Preconcentration at a carbon-paste electrode and determination by adsorptive-stripping voltammetry of rutin and other flavonoids

The non-Faradaic preconcentration behaviour of nine flavonoids (six flavones: fisetin, galangin, morin, quercetin, rhamnetin, rutin, and three flavanones: hesperidin, hesperitin, naringin) at a carbon-paste (nujol/graphite) electrode and the factors affecting it (pH, accumulation potential, presence of various surfactants) for their subsequent differential pulse voltammetric determination are examined. All flavones tested are readily accumulated on the carbon paste electrode resulting in a considerable signal enhancement making determinations feasible down to 10(-8)-10(-7) M after preconcentration for 1-4 min. Flavanones are not preconcentrated so their lower determination limits are of the order of 10(-6) M. A simple voltammetric procedure for the determination of rutin in a multivitamin preparation is presented.