亚硝酸盐氮对硫化物测定的干扰及消除方法研究

Study on the Interference of Nitrite in the Determination of Sulfides and the Method of Avoidance

[目的]研究亚硝酸盐氮对硫化物测定的干扰及其消除方法。[方法]用对氨基二甲基苯胺光度法和碘量法测定硫化物含量。[结果]在对氨基二甲基苯胺光度法和碘量法测定硫化物含量过程中,高浓度的亚硝酸盐氮(NO2--N)会对分析测定产生明显干扰。NO2--N浓度为150 mg/L左右,S2-加标量为100 mg/L时,2种测定方法的加标回收率分别为68.27%和58.21%。在用碘量法测定硫化物时,若用无CO2水重复冲洗滤纸3次,其加标回收率可达103.84%。[结论]为减小硫化物测定误差提供参考。

[ Objective ] The research aimed to study the interference of nitrite in the determination of sulfides and the method of avoidance. [ Method] The contents of sulfides were determined by the methylene blue spectrophotometric method and the iodometric method respectively. [Result] During the determination of sulfides with the methylene blue spectrophotometric method and the iodometrie method, the determination of sulfides was seriously interfered by nitrite with high concentration. When the nitrite concentration was about 150 mg/L and the S^2- concentration was 100 mg/L, the recovery rates of the two methods were 68.27% and 58.21% respectively. The experiment proved that if filter papers had been washed 3 times repeatedly when the iodometric method was used to measure sulfides, the recovery rate could up to 103.84%. [ Conclusion] The research can provide reference for reducing the error of determination.