Location of double-bond position in long-chain aldehydes and acetates by mass spectral analysis of epoxide derivatives [in extracts obtained from insects]

An analytical procedure has been developed for the identification of the position of a double bond in an otherwise fully characterized long-chain aldehyde or acetate. Less than a microgram of the monounsaturated test compound is treated with m-chloroperbenzoic acid to form the epoxide. This derivative is then injected into a combined gas chromatograph/mass spectrometer for analysis. Preferential cleavage alpha to the epoxy group produces identifiable fragments that indicate the position of the epoxy group and thus the position of the double bond in the original compound. The procedure has been applied to naturally occurring pheromonal aldehydes and acetates in extracts obtained from insects. Mixtures of isomers differing only in double-bond position can often be analyzed by this procedure.