Measurement of Organic Vapors at Sub-TLV® Concentrations Using Fast Gas Chromatography

Abstract

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.

Performance evaluation of a surface acoustic wave analyzer to measure vocs in air and water

“…BTEX (Benzene, Toluene, Ethylbenzene and Xylene) compounds (1-4) are important components of gasoline and are typically encountered in Leaking Underground Fuel Tanks (LUFT) at garages or fuel depots. The second group (5)(6)(7)(8)(9)(10)) is representative of a large class of chlorinated hydrocarbon compounds (CHC). These analytes are often encountered as DNAPL (Dense Non-Aqueous The LOD, MDL, and PQL parameters were determined by taking appropriate replicate measurements.…”

A Gas Chromatographic Continuous Emissions Monitoring System for the Determination of VOCs and HAPs

“…6 However, its use as a multicomponent, completely automated continuous emissions monitor is not documented in the literature.…”

Cryogenically Cooled Microloop System for Sampling and Injection in Fast GC

“…Unfortunately, all of these approaches result in only a small portion of the original sample being injected onto the column, making them inadequate for the analysis of trace samples. A more efficient means of minimizing injection band duration has been developed by Sacks and co-workers. ,− In their technique, compounds in the gas phase are cryofocused onto metal tubes, followed by ballistic heating of the tube to ∼200 °C in a few milliseconds. The trapped compounds are rapidly vaporized and injected into the chromatographic column with a band duration on the order of 10 ms.…”

“…A more efficient means of minimizing injection band duration has been developed by Sacks and co-workers. 13,[16][17][18][19][20][21][22][23][24][25] In their technique, compounds in the gas phase are cryofocused onto metal tubes, followed by ballistic heating of the tube to ∼200 °C in a few milliseconds. The trapped compounds are rapidly vaporized and injected into the chromatographic column with a band duration on the order of 10 ms.…”

“…The trapped compounds are rapidly vaporized and injected into the chromatographic column with a band duration on the order of 10 ms. Initially, this interface was used to focus sample plugs from a split injector, but it also has been used for gas samples taken from loops 19,20 and bags. 24 The latter applications allow sampling of larger volumes, resulting in higher analyte signals for a given concentration.…”