若测量值定义为抽样目标中的分析物浓度,那么与抽样相关的不确定性必然导致最终测量结果的不确定度。抽样不确定度主要来源于抽样目标的不均匀性、抽样方案不明确、抽样和样品制备过程中引入的交叉污染、分析物损失等。以欧洲分析化学会的指南为基础,介绍了抽样不确定度评定的经验方法,该方法将测量不确定度来源区分为抽样过程和分析过程中的随机效应与系统效应。通过实例说明了如何通过重复实验和方差分析来量化抽样和分析过程中的随机效应,从而评估抽样和样品制备所引入的不确定度。
Abstract
If the objective of the measurement is to estimate the value of the analyte concentration in a sampling target, then the uncertainty associated with the sampling process inevitably contributes to the uncertainty of the measurement result. Heterogeneity, ambiguity in the sampling protocols, loss of analyte and fine particles, or contamination from equipment or previous samples are among the most important factors contributing to uncertainty associated with sampling. The empirical approach by EURACHEM is introduced, the general error sources are quantified as the sampling precision, analytical precision, sampling bias and the analytical bias respectively. The uncertainties associated with sampling precision and analytical precision are evaluated through duplicate methods and analysis of variance. An example is given to demonstrate how to evaluate the uncertainty associated with the sampling and sample preparations.
关键词
计量学 /
测量不确定度 /
抽样 /
评定 /
方差分析
Key words
metrology /
measurement uncertainty /
sampling /
evaluation /
analysis of variance
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
［1］Ellison S L R, Ramseyb M H, Lawrancea P, et al. Is measurement uncertainty from sampling related to analyte concentration?［J］. Analytical Methods, 2017, (42): 5989-5996.
［2］ISO/IEC 17025: 2017, General Requirements for the Competence of Calibration and Testing Laboratories［S］. 2017.
［3］王宏涛, 王汉斌, 陈晓怀, 等, 测量不确定度引起的批量产品检验误判风险评估［J］. 计量学报, 2017, 38(5): 559-562.
Wang H T, Wang H B, Chen X H, et al. Evaluation of Misjudgment Risks Caused by Measurement Uncertainty for Batch Product Inspection［J］. Acta Metrologica Sinica, 2017, 38(5): 559-562.
［4］EURACHEM/CITAC Guide. Quantifying Uncertainty in Analytical Measurement (third edition, 2012)［S］. Available from http://www.eurachem.org.
［5］倪晓丽.化学分析中不确定度的评估指南［M］. 北京: 中国计量出版社, 2008.
［6］EURACHEM/CITAC Guide. Measurement uncertainty arising from sampling: A guide to methods and approaches (first edition, 2007)［S］. Available from http://www.eurachem.org.
［7］Horwitz W. Nomenclature for sampling in analytical chemistry (Recommendations 1990)［J］. Pure and Applied Chemistry, 1990, 62(6): 1193-1208.
［8］纪洁, 李秀琴, 毛婷. 苹果醋中安赛蜜、山梨酸和日落黄成分分析标准物质的研制［J］. 计量学报, 2017, 38(4): 507-512.
Ji J, Li X Q, Mao T. Development of Component Analysis Reference Material for Acesulfame Potassium, Sorbic Acid and Sunset Yellow in Apple Vinegar Beverage［J］. Acta Metrologica Sinica, 2017, 38(4): 507-512.
［9］隋志伟,刘晓夏,王晶, 等, 粘质沙雷氏菌测量方法研究［J］. 计量学报, 2018, 39(4): 588-592.
Sui Z W, Liu X X, Wang J, et al. Study on Measurement Method of Serratia Marcescens［J］. Acta Metrologica Sinica, 2018, 39(4): 588-592.
［10］Lyn J A, Ramsey M H, Damant A P, et al. Empirical versus modelling approaches to the estimation of measurement uncertainty caused by primary sampling,［J］. Analyst, 2009, 134(9): 1234-1235.
［11］Ramsey M H, Squire S, Gardner M J. Synthetic reference sampling target for the estimation of measurement uncertainty［J］. Analyst, 1999, 124 (11): 1701-1706.
［12］Gardner M. Estimating sampling uncertainty-how many duplicate samples are needed［J］. Analytical Methods, 2014, 6(1): 24-26.
PDF(1033 KB)
