Measurement of organic vapors at sub-TLV concentrations using fast gas chromatography

Gas chromatography usually is considered too slow a method to be useful for real-time or near real-time monitoring. If the chromatographic system is optimized for speed, however, it is possible to reduce retention times significantly. Recently, a fast gas chromatograph (GC) was described that allows many simple separations to be completed in 10 sec or less. The system features a gas-cooled, electrically heated, capillary cold trap that focuses the sample as an extremely narrow band at the front of the column. In this study the fast GC was used to measure the concentrations of benzene, toluene, and xylene in test atmospheres generated in the laboratory. The measurements then were compared to simultaneous measurements made with a conventional GC. At concentrations ranging from the threshold limit value (TLV) to one-tenth of the TLV, the fast GC decreased retention times by a factor of 10- to 100-fold relative to the conventional GC, with no loss of precision or accuracy. These results indicate that it may be feasible to develop a high-speed monitoring system based on a GC design similar to the one in this study.