Determination of four organophosphorus pesticide residues in apples by gas chromatography

A method for the determination of four organophos phorus pesticide residues (methamidophos, acephate,isocarbophos,chlorpyrifos) in apples has been developed by gas chromatography equipped with NPD detector.It disussed the effect of extraction and elution to the recoveries in this paper,and improve the determination method by gas chromatography.The result indicates:50 mL acetone as extraction,50 mL pe- troleum eher and acetone (3:1) as elution.The recoveries of these organophosphorus pesticidesare between the range of 76.63%～90.60%,and the precision are between the range of 1.69%～4.61%,The linear ranges are 0.40～10.00μg/mL,the detection limits are 0.02-0.10 mg/kg.The method introduced here is simple,feasible and reliable.