Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) composite electrode as sensing platform for the simultaneous electrochemical determination of dihydroxybenzene isomers

Dihydroxybenzene isomers catechol (CC), resorcinol (RC), and hydroquinone (HQ) were simultaneously determined using a simple, inexpensive, water-stable, and conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite sensing electrode by linear sweep voltammetry. The sensing electrode was prepared by dip-coating a mixture of PEDOT:PSS, Nafion, and carboxylic acid-functionalized single-walled carbon nanotubes on a gold electrode, then modifying by electrochemical doping in a hydrophobic ionic liquid. Nafion was selected as a binding agent to improve the adhesion and binding force between films and electrode interface, and ionic liquid was employed to improve the conductivity and water resistance of the composite electrode. The as-proposed sensing electrode displayed excellent electrochemical catalytic activities towards CC, RC, and HQ. Large peak separations were obtained between HQ and CC as well as CC and RC, i.e., up to 109 and 496 mV, respectively. The calibration curves for CC, RC, and HQ were obtained in the ranges of 0.56-70, 0.18-50, and 0.56-50 mu M, with detection limits (S/N = 3) of 0.19, 0.08, and 0.20 mu M, respectively. Finally, the sensing electrode was applied to river water sample analysis with reliable recovery. Satisfactory results revealed that the PEDOT:PSS composite can provide a promising platform for the design and application of sensing devices.