硝酸银电位滴定法测定高纯二氧化锗中氯

我国行业分析标准采用硫氰酸汞分光光度法测定二氧化锗中氯含量,由于硫氰酸汞是一种剧毒试剂,影响工作人员身体健康和污染环境,为此,建立了一种无毒的测定高纯二氧化锗中氯的电位滴定法。实验结果表明:在pH 2～4的乙醇-水的介质中,以硝酸银标准溶液作为滴定剂,二级微商法确定滴定终点,滴定曲线突跃明显,终点准确,基体锗、大量的Na⁺、NO₃^-和二氧化锗中微量金属元素不影响氯的测定。方法用于高纯二氧化锗样品中氯的测定,测定结果与行业标准方法(硫氰酸汞分光光度法)相一致,相对标准偏差在0.89%～1.6%之间。

Determination of chlorine in high-purity germanium dioxide by silver nitrate potentiometric titration

The mercuric thiocyanate spectrophotometry was adopted in industrial standard method for the determination of chlorine content in germanium dioxide in China. The mercuric thiocyanate was a kind of poisonous reagent, which influenced the operators' health and caused environmental pollution. Therefore, a kind of nontoxic potentiometric titration method was established for the determination of chlorine content in high-purity germanium dioxide. The results indicated that the titration endpoint could be determined by secondary derivative method in ethanol-water medium at pH 2-4 using silver nitrate standard solution as titrant. The jump of titration curve was obvious and the endpoint was accurate. The determination of chlorine was not affected by the matrix germanium, much Na⁺ and NO₃^-, and micro metal elements in germanium dioxide. The proposed method was applied to the determination of chlorine in high-purity germanium dioxide samples, and the found results were consistent with those obtained by industrial standard method (mercuric thiocyanate spectrophotometry). The relative standard deviation (RSD) was 0.89%-1.6%.