AIC's 44th Annual Meeting

This presentation will offer an overview of the challenges facing those seeking to use ED-XRF for quantitative analysis of cultural heritage copper alloys, and will describe a proposed method for maximizing the reproducibility of measurements between laboratories. By maximizing inter-laboratory reproducibility, this method should facilitate collaboration among researchers and allow the rigorous use of shared data and databases. Recently, interlaboratory reproducibility has been shown to be quite poor. The results of a 2010 round robin study will be discussed and possible explanations for the difficulties encountered will be described. The proposed method for improving reproducibility, nicknamed CHARMed PyMca, calls for the use of free, open source, fundamental parameters software called PyMca. PyMca allows for a consistent and transparent application of the fundamental parameters approach independent of the ED-XRF instrumentation used. In order to further improve reproducibility, the proposed method calls for the calibration of standardless PyMca results against a set of high-quality certified reference materials designed specifically for use with heritage copper alloys, the so-called copper CHARM set. Finally, this method calls for the calibration-to-standards to be carried out following a consistent strategy, including error modeling and the incorporation of a validation procedure. The results of a second round robin reproducibility study will be presented which demonstrate the efficacy of the method.