Quantitative analysis of individual particles by x‐ray microfluorescence spectrometry

A fundamental parameters method using polychromatic x-ray microbeam excitation was developed and applied to the quantitative analysis of individual particles from 50-160 μm. From the ratio of the projected area of a particle to the cross-sectional area of the microbeam, an effective portion of the microbeam irradiating the particle can be determined and used to correct the measured x-ray intensities. Because particles in this size range may not be infinitely thick and may contain unmeasurable elements such as C and O, calculation of the average mass thickness of the particle allows complete matrix absorption corrections to be made. For this purpose, the ratio of coherent to incoherent x-ray tube target lines scattered from the particle was used to calculate the average atomic number of the particle, and its mass thickness was determined from incoherent scatter. A parametric equation was derived and tested. In addition, irregularly shaped particles were analyzed using a well known equation usually applied to flat samples having intermediate thickness. Both models were tested with homogeneous glass particles of known composition and size.