Patent ID: 8858769

Claim:
A Karl Fischer titration method by means of a Karl Fischer titration apparatus having a titration flask provided with electrolytic electrodes including an anode and a cathode with a membrane therebetween, a detection electrode for detecting a polarization state of a solution in the titration flask, and a reference electrode for detecting a potential between the anode and the reference electrode, the method comprising steps of: forming a state that iodine exists in a solution contained in the titration flask; performing a back coulometric titration employing a potential control method to produce iodine ions from the iodine at the anode by flowing the current in an area where the current between the cathode and the anode is kept constant regardless of the potential change between the reference electrode and the anode while a minus potential is applied on the anode and a plus potential is applied on the cathode; terminating the back coulometric titration when the potential at the detection electrode is a specific value; and finding a water content corresponding to a quantity of electricity consumed during the back coulometric titration.