Development of Karl Fischer Reagents

Chapter I: Basic Knowledge
electrodes, such as anilines, diamines and some phenols. Volumetric
titration is carried out using a suitable dehydrated solvent.
(4) Solids that do not dissolve in electrolyte
Solids that do not dissolve in organic solvents can reduce current
efficiency by obstructing electrodes and diaphragms. In principle,
coulometric titration should be avoided in such cases. Use volumetric
titration with a suitable dehydrated solvent, or the moisture vaporization
method.
Q5
[Outline]
What is the moisture vaporization method, and when is it
used?
The moisture vaporization method is used to measure samples of solids that
cannot be dissolved in dehydrated solvents or electrolytes, or samples that
include interfering substances. The moisture content is vaporized by
heating the sample in a flow of dried nitrogen gas. It is then captured in a
dehydrated solvent or electrolyte and subjected to Karl Fischer titration.
Either coulometric or volumetric titration is used.
This method is commonly used with natural substances, such as minerals
and rocks, and with macromolecules such as polymers and rubber. New
areas of use include electronic materials, including printed circuit boards
and wafers, and printing materials, such as toners. This method is also
useful for petroleum products containing additives, such as lubricants.
Convenient moisture vaporization systems are available commercially to suit
various purposes. They can be connected to either volumetric or
coulometric titration systems and used to measure moisture content.
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