The carbazole reaction in H,SO, is a convenient and commonly used method for the quantitative determination of hexuronic acids. The original description of this reaction by Dische (1, 2) has been modified by several authors (3, 4). All these methods require "hydrolysis" of the carbohydrates in H,SO, before the development of the carbazole reaction. The temperature at which the "hydrolysis" takes place has been said to differentiate the hexuronic acids in glycosaminoglycansS (GAG) (5, 6). After "hydrolysis" at high temperatures, the carbazole color developed in either the presence or the absence of borate (3, 4) at room temperature
(2) or in boiling water (3, 4). Green (7) working in my laboratories noted that sulfamate depressed the carbazole color with glucuronic acid to a lesser degree than that with glucose.
The following experiments were performed to study the kinetics of the carbazole reaction with hexoses and with compounds containing hexuronic acid at various temperatures and to evaluate the effect of borate and sulfamate on the sensitivity and specificity of the carbazole reaction with hexuronic acids and GAG.
MATERIALS AND METHOD
Freshly prepared, purified, commercial samples of hyaluronic acid (from vitreous humor, Worthington) ; chondroitin sulfate (from bovine nasal septum, Sigma) ; heparin, glucuronic acid, galacturonic acid, glu-