FLOW-INJECTION FLAME ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATION OF COPPER WITH PRECONCENTRATION ON LIGAND LOADED AMBERLITE XAD-2

Chelating sorbents obtained by loading a non-polar sorbent, Amberlite XAD-2, with Pyrocatechol Violet (PV), 4-(2-pyridylazo)resorcinol (PAR) or Eriochrome Blue Black R were used for a time-based preconcentration of Cu(II). The effect of preconcentration and elution flow-rate on the detection limit and the effectiveness of Cu(II) sorption were examined. Pyrocatechol Violet loaded XAD-2 was employed for the determination of Cu(II) by flow injection flame atomic absorption spectrometry in natural waters at the ppb level using a preconcentration time of 20 min. Superior dynamic properties of PV loaded sorbent in comparison with an hydroxyquinoline chelating resin is demonstrated. The effect of the presence of alkali, alkaline earth and some transition metal ions on Cu(II) sorption was examined. Significant interference was observed for concentrations of Ca above 50 ppm. Interference from Fe(III) can be reduced by the addition of fluoride to the preconcentrated sample.