In this work, differential pulse anodic stripping voltammetry (DP-ASV) for the determination of trace amounts of hexavalent chromium (Cr(VI)) at a silver plated glassy carbon electrode (Ag plated-GCE) is described in detail. A Ag film was prepared by in situ plating of silver on the glassy carbon electrode surface. Several solution conditions and instrumental parameters influencing the electroanalytical response of the Ag plated-GCE were examined and optimized for the determination of Cr(VI). Under the optimized conditions, the calibration curve obtained in CH₃COOH/NH₃ (aq) medium at pH 5.9 was linear over the wide concentration range of 0.35–40 μM Cr(VI). The present method shows a low limit of detection of 0.10 μM. After evaluation of effects from possible interferences, the proposed method was successfully applied for the quantification of Cr(VI) in real water samples, with satisfactory recovery (97–105%). This method is useful for the determination of chromium in drinking water and achieves sensitivity capable of detecting the limits set by the World Health Organization (WHO).

Due to its toxicity, mercury determination is of great importance in human health and pollution monitoring. The mercury compounds can be released into our environment in several ways. Therefore, so many analytical procedures have been developed for detection of mercury. In this review, the analytical methods used for determination of mercury ions have been reported highlighting the electrochemical methods and in particular electrochemical biosensors. The electrochemical biosensors for determination of mercury were categorized into three groups including DNA-based, enzyme-based and whole-cell based biosensors and the mechanisms of the function of each group were described. The advantages and challenges of each class of biosensors are discussed in this review.

The removal of selenium from superficial and waste water is a worldwide problem. The maximum limit according to the World Health Organization (WHO) for the selenium in the water is set at a concentration of 10 μg/L. Carbon based adsorbents have attracted much attention and recently demonstrated promising performance in removal of selenium. In this work, several materials (iron oxide based microparticles and graphene oxides materials) and their composites were prepared to remove Se(IV) from water. The graphene oxides were prepared according to the simplified Hummer’s method. In addition, the effect of pH, contact time and initial Se(IV) concentration was tested. An electrochemical method such as the differential pulse cathodic stripping voltammetry was used to determine the residual selenium concentration. From the experimental data, Langmuir adsorption model was used to calculate the maximum adsorption capacity. Graphene oxide particles modified by iron oxide based microparticles was the most promising material for the removal of Se(IV) from its aqueous solution at pH 2.0. Its adsorption efficiency reached more than 90% for a solution with given Se(IV) concentration, meanwhile its maximal recorded adsorption capacity was 18.69 mg/g.

A novel unique device for automated screen printed electrodes testing and processing is described. It simplifies electrochemical optimization studies, and/or processing steps during SPE sensor/biosensor development.