Glassy carbon electrodes coated with poly(allylamine hydrochloride), PAH: Characterization studies and application to ion-exchange voltammetry of trace lead(II) at combined PAH/mercury film electrodes

Glassy carbon electrodes coated with adsorbed single layers of the cationic polyelectrolyte poly(allylamine hydrochloride), PAH, were produced by solvent evaporation for subsequent development of PAH modified thin mercury film electrodes (PAH/TMFE). The present work describes the preparation, incorporation features towards lead(II) species, as well as the morphological characterization of PAH coatings of different molar loadings, prepared from polyelectrolyte solutions of different composition. The present PAH films revealed interesting morphologic features, related to the process of solvent evaporation and to the specific structural properties of the PAH polyelectrolyte in the assembling medium.The novel PAH-thin mercury film electrodes, developed for the determination of trace lead(II) as its anionic forms in chloride medium, were found to be stable, sensitive and reproducible. Concentrations in the ppb concentration region could be easily assessed using 20 s accumulation time (detection limit 1.2 ppb, i.e. 6 nM, 3σ) with low relative standard deviations (<2.5%). The sensitivity of the SWASV determination of lead(II) increased 20% compared to the uncoated TMFE. The linearity range reached at least two orders of magnitude. Additionally, the PAH-coated mercury film electrodes presented an improved resistance to fouling by common surfactants.