Screen-Printed Electrodes Modified by Bismuth Film for the Determination of Released Lead in Moroccan Ceramics

Screen-printing technology is a particularly attractive technique for the mass production of cheap and disposable sensors, and the use of screen-printed electrodes (SPEs) in conjunction with portable, electrochemical instrumention greatly facilitates the feasibility of on-site testing. In this work, a simple, electrochemical method using screen-printed probes has been applied to test for the presence of released lead (Pb) in the glazes of different ceramic tajines collected randomly from a local market square in Morocco. Square-wave anodic voltammetry (SWAV) was employed with SPEs that had been modified with a bismuth film and 5l of 0.5% nafion (SPEBi-Na). This probe displayed excellent linear behavior over the examined concentration range, from 5 to 80g/L Pb2+ in 100mM acetate buffer, pH 5, with a detection limit of 4 ppb for lead and (r2=0.9972). The good reproducibility obtained with this system led us to apply it to determine lead in this typical Moroccan cookware under conditions relevant to its use. The results showed that when tajines containing 3% acetic acid were heated for 30min, the amounts of leached lead ranged from 16.8 to 26.4ppm. When the tajines contains lemon instead of 3% acetic acid and was heated for 30min, then amounts of lead released exceeded 37ppm. These values are greater than the allowed maximum concentrations in the United States and Canada.