SUPERCRITICAL CARBON-DIOXIDE EXTRACTION OF RESIN AND FATTY-ACIDS FROM SEDIMENTS AT PULP-MILL SITES

A rapid and efficient method for the extraction of resin and fatty acids commonly found in sediments collected from pulp mill locations was developed by using modified supercritical carbon dioxide. In the presence of a 1:1 mixture of methanol and formic acid, quantitative recovery of all acids except for palustric and neoabietic acids was achieved with a 5 min static and 10 min dynamic extraction with carbon dioxide at 365 bar and 80-degrees-C. Although the above two resin acids were only 40% recovered from spiked samples, these values were at least 250% better than those obtained by the classical Soxhlet technique. The cleaner supercritical fluid extract permitted a less stringent cleanup after the off-line derivatization of the acids, thus it further reduced analytical time and the use of solvent. An in situ extraction and on-line derivatization of the resin and fatty acids also proved feasible for the semi-quantitative screening of the toxic acids in sediments near pulp mill locations.