voltammetria

Voltammetry, or voltammetria in some languages, is an electrochemical technique in which current is measured while the potential of an electrode system is varied with time. The resulting current–potential response, or voltammogram, provides information about the redox behavior of species in solution and can be used for qualitative and quantitative analysis.

Experiments typically use a three-electrode cell: a working electrode where the redox reaction occurs, a reference electrode that fixes the potential, and a counter electrode to close the circuit. The potential at the working electrode is controlled according to a program (sweeps, steps, or modulation) while the resulting Faradaic current is recorded. Non-Faradaic currents from double-layer charging accompany the signal and are managed by experimental design. In diffusion-controlled systems, the peak current relates to concentration and scan rate by relations such as Randles-Sevcik; in kinetically limited cases, other analyses are used.

Major voltammetric techniques include cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry, square-wave voltammetry, and stripping voltammetry. Cyclic voltammetry reveals redox potentials and reversibility; differential and square-wave formats improve sensitivity and resolution for trace analysis. Stripping voltammetry first pre-concentrates analyte at the electrode and then measures voltammetric response to achieve very low detection limits, especially for metals and organic pollutants.

Electrodes commonly used are glassy carbon, gold, or platinum for the working electrode; reference electrodes such as Ag/AgCl or saturated calomel provide a stable potential; a counter electrode completes the circuit. The choice of electrolyte, pH, and surface condition influence sensitivity and reproducibility.

Voltammetry is applied in environmental monitoring, clinical analysis, materials science, and sensor development to quantify trace metals, organic compounds, and biomolecules. The technique originated from polarography in the early 20th century, developed by Jaroslav Heyrovský, who received the Nobel Prize in Chemistry in 1959 for his work in electrochemical analysis.