提出了用极谱法测定铅合金中主量及次量锡。选择测定的溶液介质中含硫酸(1+1)溶液4 mL,2 g·L-1次甲基蓝溶液10滴,并用32 g·L-1草酸溶液定容至50 mL。仪器工作条件选择反向扫描,扫描速率为500 mV·s-1,并采用二阶导数测定。试样(0.100 0 g)用水10 mL,酒石酸2 g及硝酸3~4 mL溶解。大量铅采用加入硫酸(1+1)溶液5 mL使生成硫酸铅沉淀除去。加入100 g·L-1氯化钡溶液5滴,使与Pb2+生成共晶沉淀而更完全地除去铅。锡的质量浓度在20.0 mg·L-1以内与相应的峰电流呈线性关系。按此方法测定了7个铅合金样品中的锡量,其测定值与已知值相符,相对标准偏差(n=6)均小于6%。

It was reported that major and minor amount of tin in lead alloys were determined by polarography in testing solution containing 4 mL of H2SO4 (1+1) and 10 drops of 2 g·L-1 methylene blue solution, and diluting to a definite volume of 50 mL with 32 g·L-1 oxalic acid solution. Anodic scanning at the rate of 500 mV·s-1 and 2nd derivative of the measured polarographic wave were adopted in the determination. The sample (0.100 0 g) was dissolved in distilled water (10 mL), tartaric acid (2 g) and HNO3 (3-4 mL), and Pb2+ was separated by addition of H2SO4 (1+1) (5 mL). Five drops of 100 g·L-1 BaCl2 solution were added to separated Pb2+ completely as compound sulfate precipitate. Linear relationship between values of peak current and mass concentration of Sn was obtained in the range within 20.0 mg·L-1. 7 samples of lead alloys were analyzed by the proposed method for their tin contents, giving results consistent with the known values, and RSD′s (n=6) found were less than 6%.