双峰双波长分光光度法测定食盐中微量硒

Double-peak-double-wavelength spectrophotometric determination of trace selenium in salt

在pH10.8的NaHCO3-NaOH缓冲介质中,Se(IV)与镁试剂I形成稳定的1:6络合物,该络合物在448nm处有正吸收峰,560nm处有负吸收峰,据此建立双峰双波长光度法测定微量硒。Se(IV)浓度在0～1.4μg/mL范围内符合比尔定律。表观摩尔吸光系数为3.89×104L/mol.cm,检出限为0.096μg/mL。用于测定硒强化营养盐中硒含量,相对标准偏差为0.43%(n=5),平均回收率为99.4%。

A new method for determination of trace selenium by double-peak-double-wavelength spectrophotometry was developed. It was based on the reaction between Se （Ⅳ） and magneson I to form a stable complex （1 ： 6） in NaHCO3-NaOH buffer solution at pH 10.8. The complex exhibited a positive absorption peak at 448 nm and a negative absorption peak at 560nm. Beer＇s law was obeyed in the concentration range of 0- 1.4 μg/mL for selenium. The apparent molar absorptivity was found to be 3.89 × 10^4 L · mol^-1 · cm^-1. The limit of detection was 0.096 μg/mL. The method was applied to determine selenium content in salt fortified with selenium. RSD was 0.43% （n = 5）, and the average recovery was 99.4%.