The Karl Fischer Method is a method for determining water using Karl
Fischer reagents (consisting of compounds such as iodine, sulfur dioxide,
bases, and alcohols), which react selectively and quantitatively with water
as shown in Formula (1)
I2+SO2+ 3Base + ROH + H2O -> 2Base + HI + Base + HSO4R ····· (1)
| Coulometric Titration Method - For Model CA-200 |
 |
Electrolytic oxidation is carried out in the anolyte, which consists
mainly
of iodide, sulfur dioxide, bases, and solvents such as alcohols. Electrolytic
oxidation proceeds when a sample is added to the anolyte. The Karl Fischer
reaction occurs to produce ircodine as shown in Formula (2).
2I- -- 2e -> I2 ····(2)
Iodine is produced in proportion to the quantity of electricity according
to Faraday's Law, so the water content can be estimated based on the coulombs
required electrolytic oxidation.
1mg of water = 10.71 coulombs
Two kinds of coulometric reagents are needed: one is for the anode
chamber and the other for the cathode chamber of the cell, as shown in
Fig. 1.
Coulometric reagents do not require standardization and have the
advantage of being able to be used repeatedly.
|
| Volmetric Titration Method - For Model KF-200 |
Fig. 2. :Volmetric Moisture Meter |
A sample is added to the titration flask containing a titration solvent,
which is preliminarily dehydrated with a Karl Fischer reagent.
Titration is then carried out using Karl Fischer reagent of previously
determined titer (mgH2O/ml). Water content is determined based on the titration volume (ml).
The polarization-current potential-difference method is employed
as an end-point detection method. Typical commercially avaliable automotiv
volumetric titration systems are shown in Fig. 2. |
|
Mitsubishi Chemical Group is only one manufacturer of Karl Fischer
Method Moisture Meter and Reagent in the world.
>Regarding the Karl Fischer reagent which are produced by Mitsubishi
Chemical Corp(MCC), Mitsubishi Chemical Analytech Co.,Ltd. started
the distribution of the goods on behalf of MCC effected from 1st day of
July 2008.
|
| http://www.mcckf.com |
API Corporation - Karl Fischer Reagents (Mitsubishi Chemical Group) |
|
