Supercritical fluid extraction of wood pulp with analysis by capillary gas chromatography-mass spectrometry

A supercritical fluid (SF) extraction method for the analysis of extractable material in eight hardwood and softwood pulp samples was investigated. While the majority of the extractable material in a Soxhlet extract with methylene chloride was determined to be fatty acids, the presence of their corresponding methyl esters along with fatty acids was noted in the SF extract. Grinding the samples increased extractable fatty acid methyl esters (FAMEs) by 10-fold, and in-situ derivatizations resulted in higher FAME recoveries than derivatization after SFE. Liquid trapping enhanced recoveries of lower FAMEs when compared with tandem (solid/liquid) trapping. In-situ acetylations sometimes yielded acetylated glucoses during SFE. Large differences in FAME concentrations were seen for hardwood samples, but lesser differences were seen for the softwood pulp samples.