Rapid identification of insect cuticular hydrocarbons using gas chromatography-ion-trap mass spectrometry

Insect cuticular hydrocarbons (CHCs) are not only essential for desiccation resistance, they also play an important role as chemical signals and cues in social as well as solitary insects. The identification of CHCs is, therefore, crucial to an understanding of the chemical communication within and between insect species. We describe a method for rapid, simple, and unambiguous identification of CHCs using gas chromatography-ion-trap mass spectrometry. External ionization configuration in combination with a low ion-trap temperature resulted in dramatically increased intensities of molecular ions for alkanes, alkenes and alkadienes, and in high-mass fragmentation patterns with intense ions characteristic for methyl-branched hydrocarbons comparable to those obtained with quadrupole instruments. Additionally, we present an external chemical ionization-tandem mass-spectrometric method that allows for the determination of double-bond positions in alkenes and alkadienes without the need for derivatization prior to analysis.