乳粉中硝酸盐、亚硝酸盐分析标准样品研制

Development of reference material for the analysis of nitrate and nitrite in milk powder

研制乳粉中硝酸盐、亚硝酸盐分析标准样品。获得原料并确认后,对原料添加目标物,混匀,喷雾干燥,分装,包装制成标准样品。对样品进行均匀性、稳定性检验,通过多家实验室联合定值的方式对样品进行定值,从而获得标准值及其不确定度。样品中硝酸盐、亚硝酸盐均匀性检测数据经F检验在95%置信水平时单元件不具有统计显著性,表明样品是均匀的;样品稳定性检测数据经t检验,表明样品在-20℃保存条件下18个月内量值稳定;对8家有能力的实验室联合定值数据统计分析得到样品中硝酸盐标准值为22.4 mg/kg,不确定度为0.95 mg/kg(k=2);亚硝酸盐标准值为23.0 mg/kg,不确定度为0.93 mg/kg(k=2)。样品均匀性、稳定性、赋值和不确定度评估等均符合有证标准样品的要求,能够满足预期用途。

The reference material for the analysis of nitrate and nitrite in milk powder was developed.After the raw materials were obtained and confirmed,added with target,mixed,spray dried,and packaged to make reference materials.The homogeneity and stability of the reference material were tested,the coordinated values were determined by multiple laboratories,and the standard value and uncertainty were evaluated.According to the F-test of the homogeneity detection data of nitrate and nitrite in the reference material,the element was not statistically significant at the 95%confidence level,indicating that the reference material was homogeneous;the stability test data was tested by t-test,indicating that the quantity value of the reference material was stable under the condition of-20℃for 18 months;the statistical analysis of the joint determination data of 8 laboratories obtained the standard value of the nitrate in the reference material was 22.4 mg/kg,the uncertainty was 0.95 mg/kg;the standard value of nitrite was 23.0 mg/kg,the uncertainty was 0.93 mg/kg,and the uncertainty includes factor k=2.The homogeneity,stability,assignment of standard value and uncertainty evaluation of the reference material by this research ful fill the standard requirements,which ensure this reference material to meet the intended use.