Can alternative solvents be used to completely dissolve samples for Karl Fischer titrations on the KF1000?

Document ID

Document ID TE6910

Version

Version 3.0

Status

Status Published

Published Date

Published Date 09/20/2018
Question
Can alternative solvents be used to completely dissolve samples for Karl Fischer titrations on the KF1000?
Summary
Non-Methanol or Ethanol solvents for use in Karl Fischer titrations.
Answer
Depending on the nature of the sample, select the most appropriate solvent. The role of the solvent is to contribute to the chemical reaction and to ensure the sample is releasing all its moisture content. Most liquid samples dissolve in ethanol. To determine the total amount of water, the sample must dissolve completely. Other solvents can be added to ethanol or methanol in specific proportions to liberate the water more efficiently and completely dissolve the sample. For example, chloroform is a good solvent for fats, and formamide improves the solubility of polar substances. Ethanol or methanol depending on which application is in use should always be present in the solvent in a proportion not lower than 25%. Otherwise unknown stoichiometric ratios will occur for the Karl Fischer reaction.

What would be unknown is how these alternate solvents would interact with the reagents. So it would be recommended to contact your preferred supplier for Karl Fischer reagents on any restrictions or recommendations they would have. They may be able to provide additional details on what reagents and solvents would be recommended for specific sample types that don't completely dissolve in methanol or ethanol, so defer to their expertise in this matter.

It would be recommended to run a water standards to verify that any additions to the solvent make up do not interfere.

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