Identification limits for volatile organic compounds in the blood by purge-and-trap GC-FTIR

An analysis method for volatile organic compounds in blood based on purge-and-trap extraction coupled with gas chromatography-Fourier transform infrared spectroscopy (GC-FTIR) was developed. The sample volume was 5 mL, and the internal standard was diethyl ketone. The chromatographic separation was carried out on a PoraPLOT Q capillary column, and the effluent was first directed to the FTIR and then to a flame ionization detector (FID). FTIR identification limits were measured for 27 volatile organic compounds; the criteria for the limit were that the first hit-list position should be obtained against the Sadtler library, which contains 3240 spectra, and that the correlation value should exceed 0.5. It was required that the peak be seen by FID but not necessarily by a Gram-Schmidt chromatogram. The FTIR identification limits, ranging from 0.01 mg/L for ethyl acetate, methylethyl ketone, and sevoflurane to 24 mg/L for methanol, generally allowed the detection of volatile-substance exposure at a lower level than is acutely toxic. Quantitative calibration data were presented for selected substances, based on the FID response, which shows that the method is also amenable to quantitative analysis. The throughput of the method without additional automation is five samples per day, the purge-and-trap stage being the limiting factor.