SEC of mono-carboxymethyl cellulose (CMC) an a wide range of pH; Mark-Houwink constants

A method for determination of carboxymethyl cellulose (CMC) molecular weight (M-w) and chemical heterogeneity (degree of oxidation (DO)) using a bi-detector HPSEC (UV-detector online with refractometer) has been developed. It has been found that the use of 0.5 N NaOH or 0.4 M acetate buffer as the eluent ensures CMC separation according to Mw. It has been revealed that the universal calibration for the polyelectrolyte CMC and the neutral polymer dextran is valid under the conditions applied. The Mark-Houwink equations for CMC in 0.5 N NaOH and 0.4 M acetate buffer have been estimated to be [eta] = 5.37x10(-4) M-w(0.73) and [eta] = 2.24x10(-4) M-w(0.83) dl g(-1), respectively. The equation log K = 1.64 - 4.00 alpha ml g(-1) for CMC has been estimated. An approach for determining DO from adsorption at 290 or 313 nm has been developed. (C) 1998 Elsevier Science Ltd. All rights reserved.