Capillary electrochromatography coupled with dispersive liquid-liquid microextraction for the analysis of benzimidazole residues in water samples

Assessing the greenification potential of cyclodextrin-based molecularly imprinted polymers for pesticides detection

Cyclodextrins, with their unparalleled attributes of eco-friendliness, natural abundance, versatile utility, and facile functionalization, make a paramount contribution to the field of molecular imprinting. Leveraging the unique properties of cyclodextrins in molecularly imprinted polymers synthesis has revolutionized the performance of molecularly imprinted polymers, resulting in enhanced adsorption selectivity, capacity, and rapid extraction of pesticides, while also circumventing conventional limitations. As the concern for food quality and safety continues to grow, the need for standard analytical methods to detect pesticides in food and environmental samples has become paramount. Cyclodextrins, being non-toxic and biodegradable, present an attractive option for greener reagents in imprinting polymers that can also ensure environmental safety post-application. This review provides a comprehensive summary of the significance of cyclodextrins in molecular imprinting for pesticide detection in food and environmental samples. The recent advancements in the synthesis and application of molecularly imprinted polymers using cyclodextrins have been critically analyzed. Furthermore, the current limitations have been meticulously examined, and potential opportunities for greenification with cyclodextrin applications in this field have been discussed. By harnessing the advantages of cyclodextrins in molecular imprinting, it is possible to develop highly selective and efficient methods for detecting pesticides in food and environmental samples while also addressing the challenges of sustainability and environmental impact.

A benzenesulfonic acid-modified organic polymer monolithic column with reversed-phase/hydrophilic bifunctional selectivity for capillary electrochromatography

Here, a styrene-based polymer monolithic column poly(VBS-co-TAT-co-AHM) with reversed-phase/hydrophilic interaction liquid chromatography (RPLC/HILIC) bifunctional separation mode was successfully prepared for capillary electrochromatography by the in situ polymerization of sodium p-styrene sulfonate (VBS) with cross-linkers 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) and 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAT). The preparation conditions of the monolith were optimized. The morphology and formation of the poly(VBS-co-TAT-co-AHM) monolith were confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The separation performances of the monolith were evaluated systematically. It should be noted that the incorporation of VBS functional monomer can provide π-π interactions, hydrophilic interactions, and ion-exchange interactions. Hence, the prepared poly(VBS-co-TAT-co-AHM) monolith can achieve efficient separation of thiourea compounds, benzene series, phenol compounds, aniline compounds and sulfonamides in RPLC or HILIC separation mode. The largest theoretical plate number for N,N'-dimethylthiourea reached 1.7 × 10⁵ plates/m. In addition, the poly(VBS-co-TAT-co-AHM) monolithic column showed excellent reproducibility and stability. This novel monolithic column has great application value and potential in capillary electrochromatography (CEC).

Efficient preparation of graphene oxide-immobilized copper complex and its catalytic performance in the synthesis of imidazoles

This paper focused on the synthesis of phenylthiocarbamide-grafted graphene oxide (GO)-supported Cu complex (Cu-PTC@GO) as a highly efficient and recyclable catalyst synthesis by various analytical techniques such as TG, FT-IR, XRD, BET, N₂ adsorption-desorption isotherms, SEM, EDX, and elemental mapping analysis. Cu-PTC@GO showed outstanding results in preparing various imidazoles with higher yields, reduced reaction time, ease of product separation, and a simple procedure. In addition, the catalyst demonstrated appreciable recyclability up to five successive runs, and there was no substantial loss in catalytic performance. The result indicated that the heterogeneous base GO catalyst performed high activity and excellent recyclability in synthesizing various imidazoles and their derivatives, owing to the unique state of the GO-supported copper complex.

Determination of benzimidazoles in fruits by open-tubular capillary electrochromatography based on ionic liquids grafted covalent organic frameworks

A novel capillary electrochromatography method has been developed for the simultaneous quantification of ten benzimidazole fungicides in fruits. Herein, covalent organic frameworks (COFs) and ionic liquids (ILs) were successfully introduced to prepare open-tubular capillary column to improve the loading capacity and separation performance. The parameters effecting the analytical performance including pH and concentration of running buffer, separation voltage and the addition of organic solvent were investigated systematically. Under the optimized conditions, the method allowed the baseline separation of ten benzimidazole fungicides, and showed a good linearity in the range of 3.5-200 μg kg^-1 with the detection limits between 1.0 and 2.8 μg kg^-1. The intraday and interday precisions for recoveries were lower than 7.9% and 12.2%, respectively. Intraday and interday precisions for their retention times were lower than 3.2% and 6.6%, respectively. Satisfactory recoveries for grape, pear and orange samples at two concentrations were obtained ranging from 85.0 to 95.9% with RSDs lower than 7.8%, demonstrating the potential applications of the open-tubular capillary electrochromatography method for trace benzimidazole fungicides analysis in fruits.

UV-visible light-induced photochemical synthesis of benzimidazoles by coomassie brilliant blue coated on W-ZnO@NH2 nanoparticles

Heterogeneous photocatalysts proffer a promising method to actualize eco-friendly and green organic transformations. Herein, a new photochemical-based methodology is disclosed in the preparation of a wide range of benzimidazoles through condensation of o-phenylenediamine with benzyl alcohols in the air under the illumination of an HP mercury lamp in the absence of any oxidizing species catalyzed by a new photocatalyst W–ZnO@NH₂–CBB. In this photocatalyst, coomassie brilliant blue (CBB) is heterogenized onto W–ZnO@NH₂ to improve the surface characteristics at the molecular level and enhance the photocatalytic activity of both W–ZnO@NH₂ and CBB fragments. This unprecedented heterogeneous nanocatalyst is also identified by means of XRD, FT-IR, EDS, TGA-DTG, and SEM. The impact of some influencing parameters on the synthesis route and effects on the catalytic efficacy of W–ZnO@NH₂–CBB are also assessed. The appropriate products are attained for both the electron-withdrawing and electron-donating substituents in the utilized aromatic alcohols. Furthermore, preparation of benzimidazoles is demonstrated to occur mainly via a radical mechanism, which shows that reactive species such as ·O₂⁻, OH˙ and h⁺ would be involved in the photocatalytic process. Stability and reusability studies also warrant good reproducibility of the nanophotocatalyst for at least five runs. Eventually, a hot filtration test proved that the nanohybrid photocatalyst is stable in the reaction medium. Using an inexpensive catalyst, UV-vis light energy and air, as a low cost and plentiful oxidant, puts this methodology in the green chemistry domain and energy-saving organic synthesis strategies. Finally, the anticancer activity of W–ZnO nanoparticles is investigated on MCF7 breast cancer cells by MTT assay. This experiment reveals that the mentioned nanoparticles have significant cytotoxicity towards the selected cell line.

A new photochemical route is disclosed in the preparation of a wide range of benzimidazoles in air under the illumination of an HP mercury lamp in the absence of any oxidizing species catalyzed by heterogenized W–ZnO@NH₂–CBB.

Benzoic acid-modified monolithic column for separation of hydrophilic compounds by capillary electrochromatography with high content of water in mobile phase

Hydrophilic column combined with mobile phase containing high content of water is a green method for the separation of polar compounds, but there are few related studies, and the separation efficiency and performance of existing columns still needs to be improved. In this work, a novel monolithic column for separation of hydrophilic compounds under both high water content and HILIC condition, was prepared by in-situ polymerization using 4-vinylbenzoic acid (VBA) and 1-(Acryloyloxy)-3-(methacryloyloxy)-2-propanol (AMAP) as functional monomers. The poly(VBA-co-AMAP) monolithic column showed good separation performance towards various polar compounds under different chromatographic conditions based on the π-interaction, hydrophobic and hydrogen bonding interactions provided by 4-vinylbenzoic acid functional monomer. The highest column efficiency for adenine was over 2.15 × 10⁵ plates m^-1 (theoretical plate, N). In addition, the monolith showed good stability and reproducibility, the relative standard deviations (RSDs) of retention times within days (n = 5), between days (n = 5), between columns (n = 3) and between batches (n = 3) were 0.47-1.13%, 1.20-2.68%, 0.59-1.78% and 1.54-3.60%, respectively. This novel type of monolith has great application potential in the separation of hydrophilic compounds.

Pretreatment and determination methods for benzimidazoles: An update since 2005

Benzimidazoles, commonly used as pesticides and veterinary drugs, have posed a threat to human health and the environment due to unreasonable use and lack of valid regulation. Therefore, an up-to-date and comprehensive summary of the pretreatment and analytical approaches in different substrates is urgently needed. The present review consequently updates and covers various newly developed pretreatment methods (e.g., cationic micellar precipitation, magnetic-solid phase extraction, hollow fiber liquid phase microextraction, disperse liquid-liquid microextraction-solidified floating organic drop, stir cake sorptive extraction, solid phase microextraction method, QuEChERS, and molecular imprinted polymer-based methods) since 2005. The review also elaborates and discusses different determination methods (e.g., newly developed HPLC and related methods, improved spectrofluorimetry methods, capillary electrophoresis, and the electrochemical sensor). Furthermore, some critical points and prospects are highlighted, to describe the trends in this area.

Determination of 19 anthelmintics in environmental water and sediment using an optimized PLE and SPE method coupled with UHPLC-MS/MS

A sensitive quantification method using pressurized liquid extraction (PLE) and solid phase extraction (SPE) coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for determination of 19 anthelmintic drugs (ADs) belonging to seven structural groups (Benzimidazoles, Diphenylsulfides, Imidazothiazoles, Hexahydropyrazines, Macrocylic lactones, Salicylanilides, Tetrahydropyrimidines) in environmental water and sediment samples. Eleven SPE cartridges, sample pH, elution solvents were tested to determine the optimal conditions for extraction. Among these investigated SPE types, the best recoveries for 19 target ADs were obtained from Oasis HLB cartridge with 37-102%, 45-103%, 37-88%, 28-82% and 31-90% for spiked river water, tap water, rainwater, wastewater, and sediment respectively (with RSD < 15%), except for closantel. The 19 ADs were separated within 10 min by a BEH C18 column and monitored in both positive and negative ions modes with switching electrospray ionization source. The cross-talk interferences were solved by identification of secondary mass spectrum of substances through MRM-IDA-EPI scanning using Qtrap. These interference peaks could be efficiently eliminated by setting MRM segments or using Qtrap to obtain tertiary fragmented information. The developed methods were satisfactory in terms of linearity, accuracy, and precision, and used eight isotopically labeled compounds as internal standards to correct matrix effects. Method quantification limit (MQL) for 19 ADs was below 1.1 ng/L, 0.4 ng/L, 5.4 ng/L and 2.3 ng/g for river water, tap water, wastewater, and sediment, respectively. The validated method was successfully used to investigate the occurrence of anthelmintics in water and sediment samples from Chengdu, China. All ADs were detected in environment with the concentrations at ng/L level.

Advances in the Analysis of Veterinary Drug Residues in Food Matrices by Capillary Electrophoresis Techniques

In the last years, the European Commission has adopted restrictive directives on food quality and safety in order to protect animal and human health. Veterinary drugs represent an important risk and the need to have sensitive and fast analytical techniques to detect and quantify them has become mandatory. Over the years, the availability of different modes, interfaces, and formats has improved the versatility, sensitivity, and speed of capillary electrophoresis (CE) techniques. Thus, CE represents a powerful tool for the analysis of a large variety of food matrices and food-related molecules with important applications in food quality and safety. This review focuses the attention of CE applications over the last decade on the detection of different classes of drugs (used as additives in animal food or present as contaminants in food products) with a potential risk for animal and human health. In addition, considering that the different sample preparation procedures have strongly contributed to CE sensitivity and versatility, the most advanced sample pre-concentration techniques are discussed here.