Headspace membrane extraction combined with multiplex gas chromatography and mass selective detector for monitoring of volatile organic compounds

Abstract

A new analytical method, the membrane extraction with a sorbent interface (MESI) technique in multiplex mode combined with a gas chromatograph/mass selective detector (GC/MSD), has been developed to allow rapid screening analysis and long-term on-line monitoring of volatile organic compounds (VOCs). The advantages of the multiplex MESI system include simplicity, durability, low cost, time efficiency, elimination of solvents, and easy automation. The headspace membrane extraction configuration effectively eliminates the need for a sampling pump and flow metering thus prevents the extraction system from plugging and greatly simplifies the extraction process. The sorbent interface minimizes the loss of analytes by directly connecting the membrane extraction module to the GC/MSD. The sensitivity of the system is significantly enhanced due to the multiplex and high sample throughput advantages. The multiplex technique also reduces the demand on the sorbent interface which allows the use of a simpler interface than the MESI batch technique. The use of a MSD in the selective ion monitoring (SIM) mode not only selectively detects minor components in a sample, but also leads to a significant improvement in the system sensitivity. The MESI program provides an easy-to-use graphical user interface for system automation from sample introduction to report preparation. At optimum experimental conditions, the limit of detection for trichloroethylene in water was 0.5 μg/L, and a RSD below 6% was achieved in the SIM mode. Parameters influencing the sensitivity and precision of the system were studied. Quantitative contaminant determination of a soil leachate sample was performed with the standards addition method. A fumehood air sample was also analyzed using the new method. © 1996 John Wiley & Sons, Inc.