Water content needs to be determined at all stages of the manufacturing process from raw materials to finished goods. The quality of the product depends on it. In products such as kerosene, transformer insulation oil or brake oil, the presence of unwanted moisture can have disastrous consequences. In the pharmaceutical industry, it is essential to know the amount of water contained in the ingredients of a drug in order to correctly predict its lifetime, stability and effectiveness. In the food industry, the water content of both raw materials and the finished foodstuff needs to be carefully monitored. The technique most commonly used for these analyses because of its rapidity, accuracy and ease of use is Karl Fischer titration. Thanks to its design and its titration algorithm, the TIM550 Volumetric Karl Fischer Titrator provides accurate results and clear sample information. An uncertainty calculation plug-in allowing all the measurement parameters to be taken into account is also available. Radiometer Analytical makes it easy for the user to comply with Quality Control requirements and follow Good Laboratory Practice. The instrument is easy to program due to preset methods for titrations in the most common samples. The last calibration results of titrants, blanks and samples are stored. When used in conjunction with TitraMaster 55 software, archiving of results and methods is limited only by available storage space. (ASTM Method DE 203 – 96, 1996)
The titration is based on the oxidation of sulfur dioxide by iodine in the presence of water. It is the same reaction as the iodometric titration of sulfur dioxide in water. I2 + SO2 + 2H2O 2HI + H2SO4 (I) In 1935, Karl Fischer published a description of “a new procedure for the titration of water” using the above reaction in an anhydrous nonaqueous solvent. However, in order to shift the equilibrium (I) to the right, it was necessary to neutralize the acids produced. Originally pyridine was used as the neutralizing base.....................
