EXTRACTION OF PESTICIDES USING SUPERCRITICAL TRIFLUOROMETHANE AND CARBON-DIOXIDE

The off-line supercritical fluid extraction of pesticides using trifluoromethane (CHF3) and carbon dioxide (CO2) is described. Pesticides containing nitrogen or phosphorus heteroatoms were used as analytes to determine the extraction ability of CHF3 in comparison with CO2 at various pressures and densities. A 15% increase in extraction efficiency was obtained when CHF, was used as the extraction solvent rather than CO2. No selectivity was observed for different groups of pesticides, although CHF3 has a dipole moment whereas CO2 does not. Because in environmental matrices the hydrocarbons are mostly present in high excess compared with the pesticides, extractions were carried out without and with addition of alkanes and polycyclic aromatic hydrocarbons (PAHs). The extraction efficiency of the pesticides with CHF3 performed without addition of alkanes and PAHs was significantly decreased.