A Technique for Thermal Desorption Analyses Suitable for Thermally-Labile, Volatile Compounds
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Many plant and insect interactions are governed by odors released by the plants or insects and there exists a continual need for new or improved methods to collect and identify these odors. Our group has for some time studied below-ground, plant-produced volatile signals affecting nematode and insect behavior. The research requires repeated sampling of volatiles of intact plant/soil systems in the laboratory as well as the field with the help of probes to minimize unwanted effects on the systems we are studying. After evaluating solid adsorbent filters with solvent extraction or solid phase micro extraction fiber sample collection, we found dynamic sampling of small air volumes on Tenax TA filters followed by thermal desorption sample introduction to be the most suitable analytical technique for our applications. Here we present the development and evaluation of a low-cost and relatively simple thermal desorption technique where a cold trap cooled with liquid carbon dioxide is added as an integral part of a splitless injector. Temperature gradient-based focusing and low thermal mass minimizes aerosol formation and eliminates the need for flash heating, resulting in low sample degradation comparable to solvent-based on-column injections. Additionally, since the presence of the cold trap does not affect normal splitless injections, on-the-fly switching between splitless and thermal desorption modes can be used for external standard quantification.
KeywordsGC/MS Thermal desorption Thermally labile compounds Root volatiles Trace analysis Pregeijerene Ruta graveolens
The author would like to thank Steve Willms for design and construction of the control box and for making it all work and to Robert Bruton for improving the trap and for never complaining when yet another system was requested to be fabricated. Also, a special thanks to Heather McAuslane, Sandy Allen, John Beck and David Hall for valuable comments and suggestions to improve the manuscript.
- Ali JG, Alborn HT, Campos-Herrera R, Kaplan F, Duncan LW, Rodriguez-Saona C, Koppenhöfer AM, Stelinski LL (2012) Subterranean, herbivore-induced plant volatile increases biological control activity of multiple beneficial nematode species in distinct habitats. PLoS One 7:e38146CrossRefPubMedPubMedCentralGoogle Scholar
- Anderson BA, Lundgren L, Stenhagen G (1979) Capillary gas chromatograms of leaf volatiles. A possible aid to breeders for pest and disease resistance. In: Waller G (ed) Biochemical applications of mass spectrometry, vol 11. Wiley, New York, pp 855–894Google Scholar
- Deasy W, Shepherd T, Alexander CJ, Birch ANE, Evans KA (2016) Development and validation of a SPME-GC-MS method for in situ passive sampling of root volatiles from glasshouse grown broccoli plants undergoing below ground herbivory by larvae of cabbage root fly, Delia radicum. Phytochem Anal 27:365–393Google Scholar
- Stenhagen G, Alborn HT, Lundborg T (1987) Variation of rhizosphere (root and microflora) exudates in genotypes of barley. In Waller G (ed) Allelochemicals: Role in Agriculture and Forestry. ACS Symposium Series 330, New York, pp76–88Google Scholar
- Taylor T (2001) Sample injection systems. In: Hanly AJ, Adlard ER (eds) Gas chromatographic techniques and applications. CRC press, Boca Raton, p 91Google Scholar