Determination of linear alkylbenzensulfonates in aqueous matrices by ion-pair solid-phase microextraction–in-port derivatization–gas chromatography–mass spectrometry

Trace determination (low ng/ml) of linear alkylbenzensulfonates (LASs) in water was achieved by solid-phase microextraction (SPME) of ion-pairs formed with tetrabutylammonium. This ion-pairing reagent served two purposes. First, it allowed the extraction of LAS with the polydimethylsiloxane fiber by counterion association and second, the derivatization of the formed LAS ion pairs in the GC injection port at 300 °C to form the corresponding sulfonated butyl esters. The methodology developed allows the isomer specific determination of LAS at low detection limits (0.16–0.8 ng/ml), depending on the alkyl chain lengths of LASs with RSDs of 10–12%. Furthermore, the developed methodology was applied to urban wastewater and sea water and compared with a solid-phase extraction (SPE) method (e.g. C18 and strong anion-exchange sorbent) to obtain concordant values for urban wastewater. Moreover, the developed SPME methodology overcame the procedural blank and matrix-dependent recoveries found in the SPE methodologies at low LAS concentrations.