Analytical artefacts: H-2 carrier gas hydrogenation of plant volatiles during headspace solid-phase microextraction gas chromatography

Introduction Hydrogen is the most efficient and economical carrier gas for gas chromatography (GC). However, there are rare reports of artefact formation by hydrogenation of unsaturated compounds on GC. Head space solid-phase microextraction (HS-SPME) GC conditions for hydrogenation were studied. Methodology HS-SPME-GC-mass spectrometry (MS) analyses of common classes of plant volatiles were carried out using hydrogen (H-2) and helium (He) carrier gases with different SPME fibre coatings, GC inlet temperatures, and desorption times. Results Common phenylpropanoids, monoterpenes, and green leaf volatiles were hydrogenated to varying degrees on HS-SPME-GC with H-2 carrier gas and SPME fibres coated with polydimethylsiloxane (PDMS)/Carboxen (CAR), PDMS/divinylbenzene (DVB), and PDMS/CAR/DVB. No artefacts were detected using PDMS-only coated fibres or He carrier gas. Conclusion Unsaturated plant volatiles may be hydrogenated on HS-SPME-GC when using H-2 carrier gas with SPME fibre coatings containing DVB polymer or CAR porous particles. Parallel analyses with He and H-2 carrier gases are recommended when developing HS-SPME-GC methods for plant volatiles, or use of PDMS-only coated fibres.

Automated summary

Hydrogen is the most efficient carrier gas for gas chromatography, but there are rare reports of artefact formation by hydrogenation of unsaturated compounds on GC. The study found that unsaturated plant volatiles may be hydrogenated on HS-SPME-GC when using H-2 carrier gas with SPME fibre coatings containing DVB polymer or CAR porous particles. It is recommended to conduct parallel analyses with He and H-2 carrier gases or use PDMS-only coated fibres when developing HS-SPME-GC methods for plant volatiles.