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 11 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 microg/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 microg/l) to 155 microg/l.