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Evaluation of a nitrogen-cooled, electrically heated cold trap inlet for high-speed gas chromatography.

Gas chromatography has the potential to be a much faster method of separation than is usually realized. If column operating conditions are optimized for speed and injection band width is minimized, some simple separations can be completed in a few seconds. A prototype cryofocusing system for producing narrow injection bands with 0.25-mm i.d. columns is described here. The gas-cooled and electrically heated inlet produces injection bands with widths of about 10-20 ms. In the present study the system is evaluated using mixtures of common organics, including alkanes, aromatics, alcohols, ketones, and chlorinated hydrocarbons. Quantitative trapping and reinjection is achieved for all tested compounds. Coefficients of variation are less than 3% for peak area and less than 0.2% for retention time. Base-line separation of simple mixture is achieved with retention times of less than 10 s. By using the cold trap inlet with a low-dead-volume detector and a high-speed electrometer, the efficiency available from commercial capillary columns can be better utilized, and retention times for some routine separations may be reduced to a few seconds.