Analysis of volatile sulphur compounds in breath by gas chromatography-mass spectrometry using a three-stage cryogenic trapping preconcentration system

A method for the determination of trace volatile sulphur compounds (VSCs) i ncluding methanethiol, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) at low ppbv (volume/volume) in breath has been developed using a large vol ume preconcentration technique prior to capillary GC-MS analysis. The breat h sample was collected in a 6-l fused-silica-lined stainless steel canister and introduced into the three-stage cryogenic trapping preconcentration sy stem by GC-MS in the total ion monitoring (scan) mode. The water condensati on effect of breath sample inside the canister, which is due to the differe nce between human body temperature and laboratory temperature, was examined . The condensed water in the fused-silica-lined canister at 24 degreesC did not affect the recoveries of VSCs within 12 h. As this three-stage cryogen ic trapping preconcentration. technique made it possible to remove excess w ater {relative humidity (RH) > 95%} and carbon dioxide (3.8%) without loss of the VSCs, more than 400 ml of the breath sample could be concentrated. T he detection limits of methanethiol, DMS and DMDS in a breath sample using this method were 0.13, 0.09 and 0.15 ppbv, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.