Determination of some quinoxaline- N-dioxide derivatives by adsorptive stripping voltammetry

Abstract

Some derivatives of quinoxaline- N-dioxides, which are used as growth promoters in animals (Carbadox, Cyadox, Olaquindox), can be determined at nanomolar concentrations by stripping volatammetry from a static mercury drop electrode after adsorptive accumulation on the electrode surface. With differential pulse voltammetry, in 0.1 M sodium perchlorate with 5% (v/v) dimethylformamide, the detection limit for Cyadox is 3 × 10 −10 mol 1 −1 after accumulation for 300 s in stirred solution; detection limits are 2 × 10 −9 mol 1 −1 (180 s accumulation) for Carbadox and 7 × 10 mol 1 −1 (60 s accumulation) for Olaquindox. The relative standard deviations are 0.85% for Cyadox (4 × 10 −9 mol 1 −1), 0.54% for Carbadox (2 × 10 −8 mol 1 −1) and 0.95% for Olaquindox (2 × 10 −8 mol 1 −1). Surfactants interfere.