Electrochemical determination of lead and cadmium in rice by a disposable bismuth/electrochemically reduced graphene/ionic liquid composite modified screen-printed electrode

In this study, a disposable graphene/ionic liquid composite modified screen-printed electrode was prepared by electrochemically reduction of graphene oxide onto the ionic liquid doped screen-printed electrode (IL-SPE). Then a bismuth film was in situ deposited on the surface of electrode to receive an electrochemical sensor, which was used for sensitive determination of trace lead and cadmium ions by square wave anodic stripping voltammetry (SWASV). The physicochemical and electrochemical characterizations of obtained sensor were investigated in detail. It was found that the prepared electrode possessed many attractive properties, such as large surface area, good ionic and electronic conductivity, wide electrochemical window as well as high stability and sensitivity. Under optimized conditions, the linear range of electrode was from 1.0 to 80.0 μg L−1 for both metal ions with a detection limit of 0.08 μg L−1 for cadmium and 0.10 μg L−1 for lead (S/N = 3). Finally, the proposed analytical procedure was applied to detect trace metal ions in rice samples with satisfactory results.