Electroanalytical methods
Electroanalytical methods are a class of techniques in
Potentiometry
A variant of potentiometry is chronopotentiometry which consists in using a constant current and measurement of potential as a function of time. It has been initiated by Weber.[7]
Coulometry
Coulometry uses applied current or potential to convert an analyte from one oxidation state to another completely. In these experiments, the total current passed is measured directly or indirectly to determine the number of electrons passed. Knowing the number of electrons passed can indicate the concentration of the analyte or when the concentration is known, the number of electrons transferred in the redox reaction. Typical forms of coulometry include bulk electrolysis, also known as Potentiostatic coulometry or controlled potential coulometry, as well as a variety of coulometric titrations.
Voltammetry
Voltammetry applies a constant and/or varying potential at an electrode's surface and measures the resulting current with a three-electrode system. This method can reveal the reduction potential of an analyte and its electrochemical reactivity. This method, in practical terms, is non-destructive since only a very small amount of the analyte is consumed at the two-dimensional surface of the working and auxiliary electrodes. In practice, the analyte solution is usually disposed of since it is difficult to separate the analyte from the bulk electrolyte, and the experiment requires a small amount of analyte. A normal experiment may involve 1–10 mL solution with an analyte concentration between 1 and 10 mmol/L. More advanced voltammetric techniques can work with microliter volumes and down to nanomolar concentrations. Chemically modified electrodes are employed for the analysis of organic and inorganic samples.
Polarography
Polarography is a subclass of voltammetry that uses a
Amperometry
Amperometry indicates the whole of electrochemical techniques in which a current is measured as a function of an independent variable that is, typically, time or electrode potential. Chronoamperometry is the technique in which the current is measured, at a fixed potential, at different times since the start of polarisation. Chronoamperometry is typically carried out in unstirred solution and at the fixed electrode, i.e., under experimental conditions avoiding convection as the mass transfer to the electrode. On the other hand, voltammetry is a subclass of amperometry, in which the current is measured by varying the potential applied to the electrode. According to the waveform that describes the way how the potential is varied as a function of time, the different voltammetric techniques are defined.
References
- ISBN 978-0-03-005938-4.
- ISBN 978-0-8247-9445-3.
- ISBN 978-0-471-04372-0.
- ISBN 978-0-444-51958-0.
- .
- PMID 23947748.
- ^ H. F. Weber, Wied. Ann., 7, 536, 1879
Bibliography
- Wang, Joseph C. (2000). Analytical electrochemistry. Chichester: John Wiley & Sons. ISBN 978-0-471-28272-3.
- Hubert H. Girault (2004). Analytical and physical electrochemistry. [Lausanne: EPFL. ISBN 978-0-8247-5357-3.
- Ozomwna, Kenneth I., ed. (2007). Recent Advances in Analytical Electrochemistry 2007. Transworld Research Network. ISBN 978-81-7895-274-1.
- Dahmen, E. A. M. F. (1986). Electroanalysis: theory and applications in aqueous and non-aqueous media and in automated chemical control. Amsterdam: Elsevier. ISBN 978-0-444-42534-8.
- Bond, A. Curtis (1980). Modern polarographic methods in analytical chemistry. New York: M. Dekker. ISBN 978-0-8247-6849-2.