关键词: 亚硝酸盐, 硝酸盐, 离子色谱法, 乳制品, 电导检测器

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