Solid-phase microextraction may catalize hydrogenation when using hydrogen as carrier in gas chromatography

Abstract

When hydrogen is used as carrier gas, carbon-carbon double bonds may be hydrogenated in the hot gas chromatograph (GC) injector if introduced by solid-phase microextraction (SPME). SPME fibers coated with polydimethylsiloxane (PDMS)/carboxen/divinylbenzene (DVB), PDMS/carboxen, polyacrylate, PDMS/DVB and PDMS on fused silica, stableflex or metal alloy core have been tested with fatty acid methyl esters (FAMEs) from olive oil. Using coatings containing DVB, hydrogenation took place with high conversion rates (82.0–92.9%) independently of the core material. With all fibers having a metal core, hydrogenation was observed to a certain extent (27.4–85.3%). PDMS, PDMS/carboxen and polyacrylate coated fibers with a fused silica or stableflex core resulted in negligible hydrogenation (0.2–2.5%). The occurrence of hydrogenation was confirmed also with other substances containing carbon-carbon double bonds (n-alkenes, alkenoic acids, mono- and polyunsaturated fatty acid methyl and ethyl esters).