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

A highly selective and sensitive adsorptive stripping procedure for simultaneous determination of trace tin and zinc is presented in this study. The method is based on the 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 optimized conditions, linear calibration curves were established for the concentration of Sn(II) and Zn(II) in the range of 0.2-100.0 µg/L and 0.1-120.0 µg/L, respectively, while the detection limit is 0.09 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.