The selective electrochemical detection of dopamine in the presence of ascorbic acid and uric acid using electro-polymerised-β-cyclodextrin incorporated f-MWCNTs/polyaniline modified glassy carbon electrode

Abstract

The present work describes a differential pulse voltammetric determination of dopamine (DA) using a glassy carbon electrode (GCE) modified with poly-beta-cyclodextrin incorporated with oxidised (OH) multi-walled carbon nanotubes (poly-β-CD(f-MWCNTs) and anion-doped polyaniline (PANI) composite. The poly-β-CD(f-MWCNTs)/PANI composite modified electrode was prepared by electropolymerisation of β-CD(f-MWCNTs) on anion-doped polyaniline by scanning repetitively in the phosphate buffer solution (pH 7) from −2.0 to 2.5 V. The as-prepared poly-β-CD(f-MWCNTs)/PANI composite was characterized by scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy and Fourier transform infrared spectroscopy. The composite presented excellent synergistic effect and shows an enhanced catalytic activity than electrodes modified with poly-β-CD and PANI. In comparison to the CV results of bare GC and modified GCE, the large electrochemical potential difference has achieved via the used of the poly-β-CD(f-MWCNTs)/PANI composite to distinguish the DA from AA and UA with peak-to-peak separations recorded at 244 mV (AA-DA) and 135 mV (DA-UA). Under optimum conditions, differential pulse voltammetric was used to determine the DA, and the voltammetric response of DA was linear over the concentration ranging from 2 μmol L−1 to 24 μmol L−1 with low detection limit (LOD) of 0.0164 μmol L−1 (S/N = 3) and high sensitivity of 26.79 μA μM−1 cm−2. The poly-β-CD(f-MWCNTs)/PANI composite modified electrode exhibits high selectivity in the presence range of potentially interfering uric acid and ascorbic acid even in high concentration. As a proof of concept, the practicality of the sensors was examined in human urine samples, and shows acceptable practicality for the determination of DA.