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有机砷化合物中砷的微量分析有碘量法,电位法,比色法及库仑法等,但这些方法均不十分理想。我们对用Th~(4+)试剂沉淀滴定As~(5+)的方法进行了研究。样品在特殊设计的氧瓶中燃烧分解,以含有碘化钾的碘溶液作为吸收液,吸收液不必转移,直接在同一系统中进行光度滴定。为了使终点灵敏准确,采用了光敏场效应管光度检测器获得了满意的结果。此外并用加高氯酸钡的方法消除了硫酸根的干扰。分析绝对误差在0.5％以内。
Trace amounts of arsenic in organic arsenic compounds are iodine, potentiometric, colorimetric and coulometric methods, but these methods are not very satisfactory. We investigated the method of titration of As ~ (5+) with Th ~ (4 +) reagent. The samples were burned and disintegrated in a specially designed oxygen bottle. The iodine solution containing potassium iodide was used as the absorption liquid. The absorption liquid did not have to be transferred and photometric titration was carried out directly in the same system. In order to make the endpoint sensitive and accurate, the photodetector photometric detector obtained satisfactory results. In addition, the method of adding barium perchlorate eliminated the interference of sulfate. Analysis of the absolute error within 0.5%.