Synthesis and application of a new chelating resin functionalized with 2,3-dihydroxy benzoic acid for Fe(III) determination in water samples by flame atomic absorption spectrometry

To obtain a selective chelating resin for separation and preconcentration of Fe(III) ions in various water samples, amberlite XAD-4 was functionalized with 2,3-dihydroxy benzoic acid by coupling it through an -NN- spacer. The resulting resin, characterized by thermogravimetric analysis and infrared (IR) spectroscopy, was packed in a minicolumn to be used as a sorbent. It was shown that Fe3+ ions could be sorbed at a pH of 3.5 in the minicolumn and that they could be then eluted using 0.5 mol dm−3 H3PO4. The released amount of Fe3+ was determined by flame atomic absorption spectrometry with a recovery of more than 98%. A linear calibration graph was obtained in the range of 5.0 × 10−8-1.5 × 10−6 mol dm−3 in treatment with aliquots of 500 ml of the solutions in which the experimental preconcentration factor was 100. By using the blank and 2.0 × 10−7 mol dm−3 solutions (n = 7), the DL and RSD were found to be 6.0 × 10−9 mol dm−3 and 2.1%, respectively. None of the metal ions that are naturally present in water samples interfered in this analysis, even when the concentrations were in excess of two orders of magnitude. The resin is durable with >35 cycles resulting in no major change in its quantitative metal uptake nature. The practical applicability of the method was examined using various real water samples. The recoveries obtained for the spiked trace amount of Fe(III) ions were >95%, which confirmed the reliability of the method.