Studies on the Determination of Organic Snbstances. III

Abstract

A new method for the estimation of potassium xanthate was found in the course of investigation for the determination of alcohols as xanthate. The method consists in precipitating xanthate as the nickel salt, followed by titrating the combined nickel by use of E.T.A. This procedure is not subject to undesirable effects which are caused by the presence of foreign organic substances as in the case of oxidation-reduction method. The standard deviation of the present method was 0.22% against the average of 99.40%. By using the foregoing method of determination of xanthate, the stability of potassium xanthate solution was studied under varying conditions to find out a suitable procedure for eliminating the by-product, thiocarbonate, which exerted interference on the determination of xanthate.The reaction of the formation of potassium xanthate from aqueous solution of ethyl alcohol, carbon disulfide and potassium hydroxide was investigated. It was realized that this reaction could be applied to the determination of ethyl alcohol in low concentration. The optimum concentration of ethyl alcohol is in the range of 10 to 50 mg per 5 cc, and the reproducibility is 1.6% as a standard deviation against the average of 99.8%. In order to apply this method to the determination of alcohol in alcoholic beverage, the effect of foreign organic substances which may be present together was then studied. The influence of glycocol and tartaric acid could be eliminated by increasing the concentration of alkali. The amount of glucose should be less than 10 mg per 5 cc.