A colorimetric method for the determination of glucosamine and chondrosamine

Abstract

A COLORIMETRIC method for the determination of glucosamine has recently been described by Zuckerkandl and Messiner-Klebermass [1931].According to their procedure the test-solution, which should contain between 1 and 4 mg.glucosamine hydrochloride, is evaporated to dryness and treated with a freshly prepared solution of sodium methoxide.The free glucosamine base is then cautiously acetylated with acetic anhydride to yield the N-monoacetyl derivative which can be estimated by means of the intense reddish-purple colour that develops when, after a preliminary treatment with dilute alkali, p-dimethylamino- benzaldehyde in acid solution (Ehrlich's reagent) is added.We have found this method unsatisfactory.The acetylation of glucosamine which yields the N- monoacetyl derivative, under the conditions described by Zuckerkandl and Messiner-Klebermass does not appear to be quantitative and, moreover, rapid fading of the colour that develops on the addition of the p-dimethylamino- benzaldehyde reagent increases the difficulty of colorimetric estimation.That Zuckerkandl and Messiner-Klebermass were aware of the difficulties involved