Measurement Uncertainty Estimation in Chemical Analyse, a Study Case

Abstract

The increasing demand of reliable results gives to measurement uncertainty a key importance and imposes the need of correct estimation to analytical laboratories. This paper presents an estimation of measurement uncertainty in the determination of sulphate in water, using GUM approach and the analysis of some associated aspects. The main sources identified were, absorbance influenced by matrix effect and the mathematical regression model used. It was determined the uncertainty variation trend with concentration and emphasized the need of informing the uncertainty according to the concentration level of the result. It was demonstrated the importance of verifying the uncertainty estimates and the inconvenience of using specially prepared solutions to obtain it. It became evident the contribution of sampling component into global uncertainty of result.

Keyword: measurement uncertainty, GUM, sulphate determination, metrology in chemistry.