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本文报道用双波长胶束增溶分光光度法测定水中痕量镉。方法基于在非离子型表面活性剂TritonX-100存在下镉与对-磺基苯重氮氨基偶氮苯(SDAAB)的显色反应。研究表明,于pH10.80的缓冲介质中及在Triton X-100的存在下,镉与SDAAB形成红色络合物,其最大吸收波长位于525nm处。络合物非常稳定,在10天内吸光度保持不变,其mol吸光系数高达2.84×10~5L·mol~(-1)·cm~(-1)。镉浓度在0～4μg/25ml范围内符合比耳定律。用平衡移动法和Asmus直线法测得镉与SDAAB的络合比均为1:2。经实践证明,由于用此法测定水中的镉具有简便、准确、灵敏度极高,选择性和重现性好等优点,故有较大的实用价值。
This paper reports the determination of trace cadmium in water by dual wavelength micellar solubilization spectrophotometry. The method is based on the color reaction of cadmium with p-sulfobenzenediazoaminoazobenzene (SDAAB) in the presence of the non-ionic surfactant TritonX-100. The results show that cadmium and SDAAB form a red complex in the buffer medium of pH10.80 and in the presence of Triton X-100, with the maximum absorption wavelength at 525 nm. The complex is very stable. The absorbency remains unchanged within 10 days, and its mol absorption coefficient is as high as 2.84 × 10 ~ 5L · mol ~ (-1) · cm ~ (-1). Beer’s law is in line with the cadmium concentration in the range of 0-4 μg / 25 ml. The complex ratio of cadmium to SDAAB was 1: 2 by the equilibrium shift method and the Asmus line method. Practice has proved that, because of this method for the determination of cadmium in water has the advantages of simple, accurate, high sensitivity, selectivity and good reproducibility, it has greater practical value.