SQUARE WAVE STRIPPING VOLTAMMETRY OF TITANIUM BASED ON ADSORPTIVE ACCUMULATION OF ITS HYDROXYNAPHTHOL BLUE (HNB) COMPLEX AT THE STATIC MERCURY DROP ELECTRODE

Abstract

A new method is described for the determination of titanium based on the square wave adsorptive stripping voltammetry of Ti(IV) complexed with Hydroxynaphthol blue (HNB) at the static mercury drop electrode. Optimal conditions were found to be: preconcentration potential, −0.140 V vs. Ag/AgCl (KCl 3M); preconcentration time, 30 s (with stirring solution); pulse height, 75 mV;frequency, 100 Hz; scan increment, 4 mV; step time, 0.010 s; supporting electrolyte, acetate buffer (0.1 M, pH 3.2), and concentration of hydroxynaphthol blue, 1.0 × 10⁻⁵ M. The response of the system was found to be linear in a range of Ti(IV) concentrations from 5.0 to 20.0 μg/L. The limit of detection was found to be 0.18 μg/L and the limit of determination to be 1.09 μg/L, both using 30 s of preconcentration time. The effects of various potential interferences were also studied including a variety of cations, anions, and organic surfactants. The merits of the procedure were demonstrated in the analysis of certified NIST SRM 1633b and 1646a samples.

Keywords:

• Titanium
• Hydroxynaphthol blue (HNB)
• Square wave stripping voltammetry
• Certified samples

ACKNOWLEDGMENTS

The authors gratefully acknowledge the MCT, PADCT, CNPq and CAPES of the Government of Brazil and PUC-Rio for support of this work. We are indebted to Dr. Silvia M. Sella for revision of the manuscript. The experimental assistance of Anselmo B. Neves is appreciated.