amperometric

Amperometric refers to methods or detectors in electrochemistry that measure current as a function of time or potential, with the current arising from a redox reaction at an electrode held at a constant potential. In amperometric detection, the electrode potential is controlled by a reference electrode and the resulting faradaic current is monitored, providing information about the concentration of an electroactive species.

The underlying principle is that, at a fixed potential, the rate of electron transfer at the electrode surface depends on the concentration of the analyte capable of undergoing oxidation or reduction. Under diffusion-controlled conditions, the measured current is proportional to the analyte concentration, at least within a linear range. The transient or steady-state current can be described by appropriate electrochemical models, such as chronoamperometry for a potential step or steady-state amperometry for constant-potential operation.

Amperometric techniques are commonly implemented using three-electrode setups (working, reference, and counter electrodes) or two-electrode configurations in compact devices. Variants include chronoamperometry (monitoring current after a potential step) and steady-state amperometry (recording constant current after stabilization). In many modern applications, amperometric detection is integrated into biosensors and enzyme-based sensors, where enzymatic reactions generate or consume electrons that produce a measurable current. Glucose sensors, lactate sensors, and other clinical and environmental sensors frequently rely on amperometric readouts, often employing mediators or direct electron transfer to improve performance.

Advantages of amperometric methods include rapid response, simplicity, and good sensitivity over a broad range. Limitations include potential interference from species with overlapping redox potentials, drift and calibration needs, and, in some systems, limited selectivity.