Application of X-ray fluorescence techniques for the determination of hazardous and essential trace elements in environmental and biological materials

The utilization of X-ray fluorescence technique for the determination of trace element concentrations in environmental and biological samples is presented. The analytical methods used include energy dispersive X-ray fluorescence with polarizing secondary targets, total reflection X-ray fluorescence, direct in-situ X-ray fluorescence, and micro-beam X-ray fluorescence spectrometry. These methods were applied to analysis of different samples including soil, water, plant material and airborne particulate matter collected on polycarbonate filters. The performance and achieved detection limits of elements for different techniques, established by measuring appropriate reference standards, are presented. Also described is the utilization of micro-beam X-ray fluorescence technique for studying element distribution in heterogeneous samples and investigating the 2D- and 3D-morphology of minute samples by means of computerized X-ray absorption and X-ray fluorescence tomography. The different X-ray techniques have their unique advantages. The micro-beam X-ray fluorescence set-up has an advantage of producing very well collimated primary X-ray beam (about 15 mm in diameter), in front of which the analyzed sample can be precisely positioned, providing local information about the sample composition. The energy dispersive X-ray fluorescence with secondary targets offers rapid analysis of broad range of elements (Na–U) combined with a simple sample preparation method. Total reflection X-ray fluorescence technique, characterized by the lowest detection limits of elements, has its leading edge in analysis of liquid samples, and dealing with particle size effects in air particulates collected on filter papers. In-situ X-ray fluorescence spectrometers are truly portable and enable on the spot, in field analysis. It is shown that the combination of several XRF methods