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利用掩蔽剂以提高络合滴定的选择性,在分析化学中已广泛应用.迄今为止,用以掩蔽汞的掩蔽剂已有不少,如碘化钾、二巯基丙烷磺酸钠,二乙氨基二硫代甲酸钠等.本文对DL—半胱氨酸盐酸盐作汞的掩蔽剂进行了研究,认为它在pH3～10范围内,对汞有较强的络合能力,是汞的良好掩蔽剂.此法基于pH5～6的缓冲溶液中,铅离子和汞离子均能与EDTA生成1:1的络合物,但Hg—EDTA络合物能被DL—半胱氨酸盐酸盐解络而析出相当量的EDTA,以
The use of masking agents to improve the selectivity of complexometric titration has been widely used in analytical chemistry. To date, there have been many masking agents used to mask mercury, such as potassium iodide, sodium dimercaptopropanesulfonate, diethylaminodisulfide Sodium formate, etc. In this paper, DL-cysteine hydrochloride as a mercury masking agent was studied, that it is in the pH range of 3 to 10, a strong ability to complex mercury, mercury is a good masking agent. This method is based on pH5 ~ 6 buffer solution, both lead and mercury ions can form a 1: 1 complex with EDTA, but the Hg-EDTA complex can be DL-cysteine hydrochloride solution and Precipitation of a considerable amount of EDTA