SIMULTANEOUS DETERMINATION OF HYDROQUINONE AND CATECHOL AT POLY(P-ASA)/MWNTS COMPOSITE FILM MODIFIED GLASSY CARBON ELECTRODE

Abstract

A poly p-aminosalicylic acid (Poly(p-ASA)) and multiwall carbon nanotubes (MWCNTS) composite modified glassy carbon (GC) electrode was constructed by casting the MWNTS on the GC electrode surface followed by electropolymerization of the p-ASA on the MWCNTS/GCE. The electrochemical behaviours of hydroquinone (HQ) and catechol (CC) were investigated using cyclic voltammetry at the composite-modified GCE. The observed oxidative peak separation for HQ and CC of about 115 mV in phosphate buffer solution (PBS) pH 7.0 made possible the simultaneous determination of HQ and CC in their binary-mixture using the modified electrode. In the presence of 1.0×10⁻⁴ mol L⁻¹ CC, the differential pulse voltammetric (DPV) oxidative peak current responses of HQ were linear in the concentration range 2.0×10⁻⁵ to 7.0×10⁻⁴ mol L⁻¹, with a detection limit (based on S/N=3) of 8.35×10^-7 M. Similarly, in the presence of 1.0×10⁻⁴ mol L⁻¹ HQ, the DPV oxidative peak current responses of CC were linear in concentration range of 2.0×10⁻⁵ to 6.0×10⁻⁴ mol L⁻¹, with a detection limit (based on S/N=3) of 3.9×10^-7 M. The proposed method was tested for the simultaneous determination of HQ and CC in tap water binary mixture. The applicability of the method was shown by the satisfactory recoveries obtained for both isomers.