流动注射-水杨酸法测定氨氮的余氯干扰及脱氯方法试验

Study on the Interference of Residual Chlorine on the Determination of Ammonia Nitrogen by Flow Injection-sodium Salicylate Method and the Dechlorination Effect of Different Reducing Agents

流动注射-水杨酸钠法测定氨氮的含量时,次氯酸钠会对检测过程产生干扰,导致检测结果在谱图中显示为负峰。笔者试验了在含氯水样中滴加硫代硫酸钠、抗坏血酸、亚硝酸钠、亚硫酸氢钠这几种不同还原剂及不同用量对峰形的影响程度,结果表明,抗坏血酸脱氯效果及精确度更好。用抗坏血酸对氨氮0.50 mg/L(以N计)、100 mg/L次氯酸钠(以有效氯计)的标准溶液进行脱氯后进行测定,其相对标准偏差为0.227%,加标回收率P为112%,数据准确度高,重现性好,回收率符合定量检测要求。

When the flow injection-sodium salicylate method is used to determine the content of ammonia nitrogen, sodium hypochlorite will interfere with the detection process, resulting in a negative peak in the spectrum. The influence of different reducing agents such as sodium thiosulfate, ascorbic acid, sodium nitrite, and sodium bisulfite on the peak shape was tested dropwise in the chlorine-containing water sample. The results showed that the dechlorination effect and accuracy of ascorbic acid are better. The standard solutions of ammonia nitrogen 0.50 mg/L(calculated by nitrogen) and 100 mg/L sodium hypochlorite(calculated by available chlorine) were dechlorinated with ascorbic acid. The RSD was 0.227 %, and the recovery rate of spiked standard was 112 %, The data accuracy is high, the reproducibility is good, and the recovery rate meets the quantitative detection requirements.