UC Davis

Ethanol, drinking alcohol, is the most commonly consumed psychoactive drug in the United States and one of the most abused drugs worldwide (Perry et al., 2017). Ethanol is often associated with criminal prosecutions, and the measurement of blood alcohol concentration (BAC) is used to determine the level of impairment at the time of the crime, to further determine the individual’s criminal liability (Perry et al., 2017). BAC analysis is commonly accomplished in forensic laboratories and insufficient sample volume of the collected blood can result in laboratory-based testing not being utilized, thus the ability to reduce the necessary sample volume may increase the ability for successful prosecution of cases. A headspace gas chromatography with flame ionization and mass spectrometry method capable of detecting and quantitating ethanol in blood and aqueous samples using 100 and 150 µl sample volumes with acceptable calibration, bias, and precision was developed and validated. The results showed acceptable agreement with previously utilized approaches using 250 µl as the sample volume. The approach was validated over 5 days at 100, 150, and 250 µl of blood and aqueous specimens fortified with ethanol. Each volume set included quality control levels of 0.03, 0.15, 0.40 g/dL of ethanol (n=4/day). For each of the 15 analyses, the quadratic calibration curves’ included ethanol concentrations at 0.010 to 0.500 g/dL with R2 values of 0.999. The coefficient of variation for within and between-run replicate analyses were less than 4% for each concentration in blood and aqueous matrices for three separate volumes. Quantitative accuracy for ethanol spiked blood and aqueous specimens were within ±5% of their established ethanol concentrations for three separate volumes. The methodology was shown to be fit-for-purpose for use in routine forensic alcohol testing, allowing for a 2.5x reduction in sample volume as compared to the current approach in use.