Applications of Chemical Precipitation Methods for Improving Sensitivity in X-Ray Fluorescent Analysis

Abstract

X-ray fluorescent analysis has limited application to the determination of traces in metals because of insufficient sensitivity when absorption by the matrix is significant. By applying chemical precipitation methods to concentrate the elements to be determined, orders of magnitude increase in sensitivity can be obtained. In addition to gaining sensitivity, absorption and enhancement effects become negligible since the precipitate is exposed to the X-ray beam as a thin film, producing a linear relationship between intensity and concentration. Because the elements to be determined are separated from the matrix, a single set of standards can often be used for the analysis of samples with varying composition. Application of chemical precipitation methods to the determination of parts-per-million concentrations of zirconium in cobalt, iron, and nickel alloys and to the determination of chlorides in high-purity titanium metal has been accomplished.