Synthesis of dl-DOPA functionalized chelating resin: Its application in separation of metal ions from environmental samples

Abstract

Chloromethylated polystyrene-divinylbenzene has been functionalized with 3-(3,4-dihydroxyphenyl) dl-alanine (dl-DOPA). The resulting chelating resin has been characterized by its elemental analyses, infrared spectroscopy, thermogravimetric analysis and metal ion sorption capacities. It has been used for the preconcentration and separation of Ni, Co, Zn II , Cd and Pb and their determination by FAAS. Parameters such as the amount of resin, effect of pH, equilibration rate, sorption and desorption of metal ions and effect of diverse ions have been studied. The sorption capacities increase with increase in pH. Recoveries of the metal ions were 96 ± 5, 97 ± 6, 96 ± 5, 95 ± 8 and 96 ± 5 at 95% confidence level whereas the limits of detection (LOD) are 4.0, 5.0, 0.5, 1.3 and 25.0 mg L -1 for Ni, Co, Zn, Cd and Pb respectively, The calibration curves were linear up to 8 mg L -1 (R 2 = 0.998), 10 mg L -1 (R 2 = 1.000), 2 mg L -1 (R 2 = 0.998), 2 mg L -1 (R 2 = 1.000) and 5 mg L -1 (R 2 = 0.979) for Ni, Co, Zn, Cd and Pb respectively. The reliability of the environment friendly method has been tested by analyzing certified samples.