Trace element analysis by means of synchrotron radiation, XRF, and PIXE: selection of sample preparation procedure

When it comes to biological samples, trace element (TE) determination has to cope with very low concentrations, sometimes even below the minimum detectable limit (MDL). This is why special sample preparation procedures have to be employed so that the TE concentration in the specimen is effectively enhanced in a known way. The aim of this study was the selection of a proper sample preparation procedure by determination of selected element concentrations in different types of biological samples. In this work several sample preparation procedures were applied in order to choose the best one for specific experimental needs. The methods included: (a) tissue sectioning method (if appropriate); (b) dry method without chemical treatment - the samples were dried, homogenized and pressed into pellet; (c) wet method with chemical treatment - the samples were mineralized. The analyses were performed with different analytical methods in order to confirm the results obtained and in order to determine the influence of target preparation procedure on the level of elemental concentrations determination. The measurements were done by means of SRIXE (synchrotron radiation induced X-ray emission), EDXRF (energy dispersive X-ray fluorescence), TR-XRF (total reflection X-ray fluorescence), and PIXE (proton-induced X-ray emission). The above methods are described and the analytical results discussed. The results of the elemental analyses per-formed with different techniques show a good agreement only for some elements. The mineralization process increases the sensitivity of elemental determination only for selected elements. In other cases one could observe decreasing of elemental concentration in respect to non mineralized samples. Selection of sample preparation procedure depends on analytical requirements. (C) 2001 Elsevier Science BY All rights reserved.