of this at the conference, he says. “Nobody demonstrated by practical, experimental data that there is an improvement in sensitivity— and theory says that there shouldn’t be. That part of my statement, I believe, was the most controversial.” Also, he adds, some people say that the improvement in peak capacity between conventional GC and 2-D GC is so “huge” that one doesn’t need to optimize. “This is not true,” he says. “Find out what is the best you can do with one-dimensional GC, and then
compare improvements on top of that. So, don’t make one-dimensional GC intentionally look bad.” According to Blumberg, 2-D GC doesn’t provide “more room” for peaks; it provides a more sophisticated pattern for peaks to be laid out in two dimensions, allowing one to identify groups of compounds, he says. “But don’t tell me that on that chromatogram there are many more peaks than in [a] onedimensional chromatogram.” Marriott, however, argues that there is improved sensitivity, peak capacity, and the ability to fingerprint in two dimensions, which clearly shows the advantage of 2-D GC over conventional GC. But perhaps part of Blumberg’s objection is semantics, adds Marriott, and maybe saying there is increased detectability, rather than sensitivity, is a better way of rephrasing it. “These things are things that, again, we never had to think about in one dimension,” he says. “But now we’ve got the opportunity to think about them, and maybe the . . . truth will be revealed. It’s out there somewhere.”
26th International Symposium on High-Performance Liquid-Phase Separation and Related Techniques (HPLC 2002)—Cheryl M. Harris reports from Montreal, Canada
News from the
Capturing the entire separations process Jiaqi Wu and colleagues at Convergent Bioscience (Canada) present an analyzer that expands isoelectric focusing (IEF) applications through imaged capillary isoelectric focusing (Imaged cIEF). The analyzer offers whole-column detection and real-time monitoring of the IEF focusing process and the final focus pattern of proteins and peptides in a capillary column under free-solution conditions. “The most distinctive aspect of our technology is that we image, or capture, the separation process in its entirety within the separation pathway,” says company President Arthur Watson. 410 A
For instance, says Watson, in conventional separation detection using HPLC, or even CE, the analytes are separated and flow past a point detector. “In our case, we have a [charge-coupled device] camera that takes a picture of the entire separation path at once.” Imaged cIEF’s separation peak pattern is essentially comparable with that of slab gel IEF, but the new technique offers the advantages of a column-based separation method, such as higher analysis speed (up to 8 samples/h), automation, ease-of-use, and quantitation, say company officials. Compared with ionexchange chromatography, Imaged cIEF offers higher analysis speed and resolu-
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tion, and an Imaged cIEF separation method can often be developed in
