The colorimetric determination of hexoses with carbazole

The optimum conditions for the calorimetric estimation of hexoses by reaction with carbazole in hot sulfuric acid solution have been determined and a convenient procedure, giving results with a precision of 2 to 5 per cent in the range of 50 to 150 γ of glucose, is described. The colors obtained with glucose, galactose, fructose, and mannose are not sufficiently distinctive to allow their ready differentiation and identification by spectral measurements. The significance of the ultraviolet spectra of heated and unheated sulfuric acid solutions of hexoses to the problem of estimation and identification of hexoses is discussed.