EXTRACTION OF PESTICIDES FROM AQUEOUS SAMPLES - A COMPARATIVE-STUDY

Three different extraction procedures for eight pesticides (chlorfenvi nphos, diazinon, ethyl parathion, ethiofencarb, fenitrothion, malathio n, metal-axyl, pirimicarb) in water samples are compared. The extracti on procedures are: liquid-liquid extraction (LLE), solid-phase extract ion (SPE) and microextraction (ME). For each procedure the most suitab le conditions were obtained experimentally, with special remarks on ME , in which the effects of different mixtures of Kaltron with other sol vents were tested. A preconcentration factor (PF) was used to rank the methods; the best results were observed for ME, (PF 15-45, whereas PF < 10 for SPE, and PF less than or equal to 13 for LLE). In all cases, the determination was performed by gas chromatography, using a nitrog en phosphorus detector and the internal standard method (methyl parath ion) as the quantification procedure.