Extraction and isolation of linear alkylbenzenesulfonate and its sulfophenylcarboxylic acid metabolites from fish samples

Linear alkylbenzenesulfonate (LAS) is the most widely used synthetic surfac tant. In fish, assessment of the environmental risk and investigation of th e biotransformation behavior of LAS require compound-specific methods for e xtraction and isolation of LAS and its biotransformation products, sulfophe nylcarboxylic acids (SPC). Matrix solid-phase dispersion (MSPD) extraction with subsequent ion-pair liquid-liquid (IP-LL) partitioning of the extract was a time-efficient sample preparation method for analysis of LAS, The rec overy of parent LAS from spiked fish exceeded 70%, and the limit of quantit ation ranged around 0.2 mg.kg(-1) corresponding to 0.6 mu mol.kg(-1), In a simultaneous determination of LAS and SPC in fish, the analytes were MSPD e xtracted in different fractions. The target compounds were separated from t he sample matrix by protein precipitation and subsequent isolation of (a) S PC by graphitized carbon black solid-phase extraction of the supernatant an d (b) parent LAS by IP-LL partitioning of the pellet obtained after protein precipitation. The recoveries of the model compounds C-12-2-LAS and C-4-3- SPC were 84 +/- 6 and 65 +/- 11%, respectively. The use of C-3-3-SPC as an internal standard corrected for the loss of the biotransformation product d uring sample workup, The suitability of both methods was demonstrated by an alyzing fish containing LAS and SPC incurred during aqueous exposure.