EXTRACCIóN DE RESIDUOS DE PLAGUICIDAS EN SUELOS ASISTIDA POR ULTRASONIDO

a multiresidue method for determination of pesticides in soil was developed by a double extraction process with ethyl acetate and methanol assisted with ultrasound. pesticides were determined by gas chromatography with micro-electron capture detection (μ-ecd) and nitrogen phosphorus detection (npd). the recovery values of the most of pesticides were between 79% and 105%, at concentration levels ranging 0.09-14.60 mg/kg, except for metamidophos, monochrotophos and oxadixyl, whose values were found at rates between 43% and 64%. the detection limits were rated at 0.02 mg/kg and 1.59 mg/kg. the quantification limits were between 0.07 mg/kg and 5.25 mg/kg. linearity and precision studies showed adequate results in the concentration range evaluated. finally, this methodology was used to evaluate recovery percentages in five soils with different physicochemical characteristics.