Abstract:

A magnetic carbon nanotube hybrid material was prepared using a chemical co-precipitation method. The Fe₃O₄ nanoparticles were enclosed onto the surface of the acid multi-walled carbon nanotubes (AMWNTs), and they were identified as Fe₃O₄/AMWNTs composites. This hybrid materials displayed typical superparamagnetic behavior, good dispersibility, and good adsorption capacity for pyrethroid pesticides. A magnetic solid-phase microextraction (MSPE) procedure based on Fe₃O₄/AMWNTs composites, combined with gas chromatography, was developed for the quantification of six pyrethroid pesticides in water and honey samples. Several important parameters affecting the extraction efficiency for six pyrethroid pesticides were optimized in sequential order, including ionic strength, extraction time and desorption time. Under the optimized conditions, this method showed wide linearity ranging from 0.5 μg/L to 50 μg/L with correlation coefficients (R²) higher than 0.990. The limits of detection (LODs) ranged from 0.07 μg/L to 0.20 μg/L at a singal-to-noise ratio of 3. The relative standard deviations (RSDs) ranged from 3.8% to 8.1%. Satisfactory recoveries (>78.4%) were obtained for the simultaneous analysis of the six pyrethroid pesticide residues in river water, fishpond water and two honey samples. This method is sensitive and simple. It can meet the actual requirement for the analysis of trace analytes from environmental water and honey samples.

Key words: carbon nanotube, gas chromatography (GC), honey, magnetic nanoparticles, magnetic solid-phase extraction, pyrethroid pesticides, water