ABSTRACT
Studies on pesticide dissipation and contamination, require both the determination of their presence and their amounts in the environment. The quantitative determination is possible by using efficient extraction methods, and preliminar tests are usually performed to establish the best methodology for extraction of active ingredients from the matrix. The efficiency of some extraction methods was studied for different pesticides in different matrices (soil, animal and vegetal tissues) using radiometric techniques. Methanol as solvent and soxhlet were very efficient for most pesticides: nearly 100% for atrazine, simazine and trifuralin; 99% for parathion ethyl; 98% for DDE; 95% for DDT; 91% for endossulfan; 90% for monocrotofos; 88% for parathion methyl; 81% for acephate; 80% for carbaryl and 75% for deltametrin. Metalaxyl was efficiently extracted by ethyl acetate using mechanical shaking (nearly 96%). Acetonitrile: water: acetic acid and mechanical shaking was the efficient system for 2,4-D (nearly 86%). However, hexachlorobenzene and paraquat were better recovered respectively, by soxhlet and hexane: acetone, and heating under reflux with sulphuric acid (98% and 94% recovery, respectively).
KEY WORDS:
Radiometric techniques; recovery methods; soil; animal and vegetal tissues.