Stability of Postmortem Blood Ethanol under Experimental Conditions

Abstract

Objective: To do analysis of ethanol in postmortem blood samples stored at different temperatures and time intervals and to compare ethanol concentration in blood samples with high and normal glucose amounts when stored at room temperature.
Methods: Blood samples collected from the fifty autopsy cases with 1% sodium fluoride as preservative were analyzed immediately by headspace gas chromatography. Each blood sample was divided into three sets. Each set of blood samples were stored at room temperature, 4o C and -20o C, respectively. The storage samples were analyzed for ethanol concentration at different time interval at: 2, 4, 7, 14, 28, 60 and 90 days after collection. Each of ten blood samples of normal (70-110 mg/dl) and high (greater than 200 mg/dl) glucose level were tested for ethanol concentration immediately and then transferred to twelve polypropylene tubes with a tightened cap. The blood sample was stored at room temperature and analyzed for various time intervals including 2, 4, 7, 14 and 28 days.
Results: Ethanol concentrations in blood stored at 4o C and -20o C were stable up to 14 and 7 days before slowly declining until 90 days. Whereas blood samples stored at room temperature the ethanol concentrations continuously decreased throughout storage time and was less stable at any storage time than those stored at 4o C and -20o C. Ethanol concentrations in the high glucose blood group were significantly increased after 7 days while those in the normal glucose blood group were mostly unchanged.
Conclusion: The stability of ethanol concentration in preserved blood stored at 4o C was longer than those stored at -20o C and room temperature. A high glucose level may lead to increased ethanol concentration when stored at room temperature.