Applications of X-Ray Analysis to Environmental and Biomedical Studies

Abstract

AbstractRecent developments in x-ray spectroscopy have shown that this technique is a very powerful tool for the analysis of small quantities of material. A distinction must be made here between microanalysis -the analysis for elemental composition of a small total amount of material - and trace analysis - the analysis of bulk material for the presence of certain elements at very low concentrations. By the use of chemical separation, a problem in trace analysis can be converted into a microanalytical situation. A major improvement in trace analysis has been achieved by the use of ion-exchange resin loaded onto filter paper to collect the element(s) of interest from a solution of the original sample. The analysis of these concentrates or of particulate matter filtered out of polluted air or water can be optimized because the total mass of the sample is small and the background due to scattered prirmary radiation can be minimized.Much interest has become manifest recently in the use of solid-state detectors for energy dispersion x-ray analysis of samples of this type. The value of energy dispersion can be demonstrated by improved detection limits for samples containing only a few widely separated elements. However, resolution of state-of-the-art solid-state detectors is not adequate to separate the Kβ of one element from the Kα of the next higher atomic number among the transition metals. Thus the presence of a large number of immediate neighbor elements at widely different concentrations as in pollution samples suggests the need for crystal spectrometers.