EXTRACTION OF TRIALLATE FROM SOIL WITH SUPERCRITICAL CARBON-DIOXIDE AND DETERMINATION BY GAS-CHROMATOGRAPHY ATOMIC-EMISSION DETECTION - COMPARISON WITH A SOLVENT-EXTRACTION PROCEDURE

The potential of supercritical CO2 for the extraction of triallate fro m soil as an alternative to a conventional acetonitrile extraction pro cedure is investigated, Triallate is extracted at a density of 0.65 g/ ml, an equilibrium time of 8 min, an extraction time of 25 min and a f low-rate of 1 ml/min. The extract is collected on an octadecylsilane t rap at 5 degrees C and eluted with 1 mi of acetonitrile. The analyte i s determined by capillary gas chromatography with atomic emission dete ction. The validity of the supercritical fluid extraction method is re sted on spiked and real soils. The triallate concentrations obtained o n aged soils are lower applying supercritical fluid extraction with pu re CO2 than applying solvent extraction, making necessary the use of C O2 modified with methanol to achieve similar results.