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In this work an automated flow methodology based on a tubular amperometric detector coupled to a multicommutated flow system was developed and applied in the determination of uric acid in urine. The exploitation of the analytical potential of multicommutated flow systems allowed the implementation of an expeditious and easily controlled on-line sample dilution, based on the zone sampling approach. The dilution capability exhibited by the developed methodology allowed a direct insertion of the samples in the flow system, without any pretreatment, assuring faster, simpler and less expensive analyses when compared to the enzymatic based methods with spectrophotometric detection commonly used in clinical analyses. The results obtained with the developed system in the determination of uric acid in urine were compared with those obtained by the enzymatic method used in clinical analysis laboratories, and no statistical difference between both methods (for a confidence level of 95%) was found. The proposed system showed good repeatability (RSD < 3%, n ¼ 10) and a detection limit of 4 Â 10 À7 mol L À1.