Suitability Test for Water Determination by Volumetric Karl Fischer Titration

This application note provides a simple method to perform the suitability test for certified liquid water standards according to European pharmacopoeia 2.5.12.

By downloading this application package, you will receive a PDF of the application note as well as the required data for the LabX™ titration software method.

The volumetric Karl Fischer titration method is used to measure the water content in various samples. Equal volumes of water present in the sample react with equal volumes of iodine present in the titrant. When all water molecules are consumed, excess iodine present will no longer be reduced and hence end point is determined.

What is the suitability test?

Water content for suitability test for volumetric Karl Fischer (KF) technique is mentioned in chapter 2.5.12. of European Pharmacopoeia. It deals with the procedure to verify the accuracy of KF determinations for a solvent, titrant and sample. The procedure is applicable for sample sizes between 2.5 to 5 mg of water per injection. The acceptance criteria for the suitability test depends upon the mean recovery, slope, and axis intercepts.

Why perform a suitability test?

Water determination is an important quality parameter, not just to define the quality of the pharmaceutical products, but also to determine the accuracy of solvents and reagents used for KF titrations as they change with time. The variations that might occur in water content determinations can compromise the products and their quality. Hence, a suitability test needs to be performed on a regular basis to verify the results obtained