A highly selective, sensitive and fast determination of trace amounts of copper (II) ion is described. The method is based on the formation of the coloured Cu(II)-N,N′-o-phenylenebis(salicylaldimine) (PBS) complex, which is then selectively monitored at 415 nm. To increase the interaction between copper(II) and the colour forming reagent and preconcentrate copper(II), a microcolumn containing strong cation-exchange resins was placed between the injection manifold and the spectrophotometer. The linear range of the proposed method was 25-100 μg L-1, and the limit of detection (signal-to-noise ratio = 2) was < 1 μg L-1 for 20 μL injection volume of copper (II) ion solution at a sampling rate of > 50 h-1. The relative standard deviation at the level of 25-100 μg L-1was 0.24 % for n = 5. The precision and accuracy of the method was checked by analysis of a certified reference material, and the applied to fiver and sea water samples.