Development and validation of a quantitative determination method of blood ethanol by gas chromatography with headspace (GC-HS)

Quantitative determination of ethanol from blood is used for scientific research, for evaluation of ethanol metabolism in the human body or in the forensic laboratory. The aim of our paper is to develop and validate a method in order to determine the quantity of blood ethanol using gas chromatography with headspace. We used a GC 6890 N Agilent equipment, with headspace G 1888, two columns for alcohol analysis (DB-ALC1 and DB-ALC2) and FID detectors. The retention tune has been higher when using column DB-ALC1 (1.362 min) rather than for DB-ALC2 column (1.313 min). Internal standard for this method was isopropanol. The developed method for ethanol is specific because the retention time is different from the internal standard. Our method is linear in the range of 0.5-4 g/L. The correlation coefficients were 0.99958 for column DB-ALC1, respectively 0.99953 for column DB-ALC2. Using standard solutions like samples, we determined method precision and the recovery in percentage from theoretical concentrations. The recovery percents were between 98.89% (theoretical concentration 3 g ethanol/L) and 107.70% (theoretical concentration 0.5 g ethanol/L). In order to establish the influence of blood matrix, blood samples with known concentration of alcohol and internal standards, have been evaluated. In this case, the values for RSD were between 0.5 and 3.5% in direct correlation with sample homogeneity. The detection limits were 0.055 g/L (DB-ALC2) and 0.053 g/L (DB-ALC2). In the same conditions, the quantification limits were 0.186 g/L (DB-ALC2) and 0.177 g/L (DB-ALC2). The developed and validated method, in the mentioned conditions, is linear, precise and accurate and could be used for ethanol determination.