Analysis of hydrocarbon contamination with membrane-assisted solvent extraction: Comparison of agitation and sonication methods

Membrane-assisted solvent extraction (MASE) coupled to large volume injection was applied to the determination of (gasoline-type) hydrocarbon contamination in water samples. Hexane was used as acceptor phase. 50 μL extract was injected in the programmed temperature vaporizer injector using combined split–splitless evaporation. The extraction conditions were optimized both for MASE with agitation and for MASE with sonication. In the course of optimization the effect of extraction time, extraction temperature, agitation speed, solvent volume, pH, ionic strength and the addition of methanol were tested. Over 75% recovery was accomplished in the range of diesel oil hydrocarbons (n-C 9–n-C 24). The developed method was validated. Linearity, accuracy and precision were tested. The method showed excellent linearity between 1 and 1000 μg L −1 for n-alkanes and between 0.05 and 50 mg L −1 for gasoline. The method was tested with comprehensive GC × GC as well and found to be non-discriminative to all major compounds of diesel oil.