Quantitative Elemental Analysis of Art Objects by Energy-Dispersive X-ray Fluorescence Spectroscopy

Abstract

Techniques have been developed for the analysis of glass and metal objects for up to 35 elements in a few minutes for aiding the curator in determining the authenticity of many museum objects. No samples are removed nor are the objects altered by the measurements. Trace elements present as impurities in older pieces and absent in modern forgeries as well as the major constituents can be measured with accuracies at least as high as wet chemical and spectrographic methods generally employed in museum laboratories. Tables of instrument response to 71 elements presented together with empirical corrections for matrix effects permit direct calculations of weight percentages within 20% of all the elements present. Employment of reference standards and the use of the principal element as an “internal standard” improve this accuracy to better than 1% of the major elements present. Charts of “peak heights” of the various spectral lines of each element plotted as a function of energy permit a rapid determination of the most probable elements that are present in a spectrum. It also aids in selecting peaks that are free of interference from other elements. Tables of peak heights and energies of the peaks of 71 elements listed in order of atomic number indicate where the spectral peaks of the various elements will be found and what their relative intensity is. Procedures are described for determining weight percent of 15 or more elements in metal and 30 or more in glass objects from spectral data. Examples of analytical results are given for typical museum objects and specially prepared samples.