Abstract: In order to develop a new method to determine nitrite and nitrate in milk and milk products, some improvements were made on the ion chromatography method specified in the national standard GB 5009.33-2016 Determination of Nitrite and Nitrate in Food. Samples were extracted with ultra-pure water and added with acetic acid to precipitate proteins before being chromatographed on AS11-HC column and detected with a conductivity detector. Under the above conditions, the calibration curves for nitrite and nitrate were linear with correlation coefficients greater than 0.99. The limit of quantitation (LOQ) for nitrite and nitrate was 0.25 and 0.8 mg/kg in milk, and 1 and 5 mg/kg in milk powder, respectively. The recoveries for spiked samples of milk powder and milk were from 80% to 110%. The improved method was simple to operate and cheap with ideal recovery and high precision. It could avoid potential problems encountered in the use of the traditional method and allow for more rapid and accurate detection of low contents of nitrite and nitrate in milk and milk products.

Key words: nitrite, nitrate, ion chromatography, dairy products, conductivity detector

摘要： 改进GB 5009.33—2016《食品安全国家标准 食品中亚硝酸盐和硝酸盐的测定》中离子色谱法测定乳制品（乳粉、生牛乳）中亚硝酸盐和硝酸盐的方法。乳制品中亚硝酸盐和硝酸盐经超纯水提取后，加入乙酸溶液沉淀蛋白，AS11-HC色谱柱分离，电导检测器检测。结果表明：在本研究条件下，亚硝酸盐和硝酸盐的标准曲线均线性关系良好，相关系数均大于0.99；纯牛乳中亚硝酸盐的定量限为0.25 mg/kg、硝酸盐的定量限为0.8 mg/kg，乳粉中亚硝酸盐的定量限为1 mg/kg、硝酸盐的定量限为5 mg/kg；乳粉和纯牛乳中亚硝酸盐、硝酸盐回收率均能达到80%～110%，方法操作便捷、成本低、回收率理想、精密度较高。该法优化了国标检测方法的条件，解决了其中可能遇到的问题，可以更加快速、准确地检测乳制品中低含量亚硝酸盐和硝酸盐。

关键词: 亚硝酸盐, 硝酸盐, 离子色谱法, 乳制品, 电导检测器