The quantitative estimation of glycuronic acid and its conjugated compounds by means of the naphthoresorcinol test of Tollens

Abstract

The most specific qualitative test for glycuronic acid and its conjugated compounds is the naphthoresorcinol test of Tollens which depends on the formation of an ether-extractable colored compound when glycuronic acid or its derivatives are heated with naphthoresorcinol and conc. HC1. This test is suitable under certain conditions for the quantitative detn. of glycuronic acid in pure soln. The modification used by Maughan, Evelyn and Browne (1938) for the estimation of pregnandiol-glycuronic acid was tested on solns. of glycuronic acid, glycurone, benzoyl-glycuronic and borneol-glycuronic acids with satisfactory results. If the sample examined contains more than 0.05 mg. glycuronic acid variable results are obtained. Single estimations cannot be relied on and series of estimations at varying dilutions are therefore necessary. The method can be applied to blood and urine but account must be taken of interfering substances. Errors can be avoided by serial estimations, choosing only the series which shows proportionality.