Novel Sampling Technique for Sex Pheromone Analysis in Air

A novel unit that integrates sampling and analysis for the determination of pest insect sexual pheromones in environmental air using fabric phase sorptive extraction (FPSE) and headspace gas chromatography coupled to mass spectrometry (HSGC–MS) has been developed at the University of Córdoba in Spain (1).

Insect pests have long been the bane of the agricultural industry, damaging crops, reducing yields, and causing significant economic and environmental damage. This problem is further exacerbated by the use of expensive pesticides following pest discovery; the surrounding environment suffers further damage and crop quality is potentially compromised by contamination. In these cases, early detection is essential to reduce crop losses.

Currently, pest detection is primarily performed using sexual pheromone-based traps where insects are captured and visually counted. Sexual pheromones are a critical part of this system and their determination in environmental air can serve multiple purposes, including as an aid to fully understand the efficiency of the deployed traps or to use the pheromone as a biomarker of the presence of pests.

However, air analysis represents a significant challenge because of its heterogeneity, and the low concentrations of target analytes. The current established practice for sampling is the use of solid sorbent traps, which is the most common, robust, and easy-to-handle strategy, however, within the preconcentration step, approaches such as chemical, thermal, and solvent elution have proven to have drawbacks (2). This is also the case for thermal desorption (TD), which despite preventing analyte loss, can potentially bleed extraction sorbent at high temperatures (1).

The research aimed to overcome these issues using FPSE, a technique which has been widely used for liquid analysis since its development. Researchers believed it could also be used for gaseous samples and designed a novel unit that incorporates sol-gel hybrid inorganic-organic polymeric coatings on a fibre glass substrate surface as a sorbent trap. The viability of this approach was tested upon the tomato pest Tuta absoluta, which has ravaged European crops for the last decade, inducing 80–100% yield loss if pest control is incorrectly applied (3).

The results obtained from initial optimization and evaluation were promising, opening the door to further applications. Researchers reported excellent fabric phase performance, allowing fast flow of the air sample and an efficient extraction of the target analyte. Some limitations were identified with the approach including the time consuming process of transforming the unit from sampling to analysis mode, issues surrounding the use of headspace mode reducing the sensitivity of method when compared to conventional thermal desorption, and limited sample throughput. Researchers highlighted their intent to consider these issues in future research.

References

1. M.Carmen Alcudia-Leóna et al., J. Chroma. A1488, 17–25 (2017).
2. N. Ramírez et al., Talanta 82, 719–727 (2010).
3. N. Desneux et al., J. Pest. Sci. 83, 197–215 (2010).