土壤中苯系物的吹扫捕集-气相色谱-质谱测定方法

Determination of Benzene and Its Analogies in Soil with Purge and Trap Gas Chromatography-Mass Spectrometry

采用吹扫捕集-气相色谱-质谱联用(PT-GC-MS)法,研究了污染土壤中苯系物(包括苯、甲苯、乙苯、对间二甲苯、邻二甲苯和异丙苯)的测定方法,优化了吹扫捕集作为北京潮土中苯系物预处理方法的参数.结果表明,吹扫时间11 min,解吸温度190℃和解吸时间0.5 min为最佳的吹扫捕集方法参数.采用PT-GC-MS法测定土壤中的苯系物的平均加标回收率为99.0%～103.9%,相对标准偏差为10.3%～17.5%(n=7);苯系物的检出限为1.6～2.8μg/kg,定量限为5.4～9.6μg/kg.将研究结果与文献中的苯系物监测质量控制参数进行比较发现,由于采用有机质含量低、砂质壤土质地的北京潮土为研究对象,使该试验的回收率均高于文献中的结果;同时,相对标准偏差和检出限与文献中的结果也存在差异,主要是由于挥发性污染物所赋存的介质及实验仪器操作条件不同所致.

BTEX（including benzene,toluene,ethylbenzene,m,p,o-xylenes and cumene） in soil were determined by Purge Trap Gas Chromatography-Mass Spectrometry（PT-GC-MS）.Extraction conditions for the PT technique for fluvo-aquic soils from Beijing were optimized through a series of tests.The results showed that the optimum PT technique conditions were purge time 11 min,desorption temperature 190 ℃ and desorption time 0.5 min.The range of average recovery was 99.0%-103.9%,the RSD was 10.3%-17.5%（n = 7）,and the detection and quantification limits were 1.6-2.8 μg /kg and 5.4-9.6 μg /kg respectively for the determination of BTEX in soil by PT-GC-MS.That recovery of BTEX was higher in this paper than that reported in other studies may be due to the fact that fluvo-aquic soil is a kind of silt and contains less organic matter.Differences of RSD and detection limits between this study and references may be caused by different phases of contaminants and operation conditions of the instruments.