The determination of ethanol content in blood is one of the most important analysis in forensic toxicology, either in samples from corpses, or in drivers suspected of driving under the influence; in any case, precise, reliable and defensible ethanol determination is necessary.
In the US limit is “higher than 0.08% or 80 mg ethanol per 100 ml” of whole blood. The average BAC permitted across the majority of European countries, including Spain, Italy, and Ireland, is 0.05%, with some countries such as the United Kingdom allowing 0.08%.
Limits can be more stringent depending on the age of the suspect.
Blood Alcohol Content (BAC) represents one of the most important and largest volume analysis in forensic toxicology. The number of samples run in a day by a forensic lab includes specimen and quality control standards and can easily reach several hundreds. Consequentely, it is paramount that the system will be able to run many unattended analysis and safely classify and store results.
Most of the forensic laboratories performing BAC analysis use different technologies among which gas chromatography may not be the main applied technology. For this reason instruments need to require minimum maintenance, easy serviceability, and safety performance.
The results obtained can be used in court during a legal dispute with possible serious repercussions on people’s life. Data has to be, therefore, defendable.
Currently, to address all the above-mentioned needs, the headspace extraction technique is preferred due to the minimal contamination produced to the injector and column of the gas chromatograph; this technique for the determination of ethanol has been refined over time, to the extent that is now possible to perform these tests quickly and accurately. Blood is a very complex biological matrix, which includes salts, proteins, lipids and other metabolites. As such, a direct analysis of blood would result in a very frequent contamination of the GC injector, leading to frequent stops in the working routines and as such very low efficiency.