A study, where uraniumwas online enriched and laser diode spectrometrywas determined, was performedwith some bottledmineralwater samples. A uranium-imprinted polymer (PMDU) was synthesized and characterized for preparation of a specific adsorbent of UO22+ cations. The homemade system preconcentrated uranium in PMDU resin and determined using an Arsenazo III complex at 650 nm in a combined laser diode spectrometer. All analytical parameters of the system were optimized at 5.5 of the retention pH, 6.0 N HClO4 of eluent concentration, 0.05% of Arsenazo III complex, and a 40 mm coil length. The effect of interferent ions was also investigated and LOD and LOQ values were found to be 0.54 and 1.80 ng mL(-1) respectively. Sample throughput was 12 h(-1), the preconcentration factor was 50, and RSD% value was 1.1. Certified reference materials of TMDA 52.3 and TMDA 62.2 were quantitatively analyzed and the proposed method was successfully applied to the bottled mineral water samples. (c) 2020 Elsevier B.V. All rights reserved.