Solid-phase microextraction pheromones

Abstract A relatively small number of mammalian pheromones has been identified, in contrast to a plethora of known insect pheromones, but two remarkable Asian elephant/insect pheromonal linkages have been elucidated, namely, (Z)-7-dodecen-1-yl acetate and frontalin. In addition, behavioral bioassays have demonstrated the presence of a chemical signal in the urine of female African elephants around the time of ovulation. Our search for possible ovulatory pheromones in the headspace over female African elephant urine has revealed for the first time the presence of a number of known insect pheromones. This search has been facilitated by the use of a powerful new analytical technique, automated solid phase dynamic extraction (SPDE)/GC-MS, as well as by novel macros for enhanced and rapid comparison of multiple mass spectral data files from Agilent ChemStation . This chapter will focus on our methodologies and results, as well as on a comparison of SPDE and the more established techniques of solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). 

More recently, solid phase microextraction (SPME) [22] has been applied to the analysis of bug pheromones, using two techniques. In the first, headspace volatiles are trapped on the SPME fiber, analogous to trapping on SuperQ [e.g., 23]. Alternatively, if the source of the pheromone is known, the SPME fiber can be wiped on the cuticle to directly adsorb the compounds [24]. In either case, the fiber is then thermally desorbed directly into a GC or GC-MS. Whereas this method is excellent for analysis, with good recoveries, it does not provide a sample that can be used for bioassays or for isolation of an active compound. 

A new major aggregation pheromone emitted by the storage mite, Chor-toglyphus arcuatus, was identified as AR, 6R, 8i )-4,6,8-trimethyldecan-2-one. To identify this new pheromone from mites, headspace of undisturbed colonies of storage mites was analyzed by GC-MS by the use of a closed-loop stripping apparatus or solid phase microextraction. The structure was then elucidated by MS, synthesis of authentic samples, and GC on a chiral... 

Peppuy A., Robert A., Semon E., Ginies C., Lettere M., Bonnard O. and Bordereau C. (2001b) (Z)-dodec-3-en-l-ol, a novel termite trail pheromone identified after solid phase microextraction from Macrotermes annandalei. J. Insect Physiol. 47, 445 -53. 

Although liquid injection is the usual method of sample introduction, there are other types of injector available. Techniques include headspace analysis for species with low molecular masses and high volatility, such as halocarbons in water thermal desorption for analytes (e.g., pheromones) trapped by passage through a cartridge packed with a retentive material such as Tenax and solid phase microextraction fiber elution for compounds that have been adsorbed onto the fiber from liquid or gaseous matrices. 

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