Wpływ sposobów mineralizacji próbek biologicznych oraz metod oznaczania niektórych, podstawowych i śladowych pierwiastków w tych próbach na wyniki analityczne

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 o f the research was to investigate the influence of different methods o f 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 o f determination of some elements in samples o f 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 o f which method was used to analyse the samples (ICP-OES or F-AAS), with the exception o f 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 o f analysis plays a significant role (e.g. in diagnosing acute poisonings by metal compounds), analysis o f urine can be carried out without preliminary decomposition o f the sample in acids: for most studied metals (besides Hg, Pb and Li), the sample only needs to be appropriately diluted. The influence o f the analytical method on results o f determination o f heavy metals (Zn, Mn, Cu, Cd and Cr) in samples of autopsy material (body fluids, sections o f 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 o f NIST Bovine Liver 1577b somewhat higher concentrations o f Cu, Mn and Zn were obtained by the ICP-OES method than by the F-AAS method

Optimization and validation of a procedure for the determination of total chromium in postmortem material by ETAAS

A study was conducted to optimize and validate a procedure for the determination of total chromium in wet digested samples of human blood and body tissues for forensic toxicological purposes. Five experimental setups of electrothermal atomic absorption spectrometry (ETAAS) using a Solaar MQZe (Thermo Electron Co.) were compared, using the following: (i) no modifier, (ii) magnesium nitrate, (iii) palladium nitrate, (iv) magnesium and palladium nitrate mixture and (v) palladium nitrate and ammonium dihydrogen phosphate mixture as chemical modifiers. Furthermore, for the mineralization process in the Ethos 1 microwave system (Milestone), it was found that the temperature program suggested by the producer should be improved, thus, four experimental setups are presented. Finally, the whole procedure was validated, obtaining a linear range of calibration from 0.22 to 12.0 µg/L, limit of detection at 0.07 µg/L, limit of quantification at 0.22 µg/L, precision (as relative standard deviation) up to 6%, and accuracy of 98.4–104.4% for the analysis of certified material (ClinChek Whole Blood Control Level III, SRM Whole Blood Level II and III and SRM 1577c Bovine Liver) and within a range from 84.5 to 103.2% for the recovery of spiked samples. It was ascertained that modified wet digestion, followed by ETAAS with magnesium nitrate as a modifier (5 µg) with 1,400/2,500°C as the pyrolysis and atomization temperatures, respectively, can be used to determine chromium at reference levels in biological materials (blood and internal organs) and levels found in chronic or acute poisonings with chromium compounds