Role of Carbon Tetrachloride in the Cathodic Reaction of Karl Fischer Coulometric Titration

Abstract

An investigation concerning the role of carbon tetrachloride, which is usually contained in the catholic reagents used for Karl Fischer coulometric titration, is described. Carbon tetrachloride is reduced in the cathode to produce an electrolyte (chloride ion), and reduces the consumption of the electrolyte (diethanolamine methylsulfonate). It therefore slows down any drop in the electric conductivity of the catholic reagents. Further, it represses the production of the reducing sulfur compound from sulfur dioxide (present in the form of methylsulfonate) and prevents its transfer to the anode through the diaphragm. This results in a high water-measurement capacity of the catholic reagents as well as accurate water-measurement values.