Improving the performance of screen-printed carbon and polished platinum and glassy carbon voltammetric electrodes by modification with poly-L-lysine

Abstract

A modification of screen-printed carbon, and polished platinum and glassy carbon, electrodes with poly-L-lysine (PLL), using a method similar to that described by Anson et. al., in 1983, was shown to facilitate the reduction of hexacyanoferrate(III) and the re-oxidation of hexacyanoferrate(II), and to decrease significantly the overpotentials involved, at these electrodes. Washing the modified polished platinum and glassy carbon electrodes gradually washed off the PLL and caused a marked deterioration in the response. The PLL film on the screen-printed carbon electrode was much more resilient. Hydration of the film on the screen-printed carbon electrode, which is required to obtain a full response, was observed to be slower when the molecular mass of the PLL sample used was increased. PLL modification of the polished platinum electrode was shown to facilitate the irreversible reduction of trioxalatocobalt(III). Preliminary studied indicated that poly-L-arginine behaves similarly to PLL. The potentialities of modifying screen-printed carbon electrodes in capillary-fill and other disposable sensor devices are considered.