Combined gas chromatography-infra-red spectroscopy for the determination of propanediol in acyclovir cream

A simple procedure is described for the determination of the 1,2-propanediol (propylene glycol) content of cream formulations containing the antiviral drug Acyclovir. Analysis of a solvent extract by gas chromatography coupled to an infra-red spectrometer enables the target analyte to be positively identified and an estimate of its concentration to be made. This application utilises the newer Tracer cryogenic deposition interface for gas chromatography and infra-red spectroscopy. This offers an alternative and complementary analytical strategy to gas chromatography coupled to mass spectrometry.