Determination of Glycols by Polarography

Abstract

For the micro-determination of glycols, polarography was utilized in the known method for glycol splitting. In the existing procedure, IO₃^- formed and excess of IO₄^- are measured and the amount of glycol is calculated from the amount of IO₄^- consumed. Attempt was made to determine this amount of IO₄^- consumed directly by polarography, and examinations were made on optimal conditions for the kind and pH of buffer solution, kind of anode to be used, amount of reagent and sample to be used, and reaction time. As a result optimal conditions for determination were determined as follows: Ten cc. of approx. 10^-3M KIO₄ in Sørensen's buffer (pH 7) is added to 1 cc. of the test solution (ca. 10^-3M) and the mixture is allowed to stand for a definite length of time (15 mins. to 1.5 hrs. according to the kind of sample used) to complete the reaction. To this mixture 0.1 cc. of 1% gelatin solution is added and this is immediately submitted to polarography, using H-type electrolyte cell. The amount of excess KIO₄ (X) is determined from the wave height of the 1st wave. The same procedure is carried out using 1 cc. of distilled water in place of the sample solution and the amount of original KIO₄ (Y) is determined. The amount of the sample is calculated from the amount of KIO₄ used, X, and Y.
This procedure was used in the determination of several kinds of straight-chain polyhydric alcohols, pentoses, and hexoses, and satisfactory results were obtained.