贝类产品中石油烃测定的不确定度评估

不确定度是一个合理表征测量结果分散性的参数,具有广泛的应用性和实用性。不确定度的评估对实际检测工作的质量控制具有重要意义。本文研究了荧光分光光度计法测定贝类产品石油烃含量过程中所产生的不确定度。分别考虑了油标准储备液本身、储备液稀释过程、标准曲线拟合、样品的称量、皂化过程、样品的溶解及重复测定过程等各方面因素。评估了各项因子的不确定度、合成不确定度以及扩展不确定度。结果表明,在现场特定情况下,当贝类产品中石油烃的浓度为9.08mg/kg时,其相对合成不确定度为11.1%,扩展不确定度为2.02mg/kg(k=2)。贝类产品石油烃测定的不确定度主要由样品的皂化反应处理过程中的损失所致。因此减少皂化反应过程中的损失,提高皂化样品的回收率,可以有效的减少测量过程中的不确定度,从而提高检测结果的正确度。

Evaluation of the uncertainty of determination of petroleum hydrocarbons in shellfish products

T he uncertainty of measurement results is a reasonable representation of dispersion parame-ters ,has extensive applicability and practicality .The evaluation of uncertainty of actual testing work of quality control is of great significance .This paper studies the fluorescence spectrophotometer meth-od shellfish products produced in the process of petroleum hydrocarbons in uncertainty .Oil respec-tively considered the standard stock solution itself ,reserve liquid dilution process ,standard curve fit-ting ,sample weighing ,specification process ,samples of dissolved and repeated measurement process of several factors .The uncertainty of evaluation of each factor ,synthetic uncertainty ,relative synthe-sis uncertainty and the expanded uncertainty .The results show that the particular situation at the scene ,w hen the concentration of the petroleum hydrocarbons in shellfish products is 9 .08 mg/kg ,the synthesis of relative uncertainty was 11 .1% ,the expanded uncertainty of 2 .02 mg/kg （k = 2） .Un-certainty is mainly caused by specifications reaction loss in the process of samples .Therefore reduce the losses in the process of specification reaction ,improve the recovery of specifications sample can ef-fectively reduce the uncertainty in the process of measurement ,so as to improve the accuracy of test results .