共沉淀分离-原子荧光光谱法测定铜矿和铅锌矿中锡

铜矿、铅锌矿石样品经过盐酸、硝酸溶解，采用氢氧化铁共沉淀锡使其与铜、铅、锌分离，含锡沉淀经过氧化钠熔融，在硫酸介质中，加入硫脲-抗坏血酸-酒石酸掩蔽滞留在溶液中的干扰元素，然后用氢化物发生-原子荧光光谱法(HG-AFS)测定锡量。确定了锡与铜、铅、锌的分离条件:用氨水调节样品溶液pH 4.5；三价铁离子加入量为20 mg。方法测定范围为0.001%～1%，检出限为3 μg/g。对样品中共存离子进行了干扰试验，结果表明，经过共沉淀处理后，主量元素铜、铅和锌大部分已与锡分离，不干扰锡的测定；砷、锑的干扰可通过稀释或减小取样量去除；其他元素均不干扰锡的测定。采用实验方法对实际样品进行测定，并进行加标回收试验，回收率为95%～102%。经全国不同地区8家实验室采用铜矿石、铅锌矿石样品验证，方法精密度好。

Determination of tin in copper ore and lead-zinc ore by atomic fluorescence spectrometry with co-precipitation separation

The copper ore and lead-zinc ore samples were dissolved with hydrochloric acid and nitric acid. Tin was co-precipitated with ferric hydroxide for the separation from copper, lead and zinc. The tin-containing precipitation was fused with sodium oxide followed by extraction with hot water.In sulfur acid medium,the thiourea-ascorbic acid-tartaric acid was added to mask the interference elements in solution. Then, the content of tin was determined by hydride generation-atomic fluorescence spectrometry (HG-AFS). The separation conditions for tin from copper,lead and zinc were obtained: the pH of sample solution was adjusted to 4.5 with ammonia water; the addition amount of ferric ion was 20 mg. The determination range of proposed method was 0.001%-1% with detection limit of 3 μg/g. The interference test of coexisting ions in sample was conducted. The results indicated that most main elements (copper, lead and zinc) were separated from tin after co-precipitation treatment without interference to the determination of tin. The interference of arsenic and antimony could be eliminated by dilution or reducing the sampling amount. The determination of tin was not affected by other elements. The proposed method was applied to the determination of actual samples. The recovery test was also performed. The recoveries were between 95% and 102%. The copper ore and lead-zinc ore samples were also determined by eight different laboratories. The results showed that the method exhibited good precision.