A functionalized carbon nanotube nanohybrids-based QuEChERS method for detection of pesticide residues in vegetables and fruits.

A self-separating, analyte-compatible, and efficient clean-up method for QuEChERS extracts was designed and developed based on dispersive solid-phase extraction using a branched polyethylenimine and nanoscale CaSO4 functionalized carboxylated multi-walled carbon nanotubes (MWCNTs) nanohybrids as sorbent. The feasibility of using a self-separating strategy based on the functionalization of sorbent in a purification procedure was analyzed for the first time in this study. Compared to the traditional QuEChERS method, the proposed method is rapid and convenient without centrifugation of numerous samples in the clean-up process. The use of nanohybrids overcame the issue of low recoveries for planar pesticides, which are easily adsorbed using MWCNTs. A better clean-up capability of the nanohybrids to remove matrix interferences and reduce matrix effect was demonstrated compared with that of traditional clean-up sorbent primary secondary amine. The method was validated by determining twenty-eight pesticides in cucumber, cabbage, apple, and orange. Limits of detections were in the range of 0.0001-0.0026 mg/kg. Spike recoveries of pesticides were within 75.3 - 113.6%, with relative standard deviations less than 14.3% at levels 0.01 mg/kg and 0.1 mg/kg. The developed method was successfully applied to monitor the multi-residues.