Abstract
Background: The measurement of blood alcohol levels is a routine analysis carried out in many forensic laboratories. Headspace and Solid-Phase Micro-Extraction techniques coupled with Gas Chromatography have emerged as the method of choice for alcohol detection in blood samples, which is too expensive and unavailable in most clinical laboratories in developing countries.

Aim: The objective of this study was to validate and develop an efficient and sensitive Gas Chromatography-Flame Ionization Detector (GC-FID) analytical method for detecting and quantifying methyl and ethyl alcohol in blood by solvent partitioning extraction technique without the need for Headspace techniques.

Methods: Analysis was performed on sheep's whole blood using chloroform as the extracting solvent and dichloromethane as the internal standard. Linearity was achieved across a concentration range of 10 mg to 320 mg/dl for methanol and ethanol. The developed method was fully validated according to the guidelines of the Scientific Working Group for Forensic Toxicology.

Results: The linearity of the method showed a correlation coefficient of 0.999 and 0.998 for whole-blood methanol and ethanol, respectively. The limit of quantification (LOQ) and limit of detection (LOD) were within the range of 7.2–10 mg/dl and 4.0–8.0 for methanol and ethanol in whole blood, respectively, and resulted in a precision of 1.17–6.5 and 0.79–2.98 and an accuracy of 1.07–5.27% and 0.37–36% for methanol and ethanol, respectively.

Conclusion: This new method was a much more convenient and reliable process to measure methanol and ethanol in whole blood samples by reducing sample pretreatment effort and cost with no need for Headspace techniques.