水道水質試験の標準液調製における不確かさと定量精度に影響を及ぼす要因

摘要

The obtained data on quantitative analysis of target compounds for water quality examination have unevenness. It is thought that uncertainty Is caused by the operations of a chain to Instrumental analysis from making standard solutions. However, the concrete evaluation method of uncertainty In each process for instrumental analysis Is not shown definitely. Therefore, the uncertainty caused in making standard solutions for the quantitative analysis was verified by the model experiment that assumed the water quality examination of pesticide butamlfos In this study. As the result of extraction of factors, we thought that the uncertainty caused by all of the electronic scale, the apparatus, the experimenter and the measuring Instrument In a chain of making standard solutions. We calculated the combined standard uncertainty which accompanied the result of a measurement of butamlfos 0.05 mg/L was 1.63%. Furthermore, the purities of butamifos standards (three companies, three products) that were measured by qNMR were 90.3, 94.7 and 94.8%. The gap with true value and the uncertainty between manufacturers that Influenced on the accuracy of Intra-laboratory became clear. In this study, we proved that error of intra-laboratory was influenced on the purity of standard and the accuracy of quantitative analysis is not secued under the present conditions. The analysis engineers have always to be recognizing current state in order to secure the reliability of quantitative accuracy.%水道水質試験の定量分析では、試料調製から機器分析の一連の試験操作に起因して、得られる値にばらつきが生じるが、この不確かさの評価法は明確にされていない。本研究では、農薬ブタミホスの定量分析をモデル実験として、標準液調製時の不確かさを検証した。その結果、天秤、調製器具、実験者、測定機器に不確かさを生じ、0．05mg／Lの測定結果に付随する合成標準不確かさは1．63％となった。さらに、qNMRによりブタミホス市販標準品3社3製品の絶対純度を測定した結果、90．3、94．7、94．8％であり、このメーカー間差が大きな不確かさを与え、分析精度に影響を及ぼしていることが明らかとなった。