Abstract
A novel strategy based on imazethapyr (IM) molecular-imprinting polymers (MIPs) grafted onto the surface of chloromethylation polystyrene resin via surface-initiated atom transfer radical polymerization (SI-ATRP) for specific recognition and sensitive determination of trace imazethapyr in soil samples was developed. The SI-ATRP was performed by using methanol-water (4 : 1, v/v) as the solvent, acrylamide as the functional monomer, trimethylolpropane trimethacrylate (TRIM) as the cross-linker, imazethapyr as the template, and CuBr/2,2′-bipyridine as the catalyst. The resulting MIPs were characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Then, the binding selectivity, adsorption capacity, and reusability of the MIPs were evaluated. The results indicated that the prepared MIPs exhibited specific recognition and high selectivity for imazethapyr. The MIPs were further used as solid-phase extraction (SPE) materials coupled with high-performance liquid chromatography (HPLC) for selective extraction and detection of trace imazethapyr from soil samples. The results showed that good linearity was observed in the range of 0.10–5.00 μg/mL, with a correlation coefficient of 0.9995. The limit of detection (LOD) of this method was 15 ng/g, and the extraction recoveries of imazethapyr from real samples were in the range of 91.1–97.5%, which proved applicable for analysis of trace imazethapyr in soils. This work proposed a sensitive, rapid, and convenient approach for determination of trace imazethapyr in soil samples.
Highlights
Imazethapyr, a type of imidazolinones herbicide, belongs to the imidazolinones family of herbicides that are being extensively used in a wide range of cropping systems to enhance crop yields and protect crops from damage by weeds and annual grasses in soybean and peanut [1, 2]. e improper or incorrect use of imazethapyr may lead to the residue and pollution of the soil and groundwater near field crops and may affect nontargeted plants [3, 4]
To avoid its harmful effects on target and nontarget organisms and to better understand the behavior of imazethapyr in the environment, it is essential to propose a sensitive, rapid and, convenient approach for adsorption of the imazethapyr. e development of analytical methods suitable to fulfill the requirement of determining imazethapyr in soil has attracted widespread interest. e methods for determination of herbicide residues in soil include solidphase extraction [7], dispersive solid-phase extraction [8, 9], Journal of Analytical Methods in Chemistry magnetic solid-phase extraction (MSPE) [10], multiple monolithic fiber solid-phase microextraction (MMF-SPME) [11], high-performance liquid chromatography (HPLC) [12], high-performance liquid chromatography with mass spectroscopy (HPLC-MS/MS) [13], gas chromatography coupled with an electron capture detector (GC-ECD) [14], and molecular imprinting [15, 16]
Preparation of Molecularly imprinted polymers (MIPs). e preparation procedures for MIPs of imazethapyr were described in Figure 2. e functional monomer initially formed complexes with the template molecules. en, their functional groups were held in position by the highly cross-linked polymeric structure after polymerization. e MIPs were grafted onto the surface of the CMCPS resin via surface-initiated atom transfers radical polymerization (SI-ATRP)
Summary
Imazethapyr, a type of imidazolinones herbicide, belongs to the imidazolinones family of herbicides that are being extensively used in a wide range of cropping systems to enhance crop yields and protect crops from damage by weeds and annual grasses in soybean and peanut [1, 2]. e improper or incorrect use of imazethapyr may lead to the residue and pollution of the soil and groundwater near field crops and may affect nontargeted plants [3, 4]. E conditions required for the polymerization reaction were simple and easy to operate, and there are many types of functional monomers that can be selected, water can be used as a medium for the reaction, and a block polymer can be synthesized. It could be well controlled by SI-ATRP reagent to avoid adverse reactions, such as radical coupling or disproportionation action. The polymer segment, template molecular density, and film thickness could be effectively controlled, which is beneficial to increase the adsorption capacity and adsorption efficiency of MIPs [34]
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