Disposable screen-printed electrode modified with bismuth-PSS composites as high sensitive sensor for cadmium and lead determination

Bismuth was incorporated in screen-printed carbon electrodes (SPCEs) modified with polystyrene sulfonate (PSS) and carbon nanopowder (CnP) composites. Different strategies, based on bulk approaches using bismuth oxide particles and bismuth (III) solutions, were assayed. The features of the modified electrodes were evaluated by differential pulse anodic stripping voltammetry (DPASV) of Pb(II) and Cd(II) solutions. The best results were obtained when bismuth was incorporated as bismuth oxide particles during the preparation of the PSS-CnP aqueous suspension used to modify the electrodes. Using this optimal modified sensor, the DPASV measurement conditions for Pb(II) and Cd(II) determination were optimized and their figures of merit were evaluated. Measurements were performed using two experimental approaches: the "drop method", by putting the test solution on the surface of the modified SPCE, and the "immersion method" performed by immersing the device in a stirred test solution. The limits of detection (S/N = 3) were 0.27 mu g L-1 (1.3 x 10(-9) M) for Pb(II) and 0.10 mu g L-1 (9.0 x 10(-10) M) for Cd(II), using the "drop method", and 0.029 mu g L-1 (1.4 x 10(-10) M) for Pb(II) and 0.012 mu g L-1 (1.1 x 10(-19) M) for Cd(II) employing the immersion procedure. The optimal bismuth modified SPCE was used for Pb(II) and Cd(II) determination in natural water samples with successful results. (C) 2016 Elsevier B.V. All rights reserved.