Topics - Electrochemical Detection
The electrochemical detector responds to substances that are either oxidizable or reducible and the electrical output results from an electron flow caused by the chemical reaction that takes place at the surface of the electrodes. The detector normally has three electrodes, the working electrode (where the oxidation or reduction takes place), the auxiliary electrode and the reference electrode (which compensates for any change in the electrical conductivity of the mobile phase) There are two modes of operation coulometric detection and ampiometric detection. If the reaction at the electrode surface exhausts all the reactant and the current becomes zero, the total charge that passes will be proportional to the mass of solute detected. For obvious reasons this process is called coulometric detection. If the mobile phase is flowing past the electrodes, the solute will be continuously replaced as the peak passes through the detector. While there is solute present between the electrodes, a current will be maintained (albeit varying in magnitude). The process is called ampiometric detection. There are a number of electrode configurations, each having claims to special attributes; the electrochemical detector has been reported to be very flow sensitive.