Evaluation of uncertainty of measurement in quantitative xrf analysis: I. Scattered Radiation Method

Abstract

The uncertainty of measurement in quantitative XRF analysis by the scattered radiation method was evaluated following internationally accepted guidelines. Calculations are illustrated by taking up measurement data for the particular example of determination of the minor concentration of a heavy element analyte in a light matrix specimen. The standard uncertainty is calculated for each of the quantities on which the concentration of the analyte is considered to depend. These are then appropriately combined to obtain the combined uncertainty of measurement. This combined uncertainty is multiplied by a suitable coverage factor to give the expanded uncertainty. The coverage factor selected is such that the expanded uncertainty defines an interval about the measurement result that covers a desired fraction of the probability distribution characterized by the result and its combined uncertainty. The final result is expressed as the estimated value of the analyte concentration accompanied by the expanded uncertainty. Copyright © 1999 John Wiley & Sons, Ltd.