研究了显色剂二溴对甲偶氮二溴羧与钴(Ⅱ)的显色反应.在pH 10.2的柠檬酸铵-氨水缓冲溶液中,钴(Ⅱ)与二溴对甲偶氮二溴羧反应形成绿色配合物,最大吸收波长为650 nm,表观摩尔吸光率为2.59×104L·mol-1·cm-1.钴质量浓度在1.0 mg·L-1以内符合比耳定律.方法用于锌钴镀液中钴的直接测定,测得相对标准偏差(n=5)平均值为1.65%,平均回收率为100.5%.

In an ammoniacal citrate buffer medium of pH 10.2,a green colored coordination complex was formed by the reaction of Co(Ⅱ) ion with the chromogenic reagent of dibromo-p-methyl-dibromocarboxyazo,having its absorption maximum at the wavelength of 650 nm,and apparent molar absorptivity of 2.59×104L·mol-1·cm-1.Lambert-Beer′s law was obeyed in the range within 1.0 mg·L-1.The proposed method was used to determine cobalt in 2 samples of Zn-Co plating solutions,giving results in consistency with those found by the method given in literature,and average values of recovery and RSD (n=5) found were 100.5% and 1.65% respectively.