Improved recovery and stability of ethanol in automated headspace analysis

Solutions are reported here for two problems in automated headspace gas chromatographic analysis for ethanol. The first is the catalytic oxidation of ethanol by oxyhemoglobin, a process that is limited only by the amount of oxygen in the sealed vessel. This reaction is prevented by the addition of sodium dithionite. The other problem, the lack of a suitable salting-out agent, led to the selection of ammonium sulfate, which improved recovery of ethanol as well as enhancing method precision. A procedure incorporating these improvements is described.