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目前常用于测定微量铜的试剂有铜试剂,新亚铜灵,双环己酮二腙(BCO),2,4-二甲基-4,7-二苯基-1.10-邻二氮菲等,但大多需要萃取分离,操作麻烦,灵敏度欠佳。本文提出以5-〔(5-氯-2-吡啶)偶氮〕-2,4-二氨基甲苯(简称5-Cl-PADAT)作为测定微量铜的新试剂。实验结果表明,在pH4.5～5.2的溶液中,试剂与铜形成紫红色1:1络合物,最大吸收波长为540nm,表观摩尔吸光系数为5.12×10~4,铜含量在0～25μg/25ml之间有良好的直线关系,除铁、钴、镍、钯外,三十多种常见离子不干扰测定。为了消除干扰,我们采用巯基棉在pH3的条件下使铜与干扰离子分离,进而拟定了在水相中测定铜的具体步骤,并用于铜矿、工业废水、铝合金等样品中铜含量的测定,结果满意。方法稳定,操作简单,灵敏度高,选择性好,与目前常用的显色剂相比,具有明显的优点。
Currently used in the determination of trace amounts of copper reagents copper reagent, the new cupule spirit, bicyclohexanone two hydrazone (BCO), 2,4-dimethyl-4,7-diphenyl-1,10- phenanthroline and so on, However, most of them need extraction and separation, which leads to troublesome operation and poor sensitivity. In this paper, 5 - [(5-chloro-2-pyridyl) azo] -2,4-diaminotoluene (referred to as 5-Cl-PADAT) is proposed as a new reagent for the determination of trace copper. The experimental results showed that the reagent formed a purple-red 1: 1 complex with copper at a pH of 4.5-5.2, the maximum absorption wavelength was 540 nm, the apparent molar absorptivity was 5.12 × 10 -4, the copper content was 0 ~ 25μg / 25ml between a good linear relationship, in addition to iron, cobalt, nickel, palladium, more than thirty kinds of common ions do not interfere with the determination. In order to eliminate the interference, we use thiol cotton to separate the copper from the interfering ions under the condition of pH3, and then the specific steps for the determination of copper in the aqueous phase are drawn up and used for the determination of copper content in copper mine, industrial wastewater, aluminum alloy and other samples Satisfactory results. The method has the advantages of stable operation, simple operation, high sensitivity and good selectivity, and has obvious advantages compared with the commonly used color developing agents.