Determination of Trichlorfon and Dichlorvos Residues in Shrimp Using Gas Chromatography with Nitrogen−Phosphorus Detection

Abstract

A method capable of quantifying trichlorfon and dichlorvos in shrimp at concentrations of 20−80 ng/g has been developed. Ground shrimp is homogenized in ethyl acetate and centrifuged. The supernatant is dried completely on a rotatory evaporator. The extract is dissolved in petroleum ether, concentrated on a solid phase extraction column, and analyzed by gas chromatography using a cool on-column inlet and a nitrogen−phosphorus detector. The analytes are separated from matrix components using a thermal gradient on a (cyanopropyl)phenyl-methylpolysiloxane column. The method was validated with control shrimp fortified at 20, 40, and 80 ng/g trichlorfon and dichlorvos. The average recoveries and intralaboratory coefficients of variations were 50−83% and 15−21% respectively. Keywords: Trichlorfon; dichlorvos; shrimp; gas chromatography; nitrogen−phosphorus detector