A model for the evaluation of uncertainty in routine multi-element analysis

Author: Ruth, Thomas

Source: Accreditation and Quality Assurance, Volume 9, Number 6, June 2004 , pp. 349-354(6)

Publisher: Springer

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Abstract:

A model for calculating uncertainty in routine multi-element analysis is described. The model is constructed according to the principles of GUM/EURACHEM. Control chart results are combined with other existing data and results from the actual measurement into a concentration-dependent estimate of combined standard uncertainty. Since possible sources of bias are included in the calculation, overall bias as estimated from the data is used only as a control to identify needs for modification of the model and/or the analytical procedure. For each individual sample, uncertainty can be calculated automatically based on two pre-calculated parameters together with measured concentration and instrumental standard deviation. As an example, the model is demonstrated for inductively coupled plasma-mass spectrometry (ICP-MS) analysis of sewage sludge including laboratory sub-sampling, sample preparation, and instrumental determination.

Keywords: Uncertainty; ICP-MS; Quality control; Control chart

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s00769-003-0735-4

Affiliations: 1: Analytica AB, Aurorum 10, 977 75 , Luleå, Sweden, Email: thomas.ruth@analytica.se

Publication date: 2004-06-01