Determination of the substituent pattern of heterogeneously and homogeneously synthesized carboxymethyl cellulose by using high‐performance liquid chromatography

Abstract A rapid and convenient procedure was developed for the determination of the substituent pattern of carboxymethyl cellulose (CMC) by means of high‐performance liquid chromatography. The hydrolysates of CMC are separated on a polystyrene‐based strong cation‐exchange resin into glucose, 2,3,6‐tri‐O‐carboxymethyl glucose and groups of 2‐, 3‐and 6‐mono‐O‐ and 2,3‐, 2,6‐, and 3,6‐di‐O‐carboxymethyl glucoses. By this method the determination of the average degree of substitution as well as the substituent pattern is possible. In this way we found that CMC samples which were synthesized in LiCl/N,N‐dimethylacetamide as a cellulose solvent, contain a significantly higher amount of both tricarboxymethylated and unsubstituted units than those obtained in a slurry of cellulose in isopropanol/water at comparable DS values. The substituent pattern of heterogeneously synthesized CMC is mainly determined by statistics.