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 t o cope with very low concentrations, sometimes even below the minimum detec table limit (MDL). This is why special sample preparation procedures have t o be employed so that the TE concentration in the specimen is effectively e nhanced in a known way. The aim of this study was the selection of a proper sample preparation procedure by determination of selected element concentr ations in different types of biological samples. In this work several sampl e preparation procedures were applied in order to choose the best one for s pecific experimental needs. The methods included: (a) tissue sectioning met hod (if appropriate); (b) dry method without chemical treatment - the sampl es were dried, homogenized and pressed into pellet; (c) wet method with che mical 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), EDX RF (energy dispersive X-ray fluorescence), TR-XRF (total reflection X-ray f luorescence), and PIXE (proton-induced X-ray emission). The above methods a re described and the analytical results discussed. The results of the eleme ntal analyses per-formed with different techniques show a good agreement on ly for some elements. The mineralization process increases the sensitivity of elemental determination only for selected elements. In other cases one c ould observe decreasing of elemental concentration in respect to non minera lized samples. Selection of sample preparation procedure depends on analyti cal requirements. (C) 2001 Elsevier Science BY All rights reserved.