微生物法测定乳粉中维生素B_(12)的实验室验证及结果分析

Laboratory Verification and Analysis of Vitamin B_(12) in Milk Powder by Microbiological Method

目的:基于《食品安全国家标准食品中维生素B_(12)的测定》(GB 5009.285—2022)新国家标准即将实施,验证微生物法测定乳粉中维生素B_(12)的可操作性和可行性。方法:在标准方法的基础上优化测试菌液的制备和保存方法,通过分析标准曲线线性,采用已知含量的质控样和回收率加标试验来验证方法的准确性,同时对5组不同品牌的乳粉进行精密度试验检验其重复性。结果:维生素B_(12)含量在0~0.1 ng线性关系良好,R2均达到0.99以上;测定QC-IP-703质控样结果均与其特性值相符,相对误差在-4.4%~3.4%;加标回收率为99.2%~101.0%;精密度试验试管法RSD值为2.0%~3.1%,微孔法RSD值为1.7%~3.2%,重复性良好。结论:本实验室具有开展GB 5009.285—2022中采用微生物法测定乳粉中维生素B_(12)的检测能力,可以开展此项检测工作。

Objective:Based on the new national standard GB 5009.285—2022 will be implemented,the operability and feasibility of microbiological method for the determination of vitamin B_(12) in milk powder is verified.Method:On the basis of the standard method,the preparation and preservation methods of the test bacterial solution were optimized.The accuracy of the method was verified by analyzing the linearity of the standard curve,using the quality control sample with known content and the recovery rate marking test,and the precision test was carried out to check the repeatability of 5 groups of different brands of milk powder.Result:The linear relationship of vitamin B_(12) content was good in the range of 0~0.1 ng,and the R2 was above 0.99.The results of QC-IP-703 quality control samples are consistent with their characteristic values,and the relative error was-4.4%~3.4%.The recoveries were 99.2%~101.0%.The RSD values of precision test were 2.0%~3.1% for tube method and 1.7%~3.2% for micropore method,showing good reproducibility.Conclusion:This laboratory has the ability to detect vitamin B_(12) in milk powder by microorganism method GB 5009.285—2022,and can carry out this detection work.