1. Indicator Electrodes
(Metal electrodes & Glass electrodes)
PRAVARA INSTUTE OF MEDICAL SCIENCES,LONI
(Deemed to be University)
College of pharmaceutical sciences, Loni
Presented by:
Gaikwad Pankaj
First year B.Pharm
College of pharmaceutical sciences
Presented to:
Thorat Nikita Madam
Assistant professor
College of pharmaceutical sciences
3. Introduction
Indicator electrodes are essential tools used in electrochemical analysis to detect and
measure the concentration of various chemical species in a solution. There are different
types of indicator electrodes, but two of the most commonly used are metal electrodes
and glass electrodes. Metal electrodes are typically made of an inert or reactive metal,
while glass electrodes consist of a glass membrane that is sensitive to the hydrogen ion
concentration of the solution being analyzed. Both types of electrodes play an essential
role in a wide range of industries, including healthcare, environmental monitoring, and
industrial production.
3
4. Indicator Electrodes
Defination:An electrote is useful for measuring potential or pH of a
solution is known as indicator electrode.
It is used for the potential caused by some chemical species as compare
to the rerence electrode
4
5. 5
There are two types of Indicator electrodes
1. Metallic indicator electrode
2. Glass electrode
6. 6
Metal electrodes
Metal electrodes are a type of indicator electrode commonly used in electrochemical analysis. They
are typically made of a metal or alloy that is inert or reactive to the solution being analyzed. Inert
metal electrodes do not participate in the electrochemical reaction occurring in the solution, while
reactive metal electrodes participate in the reaction.
Indicator electrodes are paired with a reference electrode like SHE, SCE, or Ag/AgCl
Used to determine concentration of analyte
7. 7
Kinds of Metal Indicator electrodes
There are two kinds of the metal indicator electrodes
• Electrodes of the first kind:
In this kind where the electrode potential responds directly in relationship to the concentration of
the metal ion of interest.
▪ Pure metal electrode in direct equilibrium with its cation
▪ Metal is in contact with a solution containing its cation
M+n(aq)+ne- M(s)
Eind=E0= 0.592/n log 1/[Mn+4]
8. 8
Disadvantages of first kind electrodes
• Not very selective
• Ag- interferes with cu2
•
• May be pH dependent
• Zn and Cd dissolves in acidic solutions
• Easily oxidized (deaeration required)
• Non reproducible response
9. 9
Electrodes of second kind
Respond to anion by forming precipitates or stable complex
Examples:
1.Ag electrode for Cl-determination
AgCl(s)+ Ag(s)+Cl- E0 =+
2. Hg electrode for EDTA determination
13. 13
Style of glass electrode
The glass membrane itself is not limited to any configuration or shapes its only requirement is
contact with solution.
Therefore, different styles of glass electrodes have envolved to maximize pH sensing ability and
some of the more difficult applications
14. 14
Properties of Glass pH electrodes
1. Potential not affected by the presence of oxidizing or reducing agents
2. Operates over a wide pH range
3. Fast response
4. Functions well in physiological systems
5. Very selective
6. Long lifespan
15. 15
Theory of the glass membrane potential
For the electrode to become operative, it must be soaked in water.
During this process, the outer surface of the membrane becomes hydrated
When it is so, the sodium ions are exchanged for protons in the solution
The proton are free to move and exchange with other ions.
