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铅在中性、酸性或碱性溶液中,均能产生良好的还原波。在通常情况下,均采用酸性溶液为介质。在此条件下,锡、铊、砷(Ⅲ)波与铅波重合,严重影响铅的定量测定。铊(Ⅰ),砷(Ⅲ)的干扰当用盐酸分解矿样时均以氯化物形式挥发除去。但锡的氯化物在酸处理过程中不易除去,特别是当矿样中含有一定量的铁时。过去一般资料介绍均采用HBr或Br_2反复蒸干处理数次方能将锡消除干净,或者另行采用其他支持电解质。本文介绍在NaCl～HCI底液的基础上引入H_3PO_4作为锡(Ⅳ)的络合剂。锡(Ⅳ)与H_3PO_4在NaCl～HCl介质中能生成稳定的络合物,此络合物在铅的还原电位范围内在电极上
Lead in neutral, acidic or alkaline solution, can produce good reduction wave. Under normal circumstances, all using acidic solution as a medium. Under this condition, tin, thallium and arsenic (Ⅲ) wave overlap with lead wave, which seriously affect the quantitative determination of lead. The interference of thallium (Ⅰ) and arsenic (Ⅲ) are all volatilized and removed as chloride when hydrochloric acid is used to decompose ore samples. But the tin chloride is not easy to remove during the acid treatment, especially when the mineral sample contains a certain amount of iron. The past general introduction of information are used HBr or Br_2 repeated steaming dry several times in order to eliminate the tin clean, or otherwise use other supporting electrolytes. This paper introduces the introduction of H_3PO_4 as the complexing agent of tin (Ⅳ) on the basis of NaCl ~ HCl base solution. Tin (Ⅳ) and H_3PO_4 in NaCl ~ HCl medium can generate stable complexes, the complex in the lead reduction potential in the electrode