Thread Content
Calibration of the titrability of Karl Fischer moisture analyzers’ reagents (commonly known as water equivalents). The accuracy of the calibration of the titrability of Karl Fischer reagents has a direct impact on the accuracy of sample analysis. Different testing environment conditions, as well as the sealing quality of the entire instrument setup, can significantly affect the titrability of these reagents, especially for samples that require high measurement accuracy. The calibration of the titrability should, in principle, be carried out before sample testing each day. The calibration of titrability can be carried out using standard substances with a certain level of moisture; some of these standard substances are in liquid form and are contained in ampoules. One is consumed each time; it offers high accuracy but at a higher cost. Some reference materials are solid, provide high accuracy, and require strict conditions for storage. It’s a problem once it gets wet. Simple and practical is pure water calibration. The amount of water is accurately measured using a micropipette; generally, 10 to 30 microliters of water are used for calibration. This process is repeated several times, and the average value is taken to determine the titrability of the Karl Fischer reagent. However, some laboratory testers do not fully understand the meaning of calibrating the titrability of Karl Fischer reagent, or out of negligence they use the same calibrated value for titrability throughout several months of sample testing, from the time a bottle of reagent is opened for such calibration until it is used up. Obviously, this leads to significant errors. The titrability of the Karl Fischer reagent changes gradually over time, and the error relative to the titrability on the first day also increases. It can be seen that using the initial titration value to calculate the measured values for several months results in a large error in those values. Therefore, the titrability of the Karl Fischer reagent should be calibrated regularly. The interval between such calibrations should be determined appropriately based on the laboratory’s temperature and humidity, the sealing quality of the instruments, as well as the requirements of the tests, in order to ensure measurement accuracy. The accuracy of sample measurement is related to the quality of the product.