Interference and rapid elimination of ferric iron in determination of nitrate nitrogen by ultraviolet spectrophotometry
Dong Zhihao, Zhang Jiao
Qingdao Engineering Research Center for Rural Environment College of Resource and Environment, Qingdao Agricultural University, Qingdao 266109, China
摘要：采用紫外分光光度法测定硝酸盐氮时，三价铁对测定结果有很大影响，干扰强度随着三价铁浓度的增加、硝酸盐浓度的降低而增加；三价铁对硝酸盐氮测定结果的影响随着pH 值的增加逐渐增强，当pH ＜ 6、三价铁浓度为10 mg/L 时，相对误差为21%～61% ；pH ＞ 7 时，干扰迅速增强，当pH 值为11 时，相对误差达530%。盐酸羟胺对三价铁有较好的掩蔽效果，当pH 值为3、三价铁与盐酸羟胺的质量浓度比为1.4∶1 时，掩蔽效果最好；当硝酸盐氮质量浓度为1～3 mg/L 且三价铁浓度低于5 mg/L 时，硝酸盐氮测定结果相对误差小于5%。
Abstract：Ferric iron has great influence on the determination result in the determination of nitrate nitrogen by UV spectrophotometry. The interference intensity increased with the increase of ferric ion concentration and the decrease of nitrate concentration. The effect of ferric iron on the determination results of nitrate nitrogen gradually increased with the increase of pH. When the concentration of ferric iron was 10 mg/L and pH < 6, the relative error ranged from 21% to 61%, and when pH > 7, the interference increased rapidly. The relative error reached 530% at pH 11. Hydroxylamine hydrochloride had good masking effect on ferric iron. The ferric iron could be well masked when pH was 3 and the ratio for mass concentration of ferric iron to hydroxylamine hydrochloride was 1.4∶1. When the concentration of nitrate nitrogen was 1-3 mg/L and that of ferric iron was lower than 5 mg/L, the relative error of nitrate nitrogen determination result was less than 5%.
Keywords：nitrate nitrogen; UV spectrophotometry; ferric iron; hydroxylamine hydrochloride
董志浩，张娇. 紫外分光光度法测定硝酸盐氮铁离子的干扰及快速去除[J]. 化学分析计量，2021，30(2)：17.
Dong Zhihao，Zhang Jiao. Interference and rapid elimination of ferric iron in determination of nitrate nitrogen by ultraviolet