Viscle
Karl Fischer Titration
Objective:
To detrmine and analyze the moisture content of a given sample using Karl Fischer volumetric titration technique.
Theory:
Karl Fischer volumetric titration is used to detect analytically the moisture content present in samples. The iodine present in the Karl fischer reagent reacts stoichoimetrically with the amount of water present in the solution. For example water reacts with iodine in 1:1 mole ratio in the reaction:
I2 + SO2 + H2O + 3Base + CH3OH
→ 2Base HI + Base HSO4CH3
From the amount of excess iodine present is indicated by the indicator electrodes after the reaction, moisture content can be calculated.
Procedure:
1. Put approximately 40-50ml of KF-grade dry methanol into the reaction kettle having silica gel desiccator, molecular seives and reagent dispenser attached to it.
2. Perform neutralization to remove any traces of water using KF reagent.
3. Add approximately 100mg of Di-sodium tartrate dihydrate in the kettle and perform titrations by method no. 47 of the auto-titrator. This is called standardization to find the strength of the reagent.
4. Add known amount of sample glycerol (approx 60μl) to the kettle and again perform titration using method no. 2 of the auto-titrator. We get the end point of titration when the voltage for the paltinum pin electrodes stabilize.
5. We get the volume of the KF reagent dispensed in the kettle and the moisture content of the sample on the display of the machine. Repeat the steps for two more same samples.
6. Perform the same procedure for KCL sample(approx 90mg).
Calculations:
The analitical moisture content is calculated from the data using the relation,
% moisture = 100*S*(KF-B-L/1000)/W;
Where, S= strength of KF reagent (mg/ml) W = wt. of sample (mg) KF = volume of KF consumed during titration (ml) B=blank vol. (ml) = 0 L=leak rate (µl/min).
Standardization of KF reagent: Weight of Di-sodium tartrate
Objective:
To detrmine and analyze the moisture content of a given sample using Karl Fischer volumetric titration technique.
Theory:
Karl Fischer volumetric titration is used to detect analytically the moisture content present in samples. The iodine present in the Karl fischer reagent reacts stoichoimetrically with the amount of water present in the solution. For example water reacts with iodine in 1:1 mole ratio in the reaction:
I2 + SO2 + H2O + 3Base + CH3OH
→ 2Base HI + Base HSO4CH3
From the amount of excess iodine present is indicated by the indicator electrodes after the reaction, moisture content can be calculated.
Procedure:
1. Put approximately 40-50ml of KF-grade dry methanol into the reaction kettle having silica gel desiccator, molecular seives and reagent dispenser attached to it.
2. Perform neutralization to remove any traces of water using KF reagent.
3. Add approximately 100mg of Di-sodium tartrate dihydrate in the kettle and perform titrations by method no. 47 of the auto-titrator. This is called standardization to find the strength of the reagent.
4. Add known amount of sample glycerol (approx 60μl) to the kettle and again perform titration using method no. 2 of the auto-titrator. We get the end point of titration when the voltage for the paltinum pin electrodes stabilize.
5. We get the volume of the KF reagent dispensed in the kettle and the moisture content of the sample on the display of the machine. Repeat the steps for two more same samples.
6. Perform the same procedure for KCL sample(approx 90mg).
Calculations:
The analitical moisture content is calculated from the data using the relation,
% moisture = 100*S*(KF-B-L/1000)/W;
Where, S= strength of KF reagent (mg/ml) W = wt. of sample (mg) KF = volume of KF consumed during titration (ml) B=blank vol. (ml) = 0 L=leak rate (µl/min).
Standardization of KF reagent: Weight of Di-sodium tartrate