OFF-LINE SOLID PHASE SELECTIVE SEPARATION AND PRECONCENTRATION OF Cu, Zn, Pb AND Cd IN DRINKING WATER BY SOLID-PHASE EXTRACTION USING 4´-(2-HYDROXYPHENYLAZO)-3´-METHYL-1´-PHENYL-2´-PYRAZOLIN-5´-ONE FUNCTIONALIZED AMBERLITE XAD-2

Document Type : Original Article

Authors

1 Chemistry department, Faculty of Science, Fayoum University, Fayoum City, Egypt

2 Chemistry Deparatment, Faculty of Science, Ain Shams University, Cairo, Egypt

Abstract

A new solid – phase extraction sorbent is developed based on stepwise anchoring of two ligand molecules for the determination of copper, zinc, lead and cadmium in drinking water by flame AAS. Amberlite XAD-2 functionalized with 4´-(2-hydroxyphenylazo)-3´-methyl-1´-phenyl-2´-pyrazolin-5´-one (HPAPyr) was utilized for preconcentration/separation of these elements. The sorbent was prepared by two successive azo coupling reactions. Firstly, 2-aminophenol was anchored to the amino groups in the resin resulted from nitration followed by reduction. Then, the resulted 2-aminophenol functionalized resin was further diazotized and coupled to pyrazolone compound and the final product HPAPyr-XAD-2 was characterized by IR and elemental analysis. The optimum pH range for sorption, shaking time, exchange capacity, sample flow rate, preconcentration factor and interference from co-existing ions are investigated.  All metal ions are quantitatively desorbed from the resin by 4.5 mol l-1 nitric acid solution. The sorbent provides limit of detection within the range 0.9 – 3.3 µg l-1 and concentration factor up to 250.  The procedure is validated by analysis of certified material NIST-SRM 1577b.  Application to drinking water showed satisfactory results with relative standard deviation RSD ≤ 8.5 %. 

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