The influence of conductivity on the Karl Fischer titration

The Karl Fischer titration is indicated voltametrically or amperometrically by polarising a double platinum electrode. The endpoint is recognised by a strong decrease of the resistance of the solution, caused by a small excess of iodine molecules. A minimum conductivity of the KF solutions is necessary for indicating the endpoint. In conventional methanolic Karl Fischer solutions, dissolved components assure a sufficient conductivity. But substitution of methanol by less polar solvents can lead to indication problems. The relationship between conductivity and indication for various volumetric one-and two-component systems is shown. e coulometric method, the conductivity of KF solutions is of especial importance. The generation of iodine at the cathode requires a higher conductivity than is necessary for indicating the endpoint. The aim of further developments is to adjust new reagent compositions to standard parameters of the instrument. Some examples of new Karl Fischer solvents are given.