KEY WORD AND DEFINITIONS
Electrode: A conductor through which an electrical
--- Content provided by FirstRanker.com ---
current enters or leaves a nonmetallic portion of a circuit.Indicator electrode: Used in potentiometry that produces
a potential representative of the species being measured.
--- Content provided by FirstRanker.com ---
Reference electrode: Is an electrode at which no
appropriate current is allowed to flow and which is used
--- Content provided by FirstRanker.com ---
to observe or control the potential of the indicator orworking electrode, respectively.
Potentiometry: An electrochemical process where the
--- Content provided by FirstRanker.com ---
potential difference is measured between an indicatorelectrode and reference electrode when no current is
allowed to flow in the electrochemical cell.
--- Content provided by FirstRanker.com ---
WORKING PRINCIPLEMembrane potentials are caused by the permeability of
certain types of membranes to selected anions or cations.
--- Content provided by FirstRanker.com ---
Such membranes are used to fabricate ion-selective
electrodes that selectively interact with a single ionic
--- Content provided by FirstRanker.com ---
species.The potential produced at membrane-sample solution
interface is proportional to the logarithm of the ionic
--- Content provided by FirstRanker.com ---
activity or concentration of the ion in question
Measurements with ISEs are simple, often rapid,
--- Content provided by FirstRanker.com ---
nondestructive, and applicable to a wide range ofconcentrations.
The ion-selective membrane is the "heart" of an ISE
--- Content provided by FirstRanker.com ---
as it controls the selectivity of the electrode.Ion-selective membranes typically consist of glass,
crystalline, polymeric materials.
--- Content provided by FirstRanker.com ---
Ionic-selective electrodes are widelyused clinically for the measurement of
pH, PCO2 and electrolytes in whole
--- Content provided by FirstRanker.com ---
blood, serum, plasma and urine.