A Cu/Co hybrid hexacyanoferrate was electrosynthesized on GC electrodes (CME).
Determination of Hg2+exploited the decrease in the oxidation current of class="smallcaps">l-cysteine.
The major interfering cations were identified.
Interference from Cu2+ was removed exploiting the slower kinetics towards class="smallcaps">l-cysteine.
The CME was applied for the determination of Hg2+ in spiked mineral water samples.