Development of a voltammetric sensor for chromium(VI) determination in wastewater sample

Screen-printed carbon electrode (SPCE) modified with poly-l-histidine film can be successfully applied for chromium(VI) determination based on its pre-concentration. Optimum adherence and stability of the poly-l-histidine film was obtained by direct addition of PH solution 1% (w/v) on the electrode surface, followed by heating at 80 °C during 5 min. Linear response range, sensitivity and limit of detection were 0.1–150 μmol L−1, 1.13 μA μmol L−1 and 0.046 μmol L−1. The repeatability of the proposed sensor, evaluated in terms of relative standard deviation, was measured as 3.2% for 10 experiments in 40 μmol L−1 using the same electrode and 4.0% using screen-printed electrode as disposable sensor, respectively. The voltammetric sensor was applied to determination of Cr(VI) and indirect determination of Cr(III) in wastewater samples previously treated by a leather dyeing industry and the average recovery for these samples was around 97%.