Development and implementation of X-ray fluorescence technique for gold determination in jewelry alloys at the analytical center of the JSC «Krastsvetmet»

Abstract

A technique of the X-ray fluorescence analysis (XRF) based on a linear regression providing correlation between the gold content in the sample and radiation intensities of the elements of the analyzed alloy is developed at the analytical center of the JSC «Krastsvetmet» (laboratory of X-ray spectral analysis) to increase the rapidity of gold determination in gold-based alloys. The regression equation chosen by the methods including the influencing factor (contributor) and estimating correlation between the disparities and influencing factor takes into account the effect of such elements as Ag, Cu, Zn, Ni, and Pd on the gold line intensity. Virtual calibration samples (VCS) — the results of the analysis of real samples (X-ray line intensities of elements and gold values obtained by the assay method) taken from electronic database (DB) are used to form a system of linear algebraic equations (SLAE) which is to be solved for determination the desired linear regression coefficients. VCS for which the line intensities of the elements are close to those measured for the analyzed sample are selected from the database using a specific filter: the filter value is determined for each of the elements (metals) in the sample. The developed and integrated into the laboratory information system (LIMS) multi-version software (MVS) for solving SLAE includes several algorithms implemented in various programming languages. The use of the presented methodology significantly reduces the time of analysis. The error of gold determination does not exceed 0.13% which is comparable with that in the assay method.