Voltammetric Method for the Simultaneous Determination of Melatonin and Pyridoxine in Dietary Supplements Using a Cathodically Pretreated Boron-Doped Diamond Electrode

Abstract

The simultaneous voltammetric determination of melatonin (MT) and pyridoxine (PY) has been carried out at a cathodically pretreated boron-doped diamond electrode. By using cyclic voltammetry, a separation of the oxidation peak potentials of both compounds present in mixture was about 0.47 V in Britton-Robinson buffer, pH 2. The results obtained by square-wave voltammetry allowed a method to be developed for determination of MT and PY simultaneously in the ranges 1-100 mu g mL(-1) (4.3x10(-6)-4.3x10(-4) mol L-1) and 10-175 mu g mL(-1) (4.9x10(-5)-8.5x10(-4) mol L-1), with detection limits of 0.14 mu g mL(-1) (6.0x10(-7) mol L-1) and 1.35 mu g mL(-1) (6.6x10(-6) mol L-1), respectively. The proposed method was successfully to the dietary supplements samples containing these compounds for health-caring purposes.