Silicon determination in human ventricular whole blood: a possible marker of drowning

This article presents the first results demonstrating that total silicon trace concentration in human ventricular whole blood may be used as a further marker in the diagnosis of drowning. The difference in silicon content between the left and right ventricles was significantly higher for drowning cases than that from individuals who had not drowned. These findings were in full agreement with autoptic responses, supporting silicon as a marker of freshwater drowning. The procedure entails an alkaline microwaveassisted digestion using tetramethylammonium hydroxide (TMAH) in the presence of H2O2 followed by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC–ICP–MS) detection, whose accuracy was obtained for Seronorm whole blood reference material. Satisfactory recoveries (91–98%) were gained on whole ventricular blood, with a silicon content lower than the method detection limit (MDL), spiked at 5 to 7 ug/g with materials consistent with drowning media constituents, that is, freshwater plankton (CRM [certified reference material] 414), silicon dioxide, diatomaceous earth powder, and a silicon standard solution. Good within-lab reproducibility (4–10%) and sensitivity (MDL = 0.46 ug/g) were achieved as well. The procedure was applied to blood samples from 18 different real cases of death.