USP <731> <921> Method 1a
By means of a specifically designed volumetric titration, we are able to determine the total water content of a sample. Due to the nature of our instrumentation, we are only able to perform this test on samples that are soluble in MeOH. This test differs from Loss on Drying (LOD) such that Karl-Fischer will not measure residual volatiles, other than water. Karl-Fischer is able to measure the water content trapped in the crystal lattice structure of a hydrated API, unlike LOD.
(USP <731> <921> Method 1a)