Chopper-stabilized gas chromatography-electroantennography: Part I. Background, signal processing and example

A new method that can improve gas-chromatography-electroantennographic detection (GC-EAD) by orders of magnitude through a technique known as chopper stabilization combined with matched filtering in colored noise is presented. The EAD is a physiological recording from the antenna of an insect which can be used to find compounds in the GC effluent that the antenna is able to detect, having important applications for pest control and understanding of chemical communication in nature. The new method is demonstrated with whole-animal male Helicoverpa zea antennal preparations for detection of major pheromone component (cis-11-hexadecenal) and compared to results obtained using traditional EAD recording techniques. Results indicate that chopper stabilization under these circumstances can increase odorant detection performance by a factor of approximately 10 ⁴ over traditional methods. The time course of the response of the antenna is also better resolved under chopped conditions. Although the degree of improvement is expected to vary with insect species, odor, and insect preparation, under most circumstances a more sensitive and robust GC-EAD instrument will result from the application of this technique.