Continuous detection of hypochlorous acid/hypochlorite for water quality monitoring and control

This work demonstrates the continuous detection of hypochlorite in tap water using bare platinum electrodes. Continuous amperometric operation is possible for several days in spite of Pt oxide formation. Pt oxides are formed both by simple contact of the Pt surface with a hypochlorite solution, and during the electrochemical reduction of hypochlorite ions. Pt oxide and hypochlorite reduction processes may overlap at moderate to high hypochlorite concentrations, resulting in erroneous concentration readings. Passivated cathodes are reactivated by cathodic cycling in supporting electrolyte. Electrode protection using suitable membranes may extend the useful life time of Pt electrodes, particularly in complex samples.