Determination of Emamectin and Metaldehyde in Pakchoi by LC-MS/MS
A method for simultaneous detection of emamectin and metaldehyde residues in pakchoi was established by LC-MS/MS.The samples were extracted by acetonitrile solution,salted out by NaCl,purified by anhydrous MgSO4 and PSA,then quantified by positive ion scanning(electrospray ion source),MRM(multiple reaction monitoring)and external standard method.The results showed that there existed a good linear relationship between emamectin or metaldehyde concentrations and their responding values with correlation coefficient of higher than 0.99 whithin 0.002 to 0.5 μg/mL concentrations of emamectin or metaldehyde.When the spiked level ranged from 0.02 to 20 mg/kg,the average recovery of the two pesticides in pakchoi ranged from 81% to 101% ,and the RSD ranged from 0.5% to 2.9% ,indicating that the method met with the basic requirements of residue analysis,and could be used to the residues of emamectin or metaldehvde in the environmental medium such as pakchoi crops.
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