Cathodic stripping of ${\mathbf{CIO}}_{\mathbf{4}}^{\mathbf{-}}$in Figure 17-26does not involve oxidation or reduction of${\mathbf{CIO}}_{\mathbf{4}}^{\mathbf{-}}$. Explain how this measurement works.

Cathodic stripping voltammetry (CSV) is the quantification of metals species from their reduction current. The stripping bit means that there is a preconcentration step that usually consists of the adsorption of a complex with a selective ligand (usually an organic ligand) on the electrode. The metal in the complex is reduced. The sensitivity is very good because the adsorption forms a single molecular layer that is reduced in its entirety. There is no diffusion during the scan so a high scan rate can be used which gives a high sensitivity. The sensitivity of CSV is sufficient to detect about 20 elements in seawater.

In the electrochemical reactions, the relation between current and voltage is noted and this technique is called voltammetry. A graph that represents current Vs voltage is called a voltammogram.

poly(3-octylthiophene) is coated on a gold electrode and on oxidizing, the polymer can conduct electrons. It is over-coated with poly(vinyl chloride) (PVC)and dipped in the sample of drinking water that contains lithium sulfate and spinning at four rpm liquid transport to electrode.$CI{O}_4^{-}$ion is soluble in the membrane. In the oxidation step,${\mathrm{CIO}}_4^{-}$transferred into the membrane to equal the charge of oxidized poly(3-octylthiophene). The electrode potential is changed from 0.83 to 0.3 V at 0.1V / s to lessen poly(3-octylthiophene) to its normal form and eject ${\mathrm{CIO}}_4^{-}$from PVC membrane. During stripping, the peak current is ${\mathrm{measured}}^{-{\mathrm{CIO}}_4^{-}}$ concentration in drinking water.