Selective trace analysis of chloroacetamide herbicides in food samples using dummy molecularly imprinted solid phase extraction based on chemometrics and quantum chemistry

Dual-template magnetic molecularly imprinted polymers for selective extraction and sensitive detection of aflatoxin B1 and benzo(α)pyrene in environmental water and edible oil

The coexistence of multiple contaminates in the environment and food is of growing concern due to their extremely hazard as a well-known class I carcinogen, like aflatoxin B1 (AFB1) and benzo(α)pyrene (BaP). AFB1 and BaP are susceptible to coexistence in environmental water and edible oil, posing a significant potential risk to environmental monitoring and food safety. The remaining challenges in detecting multiple contaminates include unsatisfied sensitivity, insufficient targets selectivity, and interferences in complex matrices. Here, we developed dual-template magnetic molecularly imprinted polymers (DMMIPs) for selective extraction of dual targets in complex matrices from the environment and food. The DMMIPs were fabricated by surface imprinting with vinyl-functionalized Fe3O4 as carrier, 5,7-dimethoxycoumarin and pyrene as dummy templates, and methacrylamide as functional monomer. The DMMIPs showed excellent adsorption ability (12.73-15.80 mg/g), imprinting factors (2.01-2.58), and reusability of three adsorption-desorption cycles for AFB1 and BaP. The adsorption mechanism including hydrogen bond, electrostatic interaction and van der Waals force was confirmed by physical characterization and DFT calculation. Applying DMMIPs in magnetic solid phase extraction (MSPE) followed by high-performance liquid chromatography (HPLC) analysis enabled detection limits of 0.134 μg/L for AFB1 and 0.107 μg/L for BaP. Recovery rates for water and edible oil samples were recorded as 86.2%-110.3% with RSDs of 4.1%-11.9%. This approach demonstrates potential for simultaneous identification and extraction of multiple contaminants in environmental and food.

Synthesis of MIL-88(Fe) coordinated to carboxymethyl cellulose fibers nanocomposite for dispersive solid phase microextraction of acetanilide herbicides from cereal and agricultural soil samples

In this study, MIL-88(Fe) coordinated to carboxymethyl cellulose fibers was successfully synthesized, characterized, and utilized as a nanocomposite for the dispersive solid phase microextraction of butachlor and acetochlor. These analytes served as representative analytes for acetanilide herbicides (AHs) present in real samples. Effective parameters on the extraction efficiency were investigated to maximize the analytical performance of the developed method. Under optimized conditions, which encompassed sorbent amount of 12 mg, solution pH of 7.0, 4.0 min of the vortex time, 3.0 min of the extraction time, chloroform as desorption agent and no salt addition, the developed method exhibited remarkable figures of merit, such as high linearity (R2> 0.99), low limits of detection of 0.90 ng mL-1, substantial preconcentration factors (between 213 and 228), relative recoveries in the range of 90.8% to 109%, and good repeatability with relative standard deviations equal or below 7.2%. After validation, the developed method was applied to detect AHs in various cereal and agricultural soil samples.

Carbon Nanotube-Supported Dummy Template Molecularly Imprinted Polymers for Selective Adsorption of Amide Herbicides in Aquatic Products

In this study, a carbon nanotube (CNTs)-supported dummy template molecularly imprinted polymer (DMIPs) material was synthesized and utilized for the detection of amide herbicides in aquatic products via matrix solid-phase dispersion technology (MSPD). The DMIPs material was characterized, and its adsorption kinetics and isotherm were determined, the adsorption model was established, and the selective adsorption coefficient was calculated. The extract parameters of the method were optimized and successfully employed for the separation, analysis and detection of real samples, with satisfactory detection limits and linear ranges obtained. By comparing with other methods, the CNTs@DMIPs combined with MSPD technology established in our study can effectively solve false negative problems caused by insufficient destructive force, using dummy template molecules can also address the issue of false positives caused by template molecule leakage in molecular imprinting. Overall, the method is appropriate for the separation and detection of endogenous substances from highly viscous and poorly dispersed samples and is used as a routine detection tool in the aquaculture industry.

The Use of Computational Methods for the Development of Molecularly Imprinted Polymers

Recent years have witnessed a dramatic increase in the use of theoretical and computational approaches in the study and development of molecular imprinting systems. These tools are being used to either improve understanding of the mechanisms underlying the function of molecular imprinting systems or for the design of new systems. Here, we present an overview of the literature describing the application of theoretical and computational techniques to the different stages of the molecular imprinting process (pre-polymerization mixture, polymerization process and ligand-molecularly imprinted polymer rebinding), along with an analysis of trends within and the current status of this aspect of the molecular imprinting field.

A Review on Molecularly Imprinted Polymers Preparation by Computational Simulation-Aided Methods

Molecularly imprinted polymers (MIPs) are obtained by initiating the polymerization of functional monomers surrounding a template molecule in the presence of crosslinkers and porogens. The best adsorption performance can be achieved by optimizing the polymerization conditions, but this process is time consuming and labor-intensive. Theoretical calculation based on calculation simulations and intermolecular forces is an effective method to solve this problem because it is convenient, versatile, environmentally friendly, and inexpensive. In this article, computational simulation modeling methods are introduced, and the theoretical optimization methods of various molecular simulation calculation software for preparing molecularly imprinted polymers are proposed. The progress in research on and application of molecularly imprinted polymers prepared by computational simulations and computational software in the past two decades are reviewed. Computer molecular simulation methods, including molecular mechanics, molecular dynamics and quantum mechanics, are universally applicable for the MIP-based materials. Furthermore, the new role of computational simulation in the future development of molecular imprinting technology is explored.

Computational design and synthesis of molecular imprinted polymers for selective solid phase extraction of sulfonylurea herbicides

A high-efficiency approach for the synthesis of molecularly imprinted polymers has been developed and further for the solid-phase extraction of sulfonylurea herbicides in food samples. Molecular simulation approach combined chemometric selected metsulfuron-methyl (MSM) and 2-trifluoromethyl acrylic acid (TFMAA) as the template and the monomer to synthesize the molecularly imprinted polymers (MIPs). Experimental validation confirmed that the MSM-imprinted polymers showed a higher selectivity and affinity to sulfonylurea herbicides. The optimized molecularly imprinted solid-phase extraction (MISPE) conditions, including loading, washing, and eluting conditions, were established. The developed MISPE technology combined HPLC-MSMS was successfully used for the determination of sulfonylurea herbicides in foods. Compared with commercial SPE columns, MISPE showed high affinity, excellent selectivity and low matrix effect. The recoveries of sulfonylurea herbicides spiked in four matrices were between 86.4% and 100.2%, with the relative standard deviations (RSD) in the range of 0.9%-10.5%.

Selective solid phase extraction of chloroacetamide herbicides from environmental water samples by amphiphilic magnetic molecularly imprinted polymers

In this study, a novel amphiphilic magnetic molecularly imprinted polymers (MMIPs) have been prepared by using Fe₃O₄ microspheres as the magnetic core, 4-vinyl pyridine (4-VP) and alkenyl glycosides glucose (AGG) as functional co-monomers. Fe₃O₄ microspheres were directly encapsulated by the polymer without any surface modification in the distillation-precipitation polymerization. The morphology and composition of MMIPs were characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Binding property and magnetic separation ability were systematically investigated through the equilibrium binding experiments. The feasibility of magnetic molecular imprinted solid phase extraction (MMISPE) was investigated for the selective enrichment of chloroacetamide herbicides from environmental water samples. The developed MMISPE-HPLC method exhibited good linearity (0.1-200μgL^-1), low limit of detection (0.03-0.06μgL^-1), and good precision (RSD<7%) under the optimized conditions. The introduced MMISPE-HPLC method was successfully used to analyze chloroacetamide herbicides in environmental water samples. Spiked chloroacetamide herbicides recoveries in three water samples ranged from 82.1% to 102.9%. These results indicated that amphiphilic MMIPs were the promising sorbents for the selective enrichment of chloroacetamide herbicides at trace levels from real environmental water samples.

High performance surface-enhanced Raman scattering via dummy molecular imprinting onto silver microspheres

A new strategy for achieving high performance SERS was proposed by using the dummy molecular imprinting technique.