Application of Stir Bar of Sorptive Extraction to Sampling of Residues of Combustion Adjuvants in Air over Fire Field

As a modification for the micro-adsorption sampling technique, a stir bar of sorptive extraction, having a length of 20 mm and coated on its surface with activated carbon and poly-dimethylsiloxane, was used in the sampling of residues of combustion adjuvants in air over fire field. The stir bar of sorptive extraction was placed into the holder in the front position of the sampling device, which was connected with the air pump at the rear. Sampling of the sample was accomplished under the following conditions:(a) flow rate of air pump was 50 mL·min^-1; (b) acquisition time was 60 s; and (c) acquisition temperature was 30℃. At the end of sampling, the stir bar of sorptive extraction was replaced into thermal separation probe of injection to have the sample of residues of combustion adjuvants for GC-MS analysis. As gasoline was the analyte and acquisition time of 60 s was taken, detection limit (5S/N) of the method of 0.1 μL·L^-1 was attained, and detection limit (5S/N) could be lowered to 1 nL·L^-1 when acquisition time of 300 s was taken. In analysis of 95^# gasoline, with volume fraction of 1 μL·L^-1, 400 characteristic compounds were detected from the TIC chromatogram with help of the soft ware AMDIS. Besides gasoline, aviation kerosene, diesel oil, ethanol and ethyl acetate were the 4 other combustion adjuvants, the residues of which were also be qualitatively analyzed by the proposed method.