Comparative evaluation of size-exclusion chromatography and viscometry for the characterisation of cellulose

The analysis using size-exclusion chromatography (SEC) with multi-angle light scattering (MALS) and differential refractive index (DRI) detection of cellulose dissolved in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) is evaluated and compared to two other methods currently used for cellulose analysis. These are SEC with low-angle light scattering (LALS) and ultra-violet detection of cellulose derivatised to tricarbanilates (CTC), and viscometry in cadmium triethylene diamine dihydroxide (cadoxen). The cellulose source is Whatman No. 1 paper, unaged or artificially aged with a combination of heat and humidity. The values of the molar mass (Mr) averages of cellulose obtained with the different methods resulted quite different for both aged and unaged paper. SEC of cellulose in LiCl/DMAc provided the highest Mr averages values, followed by SEC of CTC, while viscometry yielded the lowest values. These differences were more or less pronounced depending on the initial degradation state of the paper. Several hypotheses are presented in order to explain these discrepancies and each method is discussed on the basis of its suitability to characterise the aging-induced degradation.