Dual-Column HS-GC-FID/FID Method for In-Depth Analysis of Low-Molecular-Weight Volatile Alcohols in Postmortem Biological Material

Aim: The aim of this study was to develop and validate a reliable HS-GC-FID/FID method for the determination of ethanol and other low-molecular-weight volatile compounds in biological fluids for forensic applications. Method: The method is based on headspace gas chromatography with dual-column and dual flame ionization detection (HS-GC-FID/FID), using Zebron ZB-BAC1 and ZB-BAC2 columns. The procedure was validated in terms of linearity, limits of detection and quantification, precision, and accuracy, as well as carryover. Results: The method demonstrated linearity over the concentration range of 0.05–5.0‰, with R2 values of 0.997–0.999. The limit of quantification (LOQ) was 0.05‰, and the limit of detection (LOD) was 0.025‰. Precision and accuracy were both below 5%. Retention times (min) on the two columns were as follows: methanol (1.70/1.81), ethanol (2.06/2.29), acetone (2.60/2.59), isopropanol (2.45/2.73), n-propanol (3.24/3.98), and n-butanol (6.35/8.45). The developed method was successfully evaluated through international proficiency testing and is routinely applied in our laboratory for forensic casework. Conclusions: The developed HS-GC-FID/FID method provides accurate and reliable determination of ethanol and other relevant volatile compounds in biological fluids (i.a., blood) and meets the requirements for forensic toxicology. Additionally, the literature review conducted in this study highlights that globally unified principles for forensic alcohol analysis are still lacking, and that certain inappropriate methodological approaches remain in use. The present paper also provides recommendations defining essential methodological requirements to ensure the evidential reliability of ethanol analysis in forensic toxicology.