Characterization of Mass Spectra of Isomeric Dodecenols

The components of some insect sex pheromones are aliphatic long-chain unsaturated acetates, alcohols and aldehydes. For example, some isomers of dodecenols are the main components of sex pheromones of some noctuid moths (Δ7), olethreutine species (Δ8 and Δ9)¹ and so on. Identification of the structure, especially the position of the double bond, is a very important job. GC-MS is a good method to analyze the ng quantity of sample, which is the level of nature sex pheromones. However, the double bond of straight olefinic components has a strong tendency to migrate along the carbon chain prior to fragmentation under electron impact ionization conditions. So the spectra of isomers are very similar and difficult to be identified by the normal mass spectrometry. In this paper, we develop a new method to identify the isomers of dodecenol based on the sum of the intensity ratios of pairs of fragments.