Application of a metal ion-imprinted polymer based on salen-Cu complex to flow injection preconcentration and FAAS determination of copper

Abstract

A new Cu(II)-imprinted polymer (Cu-IIP) for preconcentration of copper by liquid-solid extraction via flow injection technique has been proposed. Cu-IIP was obtained by copolymerization of salen-Cu(II) complex with styrene and divinylbenzene using suspension polymerization technique. Granules fracion of 60-80$\mu$m in diameter was used as a microcolumn packing. Cu(II) sorption was proved to be the most effective from solutions of pH 7, whereas similar elution effectiveness was observed when applying as eluents hydrochloric or nitric acid in the concentration range of 0.5-10% (v/v). The system exhibited good long-term stability and acid resistance. Batch sorbent capacity was found to be 0.11mmolg$^{-1}$ of a dry polymer. Enrichment factor (EF) for 30s loading time was 16. Preconcentration of Cu(II) and poten- tially interfering metal ions is strongly pH dependent. Examination of Cu(II) sorption in the presence of Pb(II), Cd(II), Zn(II) and Ag(I) showed significant influence of cadmium and zinc ions only and that was for the interferent concentrations above 0.5mgL$^{-1}$ (Cu-IIP mass of ca. 35mg). The interference effect was reduced with the sorbent mass increase. Fe(III) and Mn(II) ions, present in treated tap water in rel- atively high concentrations, did not interfere. Effective pH adjusting of the loaded solution in on-line mode, when applying diluted Clark-Lubs buffering solution, allowed accurate copper determination in tap water (compared to graphite furnace atomic absorption spectrometry, GFAAS) using standard addition or combination calibration method