Experimental determination of bioconcentration, biotransformation, and elimination of linear alkylbenzene sulfonates in Solea senegalensis.

The bioconcentration, biotransformation, and elimination of anionic surfactants, linear alkylbenzene sulfonates (LAS), specifically 2ØC(10) and 2ØC(12) LAS, which are pure isomers from two different homologues, have been characterized in Solea senegalensis using an experimental flow-through system with environmental exposure levels. The LAS and their carboxylated metabolites, sulfophenylcarboxylic acids (SPCs), were analyzed by pressurized liquid extraction, followed by solid-phase extraction, liquid chromatography with fluorescence detection, and mass spectrometry. The bioconcentration factors obtained in the steady state were 17.2 +/- 1.2 L/kg for 2ØC(10) LAS and 386.5 +/- 31.5 L/kg for 2ØC(12) LAS. A kinetic study also was performed with 2ØC(12) LAS, and the rate constants of uptake and elimination were K(1) = 177.04 L/kg d and K(2) = 0.92/d, respectively. The formation of the intermediate degradation products was monitored during the 2ØC(10) LAS experiment, thus allowing, to our knowledge for the first time, the identification and quantification of SPCs from 5ØC(6) to 9ØC(10) in marine organisms and in the depuration water as a result of biotransformation by the organisms, diffusive elimination, and excretion. The elimination percentage of the surfactants is both time- and concentration-dependent, and this suggests the existence of a concentration limit for the surfactant in the fish below which the elimination processes are slow. Overall, LAS are not persistent bioaccumulative compounds at environmental exposure levels.