Problems of Forensic Sciences 2009 Vol. 80 (LXXX) 429-440
THE INFLUENCE OF THE METHOD OF DIGESTION OF BIOLOGICAL SAMPLES AND THE METHOD OF DETERMINATION OF SOME MAJOR AND TRACE ELEMENTS IN THESE SAMPLES ON ANALYTICAL RESULTS
Teresa LECH1, Danuta DUDEK-ADAMSKA2
1Institute of Forensic Research, Kraków, Poland
2Faculty of Chemistry, Jagiellonian University, Kraków, Poland
Streszczenie
Collection of a sample and securing, storing, preparing and determining it may have an influence on the end result of chemo-toxicological analysis. The aim of the research was to investigate the influence of different methods of preparing material for analysis (without mineralization, conventional heating in Bethge apparatus, microwave digestion) and also two analytical methods (F-AAS, ICP-OES) on the results of determination of some elements in samples of biological material (blood, urine, bile, sections of internal organs) which are commonly analysed in forensic expert examinations. The method of mineralization in Bethge apparatuses (with conventional heating) allowed us to obtain comparable results to those obtained by a more modern method – microwave digestion – regardless of which method was used to analyse the samples (ICP-OES or F-AAS), with the exception of Cd, for which lower results were obtained by the F-AAS method after mineralization in Bethge apparatus. Furthermore, it was ascertained that in cases where time of analysis plays a significant role (e.g. in diagnosing acute poisonings by metal compounds), analysis of urine can be carried out without preliminary decomposition of the sample in acids: for most studied metals (besides Hg, Pb and Li), the sample only needs to be appropriately diluted. The influence of the analytical method on results of determination of heavy metals (Zn, Mn, Cu, Cd and Cr) in samples of autopsy material (body fluids, sections of internal organs) was observed to be insignificant. For example, concentrations of Cr in urine collected from persons who had not been poisoned, as determined by the ICP-OES method, were about 30% higher than those obtained by the F-AAS method. In samples of NIST Bovine Liver 1577b somewhat higher concentrations of Cu, Mn and Zn were obtained by the ICP-OES method than by the F-AAS method.
Słowa kluczowe
Metals; Biological material; Method of digestion; Method of determination; Results of analysis