Increased sensitivity in thick-target particle induced X-ray emission analyses using dry ashing for preconcentration

The sensitivity in thick-target particle induced X-ray emission (PIXE) analyses of biological materials can be enhanced by dry ashing, The gain depends mainly on the mass reduction factor and the composition of the residual ash, The enhancement factor was 7 for the certified reference material Pine Needles and the limits of detection (LODs) were below 0.2 mu g/g for Zn, Cu, Rb and Sr. When ashing biological materials with low ash contents such as wood of pine or spruce (0.3% of dry weight) and honey (0.1% of wet weight) the gain was far greater. The LODs for these materials were 30 ng/g for wood and below 10 ng/g for honey. In addition, the ashed samples were more homogenous and more resistant to changes during the irradiation than the original biological samples. (C) 1999 Elsevier Science B.V. All rights reserved.