Vaporisation coulometric Karl Fischer titration: A perfect tool for water content determination of difficult matrix reference materials

Abstract

Volumetric Karl Fischer titration (V-KFT) is the reference method to determine the water content in a whole range of organic and inorganic matrices. The method has several important drawbacks e.g. a high solvent consumption and a rather large measurement uncertainty when determining the water content in reference and candidate reference materials containing starch (e.g. maize, toasted bread, etc.). It is also labour intensive for routine measurements. In order to overcome these disadvantages, a relatively new method of coulometric Karl Fischer titration, equipped with a fully automated oven system, has been established and optimised. The objective of this study was to establish the robustness of the vaporisation coulometric Karl Fischer titration method (vap-C-KFT) and to compare measurement uncertainties with those obtained by V-KFT. The overall results obtained with the proposed vap-C-KFT methods correlate well with the results obtained by V-KFT ( R 2 = 0.998). Due to the good repeatability and intermediate precision of the vap-C-KFT methods compared to V-KFT, significant lower measurement uncertainties were obtained from vap-C-KFT measurements.