INDIRECT CATALYTIC CATHODIC STRIPPING VOLTAMMETRY OF SULFIDE ION IN THE PRESENCE OF COBALT AT A HANGING MERCURY DROP ELECTRODE

Traces of sulphide ion can be determined by linear cathodic stripping voltammetry in a berate buffer at pH 10 in the presence of cobalt(II) ion. Cobalt sulphide is accumulated at -0.5 V vs. SCE presumably as co lloidal particles occluded into the mercury sulphide layer. During the cathodic scan, cobalt sulphide catalyses the evolution of hydrogen gi ving a characteristic peak at about -1.6 V. The peak current is direct ly proportional to sulphide concentration over various concentration r anges, according to the duration of the deposition time. For 10 min. a ccumulation, the detection limit is 0.5 nM. The effect of both organic and inorganic potential interferents is discussed.