碱协同光还原法测定饮用水中硝酸盐的研究

Study on the Determination of Nitrate in Drinking Water by Alkali Synergetic Photoreduction

针对镉柱还原分光光度法测定水中硝酸盐存在的操作繁琐、费时,镉柱制备复杂、镉柱毒性大等问题,设计碱协同光还原法进行样品前处理,其原理是紫外光条件下硝酸盐在碱性溶液中可选择性地分解转化为亚硝酸盐.考查光还原时间、氢氧化钠投加量对硝酸盐还原效率的影响.在最佳条件下采用该方法对不同浓度硝酸盐进行还原,其测定值与实际值相对吻合.将该方法用于某市售的纯净水、某市售的矿泉水、实验室的自来水3种实际水样测定,其RSD(相对标准偏差)为1.12%~2.84%,样品加标回收率为98.5%~101.2%.结果表明该方法具有还原效率高、选择性好、准确度和灵敏度佳等优点.同时由于简便快速、环境友好,在饮用水硝酸盐测定的前处理中具有一定优势.

In order to solve the problems of complicated operation,time-consuming,complex preparation of cadmium column and high toxicity of cadmium column in the determination of nitrate in water by cadmium column reduction spectrophotometry,an alkali synergistic photoreduction method was designed for sample pretreatment.The principle was that nitrate can be selectively decomposed into nitrite in alkaline solution under ultraviolet light.The effects of photo reduction time and sodium hydroxide dosage on nitrate reduction efficiency were investigated.Under the best conditions,the method was used to reduce nitrate of different concentrations,and the measured values were in good agreement with the actual values.The method had been applied to the determination of purified water,mineral water and tap water in the laboratory.The RSD(relative standard deviation)was 1.12%-2.84%,and the recovery rate was 98.5%-101.2%.The results showed that this method had the advantages of high reduction efficiency,good selectivity,good accuracy and sensitivity,convinience and quickness,and environmental friendliness.It had certain advantages in the pretreatment of nitrate determination in drinking water.