钴(Ⅱ)-铁(Ⅲ)-邻菲罗啉流动注射分光光度法在线间接测定水中钴

Indirect determination of cobalt in water by on-line flow injection-spectrophotometry with cobalt(Ⅱ)-iron(Ⅲ)-o-phenanthroline system

在pH4.0 HAc-NaAc介质中,以三氯化铁和邻菲罗啉混合液为显色剂,根据钴（Ⅱ）-铁（Ⅲ）-邻菲罗啉体系的显色反应原理,建立了流动注射-分光光度法间接测定水中钴离子的新方法。对温度、酸度、显色剂、反应盘管长度、载流流量、注样体积等实验条件进行了优化。在510 nm波长处和最优条件下,体系吸光度值与钴（Ⅱ）质量浓度在0.1~3.0 mg/L范围内呈现良好的线性关系,线性相关系数r为0.999 7,方法的检出限为0.08 mg/L。对0.5 mg/L和2.0 mg/L的钴标准溶液平行测定11次得到相对标准偏差（RSD）为2.3%和3.7%。实际水样的加标回收率为97%~104%。通过可编程控制器来控制系统,实现了自动操作,可直接用于工业废水的现场即时监测。

On the basis of the coloring reaction of cobalt（Ⅱ）-iron（Ⅲ）-o-phenanthroline system,a new on-line indirect determination method of cobalt in water was created by flow injection-spectrophotometry in HAc-NaAc medium at pH 4.0,using ferric trichloride and o-phenanthroline as coloring reagent.The experimental conditions were optimized,including temperature,pH,coloring reagent,length of reaction coil,flow rate of carrier liquid,injecting volume.Under the optimal conditions,the system absorbency at 510 nm showed good linear relationship with the mass concentration of cobalt（Ⅱ） in the range of 0.1-3.0 mg/L.The linear correlation coefficient was 0.999 7,and the detection limit was 0.08 mg/L.For the determination of 0.5 mg/L and 2.0 mg/L cobalt standard solution,the relative standard deviations（RSD,n=11） were 2.3 % and 3.7 %,respectively.The recovery rate of actual water sample was 97 %-104 %.The automatic operation of system could be realized by programmable logic controller.The proposed method could be directly applied to the on-site real-time monitoring of industrial wastewater.