PRECONCENTRATION OF TRACE-ELEMENTS IN BIOLOGICAL-MATERIALS BY DRY ASHING FOR TTPIXE ANALYSIS - A STUDY OF MATRIX EFFECTS

Trace elements in biological materials were preconcentrated by dry ash ing at 550 degrees C in order to improve the detection limits for thic k-target PIXE analyses. The analytical procedure was calibrated with e qually prepared ashes of certified biological standard reference mater ials (SRMs). The matrix effects were studied both theoretically and ex perimentally. A drawback of the ashing procedure is that volatile elem ents such as halogenides and sulfur can be partly lost depending on th e composition of the material studied. Thick-target PIXE combined with dry ashing is a sensitive and reliable technique for the determinatio n of elements with atomic number > 20 in biological materials with a l ow ash content.