[A simple method for analyzing insect pheromone at the nanogram level by coupling headspace adsorption and thermal...

This paper describes a simple device for analysis of insect pheromones by coupling headspace adsorption and direct nonsolvent thermal desorption injection by gas chromatography (GC). A microsyringe packed with Porapak Q as the adsorbent was mounted in the airway for enriching and collecting pheromones. After collection the microsyringe was inserted into a thermal desorption device which was coupled with a GC inlet port. The pheromone desorbed from the adsorbent was condensed on the cold head of the GC column and injected into the column by quickly increasing the temperature of the column oven. The synthetic compounds of insect pheromones, E-7-dodecyl acetate (E-7-DA) and Z-5, E-7-dodecadienyl acetate (Z-5, E-7-DDA), were used to determine the recovery of the method and to evaluate the utility of this device for GC analysis of insect pheromones at the nanogram level. The results demonstrated the potentials of this device for GC analysis of volatile components both on packed columns and capillary columns. The advantage of headspace collection is that it avoids interference from non-volatile contaminants and the advantage of nonsolvent thermal desorption injection is to avoid the loss of pheromone while concentrating the eluted solution. The reported method combines these two advantages. The author also discusses the ways to further improve the method.