An analytical method combining off-line solid phase extraction (SPE) and reversed phase high performance liquid chromatography (HPLC) has been developed for simultaneous determination of six herbicides. The compounds analyzed in natural surface water samples, were: the herbicides atrazine (AT), simazine (SI) and their major dealkylated and hydroxylated degradation products such as deisopropyl-atrazine (DIA), deethyl-atrazine (DEA), hydroxyl-atrazine (H-AT) and hydroxyl-simazine (H-SI), all of

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... em with herbicide activity too. As optimum conditions, a Kromasil C18 column as stationary phase, a mixture of acetonitrile and phosphate buffer pH 7.0 as mobile phase in gradient elution mode and 215 nm as measuring wavelength, were selected. A polymeric cartridge (Bond-Elut ENV-1000 mg) was used for a SPE procedure. The optimized off-line SPE HPLC-DAD method was evaluated in terms of validation and robustness procedure, obtaining among other parameters, limits of quantification between 81 and 100 ng L -1 , considering the enrichment factor for all of the studied herbicides. The proposed method was successfully applied to the screening of herbicides in natural surface water samples from different locations in the 23th aquifer (Albacete, Spain).