Evaluation of Residues of Chlorpyrifos and its Metabolite in Green Apples

A simple and inexpensive method was developed using solid-phase extraction, together with gas chromatographic method and high performance liquid chromatographic method for determination of chlorpyrifos and its metabolite O,O-diethyl triphosphate residues in green apples. The evaluated parameters include the extracts by silica gel packed column using methanol and water solvent mixture (90:10) and ethyl acetate solvents. The method was validated using green apple fruit samples spiked with chlorpyrifos and its metabolite (O,O-diethyl triphosphate) at different fortification levels (0.01 and 0.1 mg/kg). Average recoveries (using each concentration six replicates) of range 86-95%. The calibration solutions concentration in the range 0.01-5.0 mg/L and limit of detection (LOD) and limit of quantification (LOQ) were 0.003 mg/kg and 0.01 mg/kg respectively. Finally the green apple fruit residue samples were analyzed by GC and HPLC.