Basic Electrochemistry for the Separation Scientist

Electrochemistry refers to the chemical changes that occur in reactions in which electrons are transferred from one species to another. In addition, it represents the interchange of chemical and electrical energies. However, the electrochemical (EC) process of most interest to the analyst is the transfer of electrons between ions in solution and an adjacent electrode surface. 

In contrast to detection systems that are based on physicochemical properties e.g. UV-visible absorption, fluorescence) and typically involve homogeneous solutions, it is clear that ED must be a heterogeneous process since interfaces are involved. Furthermore, electrochemical detectors (EDs) are reaction detectors and therefore the responses may be influenced not only by the amount(s) of electroactive analyte(s) present, but also by factors such as temperature and residence time. 

By definition an electrical current is the movement of electrons and therefore electrochemistry can be seen to include two different types of processes  

The production of an electric current from an electron transfer (chemical) reaction 

It is the first of these processes that is employed in ED. The second is found and used in electrolytic reactions. 

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