硫脲紫外退色分光光度法测水中余氯

氯氧化硫脲使硫脲退色.一定条件下,硫脲紫外吸收的降低与水中余氯浓度成正比.依据这一特性建立了硫脲紫外退色分光光度法测定水中余氯的新方法.在pH值为1～6介质中,选择237 nm作为测定波长,则氯浓度在0～8.0 mg/L范围服从比尔定律.检测限为O.015 mg/L,水中常见的离子不干扰测定.该法用于自来水、游泳池水等样品中余氯浓度的测定,快速简便,加标回收率在98%～103%之间.

Determination of the residual chlorine in water supply by thiourea decolored UV-spectrophotometry

The present paper is inclined to introduce a new method for determining the residual chlorine in water supply by thiourea decolored UV-spectrophotometry.The method is based on the depression of thiourea ultraviolet absorption caused by the oxidization of chlorine,which is proportional to the density of the above said residual chlorine in water.It is found that when pH=1-6,HCl medium and sodium hypochlorite solution is taken as a standard,the absorption depression value of thiourea and chlorine density within the range of 0-8.0 mg/L would obey the Beer Law with a correlation coefficient of 0.999 4 on the condition that the absorption wave and concentration of thiourea is detected to be 10 mg/L in 237 nm.Some common coexisting ions,such as Na~+,K~+,NH~+_4,and so on wouldn't give any interference.As a result,the preliminary applications of our method to such water supplies as tap water and swimming pool water indicate that the chlorine-sign-return ratio stands between 98%-103% and the method is efficient,feasible,convenient as well as reliable.