建立了奶粉中亚硝酸盐和硝酸盐含量准确测定的方法，以奶粉中亚硝酸盐和硝酸盐成分分析基体标准物质作为质控品进行方法学的考察与评价。奶粉样品经低温-酸沉淀/固相萃取净化，采用离子色谱-电导检测分析。结果表明，亚硝酸盐（以NO2-计）和硝酸盐（以NO3-计）分别在0.010μg/mL~0.500μg/mL和0.100μg/mL~5.00μg/mL的范围内线性良好，相关系数（r）均大于0.99，在奶粉中的最低定量限分别为0.400/4.00 mg/kg（NO2-/NO3-）；亚硝酸盐和硝酸盐测定方法中的基质效应分别为95.6%/99.6%（NO2-/NO3-）；基于基质效应的加标回收率分别为90.3%/87.1%（NO2-/NO3-）；以奶粉基体标准物质进行方法学考察，方法的准确性分别为90.5%/89.9%（NO2-/NO3-），精密度（RSD）分别为2.1%/0.7%（NO2-/NO3-）。奶粉中亚硝酸盐和硝酸盐成分分析基体标准物质作为质控品，可以用于分析测试方法的评价、实验室结果的比对，以及相关行业奶粉中亚硝酸盐和硝酸盐含量监测量值传递体系的建立，为奶粉的质量控制和安全评价提供保障。%An accurate method was developed for the analysis of nitrite and nitrate in milk powder, which using matrix reference material as quality control tool to evaluate the analytical method. Milk powder sample was se-quence cleaned by low temperature-acid precipitation and sold phase extraction, and then analyzed by ion chromatography-conductivity detector. The results showed that nitrite and nitrate displayed good linear relation-ships over the range of 0.010μg/mL-0.500μg/mL(NO2-) and 0.100μg/mL-5.00μg/mL(NO3-), with correla-tion coefficients greater than 0.99. The quantitation limits of nitrite and nitrate in milk powder were 0.400 mg/kg and 4.00 mg/kg. The matrix effects of the method for nitrite and nitrate were 95.6%and 99.6%, and the addi-tion recoveries based on matrix effect were 90.3%and 87.1%separately. The accuracies and precisions of the method were 90.5%/89.9%(NO2-/NO3-) and 2.1%/0.7%(NO2-/NO3-) when validated by milk powder matrix reference material. Also, the matrix reference material of nitrite and nitrate in milk powder can be used as qual-ity control tool to evaluate the analytical method, to compare results among labs, to establish the value transfer-able system for nitrite and nitrate determination and monitor in milk powder industries, and to provide guarantee for quality control and safety evaluation of milk powder.
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