EXTRACTION OF PESTICIDES USING SUPERCRITICAL TRIFLUOROMETHANE AND CARBON-DIOXIDE

The off-line supercritical fluid extraction of pesticides using triflu oromethane (CHF3) and carbon dioxide (CO2) is described. Pesticides co ntaining nitrogen or phosphorus heteroatoms were used as analytes to d etermine the extraction ability of CHF3 in comparison with CO2 at vari ous pressures and densities. A 15% increase in extraction efficiency w as obtained when CHF, was used as the extraction solvent rather than C O2. No selectivity was observed for different groups of pesticides, al though CHF3 has a dipole moment whereas CO2 does not. Because in envir onmental matrices the hydrocarbons are mostly present in high excess c ompared 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 withou t addition of alkanes and PAHs was significantly decreased.