Simultaneous detection by RP-HPLC of methyl-parathion and parathion residue levels in vegetables

A method was developed for simultaneous determination of methyl-parathion and parathion residues in vegetables by reversed-phase high performance liquid chromatography. A Hypersil C18 column (4.6 × 300 mm,5μm) with CH3OH:H2O (60:40,by vol) as the mobile phase,a flow rate of 1.0 ml/min,and an ultraviolet detection wavelength of 270 nm. Methyl-parathion and parathion showed linear responses in the concentration ranges of 0.04 to 10.00 and 0.002 to 10.00 μg/ml,respectively,and detection limits of 0.036 and 0.00043 μg/ml,respectively. Recoveries of the two pesticides (total additive concentrations of 0.05,0.5,and 2 μg/g) were 91.8 to 94.8% with relative standard deviations (RSD) from 1.06 to 2.41%.