A rapid and selective method for determining a linear alkylbenzenesulfonate (LAS) and its biodegradation metabolites in sea water samples using solid-phase extraction and reversed-phase high performance liquid chromatography with UV detection is proposed. A solid-phase extraction (SPE) procedure is described for concentrating the compounds of interest on Mega Bond Elut C18 mini-column cartridges (2 g of adsorbent). Factors affecting the recovery of the investigated molecules such as conditioning of the SPE cartridge, flow-rate of the sample loaded on the cartridge, volume and pH of the sample, addition of salt to the sample, and elution of the analytes from the SPE cartridge are commented. Most of the tested compounds were extracted at recovery rates of > 70%. The obtained eluates were analyzed on a LiChrospher 100 RP-18 column and a mobile phase gradient of acetonitrile-phosphate buffer (pH=2.2) was used to separate the metabolites. The determination of LAS was made isocratically. Linear calibration curves showed good linearity for each molecule with correlation coefficients greater than 0.998. This method was applied to evaluate the LAS biodegradability in sea water during a laboratory experiment.