茶叶中痕量钴的褪色分光光度法测定

Spectrophotometric Determination of Trace Cobalt in Tea Using Wright Stain

建立瑞氏色素褪色光度法测定乳制品中微量钴的新方法。在弱酸性介质中,钴(II)能与硫氰酸根以及瑞氏色素发生离子缔合反应而使瑞氏色素发生褪色,且褪色程度与钴(II)的质量浓度在一定范围内呈线性关系,据此可以测定钴(II),在最大吸收波长660 nm处,钴(II)的质量浓度在0.04~0.40μg/mL范围内符合比尔定律,表观摩尔吸光系数为1.26×10^(5) L·mol^(-1)·cm^(-1),方法用于茶叶中痕量钴的测定,结果与电感耦合等离子体质谱法测定结果一致。

A new spectrophotometric method for the determination of cobalt(II)in tea was proposed.This method was based on the decoloration of Wright Stain by cobalt(II)in weak acid solution,which is linearly related to cobalt(II)concentration in a certain range.The wavelength of maximum absorbance was 660 nm with an apparent molar absorption coefficient of 1.26×10^(5) L·mol^(-1)·cm^(-1).The absorbance obeyed Beer-Lambert law over the range of 0.04~0.40μg/mL for cobalt(II).The proposed method was applied to determine cobalt(II)and in several kinds of tea and the results were in good agreement with those determined by Inductively Coupled Plasma Mass Spectrometry(ICP-MS).