婴幼儿配方乳粉中维生素A、E检测方法的比较研究

目的 以国家标准GB5009.82-2016第一法(GB方法)和AOAC 2012.10/ ISO20633:2015 (AOAC/ISO方法)为例,通过文本分析和实验数据比较反相液相色谱法(RF-HPLC)和正向液相色谱法(NP-HPLC)检测婴幼儿配方粉中维生素A和维生素E的差异,分析可能导致方法结果产生差异的原因,提出科学建议。方法 通过标准方法文本原理比对,分析两种方法的原理及技术步骤差异；通过质控样检测,分析两组结果的标准偏差、变异系数、95%重复性限、相对重复性限值、平均值、回收率等指标,比对两种方法的精密度和准确度差异；通过市售样品检测,分析两种方法检测结果的系统偏差和比例偏差,判别两种方法对婴幼儿配方乳粉的结果一致性。结果 从方法文本上看,AOAC/ISO方法较 GB方法的步骤更为简便,且标明了方法的适用浓度范围、重复性、重现性等关键指标,标注的检出限及定量限值也较GB方法更低；精密度方面,采用AOAC/ISO方法测得的重复性和重现性标准偏差、变异系数、95%重复性限、相对重复性限值结果,均低于GB方法测得的同类指标。准确度方面,AOAC/ISO方法和GB方法测定维生素AE时均表现出较好的回收率(100±5%)；样品对比检测结果表明,维生素A两种方法的检测结果不存在系统偏差和比例偏差,结果一致；维生素E两种方法的结果既有系统偏差也有比例偏差,结果不一致。结论 AOAC/ISO 方法和GB方法原理及操作步骤存在明显不同,可能导致两种方法在测定维生素E含量时,结果呈现统计学显著差异。建议加强国内外检测标准的沟通协调,在检测目标物,样品称量方式,样品适用浓度范围等方面做进一步改进和完善。

Comparison study of analytical methods on vitamin A and vitamin E in infant formula

ABSTRACT: Objective Taking the China national standard GB 5009.82-2016 method 1 and AOAC 2012.10/ISO 20633:2015 as examples, the methods of RF-HPLC and NP-HPLC for vitamin A and vitamin E analysis in infant formula were compared by the method context and experiment data. The root causes of result differences were discussed, and the method revision suggestions based on science were generated. Methods Compared the method principle and the operation procedures between these two methods through the text file; compared the precision and trueness by analyzing the key parameters e.g. standard deviation, coefficient of variation, 95% repeatability limit, relative repeatability limits, mean value and recovery of standard reference materials; analyzed the systematic and proportional bias of these two methods by comparing the analytical results of infant formula samples purchased from China market. Results The text file comparison result showed that AOAC/ ISO method was easier for operation, its key parameters was clearly indicated (e.g. applicable concentration range, repeatability, reproducibility, etc), and has lower LOD and LOQ than GB method. The precision results showed that, the key parameters of method repeatability and reproducibility (e.g. standard deviation, coefficient of variation, 95% repeatability limit, relative re-peatability limits) were lower by performing AOAC/ ISO method. The trueness result showed that both AOAC/ISO method and GB method had good recovery (100±5%). The comparison results of sample test showed that there was no systematic deviation and proportion deviation between GB and AOAC/ISO method for Vitamin A analysis, whereas there were both systematic deviation and proportion deviation be-tween GB and AOAC/ISO method for Vitamin E analysis. Conclusion The principle and operation proce-dure of AOAC/ISO method and GB method are different, which may lead to significant differences when performing these two methods to test Vitamin E in infant formula samples. It is suggested to strengthen the communication between GB and international standard method, improve the scientificity of method ana-lytes scope, sample weighting process, the applicable sample concentration range, etc.