Micelle-mediated extraction and determination of tin in soft drink and water samples

Abstract

A micelle-mediated phase preconcentration of trace quantities of Sn(IV) as a prior step to its determination by spectrophotometry has been developed, based on cloud point extraction (CPE) of the complex of Sn(IV) with pyrocatechol violet complex in surfactant media. Pyrocatechol violet (PCV) and cetyltrimethylammonium bromide (CTAB) were used as chelating agent and cationic surfactant, respectively. The optimal extraction and reaction conditions (e.g. surfactant concentration, reagent concentration and the effects of pH and time) were studied and the analytical characteristics of the method (e.g., limit of detection, linear range and preconcentration factor) were obtained. Linearity was obeyed in the range of 0.30-175.00 ng mL-1 (2.0 × 10-9 to 1.5 × 10-6 mol L-1) of Sn(IV). The detection limit (LOD) of the method was 0.16 ng mL-1 (1.3 × 10-9 mol L-1) of Sn(IV). The relative standard deviation (R.S.D.) and relative error for five replicate measurements of 30.00 ng mL-1 Sn(IV) were 0.71% and 2.9%, and for 50.00 ng mL-1 of Sn(IV) were 1.6% and 3.4%, respectively. The interference effect of some anions and cations was also tested. The method was applied to the determination of tin in soft drinks (canned juices) and water samples, with satisfactory results.