Comparison of Immediate and Delayed Blood Alcohol Concentration Testing

The effects of storage time and temperature on blood alcohol concentration were evaluated in this two-part study involving 34 ethanol-negative and 21 ethanol-positive volunteers. Multiple 10-mL Vacutainer(®) blood tubes containing 100 mg of sodium fluoride and 20 mg of potassium oxalate were collected from living persons and subjected to various storage conditions. The time from collection to analysis ranged from 0 to 60 days and storage temperatures ranged from 3 to 20°C. Regardless of the storage conditions, all ethanol-negative samples remained negative (<0.0025 g/100 mL) throughout the study. There was no increase in the concentration of ethanol-positive samples beyond the expected variability of the method, regardless of storage time or temperature. Many ethanol-positive samples demonstrated decreases in concentration during storage compared with the original immediate analysis. The findings from this study support previous research, which demonstrates that microbial formation of ethanol in properly collected antemortem blood is unlikely.