Voltammetry and Electroanalysis
Voltammetry and electroanalysis use controlled electrical signals at electrodes to identify and quantify chemical species and to probe reaction mechanisms.
Definition
The application of controlled-potential and controlled-current electrochemical measurements to qualitative and quantitative chemical analysis and to the study of electrode reaction mechanisms.
Scope
This area covers the principal electroanalytical techniques: voltammetry, in which current is recorded as potential is swept; potentiometry, which measures equilibrium potential to infer activity; amperometry, which monitors current for sensing; and impedance spectroscopy, which characterizes interfaces with small-amplitude alternating signals. It addresses instrumentation, signal interpretation, and analytical figures of merit such as sensitivity and detection limit.
Sub-topics
Core questions
- How do controlled-potential and controlled-current measurements reveal the identity and concentration of species?
- How does the shape of a current–potential curve diagnose reaction mechanism and reversibility?
- What determines the sensitivity and detection limit of an electroanalytical method?
- How is a three-electrode cell used to control the working electrode's potential precisely?
Key theories
- Three-electrode potential control
- A potentiostat fixes the working-electrode potential against a non-current-carrying reference while a counter electrode carries the current, isolating the interface of interest from ohmic and reference artifacts.
- Current–potential response as analytical signal
- Peak or limiting currents scale with concentration while peak potentials identify species and indicate reversibility, allowing simultaneous qualitative and quantitative analysis.
Clinical relevance
Electroanalytical methods power glucose biosensors, blood-gas and electrolyte analyzers, environmental trace-metal detection, pharmaceutical quality control, and battery and corrosion diagnostics, valued for low cost, portability, and high sensitivity.
History
Heyrovský's invention of polarography in 1922, recognized by the 1959 Nobel Prize in Chemistry, founded modern electroanalysis; the development of the potentiostat, solid microelectrodes, and pulse and impedance techniques through the 20th century vastly expanded sensitivity and scope.
Key figures
- Jaroslav Heyrovský
- Allen J. Bard
- Joseph Wang
Related topics
Seminal works
- bard2001
- wang2006
- kissinger1996
Frequently asked questions
- What is the difference between voltammetry and potentiometry?
- Voltammetry applies a varying potential and measures the resulting current, driving a reaction to obtain information, whereas potentiometry measures the equilibrium potential at essentially zero current to infer the activity of a species.
- Why are three electrodes used instead of two?
- Separating the reference (which sets the potential) from the counter electrode (which carries the current) keeps the reference free of polarization, so the working electrode's potential is controlled accurately even at high currents.