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Keywords:

  • Linear alkylbenzene sulfonates;
  • Sulfophenylcarboxylic acids;
  • Bioconcentration factor;
  • Biotransformation;
  • Marine organism

Abstract

The bioconcentration, biotransformation, and elimination of anionic surfactants, linear alkylbenzene sulfonates (LAS), specifically 2ØC10 and 2ØC12 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 2ØC10 LAS and 386.5 ± 31.5 L/kg for 2ØC12 LAS. A kinetic study also was performed with 2ØC12 LAS, and the rate constants of uptake and elimination were K1 = 177.04 L/kg d and K2 = 0.92/d, respectively. The formation of the intermediate degradation products was monitored during the 2ØC10 LAS experiment, thus allowing, to our knowledge for the first time, the identification and quantification of SPCs from 5ØC6 to 9ØC10 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.