Study On Analytical Methods Of Multiple Pesticide Residues In Ceral Grains

This paper present a rapid method for determining 28 pesticides in cereal grains on the basis of organic pesticides's character.The extraction,clean-up and concentration of samples's perpatation are optimized.The accuracy precision and sensitivity of the whole experiment method are wholly tested and verified.Optimized chromatograph condition of monitoring method:chromatographic column is Welch Materials XB-C18(2.1 × 100 mm,3 ?m);Mobile phase:Acetonitrile-Formic acid in water(1‰),gradient elution;flow:0.3mL/min;column temperature:25?;injection volume:20 ?L.Optimized mass spectrographic condition:Positive ion mode electrospray interface collision gas flow rate:9 L/min;air curtain flow rate:25 L/min;auxiliary gas flow rate:75 L/min,65 L/min;electrospray ionization voltage:5000 V;ion source temperature:600?;detection method for the multiple reaction monitoring(MRM).Preparation process is detined by a series of contrast:The residues of pesticides were extracted from samples wite acetone(20 mL,twice).Brown rice and soybeans were subjected to degreasing treatment by nhexane(acetonitrile saturated).And theh use the ENVI-18 solid phase extraction column to purify,acetone eluted it.The eluate was concentrated to dryness at 40?.Compounds were identified and determined according to their retention times and characteristic ions.Recoveries were botained by cereal grains at 0.01 mg/kg,0.02 mg/kg;0.03 mg/kg levels.The mean recoveries ranged from 65.10%to 114.67%,and the coefficients of variation were form 1.14 to 9.01.This method developed have been used for analyzing 27 kinds of pesticide residues in cereal grains with easy operation,good precision and linearity.The most recoveries and RSD are ideal,but some pesticides isomers,such as Chlorimuron-ethyl,Phenmedipham,Mefenpyr-diethyl,Picolinafen.