Determination of Organophosphorus Nematicide Residues in Banana-Field Soils by Gas Chromatography/Mass Spectrometry

Gas chromatographic/mass spectrometric (GC/MS) methodology is presented for the determination, in banana-field soils, of the 4 most used organophosphorus nematicides in Martinique (French West Indies): cadusafos (Rugby), ethoprophos (Mocap), isazophos (Miral), and fenamiphos (Nemacur). After extraction with 2 successive solvent mixtures, ethyl acetate–dichloromethane (8 + 2, v/v) and ethyl acetate–acetone (7 + 3, v/v), cleanup was performed using solid-phase extraction cartridges (silica SPE). Fenamiphos and its metabolites were separated in the second eluate and then oxidized to sulfone. Analysis was performed by GC/MS in fragmentometric mode. Recoveries varied from about 75 to 90%. Limits of quantitation varied from 4 to 20 μg/kg fresh soil sample, depending on the nematicide.