Determination of Organochlorine and Pyrethroid Pesticide Residues in Sweet Corn by GC-ECD with QuEChERS Extraction Method

The sample (10.00 g) was extracted with 15 mL of a mixture of acetic acid and acetonitrile (1+99) by homogenate for 1 min, then 4-6 g of NaCl was added to the solution. After homogenate treatment for 30 s and followed centrifugation, 1.5-2.0 mL of the supernatant was transferred to the QuEChERS purification tube filled with 25 mg of N-propyl ethylenediamine and 150 mg of anhydrous magnesium sulfate, and treated by vortex oscillation for 30 s. After centrifugation, 1.0 mL of the supernatant was dried at 40℃ by N₂ blowing, and the residue was diluted to 1.0 mL with N-hexane. DB-5/DB-35 columns (30 m×0.25 mm, 0.25 μm) were used for seperation, and ECD was used for detection. Linear relationships were found between the peak areas and the mass concentrations of 12 kinds of pesticides in the range of 0.080-1.60 mg·L^-1, with detection limits (3S/N) in the range of 0.10-1.5 μg·kg^-1, and the lower limits of determination (10S/N) in the range of 0.33-5.0 μg·kg^-1. Recovery rates obtained by standard addition method were 85.6%-119%, and RSDs (n=6) were 3.2%-8.0%.