Laser activated voltammetry: application to the determination of phenol in aqueous solution at a glassy carbon electrode

Clean electrode surfaces can be achieved during the electrolysis of otherwise passivating species in aqueous and other solutions by means of surface ablation using a 10 Hz pulsed Nd:YAG 532 nm laser. This ability to remove passivating electrolytically generated layers on a glassy carbon electrode in a channel flow cell was shown by an investigation of the stripping peaks formed from the electrogeneration of the neutral forms of methyl viologen and heptyl viologen during reduction in aqueous solution of the corresponding di-cations. Next, laser ablation voltammetry was conducted for the oxidation of phenol in aqueous solution. Steady state voltammograms were obtained with well defined mass transport limited currents contrasting with the current peaks seen under dark scans where the formation of a polymerised layer on the electrode surface ultimately leads to electrode passivation under flow conditions. Square wave voltammetry was then used to detect phenol under no-flow conditions using a laser intensity of 0.1 W cm(-2). A linear dependence of the peak current on the concentration was found with a detection limit of phenol of 2 mu M.