DETERMINATION OF WATER IN WASTE MATERIAL

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