Amberlite XAD resin solid phase extraction coupled on-line to flow injection systems using 4-(2-pyridylazo resorcinol) as reagent for preconcentration and determination of zinc in water

A determination of Zn(II) in water based on solid phase extraction coupled on-line to a flow injection analysis manifold is described. The method employs on-line preconcentration of Zn(II) onto a 1.3 cm × 1.0 mm (length × i.d.) column packed with Amberlite XAD-4 or Amberlite XAD-7 resins. The Zn(II) are subsequently eluted from the resin into a flowing system by 0.02 and 0.01 M HCl solution for Amberlite XAD-4 and XAD-7, respectively. Then the eluted analytes were quantified spectrophotometrically at 492 nm as the products of reaction with 4-(2-pyridylazo) resorcinol in buffer pH 11. The proposed methods have a linear calibration in range of 0.05-0.20, 0.20-0.80 mg L-1 for Amberlite XAD-4 and 0.05-0.40, 0.60-1.40 mg L-1 for Amberlite XAD-7, respectively. Detection limit of 0.016 and 0.013 mg L-1 and sample throughput of 30 and 26 h-1 were obtained for Amberlite XAD-4 and XAD-7, respectively. The procedure was successfully applied to the determination of Zn(II) in water sample, and the results were statistically compared with flame atomic absorption spectrometry. Keywords: Flow injection analysis, Zinc, 4-(2-pyridylazo resorcinol), Preconcentration