Study of Junction Carbon Paste Electrode / Indigo Carmine / Mercury (II): Application of the Law Cottrell

Electrochemical detection of mercury (II) by the carbon paste electrode modified by indigo carmine in the differential pulse voltammetry is obtained by a complexation reaction. Complexation time, pH and temperature parameters which influence the formation of the complex were investigated. The formed Hg-IC complex is electro inactive. Its adsorption to the surface of the electrode causes a decreasing variation of the intensity of the anodic peak current versus time. Applying the Cottrell law of the faradaic and adsorption current has achieved the equivalent electrical circuit modelling all phenomena at the interface of the sensor.