BEHAVIOR OF SERUM IN BORATE MODIFICATION OF CARBAZOLE REACTION

The carbazole reaction with and without borate gives a significant color with dilute human serum. The borate modification does not exaggerate the depressing effect of proteins upon the colors developed by hexuronic acids. The chromogenic properties of serum are not comparable with those of glucuronic acid in its common conjugations and are mostly retained after preliminary dialysis. The color generated by dilute serum increases during heating after addition of carbazole, and appears more slowly than that of hyaluronic acid or chondromucoprotein. When residues of serum cannot be completely eliminated, limitation of heating with carbazole may reduce the interfering colors without significant loss of sensitivity to glucuronic acid either in its free form or bound in glycosaminoglycans. © 1969.