SummaryA method for determination of alkylphenols in water samples has been developed and validated. The alkylphenols were extracted on to polystyrene solid-phase columns. Six replicates could be processed in parallel in approximately 30 min using home-made equipment. Quantification was performed by reversed-phase liquid chromatography with UV-detection at 278 nm. The method has been validated for determination of 4-n-hexylphenol, 4-tert-octylphenol and nonylphenol in the concentration range 1-100 jag L -1 with 4-n-heptylphenol and/or 4-n-octylphenol as internal standard(s). The repeatability of the method was 1-6 % RSD, and the intermediate precision was 1-3 % RSD at the 100 jag C -1 level. The accuracy, determined as recovery, was 98-104 %. The limit of detection (LOD) was 0.1-0.2 jag L -1 for 1-L water samples. The method has been used for determination of alkylphenols in samples of aquarium water.