【摘要】 将采集的土壤样品混匀并除去混入的异物,置于冷冻干燥机中脱水后研磨混匀,封存于干燥器中备用。取此样品20.00g,与硅藻土3.00g和硅镁吸附剂3.00g掺拌均匀。在加速溶剂萃取（ASE）仪的萃取池的底部铺垫硅镁吸附剂3.00g,将上述样品混合物定量移入于此池中,于其上面铺盖一层石英砂和加盖一张滤纸片。按设定条件以体积比为1∶1的二氯甲烷-正己烷混合溶液作为萃取溶剂,在90℃萃取2次。将所得萃取液合并并吹氮浓缩至体积小于1mL,加正己烷定容至1.0mL。此溶液作为试液进行气相色谱分析,测定其中19种有机氯农药（OCPs）的含量。色谱分析中,进样量为1.0μL,选择HP-5LTM和DB 1701LTM两种极性不同的色谱柱,按程序升温条件对目标物进行分离。采用双电子捕获检测器（ECD）,前ECD接在HP-5LTM色谱柱后,后ECD接在DB 1701LTM色谱柱后,经两种色谱柱分离,测定所制得标准曲线的线性范围均有两个相同的区段,即5～100μg·L^-1和100～1 000μg·L^-1。19种OCPs的检出限（3.143s）为0.15～0.56μg·kg^-1。如果目标物在两种色谱柱上的测定结果差异大于5倍,则判定此结果为假阳性;如差异小于5倍,则确定该化合物存在,并以数值较小者为测定结果。精密度试验测得目标物测定值的相对标准偏差（n=6）为2.7%～15%。用本方法分析了土壤标准物质（CRM818-50G）,所测得19种OCPs的结果均在认定值范围内。更多还原

【Abstract】 Sample of soil was collected and mixed thoroughly.After picking out foreign matters,the soil sample was dehydrated,homogenized by grinding and sealed up to keep in a desiccator for use as analytical sample.20.00 g of the sample were intermixed with 3.00 g of diatomite and 3.00 g of the adsorbent,Magnesol and then the sample mixture was transferred into the extraction cell upon a layer of silica-magnesium adsorbent（3.00 g）which was spread on the botton of the cell preliminarily.After spreading a layer of quartz sand and a piece of filter paper on the surface of the sample,ASE was carried out twice by the ASE extractor according to the predetermined program using a mixed solution of dichloromethane-n-hexane with the volume ratio of 1∶1 as extraction solvent at 90 ℃.The extracts were combined and evaporated by N₂-blowing to a volume less than 1 mL,and after cooling,the volume of the solution was made up to 1.0 mL with n-hexane.19 organochlorine pesticides（OCPs）were enriched in this solution and to be determined by the gas chromatography method.A sample injection volume of 1.0μL was adopted in the gas chromatography procedure and 2 chromatographic columns with different polarity [i.e.HP-5 LTM chromatographic column and DB 1701 LTM chromatographic column,each of the chromatographic columns was connected with an electron capture detector（ECD）]were used in the gas chromatography separation.Standard curves were prepared with mixed standard solution of the 19 OCPs by gas chromatography separation and determination on each of the 2 chromatographic columns,giving same linearity ranges in 2 mass concentration sections of 5-100μg·L^-1 and 100-1 000μg·L^-1.Detection limits（3.143 s）found for the 19 OCPs were in the range of 0.15-0.56μg·kg^-1.If the difference between results determined by the 2 chromatographic columes for a same analyte came cut to be larger than 5 times,the result should be judged as "false positive";and if the difference was less than 5 times,the analyte was determined to be existing,and the smaller one of the 2 data should be taken as the result of determination.Values of RSDs（n=6）found by precision test for the 19 OCPs were ranged from 2.7%to 15%.A CRM of soil（CRM 818-50G）was analyzed by the proposed method,results of the 19 OCPs found were all within the limited ranges of certified values.更多还原