Estimating uncertainties of analytical results using information from the validation process

A new approach for calculating uncertainties of analytical results based on the information from the validation process is proposed. This approach com plements the existing approaches proposed to date and can be applied to any validated analytical method. The precision estimates generated during the process of assessment of the accuracy take into account the uncertainties o f preprocessing steps and analytical measurement steps as long as the diffe rent factors that influence these steps are representatively varied in the whole validation process. Since the accuracy of an analytical method should be always assessed before applying it to future working samples, little ex tra work needs to be done to estimate the final uncertainty. Other sources of uncertainty not previously considered (e.g. uncertainty associated to sa mpling, to differences between the test-sample and the working sample, etc. ) are subsequently included and mathematically combined with the uncertaint y arising from the assessment of the accuracy to provide the overall uncert ainty. These ideas are illustrated with a case study of the determination o f copper in contaminated land. (C) 1999 Elsevier Science B.V. All rights re served.