e d i to ri a l
Enabling Fast GC Separations T
his Analytical Frontier Editorial has a different twist from those in the past. This one focuses on how the analytical community got to where it is, scientifically speaking, in fast GC separations. Other Editorials, yet to come, will reiterate this theme of “How did we get here?” When behind-the-scenes advances make a higher-profile technology workable or successful, technologists call it “enabling technology”; it’s really “enabling science and technology”. Fast GC today can achieve separations on time scales of a few seconds and less. What developments have made this possible? What do you need for a fast GC separation, generically speaking? The column should be short and the mobile phase velocity high. The sample must be injected on a time scale that is small in comparison with the separation time, and the detector must have a fast response to keep up with the sample peaks going by. Rapid separation usually does not mean high-resolution separation— one is giving up some resolving capacity for speed—but a useful level of resolution is necessary. These generic things can also be said about LC and CE, but here I focus on how fast GC has been enabled. A first major step, around 1958, was the conceptual advance by Golay, who set out the idea of open-tubular columns. Because these columns had lower back-pressure than packed columns, they allowed the use of higher carrier-gas velocity, yet they retained most of the column efficiency. The fast carrier-gas flow enabled faster separations. Much smaller inner diameters were required of these “capillary columns”, and this presented materials issues (fragility, straightening) until Dandeneau, in the late 1970s, described flexible, robust, fused-silica open-tubular columns. These columns attracted much wider interest in opentubular columns, which have evolved to the fused-silica “microbore” columns with inner diameters
