Titrations
Karl Fischer
Karl Fischer titration gives specific and sensitive quantitation of the water content of samples. Water is consumed by chemical reaction with iodine and sulfur dioxide in the presence of a base. Consumption of all of the water in a sample results in an excess of iodine and a large increase of electrical conductivity in the titration mixture.
The titration can be conducted either volumetrically, where the reagent is physically added to the sample, or coulometrically, where the reagent is generated in the reaction cell via electric current. Liquid samples can be analyzed by direct injection of the sample into the titration cell.
The addition of a specialized oven allows analysis of moisture in solid samples by vaporization of the moisture, which is carried into the reaction cell on a dry gas stream.
Applications:
- Moisture determination in solid plastic resins and in solvents.