Matching standard procedure and method of theorethical coeffidents in XRF spectrometry analysis of jewelry gold alloys

摘要

Samples of jewelry gold alloys have been analyzed byXRF spectrometry. Two possible approaches were considered: (a)the matching standard procedure, a simple method based on theconstruction of empirical curves requiring a number of suitablecalibrants very close in composition to the samples under analysis,and (b) the method of theoretical coefficients, a method ofcalibration with mathematical correction of matrix effects foranalysis of 8-24 carat gold alloys containing Ag, Cu, Zn, Pd and/orNi. In this case, the analyses were performed basing on one setof16 certified reference materials only.Theoretical coefficients were calculated by the method offundamental parameters with Criss XRF11 and De Jon g-ALPHASprograms. Sell' absorption effects related to go/d and silver werecorrected by using with the Rasberry-Heinrich model. Theinvestigation was performed on different spectrometerscalculated with various tubes; instrumental parametersinfluencing accuracy and precision were carefully evaluated. XRFspectrometry-Heinrich model. The investigation was performed ondifferent spectrometers equipped with various tubes;instrumental parameters influencing accuracy and precision werecarefully (other elements) results: the gold fineness isdetermined with an accuracy of 0.3 per thousand to 1.2 per thousand,depending on the method, and hence very close to cupellation,while for other alloy constituents the analysis accuracy rangesbetween 1 and 2 per thousand.