Evaluation for rationality of the reproducibility standard deviation in environmental monitoring analysis methods standard with Horwitz empirical model
GUO Chao1, ZHANG Baihui1, FAN Shuang*1, YIN Huimin2,3, LI Yuwu1,2,3
1. Guohuan Oasis (Gu'an) Environmental Technology Co., Ltd.,Langfang 065500, China; 2. Environmental Development Centre of the Ministry of Ecology and Environment, Beijing 100029, China; 3. National Research Center for Environmental Analysis and Measurements, Beijing 100029, China
Abstract：The standard deviation of reproducibility (sR) was one of the basic performance parameters of the analytical method, and it was the basis to calculate the reproducibility limit in the method standard. The reproducibility limit of different concentration was one of important basis for daily quality control specifications. Taking the standard texts for different analysis methods of inorganic elements in soil, sediment and solid waste samples in the field of environmental monitoring as an example, the Horwitz's empirical model (II) and H criterion (the ratio of experimental statistical value sR to calculated value of the model) were used to examine the rationality of the reproducibility standard deviation in the standard text that had been published and implemented, and method validation report for public comment and advice published in the official website of the Ministry of Ecology and Environment.It was showed that H>4 and H<0.5 were common phenomena. When H>4, it implied: (1) there might be "outliers" in the data involved in statistical calculation; (2) there might be "double peaks" in the data, and sR data had deviated from the normal range. When H<0.5, it implied: whether the precision of the experimental data was too optimistic, and whether there were data that should not be deleted. The outlier in the data could be judged by combining the daily quality control specifications and the fact that whether the H value was in the normal range. The raw measurement data from the method verification report was used as examples to explain the identification process of outliers. In order to avoid the interference of various human factors those directly leaded to lower sR, the actual (soil, sediment and solid waste) samples should be used as much as possible in precision verification experiments. When certified reference materials was selected, it was not required that the reported results must be located in the uncertainty interval of the certified value of certified reference materials, and it was considered as meeting the requirements for satisfying the daily quality control specifications. Using password coding was also an effective way to effectively avoid human interference. The Horwitz empirical model and H criterion were useful tools for quickly checking the rationality of reproducibility standard deviation data.
郭超, 张百慧, 范爽, 殷惠民, 李玉武. 用Horwitz经验模型评估环境监测分析方法标准再现性标准偏差数据合理性[J]. 冶金分析, 2021, 41(6): 27-34.
GUO Chao, ZHANG Baihui, FAN Shuang, YIN Huimin, LI Yuwu. Evaluation for rationality of the reproducibility standard deviation in environmental monitoring analysis methods standard with Horwitz empirical model. , 2021, 41(6): 27-34.
