Amperometric sensor based on MWNT and electropolymerized carminic acid for the simultaneous quantification of TBHQ and BHA

Amperometric sensor based on the layer-by-layer combination of multi-walled carbon nanotubes and electropolymerized carminic acid deposited on the glassy carbon electrode surface (poly(carminic acid)/MWNT/GCE) has been developed for the simultaneous quantification of tert-butylhydroquinone (TBHQ) and butylated hydroxyanisole (BHA). Conditions of poly(carminic acid) coverage obtaining have been found on the basis of TBHQ and BHA peak potential separation and oxidation currents. The best parameters have been observed for poly(carminic acid) electrodeposited from 50 μmol L−1 monomer solution by seven-fold cycling of potential in the range of 0.3–0.8 V with the scan rate of 50 mV s−1 in Britton-Robinson buffer (BRB) pH 2.0. Electrodes have been characterized by scanning electron microscopy (SEM) and electrochemical methods. Good resolution of TBHQ and BHA oxidation potentials equalled to 190 mV has been obtained on the poly(carminic acid)/MWNT/GCE vs. 146 mV on MWNT/GCE. The oxidation currents are 2.1- and 1.8-fold increased on polymer-modified electrode for TBHQ and BHA, respectively. Parameters of TBHQ and BHA electrooxidation on poly(carminic acid)/MWNT/GCE have been calculated. Sensor response is linear in the range of 0.50–75 μmol L−1 for TBHQ and 0.25–75 μmol L−1 for BHA with the limits of detection of 0.36 and 0.23 μmol L−1, respectively. Sensor selectivity in the presence of inorganic ions, ascorbic acid and α-tocopherol is confirmed. The sensor developed has been tested on the linseed oil. The recovery of 100–103% confirm high accuracy of the approach.