Journal of Chromatography A, 805 (1998) 93–99 Evaluation of size-exclusion chromatography and viscometry for the determination of molecular masses of oxidised cellulose a, b c a ˇ * ˇ Matija Strlic , Jana Kolar , Majda Zigon , Boris Pihlar a ˇ ˇ Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, SI-1000 Ljubljana, Slovenia b ˇˇ Pulp and Paper Institute, Bogisiceva 8, SI-1000 Ljubljana, Slovenia c National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia Received 16 October 1997; received in revised form 5 December 1997; accepted 30 December 1997 Abstract The molecular masses of oxidised cellulose samples from two different sources were determined by size-exclusion chromatography (SEC) and viscometry. SEC was performed at room temperature using a cross-linked polystyrene– divinylbenzene column and 1% LiCl (w/v) in N,N-dimethylacetamide (DMAc) as the eluent. Cellulose samples were oxidised using aqueous solutions of H O , NaClO or KIO , and dissolved in the LiCl–DMAc solvent system using 2 2 4 activation with water and a solvent exchange procedure. Viscometry in the cupriethylenediamine (CED) solvent system was performed following the standard technique. Oxidised cellulose samples are prone to degradation by alkalis. While the dissolution in LiCl–DMAc was shown not to have a degrading effect, the oxidised cellulose samples are unstable in the highly alkaline CED solvent, thus introducing a systematic error to the viscometric measurements. A stabilising reduction procedure usually recommended for such samples was tested, and shown to be advantageous, although degradation cannot be completely avoided.  1998 Elsevier Science B.V. Keywords: Viscometry; Molecular mass determination; Cellulose 1. Introduction systems has made a rapid and easy determination of relative molecular masses ( M ) or relative molecular r The application of size-exclusion chromatography mass distributions (MWD) impossible. Cellulose (SEC) for the analysis of cellulose is not as wide- derivatives are generally more soluble in organic spread as it is for synthetic polymers. The main solvents, such as tetrahydrofuran, methylethylketone reason for this is that the highly ordered crystalline or dimethylsulfoxide, but the derivatisation process structure of cellulose does not allow solvents to may not be entirely uniform and may induce degra- easily penetrate the cellulose fibres and break the dation of the polymer [1]. After the description of intermolecular hydrogen bonds. The need, therefore, the capacity of the LiCl– N,N-dimethylacetamide to use either cellulose derivatives or complex solvent (DMAc) system for the dissolution of cellulose [2] different procedures were described which involve sample activation by swelling in hot DMAc, liquid NH , water, or NaOH solution followed by solvent 3 * Corresponding author exchange and addition of LiCl [3]. The exact struc- 0021-9673 / 98 / $19.00  1998 Elsevier Science B.V. All rights reserved. PII S0021-9673(98)00008-9