Electrochemical analyses can be thought of in terms of two broad classes of
measurement, one in which the potential that develops between two electrodes is measured
(potentiometry) and another in which the current that flows between two electrodes is measured
(amperometry). In potentiometry, it often proves helpful to arrange things such that the current
is very low (e.g., by placing a high-resistance voltmeter in series between two electrodes). The
electrochemical potential of one electrode (the reference electrode) is usually fixed, so the
measured cell potential can be interpreted in terms of an equilibrium half-cell reaction involving
an analyte species in contact with the other electrode (the working electrode). In favorable cases,
one can use data from potentiometric measurements to calculate analyte concentrations directly
from the Nernst equation. Potentiometry is a simple and straightforward analytical method, and
is routinely used to solve many problems in the analysis of electrochemically active and/or
charged analytes. Electrochemical analyses can be thought of in terms of two broad classes of
measurement, one in which the potential that develops between two electrodes is measured
(potentiometry) and another in which the current that flows between two electrodes is measured
(amperometry). In potentiometry, it often proves helpful to arrange things such that the current
is very low (e.g., by placing a high-resistance voltmeter in series between two electrodes). The
electrochemical potential of one electrode (the reference electrode) is usually fixed, so the
measured cell potential can be interpreted in terms of an equilibrium half-cell reaction involving
an analyte species in contact with the other electrode (the working electrode). In favorable cases,
one can use data from potentiometric measurements to calculate analyte concentrations directly
from the Nernst equation. Potentiometry is a simple and straightforward analytical method, and
is routinely used to solve many problems in the analysis of electrochemically active and/or
charged analytes.