固相萃取-气相色谱法测定沉积物中六氯环己烷、双对氯苯基三氯乙烷的残留量

Determination of HCH and DDT residues in sediments by solid phase extraction with gas chromatography

通过对样品前处理方法和气相色谱条件的改进,建立一套稳定的沉积物中六氯环己烷、双对氯苯基三氯乙烷残留的气相色谱检测方法,满足实验室批量测定样品的要求。选择40 mL正己烷和丙酮混合液(V正己烷∶V丙酮=1∶1)作为提取液,并加入2 g铜粉去除硫化物,用Florisil SPE小柱和Carbon-GCB SPE小柱串联净化,采用10mL正己烷和丙酮混合液(V正己烷∶V丙酮=9∶1)进行洗脱,浓缩后用DB-1701气相毛细管柱分离,用带电子捕获检测器的气相色谱仪(GC-ECD)检测,外标法定量。本研究选择沙质性状的沉积物作为基准进行加标回收实验,平均回收率在74.5%～92.0%,相对标准偏差在3.09%～6.67%;检出限为α-HCH:1.96×10-4 mg/kg,β-HCH:1.45×10-6 mg/kg,γ-HCH:1.90×10-4 mg/kg,δ-HCH:1.98×10-4 mg/kg,p,p'-DDD:2.47×10-6 mg/kg,o,p'-DDT:1.08×10-4mg/kg,p,p'-DDE:1.59×10-4 mg/kg,p,p'-DDT:2.52×10-4 mg/kg。采用泥质性状的沉积物对本方法进行验证,加标回收率和相对标准偏差都符合沉积物样品的药残检测要求。研究亮点:采用固相萃取-气相色谱法测定沉积物中六氯环己烷、双对氯苯基三氯乙烷的残留量,溶剂用量少,操作步骤简单,与同类方法相比较,该方法大大提高实验室批量样品的检测效率。本方法净化效果好,灵敏度高,样品加标回收率达到70%以上,相对标准偏差小于10%,且重现性好,符合沉积物样品的药残检测要求。

A steady detection method for HCH and DDT residues in sediments is developed by improving the front disposal measure and chromatogram condition,which accords with the requirements of laboratory measurement for batch samples.The sample is extracted by acetone-hexane（1∶1） mixture with 2g copper for removing sulfide.The extraction is purified by Florisil SPE column and Carbon-GCB SPE column and eluted by acetone-hexane（1∶9）mixture.The concentration is analyzed by gas chromatograph equipped with DB-1701 column,quantified by the external standard method.The average recovery of added test in sandy sediments is between 74.5% and 92.0%,and the RSD% is between 3.09% and 6.67%.The detection limit is：α-HCH：1.96×10-4 mg/kg,β-HCH：1.45×10-6 mg/kg,γ-HCH：1.90×10-4 mg/kg,δ-HCH：1.98×10-4 mg/kg,p,p′-DDD：2.47×10-6 mg/kg,o,p′-DDT：1.08×10-4 mg/kg,p,p′-DDE：1.59×10-4 mg/kg,p,p′-DDT：2.52×10-4 mg/kg.The method is verified by the added test on muddy sediments,and the recovery and RSD% meet the detection requriements of pesticides residue in sediments.