主题：【讨论】如何按照欧盟2002/657/EC计算检测限（CCα）和定量限(CCβ)

原文由 zhufangwei(zhufangwei) 发表:
转载自http://www.antpedia.com/  板油aa_tang

对于食品安全、药物残留检测领域，偶属外行，但自己也做了n年色谱质谱分析（n>3，^_^），基于LZ的问题，探讨一下偶个人对定量分析方法学验证方面的粗浅认识。

（定性）定量分析，都必须得有方法学考察，即对所采用的分析方法进行验证，以充分表明分析方法符合检测项目的目的和要求！验证内容包括方法的专属性、线性、范围、准确度、精密度、检测限、定量限、耐用性和系统适用性等。LZ在这里讨论的是检测限（LOD）和定量限（LOQ），且是信噪比法！

其实，在ICH Q2B文件里罗列了三种方法：
(LOD=检测限，LOQ=定量限）
1. 肉眼观测 (用此方法报告LOD或LOQ时要附上色谱图）
2. S/N (LOD = 3, LOQ =10)
3. LOD = 3.3*standard deviation/slope, LOQ = 10*standard deviation/slope

所以，采用信噪比法来计算检测限（CCα）和定量限(CCβ)是没有任何问题的，完全可行！

而MRPL，即Minimum Required Performance Limit首字母缩写，通常所说的欧盟制定的最低残留限量就是指这个，说白了，贸易壁垒/技术壁垒！
“The MRPL represents the minimal concentration of the banned substance in question that must be able to determine with specified degrees of accuracy and precision by an analytical method and is based on the current limit of detection (LOD).”
——来源http://www.coextra.eu/news/news1257.html

同时， 欧盟官方指南文件（EUROPEAN COMMISSION，HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL  GUIDELINES FOR THE IMPLEMENTATION OF DECISION 2002/657/EC）上明确说明：
      “ It should be noted that the minimum required performance level is not the MRPL. The minimum required performance level is the lowest concentration of analyte which is expected to be detected (screening methods) or its identity unequivocally confirmed (confirmatory methods). It follows that for substances for which an MRPL has been proposed, the minimum required performance level should be less than the MRPL.
      It is therefore recommended that representative blank material must be used, which is fortified at and above the minimum required performance level. The lowest calibration point is that at which the method starts to detect or identify the analyte. (This does not mean that the method should detect or identify the analyte in 100 % of the cases).
      It should be noted that the two approaches are only valid for a linear curve and therefore linearity has to be proven in order to use these approaches.”

所以，个人认为，如何制定特定分析方法最低残留限量(或者说最小执行限量)标准，这依赖于你所采用的分析方法，你要的答案应该在你自己的实验数据里！

不变的法则是——某个具体药物最大残留限量标准，应符合分析方法的最低检出限。这点，偶个人打包票是千真万确滴！！！

一句话：信噪比法计算检测限和定量限肯定是可行的，除非你说统计学不是科学，或者说你不是在科学地使用统计学。^_^

ps：上述言论，纯属个人一孔之见，仅供交流切磋，对与错，大伙自己定夺。