Inverse size exclusion chromatography (ISEC) for determining the relative pore size distribution of wood pulps

A method for preparing chromatographic columns containing virgin (never-dried) or previously dried wood pulp fibres for inverse size exclusion chromatography (ISEC) has been developed. The method was optimised with regard to packing density, pump speed of the eluation solution and probe molecule concentration using a multi-factor design in order to obtain the best and the most accurate resolution with regard to the apparent pore size distribution for the never-dried wood pulps. The method is based on the packing of a fibre bed of intact fibres through which sugar standards of different molecular weight are passed. The pulps are fractionated to remove all fines and converted to their sodium form as a standard procedure before the column packing procedure. The packing was performed by filtering a fibre suspension through a growing column of packed pulp fibres. The total pore volume was determined to be 1.1 and 1.2ml/g for never-dried bleached and unbleached sulphate pulps respectively using the optimised parameters. The results indicate a good reproducibility for the method.