Determination of Microamounts of Carbon in Metals by Wet Chemical Oxidation and Nonaqueous Coulometric Titration

Abstract

A method for the determination of mcroamounts of carbon in metals which do not achieve complete combustion has been developed. This method is based on wet chemical dissolution with a mixture of 280ml of 5 to 10M sulfuric acid and 16g of potassium dichromate, with and without the addition of a small amount of copper(II) sulfate in a stream of oxygen, and on nonaqueous coulometric photometric titration of the evolved carbon dioxide. The reagents used for the wet chemical method were highly purified in order to lower the blank value. Microamounts of carbon in sucrose could be determined with good precision and accuracy. Trace amounts of carbon (0.8-166ppm) in iron, low-carbon steels, titanium alloy, indium and gallium were determined precisely and accurately. The blank value and determination limit obtained by the proposed method are lower than those previously obtained by wet chemical dissolution and volumetric titrimetry.