Determination of water by flow injection analysis with the karl fischer reagent: Minization of effects caused by differences in physical properties of the samples

Abstract

In the previously described flow-injection method for the spectrophotometric determination of water with the Karl Fischer reagent, problems can arise from the rather large variation between the calibration curves for different types of samples. Different combinations of flow-injection arrangements and detector types are described here, to establish a system which levels out this undesirable spreading between the calibration curves. One necessary condition for attaining a low spread is shown to be the use of a spectrophotometric detector especially constructed to minimize refractive index effects. The best results, including samples with large differences in refractive indices and viscosities, were obtained by a combination of peak area measurements and the use of this detector. For example, the relative mean deviation for a sample containing 0.1% water was about 2%.