Supercritical Carbon Dioxide Extraction of 2, 4-Dichlorophenol from Food Crop Tissues

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Supercritical fluid extraction with carbon dioxide has been found to be effective for the Isolation of residue levels (0.1-1 ppm) of 2, 4-dlchlorophenol from selected plant tissues. The 2.4-dlchlorophenol residues were Incompletely extracted with supercritical CO2alone, since a substantial fraction of the 2.4-dlchlorophenol was covalently attached to the plant matrix. An acid pretreatment procedure was developed to partially hydrolyze the plant tissue prior to extraction, releasing the bound 2, 4-dlchlorophenol residues. Steam distillation showed higher residue levels for field-treated straw samples. This Is attributed to the greater degree of hydrolysis Inherent In the steam dstllation procedure. Supercritical CO2extraction of field-treated seed samples showed higher levels of 2, 4-dlchlorophenol residues than did steam dlstHatlon. The supercritical fluid extractant was able to solvate 2, 4-dlchlorophenol residues In the Interior of the seed and transport them to the surface for collection. The aqueous medium used In steam diet Illation was unable to penetrate the hydrophobic seed matrix to the same degree. While the actual extraction time experienced In supercritical fluid extraction was far less than that of steam distillation (45 min vs 6 h, respectively), the total sample preparation time was similar In both methods. © 1992, American Chemical Society. All rights reserved.

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Analytical Chemistry