Volume 17, Issue 2 (April 1972)
A Gas Chromatographic Method for Ethanol Determination in Vapors of Biological Fluids
Rapid identification and quantitation of blood ethanol by gas chromatography (GC) has been especially useful to the clinical and forensic chemist, particularly as court evidence in prosecuting drunken drivers. Certain identification can be made and concentration determined rapidly by GC. A number of GC methods are available for ethanol determination in biological liquid samples. Currently, advances are being made in the area of vapor phase analysis [1–4]. Direct vapor injections overcome several disadvantages of liquid sample injection. Liquid samples containing sodium fluoride as a preservative tend to etch the syringe. Clotted samples are no longer a problem with vapor injections and frequent cleaning of the syringe is not required. With direct injection of blood or diluted blood samples, special inlets are necessary and must be changed periodically to remove protein and other nonvolatile deposits. In addition, the life of the columns is increased with vapor samples. According to Henry's law, at a given temperature there is a definite ratio between the concentration of ethanol in the blood phase and the air in direct equilibrium with it. Investigators have verified Henry's law [5–10] for both aqueous and blood ethanol solutions. The method described here consists of equilibrating blood with n-propanol as internal standard and injecting the vapors. Because of the internal standard, the volume of the injected sample is no longer a critical quantity.