简介:2.1 In the volumetric procedure, the sample or an extract of it, is added to a Karl Fischer
solvent consisting of sulfur dioxide and an amine dissolved in anhydrous methanol. This solution
is titrated with an anhydrous简介:2.1 In the volumetric procedure, the sample or an extract of it, is added to a Karl Fischer
solvent consisting of sulfur dioxide and an amine dissolved in anhydrous methanol. This solution
is titrated with an anhydrous solvent containing iodine. The iodine titrant is first standardized by
titrating a known amount of water.
2.2 In the coulometric procedure, the sample or an extract of it, is injected into an
electrolytic cell containing the Karl Fischer solvent, where the iodine required for reaction with water
is produced by anodic oxidation of iodide. With this technique, no standardization of reagents is
required.
2.3 In both procedures, the endpoint is determined amperometrically with a platinum
electrode that senses a sharp change in cell resistance when the iodine has reacted with all of the
water in the sample.
2.4 In the coulometric procedure, the coulombs of electricity required to generate the
necessary amount of iodine are converted to micrograms of water by the instrument详细>