Abstract：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%.
