Electrochemical Determination of Brucine in Urine with a Poly(Alizarin Red S)-modified Glassy Carbon Electrode

ABSTRACT

A poly(Alizarin Red S)-conducting polymer was prepared on glassy carbon electrodes by multiple scan cyclic voltammetry using 0.1 M Alizarin Red S in pH 7 phosphate buffer. The poly(Alizarin Red S)-modified electrode was used for the direct determination of 2,3-dimethoxystrychnidin-10-one (brucine). The prepared poly(Alizarin Red S) electrodes were characterized by impedance spectroscopy and cyclic voltammetry. The influence of the supporting electrolyte, pH, and scan rate on the brucine current was characterized. The second cycle and the current signal value were selected to be optimum for quantitaive measurements. An irreversible oxidative peak and two pairs of well-defined peaks were obtained at the poly(Alizarin Red S)–glassy carbon electrode. The current from the second scan increased linearly with the concentration of brucine from 30 to 1,000 nM. The limit of detection for brucine was 5.0 × 10⁻⁹ M. The developed method was successfully used for the determination of brucine in human urine.

KEYWORDS:

• Alizarin Red S
• brucine
• urine analysis
• voltammetry