A Novel Sensor Based on Manganese azo-Macrocycle/Carbon Nanotubes to Perform the Oxidation and Reduction Processes of Two Diphenol Isomers

Abstract

The present work describes the development of a selective and sensitive voltammetric sensor for simultaneous determination of catechol (CC) and hydroquinone (HQ), based on a glassy carbon (GC) electrode modified with manganese phthalocyanine azo-macrocycle (MnPc) adsorbed on multiwalled carbon nanotubes (MWCNT). Scanning electron microscopy and scanning electrochemical microscopy were used to characterize the composite material (MnPc/MWCNT) on the glassy carbon electrode surface. The modified electrode showed excellent electrochemical activity towards the simultaneous oxidation and reduction of CC and HQ. On the MnPc/MWCNT/GC electrode, both CC and HQ can generate a pair of quasi-reversible and well-defined redox peaks. Under optimized experimental and operational conditions, the cathodic peak currents were linear over the range 1-600 mu molL(-1) for both CC and HQ, with limits of detection of 0.095 and 0.041 mu molL(-1), respectively. The anodic peak currents were also linear over the range 1-600 mu molL(-1) for both CC and HQ, with limits of detection of 0.096 and 0.048 mu molL(-1), respectively. The proposed method was effectively applied for the simultaneous detection of hydroquinone and catechol in water samples and the results were in agreement with those obtained by a comparative method described in the literature.