Determination of uronic acids in cellulosic materials

Abstract

Methods for the determination of uronic acids, based on the estimation of the amount of carbon dioxide evolved by these acids in a given length of time during treatment with a boiling solution of hydrochloric acid, were found to fail when cellulose or other carbohydrate material was present, since these substances also decomposed with the evolution of some carbon dioxide. An investigation of the rates of evolution showed that pure uronic acids evolved carbon dioxide at a rapid rate and that the evolution was complete in several hours. Carbohydrates, free of uronic acids, evolved carbon dioxide at a much slower rate, which remained approximately constant during the entire treatment with acid. It is shown that this difference in rates can be used as the basis for estimating uronic acids, even when they are mixed with large proportions of cellulosic materials. A detailed description of the apparatus and its manipulation is given.