The sensitivity of gas chromatography-headspace solid phase microextraction in relationship with relative volatility of volatile organic compounds

In order to explore the analytical performance of Headspace-Solid-phase Microextraction (HS-SPME), the sensitivity of gas chromatography (GC)-Mass Spectrometry (MS) determinations was examined in terms of calibration slopes, that is, response factor values of selected volatile organic compounds (VOC). The HS-SPME was applied to extract two kinds of gaseous VOC analytes, namely group I (methyl ethyl ketone, isobutyl alcohol, methyl isobutyl ketone, and butyl acetate, all having high water solubility) and group II (benzene, toluene, styrene, and xylene, all having moderate water solubility) from water solutions. The results, derived by both external and internal calibration, were then evaluated by considering headspace sample volume and solute volatility. In the case of solutes consisting of group I, sensitivity seems to increase with increasing HS size, although there are no such discernible patterns for group II solutes. The observed relative patterns in extraction efficiency may be accounted for by the differences in intermolecular forces present between the compounds of groups I and II and the possible effects of diffusion kinetics of the VOCs to the SPME fiber or competitive adsorption between different VOCs. As such, sensitivity of HS-SPME is tightly affected by the air-water partitioning properties of the target compounds and the response of SPME to such properties.