吡咯烷二硫代氨基甲酸铵螯合-浊点萃取-氢化物发生原子荧光光谱法测定饮用水中痕量汞  

Determination of Trace Mercury in Drinking Water by Hydride Generation Atomic Fluorescence Spectrometry with Ammonium Pyrrolidinedithiocarbamate Chelation and Cloud Point Extraction

作　　者：刘景龙 韩倩 杨超 LIU Jinglong;HAN Qian;YANG Chao(Jiangsu Nanjing Environmental Monitoring Center,Nanjing 210013,China;Institute of Molecular Engineering and Applied Chemistry,Anhui University of Technology,Ma’anshan 243002,China)

机构地区：[1]江苏省南京环境监测中心,南京210019 [2]安徽工业大学分子工程与应用化学研究所,马鞍山243000

出　　处：《理化检验（化学分册）》2024年第6期570-575,共6页Physical Testing and Chemical Analysis(Part B:Chemical Analysis)

基　　金：江苏省南京环境监测中心环保科研项目(202205)。

摘　　要：鉴于标准HJ 694—2014检测饮用水中汞的检出限较高,无法满足痕量汞的分析要求,提出以吡咯烷二硫代氨基甲酸铵(APDC)溶液为螯合剂,以非离子型表面活性剂Triton X-114溶液为萃取剂,通过浊点萃取的方式将饮用水中的痕量汞富集于表面活性剂相,采用氢化物发生原子荧光光谱法测定痕量汞的方法。水样经过滤、酸化后,分取50 mL水样,加入2.0 g·L^(−1)APDC溶液1.5 mL,5%(体积分数)Triton X-114溶液1.5 mL,调节混合溶液酸度至pH 6,于40℃平衡5 min,以2900 r·min^(−1)转速离心10 min,冰水浴中冷却5~10 min。弃去上层水相,在表面活性剂相中加入由磷酸三丁酯与乙醇按体积比1∶1混合配制的消泡剂300μL,用5%(体积分数)盐酸溶液稀释至5 mL,上机检测。结果显示:汞的质量浓度在2.0μg·L^(−1)以内和对应的荧光强度呈线性关系,检出限为0.002μg·L^(−1)。按标准加入法进行回收试验,回收率为86.8%~97.9%,测定值的相对标准偏差(n=6)不大于8.0%。方法检出限较标准HJ 694—2014低一个数量级,能够满足饮用水等清洁水样中痕量汞分析的检出限要求。Considering that the standard of HJ 694—2014 for detecting mercury in drinking water has a high detection limit and cannot meet the analysis requirements for trace mercury,the method was proposed with ammonium pyrrolidinedithiocarbamate(APDC)solution as chelating agent and non ionic surfactant Triton X-114 solution as extractant.Trace mercury in drinking water was enriched in the surfactant phase through cloud point extraction,and determined by hydride generation atomic fluorescence spectrometry.After filtration and acidification,50 mL of the water sample was taken,and 1.5 mL of 2.0 g·L^(−1) APDC solution and 1.5 mL of 5%(volume fraction)Triton X-114 solution were added.The mixed solution was adjusted its acidity to pH 6,equilibrated at 40℃for 5 min,centrifuged at rotational speed of 2900 r·min^(−1)for 10 min,and cooled in the ice water bath for 5-10 min.The upper aqueous phase was discarded,and 300μL of the defoamer prepared by mixing tributyl phosphate and ethanol at volume ratio of 1∶1 was added into the surfactant phase.The resulting solution was diluted to 5 mL by 5%(volume fraction)hydrochloric acid solution for intrumental detection.It was shown that linear relationship between values of the mass concentration and the fluorescence intensity of mercury was kept within 2.0μg·L^(−1),with detection limit of 0.002μg·L^(−1).Test for recovery was made according to the standard addition method,giving recoveries in the range of 86.8%-97.9%,and RSDs(n=6)of the determined values were not more than 8.0%.The detection limit of the method was one order of magnitude lower than that given by the standard of HJ 694—2014,which could meet the detection limit requirements for trace mercury analysis in clean water samples such as drinking water.

关 键 词：浊点萃取 螯合剂 氢化物发生原子荧光光谱法 汞 预富集 

分 类 号：O657.31[理学—分析化学]