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确定了偶氮氯膦—mN(CPA—mN)与钍产生显色反应的最佳条件。在澳化十六烷基三甲基铵(CTM AB)存在下,0.5N 盐酸介质中,钍与 CPA—mN 形成紫红色络合物,络合物组成比为 Th:CP AmN=1:5,最大吸收波长为675nm,摩尔吸光系数为1.22×10~5,钍含量在0—12.5微克/25毫升范围内符合比耳定律。实验表明,显色体系中加入 CTM AB,除对显色反应有增敏作用外,还对铀(Ⅵ)、铈(Ⅳ)与 CP AmN 的显色反应有一定的抑制减敏作用,其他干扰如锆、铁等可采用草酸、抗坏血酸、EDTA 掩蔽,因而具有较高选择性,可以不经分离测定矿样中微量钍。偶氮氯膦 mN 是华东师范大学研制的一种不对称变色酸双偶氮氯膦型铈组稀土显色剂简称 CPAmN,该试剂与溴化十六烷基三甲基铵(CTMAB)体系已有文献。报导用于钍的测定,但本文研究表明,CTMAB 在体系中对钍增敏同时,对铀(V1)、铈(1V)却有一定的抑制作用,其它干扰如锆、铁等可采用草酸,抗坏血酸、EDTA 掩蔽,因而具有较高选择性,可不经分离直接测定矿样中微量钍。
The optimum conditions for the chromogenic reaction of chlorophosphonazo-mN (CPA-mN) with thorium were determined. Thorium forms a purple-red complex with CPA-mN in a 0.5N hydrochloric acid medium in the presence of Ammonium Cetyltrimethylammonium (CTM AB) with a complex composition ratio of Th: CP AmN = 1: 5 , The maximum absorption wavelength of 675nm, the molar absorption coefficient of 1.22 × 10 ~ 5, thorium content in the range of 0-12.5 micrograms / 25 ml Beer’s law. Experiments show that addition of CTM AB to the chromogenic system not only sensitizes the chromogenic reaction, but also inhibits the chromogenic reaction of uranium (Ⅵ), cerium (Ⅳ) and CP AmN to a certain degree. Other interferences Such as zirconium, iron, etc. can be used oxalic acid, ascorbic acid, EDTA masking, which has high selectivity, can be determined without isolation trace trace thorium. Chlorophosphonazo mN is developed by East China Normal University as an asymmetric chromotropic acid bis-chlorophosphonated cerium rare earth chromophore reagent abbreviation CPAmN, the reagent and cetyltrimethylammonium bromide (CTMAB) system has been There is literature. Reported in this paper is used for the determination of thorium. However, the results of this study show that CTMAB can inhibit the growth of uranium (V1) and cerium (1V) while enhancing its sensitivity to thorium. Other interferences such as zirconium and iron can be oxalic acid, Ascorbic acid, EDTA masking, which has high selectivity, can be directly measured without isolation trace thorium in the mine.