2,2-Hydroxyphenylbenzoxazole as a selective chelating agent for complexation with Tin and Zinc: a voltammetry study

Abstract

A highly selective and sensitive adsorptive stripping procedure for simultaneous determination of trace tin and zinc is presented. The method is based on adsorptive accumulation of the complexes of Sn (II) and Zn (II) ions with 2, 2-hydroxyphenylbenzoxazole (HBO) onto a hanging mercury drop electrode, followed by the reduction of the adsorbed species by differential pulse cathodic stripping voltammetry. The optimal experimental conditions include the use of 0.1 M acetate buffer (pH 5.0), 2.0×10-5 M HBO, an accumulation potential of -0.35 V (versus Ag/AgCl), an accumulation time of 90 s and a scan rate of 100 mV/s. Under optimised conditions, linear calibration curves were established for the concentration of Sn(II) and Zn(II) in the range of 0.2 -100 µg/L and 0.1- 120 µg/L, respectively, while the detection limit is 0.009 µg/L for tin and 0.01µg/L for zinc for a 90 s adsorption time. The method was applied to the determination of tin and zinc in biological samples with satisfactory results.