索氏提取-全二维气相色谱法测定化工区江滩沉积物中20种有机氯农药和7种多氯联苯的含量  

Determination of 20 Organochlorine Pesticides and 7 Polychloro-Biphenyls in Sediments of Riverbank in Chemical Industry Area by Whole 2-Dimensional Gas Chromatography with Soxhlet Extraction

作　　者：吕爱娟[1] 时磊[1] 沈小明[1] 刘娇 蔡小虎[1] LüAijuan;SHI Lei;SHEN Xiaoming;LIU Jiao;CAI Xiaohu(Nanjing Center of Geological Survey,China Geological Survey,Nanjing 210016,China)

机构地区：[1]中国地质调查局南京地质调查中心,南京210016

出　　处：《理化检验（化学分册）》2020年第1期20-25,共6页Physical Testing and Chemical Analysis(Part B:Chemical Analysis)

基　　金：国家重点研发计划项目(2017YFF0206804)。

摘　　要：取污染区沉积物,除去其中的异杂物后充分混匀。称取混匀样品10.00g,加入适量经过在400℃烘烤4h的无水硫酸钠并充分混合拌匀,研磨成细粒状。将此样品全部装入滤纸套筒中,并置于索氏提取器中,加入体积比为1∶1的正己烷-丙酮混合溶液250 mL,在回流速率为10次·h^-1条件下提取8~12h(一般可采取多个样品同时提取过夜的操作方式)。收集所有提取液,混匀后将经活化处理的铜片置于此提取液中4~6h除去硫化物。过滤除去沉淀,滤液浓缩后经以硅酸镁为载体的固相萃取柱净化。用体积比为9∶1的正己烷-丙酮混合溶液15mL洗脱固相萃取柱,收集洗脱液经浓缩至1.0mL后,供色谱分离及测定。在此测定溶液中存在20种有机氯农药(OCPs)及7种多氯联苯(PCBs)共27种化合物。待测物在非极性一维TG-35MS色谱柱上按其沸点规律分离后,流出液经调制器聚焦后迅速升温(调制周期为4s)并送入极性二维DB-1色谱柱按被测物的极性差异分离。两柱的组合达到上述27种化合物的良好分离。采用电子捕获检测器对27种化合物进行检测。上述27种化合物的质量浓度均在1.0~200.0μg·L^-1内与其对应的峰面积之间呈线性关系,其检出限(3.14s)为0.017~0.087μg·kg^-1。按标准加入法进行回收试验,测得回收率为72.0%~96.3%,测定值的相对标准偏差(n=6)为2.1%~11%。Sediment from riverbank of polluted area was collected and after picking out those impurities(i.e.branches,leaves,stones etc.)which were mixed up in,it was mixed thoroughly and ready to be used as analytical sample.10.00 g of the sample were taken and mixed thoroughly with an appropriate amount of anhydrous Na2SO4,which has been baked at 400℃for 4 hbeforehand,and then ground to fine powdery state.The powder mixture was loaded completely into a sleeve made of filter paper,and the sleeve was replaced into the Soxhlet extractor,and extracted with 250 mL of a mixed solution of n-hexane and acetone with the volume ratio of 1∶1 for 8-12 hat a refluxing rate of 10 times perhour(the authors propose to arrange the soxhlet extraction overnight in batches,by automation).The extracts were collected,combined and mixed thoroughly.A pre-activated copper sheet was placed into the combined extract for 4-6 hto eliminate sulfide by precipitation of sulfide on the copper sheet.The solution mixture was then filtered,and the filtrate was concentrated to a smaller volume and purified by passing through SPE column packed with Florisil.The analytes were adsorbed on SPE column and were eluted from the column by 15 mL of a mixed solution of n-hexane and acetone with the volume ratio of 9∶1.The eluate was collected and evaporated to a definite volume 1.0 mL in which 27 compounds[i.e.20 organochlorine pesticides(OCPs)and 7 polychlorobiphenyls(PCBs)]were contained and be further separated and determined with ECD.In the 2-dimensional gas chromatography separation,2 chromatographic columns,i.e.the non-polar column(TG-35 MS,the 1st D)and the polar column(DB-1,the 2nd D)were used in combination.Among the 27 compounds,non-polar compounds were separated according to their differences in boiling points on the 1st D-column;the eluate from which was modulated by focusing to elevate its temperature rapidly(with gap of modulation of 4 s)and introduced into 2nd D-column through which the analysts with differences in polarities were separated.Good s

关 键 词：全二维气相色谱法 索氏提取 有机氯农药 多氯联苯 化工区江滩沉积物 

分 类 号：O657.7[理学—分析化学]