Efficient, precise and fast water determination by the Karl Fischer titration

Abstract

One of the most widely used techniques for the water content determination in food is Karl Fischer (KF) titration. The primary advantage with respect to methods based on loss of weight is its high selectivity to water. On the other hand, KF titration is only possible when water in food samples is freely available. Thus, a suitable sample preparation to release water completely has to be selected and done prior to the KF titration. Although KF titration itself is a fast method (1–2 min for a single analysis), the sample preparation step is time-consuming, e.g. 1–2 h when performing an external extraction. The use of a high-speed stirrer for internal homogenization, in addition to fast control algorithms in automatic KF titrators, offers a fast, quick and efficient alternative to more traditional sample preparation techniques. Sample preparation and stirring time can be considerably reduced, and auxiliary solvents can be avoided. The whole analysis is completely automated. In this contribution the use of high-speed homogenizers in KF titration will be discussed in detail.