HJ 741-2015试验条件的优化及在土壤中27种挥发性有机物检测中的应用

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

为改善不同基质土壤中挥发性有机物(VOCs)回收率偏低问题,优化了HJ 741-2015中提取、顶空和气相色谱条件。在提取样品时,加入0.20 mL甲醇作提取剂,同时优化顶空条件中顶空压力与柱前压力差为0.02 MPa,色谱条件中载气、燃气、助燃气流量分别为1.2,40,400 mL·min^(-1),分流比为4∶1。在优化的试验条件下,27种VOCs的加标回收率由HJ 741-2015的53.8%~114%变为82.2%~103%(特别对于1,1,2-三氯乙烷、二溴一氯甲烷、三溴甲烷、1,4-二氯苯、1,2-二氯苯、1,2,4-三氯苯等低灵敏或高沸点VOCs),检出限(3s/2)降至1.00~6.97μg·kg^(-1),测定值的相对标准偏差(n=6)降至0.50%~6.8%,适用于不同基质土壤样品中VOCs的检测。

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 741-2015were optimized.When extracting samples,0.20mL 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 1.2,40,400mL·min^(-1),and the split ratio was 4∶1.Under optimized test conditions,recoveries of 27VOCs obtained by standard addition method changed from 53.8%-114%obtained by HJ 741-2015to 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 1.00-6.97μg·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.