Determination of fluoroquinolone antibiotics in environmental water samples based on magnetic molecularly imprinted polymer extraction followed by liquid chromatography–tandem mass spectrometry

Bacterial cellulose-supported dual-layered nanofibrous adsorbent for thin-film micro-solid-phase extraction of antibiotics in municipal wastewaters

In this study, bacterial cellulose was coated with composite nanofibers of polyvinyl alcohol doped with beta cyclodextrin and alginate (PVA-SA-βCD), constructed using the electrospinning technique. This novel material served as an effective adsorbent for thin-film micro-solid-phase extraction (TF-μSPE) of antibiotics from water samples, followed by HPLC-UV analysis. The adsorbent was subjected to a comprehensive characterization using ATR-FTIR, FE-SEM, and BET techniques. These analyses provided valuable insights into its physicochemical structure and properties. Several key parameters that affect the performance of the TF-μSPE method were investigated including electrospinning factors (voltage, flow rate, needle tip-collector distance, and electrospinning time), desorption solvent type and volume, adsorbent dose, adsorption and desorption times, pH value, and salt percentage. Under the optimized conditions, the limits of detections and quantifications for target antibiotics were obtained in the ranges of 0.02-0.03 and 0.07-0.1 μg L⁻1, respectively. The linear range was 0.07-1000 μg L⁻1 with satisfactory determination coefficients (r2) of 0.9944-0.9984. The intra-day and inter-day precisions were obtained as 1.1-1.7 % and 2.2-3.5 %, respectively. The developed method was successfully applied to determine antibiotics in municipal wastewater samples, yielding recoveries within the range of 70-100 % (RSD%<3.7). The green features of the method were also assessed based on AGREE tool. This is the first report on the fabrication of a double-layered nanofibrous adsorbent and its application for the adsorption of antibiotics in wastewater. This robust approach combines efficiency with analytical accuracy, making it a valuable tool for antibiotic analysis in environmental samples.

Fabrication of a β-CD-functionalized magnetic microporous organic network for effective enrichment and detection of fluoroquinolone antibiotics in water samples

Fluoroquinolone (FQ) antibiotics, one of the leading environmental pollutants, have ecotoxic effects that can accumulate through ecosystems and harm human health. The determination of FQs is still difficult due to the complex matrix, many interfering factors, and low concentration. Hence, a magnetic microporous organic network (MON) composite denoted as Fe3O4@MON-NH2@CM-β-CD with excellent FQ adsorption performance was prepared by β-CD covalent modification of a MON. Based on the existence of π-π packing, hydrophobic interaction, and hydrogen bonding between Fe3O4@MON-NH2@CM-β-CD and FQs, a new magnetic solid phase extraction (MSPE) method for the enrichment of FQs was developed. Under optimized MSPE conditions, five FQs were detected by HPLC-UV with good linearity (R2 ≥ 0.9989) in the range of 0.02-1 μg mL-1, and detection limits (S/N = 3) in the range of 0.0014-0.0023 μg mL-1. The satisfactory recoveries ranged from 93.1 to 116.2% with RSDs lower than 8.39% when applied to actual environmental water samples. These results revealed that Fe3O4@MON-NH2@CM-β-CD as an adsorbent for MSPE had excellent performance for FQ extraction from real samples, and the MON material types were expanded through the functionalization of MONs, which would have great potential for further application in various analytical methods.

A Review on Fluoroquinolones' Toxicity to Freshwater Organisms and a Risk Assessment

Fluoroquinolones (FQs) have achieved significant success in both human and veterinary medicine. However, regulatory authorities have recommended limiting their use, firstly because they can have disabling side effects; secondly, because of the need to limit the spread of antibiotic resistance. This review addresses another concerning consequence of the excessive use of FQs: the freshwater environments contamination and the impact on non-target organisms. Here, an overview of the highest concentrations found in Europe, Asia, and the USA is provided, the sensitivity of various taxa is presented through a comparison of the lowest EC50s from about a hundred acute toxicity tests, and primary mechanisms of FQ toxicity are described. A risk assessment is conducted based on the estimation of the Predicted No Effect Concentration (PNEC). This is calculated traditionally and, in a more contemporary manner, by constructing a normalized Species Sensitivity Distribution curve. The lowest individual HC5 (6.52 µg L-1) was obtained for levofloxacin, followed by ciprofloxacin (7.51 µg L-1), sarafloxacin and clinafloxacin (12.23 µg L-1), and ofloxacin (17.12 µg L-1). By comparing the calculated PNEC with detected concentrations, it is evident that the risk cannot be denied: the potential impact of FQs on freshwater ecosystems is a further reason to minimize their use.

Biofilms as Battlefield Armor for Bacteria against Antibiotics: Challenges and Combating Strategies

Bacterial biofilms are formed by communities, which are encased in a matrix of extracellular polymeric substances (EPS). Notably, bacteria in biofilms display a set of 'emergent properties' that vary considerably from free-living bacterial cells. Biofilms help bacteria to survive under multiple stressful conditions such as providing immunity against antibiotics. Apart from the provision of multi-layered defense for enabling poor antibiotic absorption and adaptive persistor cells, biofilms utilize their extracellular components, e.g., extracellular DNA (eDNA), chemical-like catalase, various genes and their regulators to combat antibiotics. The response of biofilms depends on the type of antibiotic that comes into contact with biofilms. For example, excessive production of eDNA exerts resistance against cell wall and DNA targeting antibiotics and the release of antagonist chemicals neutralizes cell membrane inhibitors, whereas the induction of protein and folic acid antibiotics inside cells is lowered by mutating genes and their regulators. Here, we review the current state of knowledge of biofilm-based resistance to various antibiotic classes in bacteria and genes responsible for biofilm development, and the key role of quorum sensing in developing biofilms and antibiotic resistance is also discussed. In this review, we also highlight new and modified techniques such as CRISPR/Cas, nanotechnology and bacteriophage therapy. These technologies might be useful to eliminate pathogens residing in biofilms by combating biofilm-induced antibiotic resistance and making this world free of antibiotic resistance.

Application of hollow fiber-protected liquid-phase microextraction combined with GC-MS in determining Endrin, Chlordane, and Dieldrin in rice samples

This paper introduces a novel and minimized sample preparation technique based on hollow fiber-protected liquid-phase microextraction that can be used in joint with gas chromatography-mass spectrometry (GC-MS) detection to extract three organochlorine pesticides-Endrin, Chlordane, and Dieldrin-from rice samples. To that end, a single-walled carbon nanotube (SWCNT) and a proper ionic liquid (IL) were ultrasonically dispersed and injected into the lumen of hollow fiber as the extraction phase for preconcentrating and extracting the target analytes from the rice samples. The effects of the type of nanoparticles, ILs, and desorption solvent on the efficiency of extracting the analytes were investigated based on the one-factor-at-a-time (OFAT) approach. In addition, other parameters influencing the extraction procedure were optimized using an experimental design that decreased the number of experiments, reagent consumption, and costs. Under optimized conditions, the limits of detection and quantification in determining mentioned pesticides varied between 0.019-0.029 and 0.064-0.098 ng mL-1, respectively. The calibration graphs to measure Endrin, Chlordane, and Dieldrin were linear over the concentration range of 0.064-13.2, 0.098-16.7, and 0.092-11.4 ng mL-1, respectively. The relative standard deviations for inter-day and intra-day analysis were below 7.06 and 4.75% for the triplicate determination of three organochlorine pesticides. Besides, the relative recoveries and standard deviations of Endrin, Chlordane, and Dieldrin for analyzing several Iranian rice samples were between 86.0-92.9% and 4.5-5.8%, respectively. The results were compared with other similar works in literature, proving that the proposed method is efficient and useful for routine monitoring of organochlorine compounds in food samples.

Sensitive electrochemical detection of enrofloxacin in eggs based on carboxylated multi-walled carbon nanotubes-reduced graphene oxide nanocomposites: Molecularlyimprintedrecognition versus direct electrocatalytic oxidation

A sensitive electrochemical method for detecting enrofloxacin was proposed using carboxylated multi-walled carbon nanotubes-reduced graphene oxide (MWCNT-COOH-RGO) nanocomposites. The MWCNT-COOH-RGO nanocomposites were firstly electrodeposited on a bare electrode, followed by electropolymerization of molecularly imprinted polymers. Enrofloxacin was determined by the mechanisms of direct electrocatalytic oxidation and molecularly imprinted recognition, respectively. Under the optimized conditions, a response range of 5.0×10^-7 M to 5.5×10^-5 M and limit of detection (LOD) of 2.3×10^-7 M were obtained by direct electrocatalytic oxidation of enrofloxacin using chronoamperometry. By contrast, the response range of 1.0×10^-10 M to 5.0×10^-5 M and LOD of 2.5×10^-11 M were achieved by molecularly imprinted recognition of enrofloxacin using square-wave voltammetry. Moreover, the proposed method exhibited good repeatability, stability and selectivity, and could be used for enrofloxacin detection in egg samples with satisfactory results.

Fluoroquinolone antibiotics: Occurrence, mode of action, resistance, environmental detection, and remediation - A comprehensive review

Antibiotics play an essential role in the medical healthcare world, but their widespread usage and high prevalence have posed negative environmental consequences. During the past few decades, various antibiotic drugs have been detected in aquatic and terrestrial ecosystems. Among them, the Fluoroquinolones (FQ) group is ubiquitous in the environment and has emerged as a major environmental pollutant. FQs are very significant, broad-spectrum antibiotics used in treating various pathogenic diseases of humans and animals. The most known and used FQs are ciprofloxacin, norfloxacin, ofloxacin, levofloxacin, enrofloxacin, danofloxacin, and moxifloxacin. After human and animal administration, about 70% of these drugs are excreted out in unaltered form into the environment. Besides, wastewater discharge from pharmaceutical industries, hospitals, and agriculture runoff is the major contributor to the accumulation of FQs into the ecosystem. Their long-term presence in the environment creates selection pressure on microorganisms and contributes to the emergence of multi-drug-resistant bacteria. In addition to the resistance, these antibiotics also impose ecotoxicological effects on various animals and plant species. The presence of the fluorine atom in Fluoroquinolones makes them highly electronegative, strong, recalcitrant, and less compatible with microbial degradation. Many biological and chemical processes have been invented and successfully implemented during the past few decades for the elimination of these pollutants from the environment. This review provides a detailed overview of the classification, occurrence, distribution, and ecotoxicological effects of Fluoroquinolones. Their modes of action, resistance mechanism, detection and analysis methods, and remediation strategies have also been discussed in detail.

The Ultratrace Determination of Fluoroquinolones in River Water Samples by an Online Solid-Phase Extraction Method Using a Molecularly Imprinted Polymer as a Selective Sorbent

Fluoroquinolones (FQs) are broad-spectrum antibiotics widely used to treat animal and human infections. The use of FQs in these activities has increased the presence of antibiotics in wastewater and food, triggering antimicrobial resistance, which has severe consequences for human health. The detection of antibiotics residues in water and food samples has attracted much attention. Herein, we report the development of a highly sensitive online solid-phase extraction methodology based on a selective molecularly imprinted polymer (MIP) and fluorescent detection (HPLC-FLD) for the determination of FQs in water at low ng L−1 level concentration. Under the optimal conditions, good linearity was obtained ranging from 0.7 to 666 ng L−1 for 7 FQs, achieving limits of detection (LOD) in the low ng L−1 level and excellent precision. Recoveries ranged between 54 and 118% (RSD < 17%) for all the FQs tested. The method was applied to determining FQs in river water. These results demonstrated that the developed method is highly sensitive and selective.

Preparation and Adsorption Properties of Magnetic Molecularly Imprinted Polymers for Selective Recognition of 17β-Estradiol

In this paper, magnetic molecularly imprinted polymers (MMIPs) were fabricated on the surface of Fe3O4 by surface molecular imprinting technology, which can selectively adsorb 17β-estradiol (E2). The optimized experiments demonstrated that MMIPs possessed the best adsorption capacity when methanol was used as the solvent and MAA was used as the crosslinking agent, with a molar ratio of E2: MMA: EGDMA as 1:4:50. SEM, FTIR, and XRD were employed to investigate the morphologies of MMIPs and the results demonstrated that the MMIPs that can selectively adsorb E2 were successfully prepared on Fe3O4 particles. The adsorption experiments showed that 92.1% of E2 was adsorbed by the MMIPs, which is higher than the magnetic non-molecularly imprinted polymers (MNIPs). The Freundlich isotherm model was more suitable to describe the adsorption process of E2 by MMIPs. Meanwhile, MMIPs had a better recognition ability for E2 and its structural analogs such as estrone and estriol. The MMIPs still had good adsorption performance after methanol regeneration five times. The prepared MMIPs had the advantages of efficient adsorption ability and high reusability, so they can be applied for selective recognition and removal of E2.

Molecularly imprinted polymer-specific solid-phase extraction for the determination of 4-hydroxy-2(3H)benzoxazolone isolated from Acanthus ilicifolius Linnaeus using high-performance liquid chromatography-tandem mass spectrometry

The minor constituent found in Acanthus ilicifolius Linnaeus, 4-hydroxy-2 (3H) benzoxazolone alkaloid (HBOA), has a range of versatile applications. Herein, a quick and straightforward method for extracting HBOA from A. ilicifolius Linnaeus was proposed. HBOA was used as a template, whereas methacrylic acid, ethylene glycol dimethacrylate, and acetonitrile were used as functional monomers, cross-linkers, and porogens, respectively. Molecularly imprinted polymers (MIPs) were synthesized by precipitation polymerization, and their adsorption isotherms, dynamics, and selective binding ability were characterized and analyzed. The results showed that the adsorption amount of the template was 90.18 mg/g. The MIPs were used as solid-phase extraction fillers and actual sample extraction columns, with a linear range of 0–100 μg/L, average recovery of 78.50–101.12%, and a relative standard deviation of 1.20–3.26%. The HBOA concentrations in the roots, stems, and leaves were 1,226, 557, and 205 μg/g, respectively. In addition, MIP–SPE was successfully used in isolating and purifying HBOA from different parts of A. ilicifolius Linnaeus, indicating its effectiveness in extracting and determining HBOA in other herbs.

Single-drop microextraction technique for the determination of antibiotics in environmental water

Growing concerns related to antibiotic residues in environmental water have encouraged the development of rapid, sensitive, and accurate analytical methods. Single-drop microextraction has been recognized as an efficient approach for the isolation and preconcentration of several analytes from a complex sample matrix. Thus, single-drop microextraction techniques are cost-effective and less harmful to the environment, subscribing to green analytical chemistry principles. Herein, an overview and the current advances in single-drop microextraction for the determination of antibiotics in environmental water are presented were included. In particular, two main approaches used to perform single-drop microextraction (direct immersion-single-drop microextraction and headspace-single-drop microextraction) are reviewed. Furthermore, the impressive analytical features and future perspectives of single-drop microextraction are discussed in this review. This article is protected by copyright. All rights reserved.

Core-shell magnetic porous organic polymer for magnetic solid-phase extraction of fluoroquinolone antibiotics in honey samples followed by high-performance liquid chromatography with fluorescence detection

By monomer-mediated in-situ growth synthesis strategy, with hydroquinone and 1,3,5-tris(4-aminophenyl)benzene as monomers, a core-shell magnetic porous organic polymer was synthesized through a simple azo reaction. Based on this, a magnetic solid-phase extraction-high-performance liquid chromatography-fluorescence detection method was proposed for the analysis of fluoroquinolones in a honey sample. With ofloxacin, ciprofloxacin, enrofloxacin, lomefloxacin, and difloxacin as target analytes, factors affecting the extraction efficiency had been optimized. The LODs were 1.5-5.4 ng/L (corresponding to 0.23-0.81 μg/kg in honey). The linear range was 0.005-20 μg/L for difloxacin, 0.01-20 μg/L for ofloxacin, ciprofloxacin and lomefloxacin, and 0.02-20 μg/L for enrofloxacin. The enrichment factor was 84.4-91.7-fold with a high extraction efficiency of 84.4-91.7%. The method was assessed by the analysis of target fluoroquinolones in honey samples, and the recoveries for the spiked samples were 79.3-95.8%. The results indicated that the established magnetic solid-phase extraction-high-performance liquid chromatography-fluorescence detection method is efficient for the analysis of trace fluoroquinolones in honey.

Analytical Extraction Methods and Sorbents' Development for Simultaneous Determination of Organophosphorus Pesticides' Residues in Food and Water Samples: A Review

Extensive use of organophosphorus pesticides in agriculture leads to adverse effects to the environment and human health. Sample preparation is compulsory to enrich target analytes prior to detection as they often exist at trace levels and this step is critical as it determines the concentration of pollutants present in samples. The selection of a suitable extraction method is of great importance. The analytical performance of the extraction methods is influenced by the selection of sorbents as sorbents play a vital role in the sensitivity and selectivity of an analytical method. To date, numerous sorbent materials have been developed to cater to the needs of selective and sensitive pesticides' detection. Comprehensive details pertaining to extraction methods, developed sorbents, and analytical performance are provided. This review intended to provide a general overview on different extraction techniques and sorbents that have been developed in the last 10 years for organophosphorus pesticides' determinations in food and water samples.

Molecularly Imprinted Polymers for Dispersive (Micro)Solid Phase Extraction: A Review

The review describes the development of batch solid phase extraction procedures based on dispersive (micro)solid phase extraction with molecularly imprinted polymers (MIPs) and magnetic MIPs (MMIPs). Advantages and disadvantages of the various MIPs for dispersive solid phase extraction and dispersive (micro)solid phase extraction are discussed. In addition, an effort has also been made to condense the information regarding MMIPs since there are a great variety of supports (magnetite and magnetite composites with carbon nanotubes, graphene oxide, or organic metal framework) and magnetite surface functionalization mechanisms for enhancing MIP synthesis, including reversible addition-fragmentation chain-transfer (RAFT) polymerization. Finally, drawbacks and future prospects for improving molecularly imprinted (micro)solid phase extraction (MIMSPE) are also appraised.

Determination of quinolones in environmental water and fish by magnetic metal organic frameworks based magnetic solid-phase extraction followed by high-performance liquid chromatography-tandem mass spectrometry

The widespread use of quinolones has become an increasing global public health threat. In this study, IRMOF-3 coated SiO₂/Fe₃O₄ were prepared via a facile room-temperature method. The prepared IRMOF-3 coated SiO₂/Fe₃O₄ was used as a sorbent for magnetic solid phase extraction, and then combined with high-performance liquid chromatography-tandem mass spectrometry for the determination of 10 quinolines. The extraction conditions of magnetic solid phase extraction were studied in detail, and the optimal conditions were established. Under the optimal experimental conditions, the limits of quantification of 10 quinolones were in the range of 0.005-0.01 μg L^-1, the relative standard deviations were 6.58-10.6% (n=7), the enrichment factors were 21.0-23.8 for water samples. The limits of quantification of 10 quinolones were in the range of 0.10-0.20 μg kg^-1, the relative standard deviations were 5.95-14.5% (n=7), the enrichment factors were 1.08-1.24 for fish samples. The proposed method was applied for the determination of 10 quinolones in river water, aquacultural water and a fish sample, and enrofloxacin and ciprofloxacin were found in the fish sample.

Insights into the structure-performance relationships of extraction materials in sample preparation for chromatography

Sample preparation is one of the most crucial steps in analytical processes. Commonly used methods, including solid-phase extraction, dispersive solid-phase extraction, dispersive magnetic solid-phase extraction, and solid-phase microextraction, greatly depend on the extraction materials. In recent decades, a vast number of materials have been studied and used in sample preparation for chromatography. Due to the unique structural properties, extraction materials significantly improve the performance of extraction devices. Endowing extraction materials with suitable structural properties can shorten the pretreatment process and improve the extraction efficiency and selectivity. To understand the structure-performance relationships of extraction materials, this review systematically summarizes the structural properties, including the pore size, pore shape, pore volume, accessibility of active sites, specific surface area, functional groups and physicochemical properties. The mechanisms by which the structural properties influence the extraction performance are also elucidated in detail. Finally, three principles for the design and synthesis of extraction materials are summarized. This review can provide systematic guidelines for synthesizing extraction materials and preparing extraction devices.

Point-of-Care Diagnostics: Molecularly Imprinted Polymers and Nanomaterials for Enhanced Biosensor Selectivity and Transduction

Significant healthcare disparities resulting from personal wealth, circumstances of birth, education level, and more are internationally prevalent. As such, advances in biomedical science overwhelmingly benefit a minority of the global population. Point-of-Care Testing (POCT) can contribute to societal equilibrium by making medical diagnostics affordable, convenient, and fast. Unfortunately, conventional POCT appears stagnant in terms of achieving significant advances. This is attributed to the high cost and instability associated with conventional biorecognition: primarily antibodies, but nucleic acids, cells, enzymes, and aptamers have also been used. Instead, state-of-the-art biosensor researchers are increasingly leveraging molecularly imprinted polymers (MIPs) for their high selectivity, excellent stability, and amenability to a variety of physical and chemical manipulations. Besides the elimination of conventional bioreceptors, the incorporation of nanomaterials has further improved the sensitivity of biosensors. Herein, modern nanobiosensors employing MIPs for selectivity and nanomaterials for improved transduction are systematically reviewed. First, a brief synopsis of fabrication and wide-spread challenges with selectivity demonstration are presented. Afterward, the discussion turns to an analysis of relevant case studies published in the last five years. The analysis is given through two lenses: MIP-based biosensors employing specific nanomaterials and those adopting particular transduction strategies. Finally, conclusions are presented along with a look to the future through recommendations for advancing the field. It is hoped that this work will accelerate successful efforts in the field, orient new researchers, and contribute to equitable health care for all.

Rapid and sensitive determination of neomycin and kanamycin in measles, mumps, and rubella vaccine via high-performance liquid chromatography-tandem mass spectrometry using modified super-paramagnetic Fe3O4 nanospheres

A simple magnetic dispersive solid-phase extraction (MDSPE) methodology based on mesoporous Fe₃O₄@ succinic acid nanospheres and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been developed to determine kanamycin (KNM) and neomycin (NEO) contents in Measles, Mumps, and Rubella (MMR) vaccine products. The monodispersed mesoporous Fe₃O₄ nanospheres with self-assembled carboxyl terminated shell have been prepared via a simple solvothermal method. These as-synthesized mesoporous Fe₃O₄ nanospheres showed a high magnetic saturation value (M_s = 46 emu g^-1) and large specific surface area (111.12 m² g^-1) which made them potential candidates as sorbents in magnetic solid-phase extraction. The adsorption experimental data fitted well with the Freundlich-Langmuir isotherm and followed a pseudo-second-order kinetic model. Moreover influential parameters on extraction efficiency were investigated and optimized. Under optimal conditions, the limits of detection for KNM and NEO were 1.0 and 0.1 ng mL^-1, respectively. Recovery assessments using real samples exhibited recoveries in the range of 96.0 ± 4.3 to 101.5 ± 7.1 %, with relative standard deviations of <10.7% (for intra- day) and <14.6% (for inter- day). The proposed method was successfully applied for different spiked and un-spiked MMR vaccine samples. The presented extraction method provides a fast, selective, robust and practical platform for the detection of KNM and NEO in MMR vaccine samples.

A novel strategy for selective removal and rapid collection of triclosan from aquatic environment using magnetic molecularly imprinted nano-polymers

Triclosan (TCS) is a kind of chronic toxicity to aquatic organisms. Due to its highly effective antimicrobial, TCS has been widely applied in personal-care products, which naturally poses a potential risk to the ecological system and human health since its release into water-ecological environment. Therefore, it urgently demands a selective, easily separated, recyclable, and low-cost adsorbent to remove the residues of TCS from aquatic environments. In this study, a novel magnetic molecularly imprinted nano-polymers (TMIPs) were prepared for selective adsorption and convenient collection of TCS in aquatic samples, based on a core-shell technique using TCS as template molecule and SiO₂-coated Fe₃O₄ nanoparticles as the support substrate. The functional groups, particle size, morphology and magnetic property of TMIPs were characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy and vibrating sample magnetometer, respectively. The obtained TMIPs possessed excellent adsorption capacity (Q_e = 53.12 mg g^-1), speedy adsorption equilibrium time (2 min) and high selectivity (k' = 6.321) for TCS. Moreover, the pH-tolerance and stability tests manifested that the adsorption capacity of TMIPs for TCS was acid-resistance and could retain 94.2% of the maximum Q_e after 5 times removal-regeneration cycles. The feature of magnetically susceptibility can simplify the procedures of sample handling in TCS determination, because the TMIPs of TCS are easy to be recycled from aquatic samples. As an application demonstration, the toxicity test in microalgae confirmed that a tiny amount of TMIPs could significantly eliminate the toxic effect of TCS on Chlamydomonas reinhardtii via the efficient binding with TCS.

Materials for Solid-Phase Extraction of Organic Compounds

This review provides an overview of the most recent developments involving materials for solid-phase extraction applied to determine organic contaminants. It mainly concerns polymer-based sorbents that include high-capacity, as well as selective sorbents, inorganic-based sorbents that include those prepared using sol-gel technology along with structured porous materials based on inorganic species, and carbon nanomaterials, such as graphene and carbon nanotubes. Different types of magnetic nanoparticles coated with these materials are also reviewed. Such materials, together with their main morphological and chemical features, are described, as are some representative examples of their application as solid-phase extraction materials to extract organic compounds from different types of samples, including environmental water, biological fluids, and food.

One-step polymerization of hydrophilic ionic liquid imprinted polymer in water for selective separation and detection of levofloxacin from environmental matrices

A novel green hydrophilic levofloxacin imprinted polymer was presented via one-step polymerization in water using ionic liquid 1,6-hexa-3,3'-bis-1-vinylimidazolium bromine with multiple hydrophilic groups and 2-hydroxyethyl methacrylate as a co-functional monomer. Adsorption experiment revealed that the ionic liquid significantly improved the water compatible of imprinted polymer, and the excellent recognition of molecularly imprinted polymer for levofloxacin in water corresponds to the synergetic effect of H-bonding and the electrostatic and π-π interactions between the levofloxacin and co-functional monomer. Furthermore, the adsorption process of the imprinted material towards levofloxacin fitted the Langmuir model, and the maximum binding amount of levofloxacin onto the imprinted and corresponding non-imprinted polymer were 16.45 and 6.82 mg/g at 25°C, respectively. After optimizing the parameters affecting solid phase extraction performance, an enrichment and determination system was achieved to separate and detect levofloxacin from water and sediment samples with recoveries that ranged from 83.67 to 101.33% and relative standard deviation of less than 5.59%.

A novel Fe3O4/graphene oxide/citrus peel-derived bio-char based nanocomposite with enhanced adsorption affinity and sensitivity of ciprofloxacin and sparfloxacin

To create more active adsorption sites on biochar, the Fe₃O₄/GO/citrus peel-derived magnetic bio-nanocomposite (mGOCP) with hierarchically porous architectures was synthesized by a facile one-pot hydrothermal approach for efficient removal of fluoroquinolone antibiotics ciprofloxacin (CIP) and sparfloxacin (SPA). The characterization analysis of bio-nanocomposites showed that the incorporation of GO could ensure relatively higher surface area (1556 cm² g^-1), more abundant pore structure, and higher thermal stability within mGOCP bio-nanocomposites than Fe₃O₄/citrus peel-derived magnetic bio-nanocomposites (mCP). And the mGOCP-1% attained outstanding adsorption capacity for CIP (283.44 mg g^-1) and SPA (502.37 mg g^-1), respectively. The primary adsorption mechanisms for CIP and SPA included π-π electron donor-acceptor interaction, H-bonding, hydrophobic interaction and electrostatic interaction. Overall, the surface morphology and structural composition of biochars could be regulated with GO to facilitate the adsorption capacity. Moreover, the developed mGOCP could be extended as a potential adsorbent for removal of other emerging organic pollutants in water.

Core-Shell Molecularly Imprinted Polymer Nanocomposites for Biomedical and Environmental Applications

Core-shell polymers represent a class of composite particles comprising of minimum two dissimilar constituents, one at the center known as a core which is occupied by the other called shell. Core-shell molecularly imprinting polymers (CSMIPs) are composites prepared via printing a template molecule (analyte) in the coreshell assembly followed by their elimination to provide the everlasting cavities specific to the template molecules. Various other types of CSMIPs with a partial shell, hollow-core and empty-shell are also prepared. Numerous methods have been reported for synthesizing the CSMIPs. CSMIPs composites could develop the ability to identify template molecules, increase the relative adsorption selectivity and offer higher adsorption capacity. Keen features are measured that permits these polymers to be utilized in numerous applications. It has been developed as a modern technique with the probability for an extensive range of uses in selective adsorption, biomedical fields, food processing, environmental applications, in utilizing the plant's extracts for further applications, and sensors. This review covers the approaches of developing the CSMIPs synthetic schemes, and their application with special emphasis on uses in the biomedical field, food care subjects, plant extracts analysis and in environmental studies.

Uptake and depuration of eight fluoroquinolones (FQs) in common carp (Cyprinus carpio)

Fluoroquinolones (FQs) are extensively used in humans and animals, which have aroused wide attention due to the emergence of FQ resistant bacteria and frequent detection in water, sediment and organism. However, little information is available about the bioconcentration and tissue distribution of FQs in fish. In the present study, we investigated the uptake and depuration of eight FQs (balofloxacin (BAL), enoxacin (ENO), enrofloxacin (ENR), fleroxacin (FLE), lomefloxacin (LOM), moxifloxacin (MOX), ofloxacin (OFL), sparfloxacin (SPA)) in common carp under controlled laboratory conditions. The results showed that all target FQs could accumulate in fish tissues, and had a similar tendency over time during the whole uptake and depuration periods. The uptake rate constant (k₁), depuration rate constant (k₂) and half-lives (t_1/2) were in the ranges of 0.007-3.599 L/(kg·d), 0.051-0.283 d^-1 and 2.4-10.7 d, respectively. The ranges of bioconcentration factors (BCFs) were 0.24-39.55 L/kg, 0.21-24.97 L/kg and 0.04-1.07 L/kg in liver, kidney and muscle, respectively. BCFs of eight FQs decreased in the order: MOX > ENR > ENO ≈ BAL ≈ FLE ≈ OFL ≈ LOM ≈ SPA, which may be correlated with the substituents at positions 7 and 8 of the basic quinolone nucleus and the metabolic capacity. Besides, BCFs were relative with pH-adjusted distribution coefficient (log D), suggesting that molecular status of ionizable compounds strongly influenced the bioconcentration processes. The present study provides important insights for understanding the bioconcentration and tissues distribution of FQs.

Preparation of core-shell magnetic molecularly imprinted polymer nanoparticle for the rapid and selective enrichment of trace diuron from complicated matrices

A novel magnetic MIPs (DUMIPs) was prepared by surface molecular imprinting method using superparamagnetic core-shell nanoparticle (Fe₃O₄@SiO₂) as the sacrificial support matrix, herbicide diuron as template, α-methacrylic acid as the functional monomer, trimethylolpropane trimethacrylate as the crosslinker, azobisisobutyronitrile as the initiator, and acetonitrile as the porogen. Highly cross-linked porous surface and excellent magnetic property were characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometer, respectively. The adsorption capacity of DUMIPs was 8.1 mg g^-1, 2.6-fold over its corresponding non-imprinted polymers (DUNIPs). The adsorption in DUMIPs was considered as multilayer adsorption and posed high affinity to diuron, due to the better fitting to Freundilich isotherm. Competitive recognition study demonstrated DUMIPs had highly selective binding diuron. DUMIPs, as an influential sorbent has been used for selective extraction of diuron from environmental samples (paddy field water, paddy soil and grain seedlings) and the elution was determined by high efficiency liquid chromatography (HPLC). In this analytical method, various factors affecting the extraction efficiency such as pH, sorbent dosage, utilization efficiency and volumes of eluent were simultaneously investigated. Under the optimal conditions, the linearity of the method obtained is in the range of 0.02-10.0 mg L^-1. The limit of detection is 0.012 mg L^-1. In four spiked levels (0.04, 0.2, 1.0, and 4.0 mg kg^-1), the recoveries of diuron in real samples are in the range of 83.56%-116.10% with relative standard deviations in the range of 1.21-6.81%. Importantly, compared to C₁₈-SPE column, the MMIPs exhibited convenient separation by external magnetic field, strong clean-up capacity, and selective enrichment for diuron. Thus, the DUMIPs-based method is great potential for efficient sample preparation in the determination of trace amounts of diuron residues in complex matrices.

Supramolecularly imprinted polymeric solid phase microextraction coatings for synergetic recognition nitrophenols and bisphenol A

We herein firstly presented supramolecularly imprinted polymeric (SMIP) solid phase microextraction (SPME) coatings which showed synergetic recognition for nitrophenols and bisphenol A. A series of β-cyclodextrins (β-CD) with different substituents were successfully designed and synthesized. It was employed as supramolecular functional monomers for SMIPs. The orderly assembling structures settled down under the molecular imprinting process. The four of SMIPs solid phase microextraction coatings showed good selectivity for the template and could be used to extract 4-NP in real water samples. Furthermore, the inclusion effects of derived β-CDs with the 4-NP were investigated by measuring the UV-vis spectra and the theoretical calculations. The strongest intermolecular force is come from the supramolecular complex of 4-NP and β-CD-4 which shows the strongest UV-vis spectra absorption value. Meanwhile, the difference of the theoretical calculations value coming from the system of derived β-CDs and 4-NP is the largest, revealing the strongest electronic interactions between derived β-CD-4 and 4-NP. Therefore, these polymers possess inclusion interactions from β-cyclodextrin cavities and hydrogen-bonding interactions from molecular imprinting. Multiple adsorptions triggered off a synergetic recognition for target analytes. The SMIPs also performed highly selective recognition in complex real water sample with sensitive detection limits.

Determination of fluoroquinolones in food samples by magnetic solid-phase extraction based on a magnetic molecular sieve nanocomposite prior to high-performance liquid chromatography and tandem mass spectrometry

In this study, a magnetic molecular sieve material (Fe₃O₄@MCM-48) was synthesized by a combination of solvothermal and self-assembly methods. The physicochemical properties of the magnetic molecular sieve material were characterized by scanning electron microscopy, energy-dispersive spectroscopy, magnetic hysteresis loop measurements, transmission electron microscopy, powder X-ray diffraction, N₂ adsorption-desorption analysis, and Fourier transform infrared spectroscopy. The as-synthesized nanocomposite showed various advantages, including easy magnetic-assisted separation, high specific surface area, and a highly interwoven and branched mesoporous structure. The Fe₃O₄@MCM-48 nanocomposite was then used as an effective adsorbent material for magnetic solid-phase extraction of fluoroquinolones (FQs) from water samples. The FQs in the extract were determined via liquid chromatography-tandem mass spectrometry. Adsorption and desorption factors that affected the extraction performance were systematically optimized using spiked purified water samples. Good linearity (with R² > 0.99) was shown by this FQ detection system for FQ concentrations from 5 to 1000 ng L^-1. Moreover, low detection limits (0.7-6.0 ng L^-1) and quantitation limits (2.5-20.0 ng L^-1) and satisfactory repeatability (relative standard deviation < 10%, n = 6) were achieved for water samples. The developed method was also validated for the analysis of FQs in meat and milk samples. Finally, FQs in food and drinking water samples were successfully determined using the developed method. Graphical abstract.

Magnetic molecularly imprinted polymers doped with graphene oxide for the selective recognition and extraction of four flavonoids from Rhododendron species

Herein, a novel magnetic molecularly imprinted polymer doped with reticular graphene oxide (Fe₃O₄@SiO₂-GO@MIPs) was synthesized for the selective recognition and extraction of 4 flavonoids (farrerol, taxifolin, kaempferol, and hyperin) from Rhododendrons species. The Fe₃O₄@SiO₂-GO@MIPs with lamellar membranes showed outstanding adsorption capacity. The 3D cavities complementary to the "shape" of farrerol were "imprinted" on the polymer framework after removal of farrerol template. Competitive binding assays showed that the polymer has a higher selectivity for farrerol compared with other analogues and references. The Fe₃O₄@SiO₂-GO@MIPs as solid-phase extraction adsorbents combined with liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) was used for selective determination of four flavonoids from Rhododendrons samples. The limits of detection (LOD) were 0.07, 0.08, 0.06, and 0.08 μg L^-1 for farrerol, taxifolin, kaempferol, and hyperin, respectively. These results suggest that the prepared Fe₃O₄@SiO₂-GO@MIPs have the potential applicability to extract, purify, and enrich flavonoids from herbs, supplements, and other natural products.

Rapid microwave-assisted distillation–precipitation polymerization for the synthesis of magnetic molecular imprinted polymers coupled to HPTLC determination of perphenazine in human urine

Microwave-assisted distillation–precipitation polymerization (MWDPP) for the synthesis of magnetic molecularly imprinted polymers (MMIPs) under atmospheric pressure is reported.

Synthesis and Evaluation of a Molecularly Imprinted Polymer for the Determination of Metronidazole in Water Samples

A molecularly imprinted polymer was developed and evaluated for selective determination of metronidazole (MNZ) in wastewater. This was achieved by using sodium methacrylate as monomer, toluene as porogen, ethylene glycol dimethacrylate as crosslinker, azobisisobutyronitrile as initiator and metronidazole as template molecule to generate the selectivity of the polymer for the compound, as well as non-imprinted polymers were synthesized. Two different polymerization approaches were used, bulk and emulsion and the polymers obtained by emulsion presented higher retention percentages the MIP 2-M presented the higher retention (83%). The performed method, was validated in fortified water, showing linearity from 10 up to 1000 ng/mL; limit of detection and quantification for compound were between 3 and 10 ng/mL, respectively. Finally, the method was applied in samples of a wastewater treatment plant in the city of San Luis Potosí, México, and the concentrations of MNZ in these samples were 84.1-114 ng/mL.

Dispersive Solid Phase Extraction for the Analysis of Veterinary Drugs Applied to Food Samples: A Review

To achieve analytical success, it is necessary to develop thorough clean-up procedures to extract analytes from the matrix. Dispersive solid phase extraction (DSPE) has been used as a pretreatment technique for the analysis of several compounds. This technique is based on the dispersion of a solid sorbent in liquid samples in the extraction isolation and clean-up of different analytes from complex matrices. DSPE has found a wide range of applications in several fields, and it is considered to be a selective, robust, and versatile technique. The applications of dispersive techniques in the analysis of veterinary drugs in different matrices involve magnetic sorbents, molecularly imprinted polymers, carbon-based nanomaterials, and the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method. Techniques based on DSPE permit minimization of additional steps such as precipitation, centrifugation, and filtration, which decreases the manipulation of the sample. In this review, we describe the main procedures used for synthesis, characterization, and application of this pretreatment technique and how it has been applied to food analysis.

Identification of antibiotics in wastewater: current state of extraction protocol and future perspectives

The release and occurrence of antibiotics in the aquatic environment has generated increased attention in the past few decades. The residual antibiotic in wastewater is important in the selection for antimicrobial resistance among microorganisms and the possibility of forming toxic derivatives. This review presents an assessment of the advancement in methods for extraction of antibiotics with solid phase extraction and liquid-liquid extraction methods applied in different aquatic environmental media. These advanced methods do enhance specificity, and also exhibit high accuracy and recovery. The aim of this review is to assess the pros and cons of the methods of extraction towards identification of quinolones and sulphonamides as examples of relevant antibiotics in wastewater. The challenges associated with the improvements are also examined with a view of providing potential perspectives for better extraction and identification protocols in the near future. From the context of this review, magnetic molecular imprinted polymer is superior over the remaining extraction methods (with the availability of commercial templates and monomers), is based on less cumbersome extraction procedures, uses less solvent and has the advantage of its reusable magnetic phase.

Validated electrochemical and chromatographic quantifications of some antibiotic residues in pharmaceutical industrial waste water

Realistic implementation of ion selective electrodes (ISEs) into environmental monitoring programs has always been a challenging task. This could be largely attributed to difficulties in validation of ISE assay results. In this study, the electrochemical response of amoxicillin trihydrate (AMX), ciprofloxacin hydrochloride (CPLX), trimethoprim (TMP), and norfloxacin (NFLX) was studied by the fabrication of sensitive membrane electrodes belonging to two types of ISEs, which are polyvinyl chloride (PVC) membrane electrodes and glassy carbon (GC) electrodes. Linear response for the membrane electrodes was in the concentration range of 10^-5-10^-2 mol/L. For the PVC membrane electrodes, Nernstian slopes of 55.1, 56.5, 56.5, and 54.0 mV/decade were achieved over a pH 4-8 for AMX, CPLX, and NFLX, respectively, and pH 3-6 for TMP. On the other hand, for GC electrodes, Nernstian slopes of 59.1, 58.2, 57.0, and 58.2 mV/decade were achieved over pH 4-8 for AMX, CPLX, and NFLX, respectively, and pH 3-6 for TMP. In addition to assay validation to international industry standards, the fabricated electrodes were also cross-validated relative to conventional separation techniques; high performance liquid chromatography (HPLC), and thin layer chromatography (TLC)-densitometry. The HPLC assay was applied in concentration range of 0.5-10.0 μg/mL, for all target analytes. The TLC-densitometry was adopted over a concentration range of 0.3-1.0 μg/band, for AMX, and 0.1-0.9 μg/band, for CPLX, NFLX, and TMP. The proposed techniques were successfully applied for quantification of the selected drugs either in pure form or waste water samples obtained from pharmaceutical plants. The actual waste water samples were subjected to solid phase extraction (SPE) for pretreatment prior to the application of chromatographic techniques (HPLC and TLC-densitometry). On the other hand, the fabricated electrodes were successfully applied for quantification of the antibiotic residues in actual waste water samples without any pretreatment. This finding assures the suitability of the fabricated ISEs for environmental analysis.