The effect of biologic specimen type on the gas chromatographic headspace analysis of ethanol and other volatile compounds.

Gas chromatographic analyses of 37 degrees C headspace vapors above liquid phases saturated with sodium chloride demonstrated that the partitioning of isopropanol, n-propanol, and t-butanol from blood, plasma, or serum to headspace vapor was greatly reduced relative to that observed with the use of water as the liquid phase. The partitioning of ethanol and acetone was moderately reduced with these specimens relative to water, while no effect was seen with methanol or acetonitrile. Normal urine only slightly affected relative partitioning, and vitreous humor had no effect. The partitioning reductions observed with blood were not affected by changing the equilibration temperature to 25 degrees C, by lengthening the equilibration time to three days, nor by changing the concentration of the volatiles in the liquid phase. The use of saturated sodium sulfate enhanced the differences in partitioning observed between water and blood. Only with substantial dilution (5:1) of blood specimens was the effect abolished.