Poly(bromocresol purple)-based voltammetric sensor for the simultaneous quantification of ferulic acid and vanillin

Natural phenolic antioxidants are extensively studied compounds in modern electroanalysis due to their positive health effect and widely distribution in human diet. Simultaneous occurrence in the sample requires selective methods for their determination. Various types of electrochemical sensors have been developed for these purposes. Among a wide range of natural phenolics, vanillin and its biological precursor ferulic acid are of practical interest but out of consideration in electroanalysis. Electrochemical sensors based on the polyaminobenzene sulfonic acid functionalized single-walled carbon nanotubes and electropolymerized bromocresol purple has been developed for the simultaneous quantification of ferulic acid and vanillin. Conditions of bromocresol purple potentiodynamic electropolymerization (monomer concentration, number of scans, supporting electrolyte pH, electrolysis parameters) have been optimized in order to find the best voltammetric response of the co-existed analytes. The electrode has been characterized by SEM and electrochemical methods and the effectivity of the modifier developed has been confirmed. The well-resolved oxidation peaks of the ferulic acid and vanillin with potential separation of 170 mV has been obtained on the sensor created. The analytes electrooxidation parameters have been calculated. Sensor developed allows direct simultaneous quantification of ferulic acid and vanillin in the ranges of 0.1-5.0 and 5.0-25 µM for both analytes with the LODs of 72 and 64 nM, respectively. Thus, novel sensitive voltammetric sensor is simple in fabrication, reliable, cost-effective and can be applied for the foodstuff screening.