Karl fischer titration is an analytic system to determine the trace amount of water in solid, gases and liquids. It is a very efficient and accurate technique. In this presentation we go deeper about this titration system.

1. Welcome

2. Group Members
1.Afsana Afrin Urmee ( ID: 2016-3-70-010)
2.Shukla Sarkar ( ID: 2016-3-70-011)
3.A.B.M. Manzurul Hassan (ID: 2016-3-70-
012)

3. Karl Fischer Method

4. Introduction
What is Karl
Fischer Method?
What are the
advantages and
disadvantages of
Karl Fischer
method?
What is the
procedure of doing
Karl fisher method?
What are the
applications of Karl
Fischer method?

5. c
c
1
2
3
Classic titration method
Uses coulometric or
volumetric titration
Determine trace amounts of
water in a sample
That
To
What is
Karl
Fischer
Method
?

6. Present Day
What is
Karl
Fischer
Method
?
c
c
Invented By
Automatized
Karl-Fischer
titrator.
Karl Fischer
(1935)

7. I2 + SO2 + 2H2O ―›2HI + H2SO4
c
Bunsen
Reaction
Principle
1 CH3OH + SO2 + RN ―› [RNH]SO3CH3
[RNH]SO3CH3 + I2 + H2O + 2RN ―›
[RNH]SO4CH3+ 2 [RNH]I
2

8. c
Principle
Since the ,
Amount of water ≡ Amount of I2
Amount of consumed I2 Amount of water

9. Titration Curve

10. Types
of Karl
Fischer
Method
c
c
Two Types
1
2
Volumetric
Titration
Coulometric
Titration

11. Difference
 Designed for titration of
Liquids & Gases only.
 I2 is generated at an
electrode.
 Water levels in the sample:
0.001- 0.1% H2O
 Designed for titration of
Solids, liquids & gases.
 I2 is included with the
reagents.
 Water levels in the
sample:
0.1-100% H2O
Coulometric KFT Volumetric KFT

12. Difference
 Poor system flexibility.
 No option for Temperature
Modification.
 Co-solvents are limited.
 Good system flexibility.
 Modification of temperature
can be possible .
 Modified solvent system.
Coulometric KFT Volumetric KFT

13. Coulometric
KFT Two Types
1
2
Fritted Cell coulometric
KFT
A diaphragm separates the anode
from the cathode to form generator
electrode that prevent iodine
reduction.
Frittless Cell
coulometric KFT
A Combination of factors without frit,
makes it nearly impossible for iodine
to get reduced.
c
c

14. Volumetric
KFT
c
c
Two component system
• Higher titration speed
• Greater accuracy
• Higher buffer capacity
• Lower solvent capacity, more costly
One component system
• Unlimited water capacity
• Easier to handle
• Less expensive
Two Types
1
2

15. Bipotentiometric Titration
Bipotentiometric titration is simply monitoring the
extent of reaction by measuring changes in electrical
conductivity of the reaction solution.
Both Coulometric and volumetric method use
bipotentiometric titration to measure the amount of I2
consumed by the water.

16. Bipotentiometric Titration
Measuring I2
The second reaction in the KF titration is a redox
reaction:
[RNH]SO3CH3+I2+H2O+2RN 
[RNH]SO4CH3+2[RNH]I
Sulphur oxidized from alkylsulfite to alkylsulphate:
SO3CH3
-2  SO4CH3
-2+2e-
(Oxidation number increased +4 to +6)
Iodine is reduced:
I2+2e-  2I- (E0 = 0.54 V)

17. Bipotentiometric Titration
Measuring I2
The reduction of iodine consumes electrons generated by
the oxidation of Sulphur, which changes the electrical
potential of the system.
The changes in potential is detected by an electrode ( a
double platinum electrode).

18. The karl Fischer method for the determinations of water is used for prednisolone sodium
phosphate as described below:
Materials required:
• Karl Fischer reagent: 100 ml
• Prednisolone sodium phosphate: 0.2 g
• Anhydrous methanol: 20 ml

19. The Karl Fischer method for the determination of water is used for prednisolone sodium
phosphate as described below:
Procedure:
• Add about 20 ml of anhydrous methanol to
the titration vessel.
• Titrate to the amperometric endpoint with
karl fischer reagent.
• Quickly add 0.2 g prednisolone sodium
phosphate sample.
• Stir for 1 minute and again titrate in the
same way.

20. The karl Fischer method for the determinations of water is used for prednisolone sodium
phosphate as described below:
Procedure:
• The endpoint is detected by electrode.
• The minimum water equivalent is 3.5 mg of
water per ml of karl fischer reagent.Hence
the percentage of water in the given sample
may be calculated by following equation:
Water % (w/w) =
𝑣×3.5
𝑤𝑡.𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 (𝑚𝑔)
× 100

21. PH
influence
c
c
• PH between 5-7.5 is the optimum range
• Below PH 2 reaction will not happen.
• PH between 2-5 reaction will be slow.
• Above PH 8 iodine is consumed by side
reaction.

22. Application
Increased Product
Stability. E.g. pharma
product or food product.
Stopping growth of
microorganisms by
determining water level.
Analytical technique for
quantitative analysis of
total water content.

23. High accuracy and precision.
Selectivity for water.
Short analysis duration.
Easy sample preparation.
Small sample quantities required.
Nearly unlimited measuring range.
Suitability for analyzing solids, liquids and gases.

24. Limitations
High costs of Considerable amount of apparatus.
Inference of compound reaction with iodine.
Highly acidic or basic compound can not be determined.
Large amount of sample needed in some cases.
Water in carbonyl group is difficult to determine.
Can show disadvantages with solid materials.