Karl Fischer titration is a classic method in analytical chemistry that uses coulometric titration to determine the moisture content of a sample.
I2 + 2H20 + SO2 ==> 2HI + H2SO4 This reaction taking place in the presence of a base and a solvent (a typical solvent could be methanol, and a base imidazole)
A chemical reaction takes place between iodine (I) and water (W) with the reactants being in a 1 to 1 ratio between (I) and (W).
It has advantages over simple 'loss on drying' methods of moisture determination of moisture, by being specific to water. Loss on drying will detect the loss of any volatile substance. However, Karl Fischer titration is more difficult and time consuming.