Reconstruction of a case of thallium poisoning using LA-ICP-SFMS

The unique capabilities of laser ablation in combination with inductively coupled plasma sector field mass spectrometry (LA-ICP-SFMS) were employed to reconstruct details of a homicide by thallium poisoning, which took place 38 years ago in Austria. Thallium was determined in several human bone samples after acid digestion in a microwave oven. The ICP-SFMS results showed that the thallium concentration in the victim's bones was in the range 1.07-2.63 microg g(-1), which is up to 170 times higher compared to concentrations found in bones of persons who have died due to natural causes. The results were in accordance with the values obtained by graphite furnace atomic absorption spectrometry (GF-AAS). Laser ablation ICP-SFMS was applied to assess the time interval between the victim's poisoning and death. Several line scans with a laser spot size of 50 mum were performed on a thumbnail of the poisoned person and on a reference thumbnail by laser ablation ICP-SFMS. Thallium peaks were detected on the nail of the victim at a distance of 2.5 mm from the younger edge of the nail.