Cathodic Stripping Voltammetry:

It is used for the determination of anions that form insoluble mercury (I) salts at the mercury surface or insoluble silver salts on a silver electrode. The experimental design is similar to that for A.S.V. with two modifications. A decomposition step includes the oxidation of the Hg electrode to Hg²⁺ that then reacts along with the analyte to form an insoluble film at the surface. A decomposition step with Cl^- is

2Hg (l) + 2Cl^- (aq) = Hg₂Cl₂ (s) + 2 e-

The second step, that is. stripping, is followed through scanning cathodically towards a more negative potential reducing Hg²⁺ back to Hg and returning the analyte to the solution.

Hg ₂Cl₂ (s) + 2 e^- = 2Hg (l) + 2Cl^-(aq)

(A few analytes analysed are halides, mercaptan, sulphides,.)