Copper-cobalt hexacyanoferrate modified glassy carbon electrode for an indirect electrochemical determination of mercury

[Display omitted] •A Cu/Co hybrid hexacyanoferrate was electrosynthesized on GC electrodes (CME).•Determination of Hg2+exploited the decrease in the oxidation current of l-cysteine.•The major interfering cations were identified.•Interference from Cu2+ was removed exploiting the slower kinetics towards l-cysteine.•The CME was applied for the determination of Hg2+ in spiked mineral water samples. An electrochemical sensor based on a glassy carbon electrode modified with a hybrid film of copper cobalt hexacyanoferrate was prepared for the indirect electrochemical determination of Hg2+. It exploits the formation of a redox inactive complex with thiols. l-cysteine and 1,4-butanedithiol were used, with the former giving more sensitive results. Interference studies were carried out which led to Cu2+ being the major interferent. Exploiting the fact that the response of l-cysteine to Hg2+ is much more rapid compared to Cu2+, the interference from Cu2+ was avoided or minimized by quick measurement of the amperometric current after the addition of the analyte. The modified electrode showed promising results in detecting Hg2+ in spiked mineral water samples.