超声辅助碱解消除沉积物样品多氯联苯检测中有机氯农药的干扰

Ultrasonically assisted alkaline degradation method for the elimination of organochlorine pesticides interference on the determination of polychorinated biphenyls in sediment

将超声辅助碱液分解杂质与溶剂萃取相结合,建立了一种快速高效净化、萃取沉积物中多氯联苯(PCBs)的气相色谱分析方法.超声辅助条件下,在2.0 mol.L-1的NaOH甲醇溶液中超声10 min,利用NaOH甲醇溶液的碱解作用即可使有机氯农药(OCPs)完全分解,在利用有机溶剂萃取沉积物中PCBs的同时消除OCPs等干扰.在优化的实验条件下,PCBs各单体的回收率在72.1%—113.7%,相对标准偏差在0.4%—6.3%(n=6)之间.气相色谱图显示,碱解净化后杂质含量显著减少,基线得以明显改善,能满足定性定量检测的要求.利用建立的方法测定了长江口以南海域表层沉积物中PCBs的含量及其分布,24种PCBs的总含量在39.7—493.4 pg.g-1之间,总体上表现为近岸含量较高,同时自长江口沿闽浙沿岸自北向南呈现增高趋势.

For the determination of polychlorinated biphenyls（PCBs） in marine sediments based on gas chromatography,we proposed a rapid and effective procedure for simultaneous sample extraction and purification,in which an ultrasonically assisted alkaline hydrolysis was combined with solvent extraction.The organochlorine pesticides（OCPs） were completely hydrolyzed under ultrasonic treatment in 2.0 mol · L-1 NaOH-methanol solution for 10 minutes,to realize the elimination of interference from OCPs in the determination of PCBs while extracting PCBs effectively at the same time.Under the optimized conditions,the recoveries of PCB congeners were between 72.1% and 113.7%,and the RSDs were between 0.4%—6.3%（n=6）.It was shown from the chromatograms that the content of impurities was reduced significantly and the baseline was improved greatly.The contents and distribution of PCBs in the surface sediments collected in the south of Yangtze estuary were determined by using the developed method.The total amount of 24 PCBs was between 39.7 to 493.4 pg · g-1,with higher content near the coast and increasing southward from Yangtze estuary off Fujian and Zhejiang coastline.