Abstract
Magnetic multi-walled carbon nanotubes were prepared as magnetic solid-phase extraction (MSPE) adsorbent for the enrichment of six heterocyclic pesticides in environmental water samples, including imidacloprid, triadimefon, fipronil, flusilazole, chlorfenapyr and fenpyroximate. Then six heterocyclic pesticides were separated and determined by high-performance liquid chromatography-diode-array detector (HPLC-DAD). Major factors influencing MSPE efficiency, including the dose of mag-multi-walled carbon nanotubes (mag-MWCNTs), extraction time, solution pH, salt concentration, type and volume of eluent and desorption time were investigated. Under the optimized conditions, the enrichment factor of the method reached to 250. The linearity was achieved within 0.05–10.0 μg/L for imidacloprid and chlorfenapyr, 0.10–10.0 μg/L for fipronil, flusilazole, triadimefon and fenpyroximate. Limits of detection were in the range of 0.01–0.03 μg/L. Good precision at three spiked levels were 1.1–11.2% (intra-day) and 1.7–11.0% (inter-day) with relative standard deviation of peak area, respectively. The developed method was utilized to analyze tap water, river water and reservoir water samples and recoveries at three spiked concentration levels ranged from 72.2% to 107.5%. The method was proved to be a convenient, rapid and practical method for sensitive determination of heterocyclic pesticides.
Highlights
Heterocyclic pesticides have become one of the fast-growing pesticides in recent years for their higher efficiency, lower toxicity and lower residue than traditional pesticides [1]
The surface characterizations of mag-Multi-walled CNTs (MWCNTs) were investigated by transmission electron microscope (TEM) technique
Mag-MWCNTs were in Figure 3A, the micrograph of mag-MWCNTs revealed that the spherical Fe3O4 particles were linked collected by the external magnet and the supernatant water was decanted
Summary
Heterocyclic pesticides have become one of the fast-growing pesticides in recent years for their higher efficiency, lower toxicity and lower residue than traditional pesticides [1]. Our group [24] prepared magnetic metal-organic frameworks (MOFs) Fe3 O4 @SiO2 /MIL-101 as MSPE adsorbent for the enrichment and determination of four kinds of pyrazole/pyrrole pesticides in environmental water samples. Magnetic multiwall carbon nanotube composites (mag-MWCNTs) are hybrids of magnetite Fe3 O4 and MWCNTs, combining advantages of MWCNTs and magnetic particles They have been employed as adsorbents for determination of estrogens [31], phthalate acid esters [32,33], aromatic amines [34], herbicides [23], metal ions [35] and so on. The simultaneous determination method of six heterocyclic pesticides in environmental water samples was developed by MSPE coupled with HPLC-DAD.
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