Lack of fermentation in antemortem blood samples stored unstoppered in various locations.

A common defense challenge when antemortem blood ethanol results are presented at trial is the assertion that ethanol was formed in the blood tube after the blood draw through fermentation of the blood glucose by Candida albicans (C. Albicans). In contrast, decades of research into the stability of ethanol in antemortem blood collected for forensic purposes have consistently shown that any analytically significant change in ethanol concentration is a decrease and initially, ethanol-negative blood remains ethanol-negative with storage.

Testing antemortem blood samples for ethanol after four to seven years of refrigerated storage.

The previous studies on ethanol stability in antemortem blood samples stored under various conditions have shown that ethanol concentration decreases with storage. The feasibility of measuring a forensically meaningful blood ethanol concentration in antemortem blood samples stored refrigerated (~4°C) from 4-7 years after the blood draw was evaluated in this research. All blood samples were collected into two 10-ml gray top Vacutainer® tubes as part of police driving under the influence investigations.

Large-scale reanalysis of refrigerated antemortem blood samples for ethanol content at random intervals.

Ethanol stability in antemortem blood stored under various conditions has been widely studied. Most such studies have somewhat limited sample size (<50) and limited variation in the length of time between the blood draw and the first analysis and between the first analysis and the reanalysis. In the work presented here, the antemortem blood drawn for forensic purposes and stored refrigerated (~4°C) in 371 cases was analyzed for ethanol concentration using headspace gas chromatography at various times after the blood draw based on routine case flow and then also analyzed at various times within approximately 1 year after the first analysis.