Nitrosamine is one of the three most recognized carcinogens in the world, the other two are aflatoxins and benzo[a]pyrene. Nitrosamine is formed by nitrite and secondary amine in protein and is widely distributed in nature.The content of nitrosamine in salted fish, dried shrimps, beer, bacon and sausage is high.Too long placing time for filling with meat and vegetable can also produce nitrite.Nitrite and nitrate are common inorganic salts in daily diet and drinking water.It is generally believed that excessive intake of these substances may lead to methemoglobinemia and produce carcinogenic nitrosamines in the body. Nitrate and nitrite are the ionic pollutants in GB 2762-2017 named "National Food Safety Standard -Limit of pollutants in food". GB 5009.33-2016 named "National Food Safety Standards for the Determination of Nitrite and Nitrate in Food" is to standardize the determination of these two substances, and ion chromatography as the first method is included in the standard.

The samples are pretreated according to GB/T 5009.33, and after protein precipitation and fat removal, the samples are  extracted and purified by corresponding methods. Using CIC-D160 ion chromatograph ,SH-AC-5 anion column, 10.0 mM NaOH eluent and  bipolar pulse conductance method,under the recommended chromatographic conditions, the chromatogram is as follows.