|Hicks, Mathew - Matt
Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2014
Publication Date: 1/19/2015
Citation: Kuenen, L.P., Hicks, M.N. 2015. Gas chromatography column as an ambient-temperature volatile trap. Entomologia Experimentalis et Applicata. 154:35–44.
Interpretive Summary: Most insects, including agricultural pests, locate their mates and food sources by orienting and moving toward a specific odor source emanating from them. Both the identity and ratios of the chemicals that comprise these odors must be elucidated in order to make synthetic copies for luring insects into traps. However, many of these required odor components are emitted in extremely low quantities and/or from very small locations; both of these circumstances may result in the inability to replicate natural odor sources. Here we developed and validated a method that gives researchers a new tool to collect odors from small or hard to reach sources and do so with greatly reduced processing time. Chemists could use this method to make new trap lures and help entomologists better understand pest biology for more effective trapping. Trap count data are crucial for development of sustainable pest control practices.
Technical Abstract: Open tube volatile traps have largely been shunned in favor of solid-adsorbent-containing traps. Anecdotally, there is a bias against open tube volatile traps due to the belief that they are only effective when chilled as volatiles are expected to pass through unchilled tubes’ lumens or chromatograph down their lengths and out the end. We report here that at ambient laboratory temperatures, a DB-1 gas chromatography column effectively collects sex pheromone volatiles from a rubber septum. We placed glass wool “plugs” in both open tube trap types and found no volatiles in these plugs, indicating that breakthrough did not occur during one-hour collections at 25 ml/min. Comparisons with open-tube glass capillaries and a SuperQ®-containing capillary indicated that ratios of test compounds were affected in all three trap types by the air flow rate used for collections. Eluting analytes from the SuperQ required ca. 15 times more solvent than was required to collect all the pheromone from the open tube traps and the GC column enjoyed an additional three-fold reduced solvent volume compared to the glass capillary. Thus, analytes could be eluted and directly analyzed on GC without solvent condensation. Two or three sequential 3-to-5 µl injections with a two-meter retention gap in place, allowed rapid analyses with no workup. GC capillary columns are very flexible, allowing for the collection of volatiles from small or hard to reach odor sources.