For various reasons many substances cannot be analyzed by direct Karl Fischer titration:
•They release their water only slowly.
•The water is released at high temperatures only.
•The substances are poorly soluble in alcohols.
•They undergo side reactions with the KF reagent.
•They contaminate the titration cell or the electrodes.
These substances require sample preparation before their water content can be determined.
A homogeniser can be used to comminute the sample in order to improve its solubility. Normally this can be done directly in the titration cell. In many cases a homogeniser renders toxic solubilisers unnecessary. However, side reactions cannot be avoided with a homogeniser.
The oven method has the advantage that the sample itself is not introduced into the titration vessel. The sample is heated up and only the evaporated moisture is transferred to the titration cell. Side reactions as well as matrix effects cannot occur and contamination of the titration cell is avoided.
Homogenizer
KF oven
KF oven sample changer
