研究了低于GeCl4挥发温度密闭分解含锗的金合金的技术、KIO3电位滴定常量Ge的方法和提高方法选择性的条件;比较了电位与传统碘淀粉终点指示法对分析结果准确度、精密度,终点稳定性和敏锐度,方法选择性等的影响。结果表明:在优化条件下,控制消解温度不超过75℃时,9mL HCl-2 mL H2O2能完全消解0.10 g样品,且无Ge的损失。经蒸馏分离收集锗,消除Au(Ⅲ)及常见共存离子的影响。电位终点指示法与传统碘淀粉终点指示法对锗滴定结果准确度基本一致,电位终点指示法实用性更强。方法用于AuGe12、AuGeNi12-2、AuAgGe18.8-12.5、AuAgGeNi43.8-6-0.2等系列金锗合金中6%～13%锗含量的测定,标准偏差和相对标准偏差分别为0.0214%～0.0450%和0.304%～0.391%,样品加标回收率99.11%～100.99%。
The paper presents a new method of determining Ge in gold alloys by potassium iodate potentiometric titration rather than by traditional distillation separation. The influences of conditions such as the reduction acidity, dosage of sodium hypophosphite and reduction time on the determination of Ge were studied. Comparison was made between the influences of end-point indication for potential method and starch method on accruracy and precision of the analysed results, stability and sensitivity of end-point, selectivity of method and so on. The possibility of reaction in an electrochemical way was discussed. Ge in the alloys such as AuGe 12 , AuGeNi 12 2 , AuAgGe 18.8 12.5 and AuAgGeNi 43.8 6 0.2 was measured, respectively, with the relative standard deviation of 0.10%~0.31% and the recoveries of added standard Ge in sample of 99.40%～100.40% when the reduction acidity was 0.40~0.80 mol/L HCl and 3.3 mol/L H 3 PO 4, 15 g sodium hypophosphite and reduction time 40 min. The new method presented is high accuracy and precision in results, good stability and sensibility in end point, easy operation and strong selectivity of determination. When it is applied to analyse actual samples, satisfactory results are achieved.
