Which electrochemical assay measures current at a fixed potential?

Which electrochemical assay measures current at a fixed potential?

• A. Amperometry
• B. Anodic stripping voltammetry
• C. Coulometry
• D. Analysis with ISEs

Answer: (A)

Measuring current at a fixed applied potential is amperometry. In this mode, the electrode potential is held constant and the resulting current is tracked over time; the current reflects the rate of the redox reaction at the surface and, under diffusion control, scales with the analyte concentration. This contrasts with anodic stripping voltammetry, which records current while sweeping the potential to oxidize or strip analyte that was pre-concentrated, so the signal depends on changes in potential rather than a constant one. Coulometry focuses on total charge passed to drive a reaction to completion, integrating current over time rather than maintaining a steady current at a fixed potential. ISE-based measurements, meanwhile, are potentiometric, sensing a voltage that corresponds to ion activity rather than current.

Measuring current at a fixed applied potential is amperometry. In this mode, the electrode potential is held constant and the resulting current is tracked over time; the current reflects the rate of the redox reaction at the surface and, under diffusion control, scales with the analyte concentration. This contrasts with anodic stripping voltammetry, which records current while sweeping the potential to oxidize or strip analyte that was pre-concentrated, so the signal depends on changes in potential rather than a constant one. Coulometry focuses on total charge passed to drive a reaction to completion, integrating current over time rather than maintaining a steady current at a fixed potential. ISE-based measurements, meanwhile, are potentiometric, sensing a voltage that corresponds to ion activity rather than current.