Rapid multiplug filtration cleanup method for the determination of 124 pesticide residues in rice, wheat, and corn.

A simple and rapid multiplug filtration cleanup method based on multiwalled carbon nanotubes was developed to determine 124 pesticide residues in rice, wheat, and corn, which could be done in a few seconds without conditioning and elution steps. Various combinations of sorbents were optimized for each matrix with a dispersive solid-phase extraction procedure to get a satisfactory recovery and clean-up performance. Good linearity was obtained for all pesticides with calibration curve coefficients larger than 0.9958. Most recoveries for the majority pesticides were between 70 and 120% (n = 5) with relative standard deviations below 20%. The limit of detection was 0.1-1.3 μg/kg, and the limit of quantification was 0.2-4.3 μg/kg for the pesticides in all matrices. The work suggests that the multiplug filtration cleanup method is better than the dispersive solid-phase extraction method and it could be applied to routinely monitor pesticide residues in market samples.