Extracting syringe—connecting sample preparation and gas chromatography

Abstract

A device was developed incorporating a miniaturised membrane extraction unit which directly connects liquid–liquid extraction with gas chromatography. The extraction unit comprises a single hydrophobic hollow fibre, enclosed in the centre of a Kel-F piece, with a stainless steel needle extruding from one of its ends. The fibre serves as an interfacial support between an aqueous sample and an organic solvent with sample solutes partitioning between the phases. The extraction thus involves an enrichment and simultaneous phase transfer of target organic compounds. The instrument is placed directly on top of a gas chromatograph for automated extraction and injection, hence we have chosen to call it an extracting syringe (ESy). The extraction of benzene, toluene, ethylbenzene and xylenes from human blood plasma was used as a model system to show the general applicability of the presented device. The results are in line with expectations, proving the approach straightforward and an alternative means to automated sample preparation for routine gas chromatographic analysis.