A New Method for determining Ketohexoses in the Presence of Aldohexoses

Abstract

A SLIGHTLY modified anthrone method^1,2 has been described³ which is suitable for the quantitative estimation of carbohydrate in chromatographic fractions. 10 ml. of a 0.02 per cent (w/v) solution of anthrone in 70 per cent (v/v) sulphuric acid is mixed with 1 ml. of the test solution, heated for 7.5 min. in a boiling water-bath and the optical density of the cooled solution read at 625 mµ against a blank. When solutions containing sucrose were analysed by this method, it was noted that, if the mixed solutions were allowed to stand before heating, there was a slow development of colour in the cold that was not apparent with solutions of aldohexoses or of oligosaccharides built up of aldohexose units. Table 1 gives a quantitative picture of the observed differences.