Separation and preconcentration of trace amounts of Cr(III) ions on ion imprinted polymer for atomic absorption determinations in surface water and sewage samples

摘要

A new type of Cr(III)-imprinted polymer was prepared from Cr(III)-pyrrolidinedithiocarbamate complex, acrylamide functional monomer and ethylene glycol methacrylate cross-linking agent. The polymer was employed as a selective solid phase extraction material for separation of trace amounts of Cr(III) ions under dynamic conditions. The effects of the conditioning of imprinted polymer, conditions of Cr(III) retention and elution were studied. It was found that Cr(III) ions can be retained on tested sorbent with high efficiency and repeatability (87%, RSD=3.2%) from a solution of pH 3.50-4.75. The quantitative elution of analyte was obtained with 0.2molL ~(-1) nitric acid solution. The retention of Cr(VI) ions on the polymer in the studied pH range (1.0-7.0) was at the level of 10-15%. The selectivity of prepared sorbent towards Cr(III) ions was good in the presence of Cu(II) and Ni(II) ions and worse in the presence of Fe(III) ions at a concentration higher than 0.5μgmL ~(-1). The detection limit for Cr(III) obtained by electrothermal atomic absorption spectrometry (ETAAS) after preconcentration of 40mL of sample on the polymer was 0.018ngmL ~(-1). The developed separation method was successfully applied to the ETAAS determination of trace amounts of Cr(III) in tap and river water and municipal sewage.