Optimization of Test Conditions of HJ 741-2015 and Application on Detection of 27 Volatile Organic Compounds in Soil

In order to improve the low recovery of volatile organic compounds (VOCs) in soils with different matrices, the extraction, headspace and gas chromatography conditions of HJ 741-2015 were optimized. When extracting samples, 0.20 mL of methanol was added as extractor. Meanwhile, the difference between headspace pressure and pre-column pressure in headspace conditions was optimized to be 0.02 MPa. For chromatographic conditions, the flow rates of carrier gas, combustion gas and auxiliary gas were 1.2, 40, 400 mL·min^-1, and the split ratio was 4∶1. Under optimized test conditions, recoveries of 27 VOCs obtained by standard addition method changed from 53.8%-114% obtained by HJ 741-2015 to 82.2%-103% (especially for VOCs with low sensitive or high boiling point such as 1,1,2-trichloroethane, dibromo-chlorothane, tribromomethane,1,4-dichlorobenzene, 1,2-dichlorobenzene and 1,2,4-trichlorobenzene). Detection limits (3s/2) were reduced to 1.00-6.97 μg·kg^-1, and RSDs (n=6) of the determined values were reduced to 0.50%-6.8%, indicating that the proposed method was suitable for the detection of VOCs in soil samples with different matrices.