Magnetic solid-phase extraction based on magnetic amino modified multiwalled carbon nanotubes for the fast determination of seven pesticide residues in water samples.

A rapid and simple analytical method based on magnetic solid-phase extraction with magnetic amino modified multiwalled carbon nanotubes with ultra-high performance liquid chromatography-tandem mass spectrometry is reported for the determination of seven pesticides (futriafol, metalaxyl, myclobutanil, napropamide, epoxiconazole, fipronil and diniconazole) in water samples. In this study, magnetic amino modified multi-walled carbon nanotubes were synthesized and selected as a new kind of material to adsorb pesticides in the water samples. Various magnetic solid-phase extraction parameters, such as the amount and type of adsorbent, extraction methods, extraction time, the type and volume of desorption solvent, desorption time and solution ionic strength, were systematically optimized. Under optimum conditions, the method validation results showed good linearity and recoveries. The calibration curves were in the range of 1.0-100 ng mL-1 for napropamide, epoxiconazole, metalaxyl, and fipronil, while they were 5.0-500 ng mL-1 for futriafol, myclobutanil, and diniconazole, with determination coefficients (R2) higher than 0.9909. The limits of quantification were 1.0-5.0 ng mL-1 and the limits of detection were 0.3-1.5 ng mL-1. The recoveries of the seven pesticides ranged from 80.4% to 103.2%. This developed method, which is more convenient and effective in comparison with traditional methods, has been successfully applied for the analysis of pesticides in water samples qualitatively and quantitatively.