Voltammetric determination of molybdenum using polymer film modified pencil graphite electrodes

Abstract

A new indirect voltammetric method for the determination of molybdenum in water samples and food supplements using various polymer film modified pencil graphite electrodes (PFMPGEs) was described. Poly Eriochrome black T film modified pencil graphite electrodes (p-EBT/PGE), poly xylenol orange modified pencil graphite electrodes (p-XO/PGE) and poly methyl red modified pencil graphite electrodes (p-MR/PGE) were used for this purpose. The electrodes were characterized by electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The method is based on measuring the oxidation current of Tiron in the Mo-Tiron complex at the PFMPGEs. The limits of detection and analytical ranges for p-EBT/PGE, p-XO/PGE, and p-MR/PGE were estimated to be 2.60, 3.50, and 1.56 mu g/L and 8.66 to 100, 11.68 to 100, and 5.20 to 100 mu g/L, respectively. The averages of relative standard deviation values for low, medium and high molybdenum content for p-EBT/PGE, p-XO/PGE and p-MR/PGE were 5.46%, 6.30%, and 4.69%, respectively. Selectivity studies were also performed for all electrodes. The method was applied to the determination of molybdenum in water and food supplement samples. The results were statistically evaluated, and the accuracy of the proposed method was demonstrated.