One-pot fabrication of poly (ionic liquid)s functionalized magnetic adsorbent for efficient enrichment of phenylurea herbicides in environmental waters

Interaction of different chloro-substituted phenylurea herbicides (diuron and chlortoluron) with bovine serum albumin: Insights from multispectral study

In this work, the interaction between different chloro-substituted phenylurea herbicides (diuron (DIU) and chlortoluron (CHL)) and BSA were investigated and compared at three different temperatures (283 K, 298 K and 310 K) adopting UV-vis, fluorescence, and circular dichroism spectra. The quenching mechanism of the interaction was also proposed. The energy transfer between BSA and DIU/CHL was investigated. The binding sites of DIU/CHL and BSA and the variations in the microenvironment of amino acid residues were studied. The changes of the secondary structure of BSA were analyzed. The results indicate that both DIU and CHL can significantly interact with BSA, and the degree of the interaction between DIU/CHL and BSA increases with the increase of the DIU/CHL concentration. The fluorescence quenching of BSA by DIU/CHL results from the combination of static and dynamic quenching. The DIU/CHL has a weak to moderate binding affinity for BSA, and the binding stoichiometry is 1:1. Their binding processes are spontaneous, and hydrophobic interaction, hydrogen bonds and van der Waals forces are the main interaction forces. DIU/CHL has higher affinity for subdomain IIA (Site I) of BSA than subdomain IIIA (Site II), and also interacts with tryptophan more than tyrosine residues. The energy transfer can occur from BSA to DIU/CHL. By comparison, the strength of the interaction of DIU-BSA is always greater than that of CHL-BSA, and DIU can destroy the secondary structure of BSA molecules greater than CHL and thus the potential toxicity of DIU is higher due to DIU with more chlorine substituents than CHL. It is expected that this study on the interaction can offer in-depth insights into the toxicity of phenylurea herbicides, as well as their impact on human and animal health at the molecular level.

Facile construction of a stable core-shell spherically magnetic polyimide covalent organic framework for efficient extraction of phenylurea herbicides

Efficient enrichment is crucial for the highly sensitive monitoring of phenylurea herbicides (PUHs) in various environmental waters. In this work, a stable core-shell spherically magnetic polyimide covalent organic framework (COF) was synthesized via a simple template-mediated precipitation polymerization method under mild conditions using tri(4-aminophenyl)amine (TAPA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) as the building units (denoted as Fe3O4@TAPA-BPDA). The Fe3O4@TAPA-BPDA exhibits remarkable adsorption performance for PUHs with an optimized adsorption time of only 10 min. The adsorption of PUHs by Fe3O4@TAPA-BPDA followed the pseudo-second-order kinetic model and the Langmuir model. Furthermore, hydrogen bonding, halogen bonding, hydrophobic interaction, electro donor-acceptor interaction and π-π interactions are identified as the dominant mechanisms contributing to excellent adsorption performance. It was demonstrated that halogen bonds play an important role in the adsorption of substances containing chlorine atoms. The Fe3O4@TAPA-BPDA is easy to operate and highly regenerable. A simple magnetic solid-phase extraction (MSPE) method based on the Fe3O4@TAPA-BPDA was then developed for the rapid extraction of five PUHs in real samples, coupled with high-performance liquid chromatography (HPLC) determination. The analytical method developed has a linear range of 0.5-50 ng/mL, and the limit of detection (LOD) ranges from 0.06 to 0.10 ng/mL. The method exhibits good accuracy with recoveries ranged from 74.5 % to 111.4 %. The analytical method was successfully applied to the highly sensitive detection of PUHs in environmental water samples, which highlighting the potential application of the Fe3O4@TAPA-BPDA in the sample pretreatment.

Facile synthesis of hydroxylated triazine-based magnetic microporous organic network for ultrahigh adsorption of phenylurea herbicides: An experimental and density-functional theory study

Microporous organic networks (MONs) are highly porous materials that are particularly useful in analytical chemistry. However, the use of these materials is often limited by the functional groups available on their surface. Here, we described the polymerization of a sea urchin-like structure material at ambient temperature, that was functionalized with hydroxyl, carboxyl, and triazine groups and denoted as OH-COOH-MON-TEPT. A substantial proportion of OH-COOH-MON-TEPT was intricately decorated EDA-Fe3O4, creating a well-designed configuration (EDA-Fe3O4 @OH-COOH-MON-TEPT-EDC) for superior adsorption of the target analytes phenylurea herbicides (PUHs) via magnetic solid-phase extraction (MSPE). The proposed method showed remarkably low limits of detection ranging from 0.03 to 0.22 ng·L-1. Experimental investigations and theoretical analyses unveiled the adsorption mode between EDA-Fe3O4 @OH-COOH-MON-TEPT-EDC and PUHs. These findings establish a robust foundation for potential applications of EDA-Fe3O4 @OH-COOH-MON-TEPT-EDC in the analysis of various polar contaminants.

Preparation of hypercrosslinked porous polymer with manifold functional groups for sensitive determination of phenylurea herbicides in beverages and celtuce samples

Wide use of phenylurea herbicide has caused serious residue problem and threaten human health. It is important to develop viable method for their sensitive determination. Herein, a multi-functionalized porous polymer was prepared by crosslinking hexafluorobisphenol A with pyromellitic dianhydride. Using the multi-functionalized porous polymer as solid phase extraction sorbent, combined with high performance liquid chromatography, a sensitive method was established for determining phenylurea herbicides in beverages and celtuces. High sensitivity was achieved, with method detection limit (S/N = 3) of 0.01---0.025 ng mL-1 for beverages, 1.70 ng g-1 for celtuce, and quantitation limits of 0.03---0.10 ng mL-1 for beverages, 5.00 ng g-1 for celtuce. The method recoveries were 80.5---120.0 % with relative standard deviations lower than 6.1%. Adsorption mechanism mainly involved F-π, F-O, π-π, polar interactions and hydrogen-bonding interactions. This study offers a simple protocol to develop multi-functional sorbents for extraction of organic pollutants.

Quantification of trace fenuron in waste water samples by matrix matching calibration strategy and gas chromatography-mass spectrometry after simultaneous derivatization and preconcentration

This study presents a highly sensitive and accurate analytical strategy for the determination of fenuron in wastewater samples using gas chromatography-mass spectrometry (GC-MS). Simultaneous derivatization and spray-based fine droplet formation-liquid phase microextraction (SFDF-LPME) method was developed and performed to achieve low detection limits. The parameters of the derivatization and SFDF-LPME method were optimized by univariate approach to improve sensitivity and selectivity. Under the optimum SFDF-LPME-GC-MS conditions, the limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.15 and 0.49 mg/kg, respectively. In addition, the linear range was calculated as 0.51-24.50 mg/kg. Recovery studies were carried out on wastewater samples to determine the accuracy of the developed method and its applicability to real sample matrix. Matrix matching calibration strategy was applied to eliminate/reduce any possible interference effects caused by the complexity of the wastewater matrix and to increase the accuracy of the analytical results. Percent recovery results varied between 85.9 and 120.9% with small percent relative standard deviation values. These results were satisfactory in terms of the accuracy and applicability of the proposed method for wastewater samples.

Evaluation of a graphitic porous carbon modified with iron oxides for atrazine environmental remediation in water by adsorption

In the last decades, the growth of world agricultural activity has significantly contributed to the increased presence of emerging pollutants such as atrazine (ATZ) in aquatic ecosystems. Due to its high stability to the natural or artificial degradation processes, the ATZ environmental remediation by adsorption has been investigated. In this study, a graphitic-porous-carbon- (GPC) based material with magnetic domains was applied to remove ATZ from aqueous solution. ATZ high adsorption efficiency in a reduced time was achieved in the presence of the GPC adsorbent, leading to a detailed investigation of the mechanisms involved in the adsorption processes. Pseudo-first-order (PFO), pseudo-second-order (PSO), Ritchie, Elovich, and Weber-Morris models were applied to calculate the kinetic process efficiency. Likewise, adsorption isotherms based on Langmuir, Freundlich, Temkin, and Redlich-Peterson models were applied for a detailed understanding of the adsorption mechanisms. GPC was successfully applied for ATZ remediation in natural waters, confirming its high potential for treating natural waters contaminated by ATZ using adsorption process. The material can also be recovered and reused for up to 4 application cycles due to its magnetic properties, showing that in addition to ATZ adsorption efficiency, its sustainable use can be achieved.

Recent advances and applications of magnetic covalent organic frameworks in food analysis

Recently, covalent organic frameworks (COFs) have been widely used to prepare magnetic adsorbents for food analysis due to their highly tunable porosity, large specific surface area, excellent chemical and thermal stability and large delocalised π-electron system. This review summarises the main types and preparation methods of magnetic COFs and their applications in food analysis for the detection of pesticide residues, veterinary drugs, endocrine-disrupting phenols and estrogens, plasticisers and other food contaminants. Furthermore, challenges and future outlook in the development of magnetic COFs for food analysis are discussed.