Research in quantitative microscopic X-ray fluorescence analysis

Abstract

A feasibility study of quantitative elemental microanalysis of biological materials and glass samples by microbeam X-ray fluorescence spectroscopy was completed. The research included testing the homogeneity of existing standards for X-ray fluorescence calibration and verification of a fundamental parameters method for quantitative analysis. The goal was to evaluate the X-ray fluorescence spectrometer as a tool for elemental analysis at the microscale level. Glass Standard Reference Materials were analyzed. The glass specimens consisted of flat, optically polished slabs having three different thicknesses. For calibration, metal thin films were used. The microbeam X-ray fluorescence spectrometer utilizing capillary optics with effective beam diameter equal to about 30 μm has been applied in this research. Sources of uncertainties considered in this work were detector and X-ray tube stability, specimen movement, and spectral deconvolution. Concentrations of analytes were calculated using a fundamental parameters approach. Coherently and incoherently scattered lines of tube target were used for matrix correction and to estimate the mass thickness of the sample. The synchrotron microbeam X-ray fluorescence technique was used for quantitative analysis of human brain tissue samples. In measurements the monochromatic and polychromatic synchrotron microbeams were applied. The same area of tissue sample was scanned with the use of both X-ray microbeams. The concentrations of selected elements were computed. A reasonably good agreement between results of both analyses was obtained.