Evaluation of solid-state platforms for chromium (VI) potentiometric sensor development

Different platforms based on carbon pastes and composite materials, such as epoxy resin, are used to construct chromium (VI) potentiometric sensors. The materials are modified with diphenylcarbazide as selective agent for chromium (VI) ions. Matrix compositions of each sensor are optimized on the basis of graphite and ionophore amounts. The performance characteristics of all the designed solid-state potentiometric sensors are described. The same linear response range from 1.00 × 10−6 to 1.00 × 10−2 mol L−1 and similar detection limits, 6.3 × 10−7 mol L−1 for graphite-epoxy sensor and 9 × 10−7 mol L−1 for carbon paste sensor, are obtained. However, the sensor based on graphite-epoxy materials shows better selective responses and lifetime. Both sensors exhibit high selectivity to hexavalent chromium even in presence of trivalent chromium. The sensors are successfully used in direct potentiometric determinations of hexavalent chromium and are also employed as indicator electrodes in potentiometric titrations with successful results.