DETERMINATION OF ORGANOCHLORINE PESTICIDES DISSOLVED IN WATER - A COMPARISON BETWEEN SOLID-PHASE AND SOLVENT-EXTRACTION

Sixteen organochlorine pesticides (EPA priority) were spiked into water at a concentration range of 20 ng/L to 20,000 ng/L and then extracted by utilizing solid phase techniques and the method 608 of EPA. The solid phases XAD-2 and C-18 were studied. The reverse phase C-18 presented a recovery of about 85%, except for heptachlor and aldrin. The solvent extraction showed better recovery in concentrations higher or equal to 200 ng/L for about all pesticides. We concluded that both methods showed good recoveries. Nevertheless, the solvent extraction is time consuming, the apparatus is cumbersome and large volumes of solvents are required while the solid phase extraction (SPE) is quick, low solvent consuming and sometimes achieving higher sensitivity than solvent extraction. Both methods were used and compared to determine organochlorine pesticides in a river from the state of Sao Paulo, Brazil.