Determination of imidacloprid in rice by molecularly imprinted-matrix solid-phase dispersion with liquid chromatography tandem mass spectrometry

A new method based on matrix solid-phase dispersion (MSPD) coupled with liquid chromatography tandem mass spectrometry has been developed for the determination of imidacloprid in rice. The molecularly imprinted polymers were synthesized and applied as the dispersant of MSPD for selective extraction of imidacloprid from rice, while interferences originated from sample matrices were eliminated simultaneously. The satisfactory recovery of imidacloprid was obtained by the optimized extraction conditions: 1:2 as the ratio of sample to MIPs; 8 min as the dispersion time; 20% aqueous methanol as washing solvent and methanol as elution solvent. Under the optimal conditions, the linearity of imidacloprid in rice sample was achieved in the range of 10-1000 ng/g, and limit of detection was 2.4 ng/g. The relative standard deviations of intra- and inter-day tests ranging from 4.5% to 5.9% and from 4.8% to 7.1% are obtained, respectively. The proposed method was applied to the determination of imidacloprid in eight rice samples with recoveries in the range of 83.8-92.5%. (C) 2012 Published by Elsevier B.V.