X-Ray Spectrometric Analysis of Noble Metal Dental Alloys

The analysis of noble metal dental alloys for the various constituent elements is a difficult and tedious task by chemical or fire assay procedures. X-ray spectroscopy offered the possibility of increased speed, especially if solid metal samples were employed. This technique was investigated particularly with respect to the analysis of dental alloys having the nominal composition in percent, of gold 72, silver 12, copper 10, platinum 2, palladium 2, and zinc 2. Alloys were prepared by melting the component elements in a high frequency furnace and casting the metal into disk form. Compositions of the castings were determined by chemical analysis. Optimum procedures for casting the sample and for X-ray analysis were established, and analytical curves were developed relating concentrations to measured intensities of the X-ray lines Au L(β), Ag K(α), Cu K(α), Pt L(α), Pd K(α), and Zn K(α). The observed typical coefficients of variation for the method were Au 0.34 percent, Ag 0.44 percent, Cu 2.2 percent, Pt 1.6 percent, Pd 1.2 percent, and Zn 0.72 percent. The results indicate that the method is sufficiently accurate and has marked advantages of speed and simplicity compared to chemical analysis.