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The electrical charge method is based on dissolving the sample in an electrolyte containing a specific solvent with iodine; water then consumes this iodine. However, the iodine required is not determined by titration using a pre-calibrated iodine-containing reagent, but rather through an electrolytic process in which the iodide ions in the solution are oxidized at the anode to form iodine: I2 → 2e- + I2. The iodine thus produced reacts with the water present in the sample. Its endpoint is indicated by a double platinum electrode. Electrolysis is stopped when the iodine concentration in the electrolyte returns to the predetermined level. Then, according to Faraday’s law of electrolysis, the moisture content of the sample to be tested is calculated. The main difference between the volumetric method and the coulometric method lies in the source of I2: in the volumetric method, I2 comes from the titrant, whereas in the coulometric method, I2 is generated by electrolyzing an electrolyte containing I- ions. The speed of electrolysis is limited; therefore, when the water content of the sample to be measured is relatively low, using a Karl Fischer coulometric moisture meter not only speeds up the testing process but also ensures good reproducibility of the results. There is a strict quantitative relationship between the charge passed through the electrolytic cell and the amount of I (iodine); therefore, the coulometric method offers higher measurement accuracy. Therefore, for practical applications, the capacity method is more suitable for measuring samples with high water content, while the Coulomb method is only applicable to the determination of trace amounts of water.