Simultaneous GC determination of turpentine, camphor, menthol and methyl salicylate in a topical analgesic formulation (Dologex®)

A gas chromatographic assay has been developed for the simultaneous quantitative determination of turpentine camphor, menthol and methyl salicylate in a topical formulation (Dologex(R)). Eucalyptol was used as the internal standard. Compounds were separated on a crosslinked 5% phenyl polydimethylsiloxane capillary column and detected by FID. The method was validated on the basis of selectivity recovery, linearity, precision and accuracy. Calibration graphs were linear for each analyte in the range studied. Intra and inter-day precision (coefficient of variation, On did not exceed 2%. The applicability of the method was demonstrated in a stability study of these compounds in samples of the formulation which had been maintained under different temperature conditions for six months.