A rapid method for determining the extractives content of wood pulp

Accelerated solvent extraction (ASE) with acetone is used to extract thermo mechanical wood pulp (TMP). The quantity of extracts obtained through ASE i s compared with that acquired using acetone in the standard Soxhlet procedu re of the Canadian Pulp and Paper Association (CPPA test method G20). The c ontent, by weight, of acetone-soluble extractives in the TMP is 2.00 +/- 0. 05% as determined using ASE and 1.81 +/- 0.02% as determined by Soxhlet ext raction. The relative standard deviation of the ASE determination (2.6%) is slightly larger than that of the Soxhlet determination (1.1%) because of t he smaller sample size used in ASE. Analysis of the extracts indicates that ASE and Soxhlet extraction acquire similar amounts of the fatty acids, res in acids, and sterols present in the TMP. In addition, ASE extracted a grea ter amount of lignin from the TMP than did the Soxhlet procedure. In terms of the overall efficiency, ASE was 30 times faster and used 75% less solven t than Soxhlet extraction.