DETERMINATION OF TRICHLORFON AND DICHLORVOS RESIDUES IN SHRIMP USING GAS-CHROMATOGRAPHY WITH NITROGEN-PHOSPHORUS DETECTION

A method capable of quantifying trichlorfon and dichlorvos in shrimp a t concentrations of 20-80 ng/g has been developed. Ground shrimp is ho mogenized in ethyl acetate and centrifuged. The supernatant is dried c ompletely on a rotatory evaporator. The extract is dissolved in petrol eum ether, concentrated on a solid phase extraction column, and analyz ed by gas chromatography using a cool on-column inlet and a nitrogen-p hosphorus detector. The analytes are separated from matrix components using a thermal gradient on a (cyanopropyl)phenyl-methylpolysiloxane c olumn. The method was validated with control shrimp fortified at 20, 4 0, and 80 ng/g trichlorfon and dichlorvos. The average recoveries and intralaboratory coefficients of variations were 50-83% and 15-21% resp ectively.