In vitro formation of ethanol in autopsy samples containing fluoride ions

We present a case of a death of a diabetic man where the concentration of ethanol in post-mortem blood rose from 0.4 g/l 2 days after autopsy to 3.5 g/l 10 days after autopsy. The presence of fluoride ions in this blood sample was determined with ion chromatography and verified that fluoride ions were added to the vials. The concentrations of free fluoride, corresponding to 0.21 and 0.25% w/v potassium fluoride in blood and urine, respectively, were somewhat lower than the recommended 1% w/v. However, the amount of fluoride ions bound to calcium, proteins and other compounds in the samples is unknown. The blood sample was also subject to microbiological examination, which revealed growth of bacteria. In addition, a very high concentration of glucose was found in vitreous humour from the deceased. To determine whether the ethanol detected at the first analysis was of ante-mortem origin, ethyl glucuronide was analysed. Its absence, in the blood as well as the urine sample, strongly supported the theory that, in this case, all the ethanol detected was formed post-mortem. This case showed that ethanol may be formed in vitro at a very high concentration, despite the verified presence of fluoride ions. Possible reasons for this unusual formation of ethanol were the abundant presence of bacteria, a high level of glucose and, possibly, an insufficient amount of fluoride added to the vials.