Determination of Six Neonicotinoid Pesticides Residue in Rice by GC/MS

A multiresidue determination method for six neonicotinoid pesticides residues (nitenpyram, thiamethoxam, acetamiprid, pymetrozine, imidacloprid, imidaclothiz) in rice was developed by gas chromatography-mass spectrometry (GC/MS). The samples of rice were ultrasonic extracted with acetonitrile, then the extracts were further cleaned up by solid-phase extraction (SPE) with Polymer Trap cartridges and eluted with 6 mL methanol. The eluate was collected and concentrated for GC/MS analysis in selective ion monitoring (SIM) mode. The results show good linearity (correlation coefficient are 0.991 8—0.998 9) in the concentrations between 0.1 mg/kg and 10 mg/kg of the six pesticides, the limits of quantification (LOQ) is 0.05 mg/kg, the limits of detection (LOD) is 0.002—0.012 ng. The average recoveries vary from 83.1% to 101.4%, and the relative standard deviations (RSD) range from 1.3% to 8.9% for the spiked levels of 0.05, 0.2 and 1 mg/kg.