Meaning
Measure of the total amount of iodine used during a Karl Fischer titration to neutralize water and other reactive species. Stoichiometric principles dictate that one molecule of iodine reacts with exactly one molecule of water during the test. Iodine consumption is the raw data point from which the moisture content of a polymer is calculated.
Analytical Process
Electrochemical sensors in the titration cell detect the presence of excess iodine to signal the end of the reaction. In coulometric titration, the instrument generates the iodine internally by passing a current through the reagent. The total electrical charge used is directly proportional to the amount of iodine produced and thus the water measured.
Interfering Factors
Chemical additives in the resin like antioxidants or certain pigments can consume iodine independently of any moisture. This leads to an artificially high moisture reading and may cause unnecessary drying of the material. Lab technicians must identify these side reactions by comparing the titration curves of different reagent types.
Calibration Standard
Accuracy of the consumption measurement is verified using liquid or solid water standards with a known moisture value. These tests ensure that the generator electrodes and the sensing electrodes are functioning correctly. Regular calibration is a requirement for maintaining the quality certifications needed in medical and aerospace polymer sourcing.
