Water determination (also called moisture determination) is one of the most frequently performed analyses in laboratories around the world. This is not really surprising, as the water content directly influences the quality, process ability, shelf life and stability of a wide range of products.
Karl Fischer titration has established itself as a reference method for general use. It is highly specific and precise, covers a wide concentration range from pap up to 100% and has short determination times. There are two types of Karl Fischer titration: volumetry and coulometry
This procedure titrates the absolute water contents. Volumetry also has the advantage of solid or pasty samples that can be placed directly into the titration vessel and work can be conducted with a wide range of organic solvents adapted to the sample.
In contrast to volumetric Karl Fischer titration, coulometry adds no titrant, but the required iodine is generated directly in the iodide-containing electrolyte by electrochemical means (electronic buret). For this reason, coulometric water determination is primarily used for the determination of small amounts of water from 10 µg to 200 mg H2O with a resolution of 0.1 µg H2O.