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Downsizing vacuum-assisted headspace solidphase microextraction

Elefteria Psillakis, Nicolas Kalogerakis, Evangelia Yiantzi

Πλήρης Εγγραφή

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Περίληψη

Recently, we proposed a new headspace solid-phase microextraction (HSSPME) procedure, termedvacuum-assisted HSSPME (Vac-HSSPME), where headspace sampling of 10 mL aqueous sample volumestook place in 500 or 1000 mL sample containers under vacuum conditions. In the present study, we downsizedthe extraction device to a 22 mL modified sample vial and concluded that changes in the final totalpressure of the pre-evacuated vial following sample introduction were sufficiently low to allow efficientVac-HSSPME sampling. The downsized extraction device was used to extract five low molecular weightpolycyclic aromatic hydrocarbons and several experimental parameters were controlled and optimized.For those compounds whose mass transfer resistance in the thin gas-film adjacent to the gas/sampleinterface controls evaporation rates, reducing the total pressure during HSSPME sampling dramaticallyenhanced extraction kinetics in the 22 mL modified vial. Humidity was found to affect the amount ofnaphthalene (intermediate KH compound) extracted by the fiber at equilibrium as well as impair extractionof all analytes at elevated sampling temperatures. All the same, the high extraction efficiency andvery good sensitivity achieved at room temperature and within short sampling times comprised themost important features of Vac-HSSPME in this downsized extraction device. Analytically, the developedmethod was found to yield linear calibration curves with limits of detection in the low ng L−1 level andrelative standard deviations ranging between 1.3 and 5.8%. Matrix was found not to affect extraction.

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