Evaluation of intercomparison survey of EDXRF laboratories

In this paper the results are compiled and evaluated according to recognised international procedures based on z and u scores. The results obtained for the test EDXRF spectra revealed that, in general, the spectrum evaluation routines are applied correctly; problems were identified only for the low energy or high intensity characteristic X ray lines. For the analysis of water samples several incorrect results were obtained with tube or isotope excitation while most of the results obtained by total reflection XRF were satisfactory. For the geological and biological materials most of the results were not satisfactory, and some laboratories did not even identify the major elements. Classification of the laboratories based on the z and u scores was slightly different. A major reason for the differences is the fact that the uncertainties of the results submitted by the laboratories are only accounted for in the u scores and not in the z scores, and poor laboratory reproducibility was observed in some cases