Flow-injection spectrophotometric determination of copper (II) ion at low mu g L-1 levels

Abstract

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 mug L-1, and the limit of detection (signal-to-noise ratio = 2) was <1 <mu>g L-1 for 20 muL 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 mug L-1 was 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 river and sea water samples.