Ion Selective Electrodes (ISE) Quiz

Questions and Answers

Potentiometry is the measurement of an electrical current between two electrodes in a solution.

False

An Ion Selective Electrode consists of three electrodes: reference electrode, indicator electrode, and glass electrode.

False

An Ion Selective Electrode (ISE) is a transducer that converts the concentration of specific ions in a solution into electrical potential.

False

The potential difference between the two electrodes in an ISE depends on the concentration of the specific ion in the solution.

False Signup and view all the answers

Glass membranes are only used for detecting multiple charged cations.

False Signup and view all the answers

Crystaline membranes are made from a mixture of different substances.

False Signup and view all the answers

Ion exchange resin membranes are not commonly used in ISE.

False Signup and view all the answers

Enzyme membranes are not selective to specific ions.

False Signup and view all the answers

Ion exchange resin membrane is the least common type of ion selective electrode.

False Signup and view all the answers

Enzyme membrane is a true electrode with a single reaction mechanism.

False Signup and view all the answers

Ion selective electrodes are affected by sample color and turbidity.

False Signup and view all the answers

Direct ion selective electrodes require sample dilutions.

False Signup and view all the answers

Ion selective electrodes are fragile and prone to blockage by proteins.

True Signup and view all the answers

Ion selective electrodes can only measure positive ions.

False Signup and view all the answers

Study Notes

Ion Selective Electrode (ISE)

Ion Selective Electrode (ISE) is a transducer or sensor that converts the activity of a specific ion dissolved in a solution into an electrical potential.

Potentiometry

Potentiometry is the measurement of an electrical potential difference between two electrodes (reference electrode and indicator electrode) in an electrical solution.
Uses of potentiometry:
- Analytical chemistry
- Electrolyte measurement
- Body fluids like plasma, serum, sweat analysis
- Biochemistry or biophysical research

Principle of ISE

An ISE consists of two electrodes: a reference electrode and an indicator electrode.
The indicator electrode develops a potential difference due to ion exchange between the sample and the inorganic membrane.
The potential difference is measured against a stable reference electrode of constant potential.
The potential difference depends on the activity of the specific ion in the solution.

Components of ISE

Three main components of an ISE:
- Indicator electrode
- Reference electrode
- Ion selective membrane

Types of ISE

Direct ISE: measures the sample without dilution
Indirect ISE: measures the sample after dilution

Types of Ion Selective Membranes

Four main types of ion selective membranes:
- Glass membrane
- Crystalline membrane
- Ion exchange resin membrane
- Enzyme membrane

Glass Membrane

Made from ion exchange type of glass
Advantage: good selectivity
Disadvantage: only suitable for a few single-charged cations (e.g., H+, Na+, Ag+)

Crystalline Membrane

Made from mono or polycrystalline of a single substance
Advantage: good selectivity for both cations and anions (e.g., fluoride selective electrode)

Ion Exchange Resin Membrane

Made from special polymers with ion exchange ability
Most common type of ion selective electrode (e.g., potassium selective electrode)

Enzyme Membrane

Not a true electrode, as it has a double reaction mechanism:
- First mechanism: reaction between enzyme and specific substance, producing OH- or H+
- Second mechanism: detection of OH- or H+ by ISE (e.g., glucose selective electrode)