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

Abstract

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. For there to be any possibility of fermentation to occur by C. Albicans in an antemortem blood sample there must be a plausible mechanism for introduction of C. Albicans into the blood. One mechanism proffered at trial is environmental contamination resulting from ambient air drawn into the evacuated blood collection tube. Blood was drawn from ethanol-free individuals into 6 and 10-ml graytop Vacutainer® tubes containing sodium fluoride and 6-ml Vacutainer® tubes without a preservative. Following the blood draws, the tubes were stored unstoppered at room temperature for 24 or 48 h in various locations. Following unstoppered storage, the tubes were stoppered and stored refrigerated (~4°C), left at room temperature (~22°C), or placed in an oven (37°C). The refrigerated blood was analyzed for ethanol using headspace gas chromatography after both 5 days and 32 months. Unrefrigerated blood samples were analyzed after being stored at room temperature or in an oven for up to 30 days. Ethanol was not detected in any of the blood tubes after storage regardless of storage time, storage temperature, or preservative concentration.

Ethanol stability in unpreserved refrigerated antemortem blood

“…The question about how much, if any, sodium fluoride is necessary to include in stored antemortem blood has been brought up in response to a manufacturing error in which the preservative was not added to the blood collection tubes [16]. Antemortem ethanol-free blood collected from individuals using lavender-top Vacutainer® tubes without sodium fluoride and stored at either room temperature, 22°C, or elevated temperature, 37°C, for a month remained ethanol-free [17]. Early research reported a significant difference in ethanol stability between blood with and without sodium fluoride when stored refrigerated in RSA cups or glass ampoules for 4 or 8 weeks [8].…”