EFFECT OF TEMPERATURE, COLLECTION MODE, AND MODIFIER ON THE SUPERCRITICAL CO2 EXTRACTION OF DICOFOL RESIDUES FROM FISH SAMPLES

Toxicity evaluation of Dicofol to Astyanax bimaculatus schubarti, a ch aracteristic fish species living in tropical rivers and lakes was carr ied out through LC50 - 96 hours. These experiments were performed unde r laboratory controlled conditions with atmospheric air flow and dilut ion mater at 25 degrees C in the static mode. Supercritical fluid extr action (SFE) with pure CO2 and CO2 modified with hexane and methanol w ere used at 50, 70, 80, and 100 degrees C and 300 atm. Several collect ion modes were studied to extract Dicofol from fish samples. The extra ction efficiencies were directly compared with those obtained after 8 h of Soxhlet ex-traction using the same clean-up with Florisil and ana lysis by HRGC/ECD and HRGC/MS as a confirmatory analytical technique. The SFE recoveries at temperatures lower than 80 degrees C were typica lly lower than Soxhlet recoveries; however a temperature increase enha nced the efficiency of SFE. The results showed that under certain cond itions, supercritical fluid gave higher extraction power (extracted 11 % more pesticide), shorter extraction time, and lower solvent consumpt ion than Soxhlet, thus affording an excellent alternative to the conve ntional method for extracting Dicofol from fish samples.