含锡锑试样中铋的络合滴定由于在用酸处理试样过程中易析出偏锡酸和偏锑酸而导致铋共沉淀,以及在滴定过程中锡锑水解使测定结果严重偏低等原因,目前基本上都是采用排除Sn.Sb的手续。试验表明,在酸溶样时加入一定量硝酸钾和柠檬酸能防止偏锡酸和偏锑酸析出。硝酸钾与柠檬酸在滴定过程中又能有效地阻止Bi、Sn、Sb水解;加入少量氟化铵掩蔽锡,可在100mg Sn、Zn以及50mg Fe、Al、Cu、Co、Ni、Sb Pb等元素存在下直接滴定铋。方法适用于锡锑试料、易熔合金中铋的测定。主要试剂铋标准溶液:用高纯铋(99.99％)按常法配制成1 mL含铋10mg(10％HNO_2介质)标准溶液;半二甲酚橙指示剂(0.25％);0.01mol/LEDTA标准溶液。分析步骤称取0.1000—0.2000g试样于300mL烧杯中,加入0.5—1g硝酸钾、20mL(1+1)硝酸、2mL盐酸,盖上表皿,置于低温电炉上加热溶解并蒸至糖浆状(剩1—2mL试液)取下,冷却。加入 Bismuth complexation titration in tin-antimony-containing samples Bi-coprecipitation is easily caused by the partial precipitation of metastannic acid and meta-antimonous acid during the treatment of the sample with acid, and the determination results are severely low when tin antimony is hydrolyzed during the titration The reason, at present, basically used to exclude Sn.Sb procedures. Experiments show that adding a certain amount of potassium nitrate and citric acid in the acid solution can prevent the partial stannotry acid and meta-antimony acid precipitation. Potassium nitrate and citric acid can effectively prevent the hydrolysis of Bi, Sn and Sb during titration. A small amount of ammonium fluoride masking tin can be added in 100mg Sn, Zn and 50mg Fe, Al, Cu, Co, Ni, Sb Pb, etc. Bismuth is directly titrated in the presence of the element. The method is suitable for the determination of bismuth in tin-antimony samples and fusible alloys. Main reagent Bismuth standard solution: 1 mL bismuth 10 mg (10% HNO 2 medium) standard solution is prepared by high purity bismuth (99.99%) according to the usual method; half xylenol orange indicator Solution. Analysis step Weigh 0.1000-0.2000g sample in 300mL beaker, add 0.5-1g potassium nitrate, 20mL (1 + 1) nitric acid, 2mL hydrochloric acid, cover the table, placed in a low temperature electric heating dissolved and steaming to syrup (Remaining 1-2mL test solution) removed, cooled. Join