Application of TDA AAS to Direct Mercury Determination in Postmortem Material in Forensic Toxicology Examinations

Mercury is a heavy metal with high toxicity, the level of which depends on the form of the metal. One of the newer techniques for determining trace amounts of total mercury in various materials, including biological samples, is thermal decomposition, amalgamation and atomic absorption spectrometry (TDA AAS). The TDA AAS method was optimized and validated using a mercury analyzer (DMA-80). The limits of detection for mercury were 0.10 and 0.20 μg/L (nickel and quartz boats, respectively). The working range of the calibration curve was at least from 0.6 to 200 ng Hg/mL; the intra-day precision in samples (RSD)-in the range of: 1.66-6.86% (blood), 0.82-1.47% (urine) and 2.01-3.44% (hair); the inter-day precision (over 8 days): 2.51%, and 2.5% (blood spiked with 2.5 and 10 ng Hg, respectively), 5.10% and 3.16% (urine spiked with 2.0 and 6.0 ng Hg, respectively). The accuracy (as relative error, mean value) determined on the basis of the study of reference materials of blood (Seronorm Trace Elements Whole Blood L-1, L-2, L-3), urine (Seronorm Trace Elements Urine, Urine L-2), and hair (Human Hair NIES CRM No. 13) was: 2.00% (blood), 0.50% (urine) and 0.86% (hair); recovery of 2.5 ng Hg (blood): 93-97%. The method was used for the determination of mercury in 76 samples of various biological matrices, including samples of whole blood, urine, hair, bile and vitreous humor. Mercury concentrations in postmortem blood (n = 24) were in the range: 0.61-12.4 μg/L (median 3.02 μg/L); urine (n = 12): 0.16-2.19 μg/L (median 0.81 μg/L); hair (n = 14): 0.08-0.53 μg/g (median 0.22 μg/g); bile (n = 12): 1.15-7.11 μg/L (median 2.41 μg/L and vitreous humor (n = 13): 0.22-1.01 μg/L (median 0.47 μg/L). The method is suitable for the purposes of forensic toxicology analysis.