Determination of benzylsuccinic acid in gasoline-contaminated groundwater by solid-phase extraction coupled with gas chromatography–mass spectrometry

Benzylsuccinic acid (BSA) and methylbenzylsuccinic acid (methyl-BSA) are unambiguous biotransformation products resulting from anaerobic toluene and xylene biodegradation, respectively. A solid-phase extraction method based on polystyrene–divinylbenzene sorbent was developed for the quantitative BSA determination in groundwater samples as an alternative to liquid–liquid extraction. Gas chromatography coupled with mass spectrometry was used for separation and detection. The recovery from spiked 1 l groundwater samples was 88 to 100%. The precision of the method, indicated by the relative standard deviation, was ±4% and the method detection limit was 0.2 μg/l. The concentration of BSA and methyl-BSA in groundwater samples from anaerobic BTEX (benzene, toluene, ethylbenzene and xylenes)-contaminated sites ranged from below the detection limit (3 μg/l) to 155 μg/l.