微乳液析相光度法测定水中钴

Determination of Cobalt by Microemulsion Phase Spectrophotometric Analysis

建立了以OP乳化剂,正丁醇、正庚烷、水组成的微乳液介质萃取测定重金属钴的新方法。在pH为4.6的乙酸-乙酸钠缓冲溶液中,2-[(5-溴-2-吡啶)-偶氮]-5-二乙氨基苯酚(5-Br-PADAP)与钴离子发生络合反应,微乳液析相后,可显著提高灵敏度。其最大吸收波长为588 nm,表观摩尔吸收系数达3.75×105L·mol-1·cm-1。钴离子浓度在0.008~0.4 mg/L范围内符合比尔定律,RSD为0.50%,检出限为1.66×10-4mg/L。本方法选择性好,操作简单,精密度高,常见共存成分对测定无干扰。方法用于地表水、污水中Co^(2+)测定,加标回收率介于98%~103%之间,结果令人满意。

A new method for the extraction of heavy metal cobalt by microemulsion medi- um composed of OP emulsifier, n-butanol, heptane and water was developed. In pH 4.6 ace- tic acid sodium acetate buffer solution, 2- [ （ 5-bromide-2-pyridine ） -azo ] -5- two aminophe- nol （5-Br-PADAP） react with Co2 ＋, after microemulsion phase separation, the sensitivity could be improved significantly. At maximum absorption wavelength of 588 nm, and the ap- parent molar absorption coefficient was 3.75 × 105L. mol- 1. cm-1. Beer＇Cos law was obeyed at 0. 008 -0. 4 μg/mL for Co2＋ ,the relative standard deviation was 0. 50% ,and the detec- tion limit was 1.66 × 10 -4 mg/L. The method has the advantages of good selectivity, sim- ple operation and high precision, and the common coexisting components have no interfer- ence to the determination. The method was applied to the determination of Co2＋ in surface water and wastewater. And the standard sample recovery rate was 98.0% - 103%, the result is statisfying.