反相流动注射-紫外光还原-分光光度法测定饮用水中的硝酸盐

Reversed Flow Injection Analysis of Nitrate in Drinking Water with UV-induced Reduction to Nitrite and Spectrophotometric Detection

1引言硝酸盐广泛存在于各种环境水体中。当饮用水中硝酸盐浓度过高时,可能对人体健康造成危害;地表水中硝酸盐大量积累,则可能引起藻类过度繁殖,溶解氧耗竭,水质恶化。目前,检测硝酸盐的最常用方法是将硝酸盐还原为亚硝酸盐,再经重氮偶联反应后由分光光度法进行测定[1]。此类方法已较好地与流动分析技术相结合。

An environmental friendly method was developed based on reversed flow injection（r-FIA） with UV-induced reduction of nitrate to nitrite and spectrophotometric detection.Sample or standard solutions were mixed with a phosphate buffer solution containing diethylenetriaminepentaacetate（DTPA）,and then passed through a UV reduction reactor equipped with an 8 W low pressure mercury lamp,where the nitrate was reduced to nitrite.The formed nitrite was detected with spectrophotometric method through Griess reaction.Less than 20 μmol/L of nitrite showed no effect on the nitrate analysis.Reduction efficiency over 80% was obtained.The detection limit of the proposed method was 0.053 μmol/L and linear range was 0.2-40 μmol/L.A sample of 20 μmol/L nitrate was continually measured for 48 times,and a RSD of 2.22% was obtained.The recoveries of drinking waters were between 90.9%-100.6%.