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 ashing at 550 degrees C in order to improve the detection limits for thick-target PIXE analyses. The analytical procedure was calibrated with equally prepared ashes of certified biological standard reference materials (SRMs). The matrix effects were studied both theoretically and experimentally. A drawback of the ashing procedure is that volatile elements such as halogenides and sulfur can be partly lost depending on the composition of the material studied. Thick-target PIXE combined with dry ashing is a sensitive and reliable technique for the determination of elements with atomic number > 20 in biological materials with a low ash content.