Feasibility study on in situ microwave digestion prior to analysis of biological samples by total reflection X-ray fluorescence

A microwave-assisted, micro-digestion procedure was developed and evaluated for analysis of solid samples by total reflection X-ray fluorescence spectrometry. Digestion of a 1.1-mg sub-sample of the NIST Bovine Liver (1577a) standard reference material was performed directly on the surface of common, siliconized quartz reflectors with a 20-mul H2O2 + 20 mul HNO3 mixture. The method was evaluated in terms of variations in the peak-to-background ratio (detection limits) and on the recovery rates for various volatile and non-volatile analytes. The characteristics of the reflector surface, the order of addition of the digestion reagents as well as the microwave power must be carefully controlled for successful application of the methodology. (C) 2001 Elsevier Science B.V. All rights reserved.