Selective Separation and Preconcentration of Total Tin Using Quercetin as Chelating Agent

Abstract

Three methods were developed for rapid and selective extraction of total tin as Sn(IV) using quercetin (H5Q) as chelating agent, prior to its determination by hydride generation atomic absorption spectrometry (HGAAS). H5Q was chemically or physically immobilized onto silica gel or polyurethane foam, respectively, and used for the separation of Sn(IV) by the solid phase extraction (SPE) technique. The SPE methods were compared with flotation technique using the oleic acid as surfactant from H5Q solution in amyl alcohol/kerosene solvent. Elemental analysis, thermogravimetry, spectroscopic measurements (IR, UV/vis and magic angle solid state C13‐NMR) were used to characterize the resulting modified extractors. The experimental conditions for efficient extraction of Sn(IV) such as: pH, time of stirring, interfering ions and eluent concentration, were optimized for the batchwise separation process. The tolerance limits of heavy metal ions in the sorption of Sn(IV) were reported. The methods were applied for the determination of total tin in water samples, zinc shots and canned beans after digestive oxidation. The suggested SPE and flotation techniques were found to be accurate and not subject to random error with especial preference to the SPE technique as it is cheaper and simpler.