Synthesis of magnetic multiwall carbon nanotubes for enantioseparation of three pesticide residues in fruits and vegetables by chiral liquid chromatography.

In this study, magnetic multiwalled carbon nanotubes (MMWCNTs) were synthesized and used as adsorbent for preconcentration of chiral pesticide residues (including epoxiconazole, tebuconazole, and metalaxyl) in lettuce, cabbage, and apple. Several parameters affecting the treatment efficiency were investigated, including extraction solvent and absorption solvent. Under the optimal conditions, all three chiral pesticides showed decent enantiomeric separation (Rs > 1.48). The linearity of each target was good with the correlation coefficient (r ) being greater than 0.9923. The average recoveries of the three spiked levels were 73.4% to 110.9% with repeatability (RSD ) less than 7.6%, and the limit of quantification of the method was 0.10 to 0.25 mg·kg . The results indicated that MMWCNTs had a good purifying effect, which can be applied as an effective pretreatment tool for the determination of residual chiral pesticides in fruits and vegetables.