Imidazolium ionic-liquid-modified phenolic resin for solid-phase extraction of thidiazuron and forchlorfenuron from cucumbers

Porous phenolic resin regulated by alcohol-based deep eutectic solvent for selective extraction and separation of tanshinones from Salvia miltiorrhiza

Deep eutectic solvents (DES), regarded as promising green solvents, have gained attention due to their distinctive properties, particularly in analytical chemistry. While the use of DES in solvent extraction and separation has been extensively studied, its application in the synthesis of adsorbents has just begun. Phenolic resin, with its polyhydroxy structure and stable spherical morphology, could serve as an effective as adsorbents for enrichment of active ingredients in herbal medicine. Designing adsorbents with high selectivity and adsorption capacity presents a critical challenge in the enrichment of active ingredients in herbal medicine. In this study, alcohol-based DESs were employed as regulators of morphology and structure instead of organic solvents, facilitating the creation of polyhydroxy structure, adjustable pores and high specific surface areas. The resulting DES-regulated porous phenolic resin demonstrated enhanced extraction and separation capacity for active ingredients compared to conventional spherical phenolic resin owing to the alcohol-based DES offering more interaction modes with the analytes.

Enhanced Electrical Properties and Impact Strength of Phenolic Formaldehyde Resin Using Silanized Graphene and Ionic Liquid

In this study, to improve the electrical properties and impact strength of phenolic formaldehyde (PF) resin, PF-based composites were prepared by mixing graphene and the ionic liquid 3-decyl-bis(1-vinyl-1H-imidazole-3-ium-bromide) (C10[VImBr]2) via hot blending and compression-curing processes. The graphene surface was modified using a silane coupling agent. The synergistic effect of graphene and C10[VImBr]2 on the electrical properties, electromagnetic shielding efficiency, thermal stability, impact strength, and morphology of PF/graphene and PF/graphene/C10[VImBr]2 composites was then investigated. It was found that the electrical conductivity of the composites significantly increased from 2.3 × 10-10 to 4.14 × 10-3 S/m with an increase in the graphene content from 0 to 15 wt %, increasing further to 0.145 S/m with the addition of 5 wt % C10[VImBr]2. The electromagnetic shielding efficiency of the composite increased from 4.70 to 28.64 dB with the addition of 15 wt % graphene, while the impact strength of the composites rose significantly from 0.59 to 1.13 kJ/m2 with an increase in the graphene content from 0 to 15 wt %, reaching 1.53 kJ/m2 with the addition of 5 wt % C10[VImBr]2. Scanning electron microscopy images of the PF/GNP/C10[VImBr]2 composites revealed a rough morphology with numerous microcracks.

Recent Progress on Green New Phase Extraction and Preparation of Polyphenols in Edible Oil

With the proposal of replacing toxic solvents with non-toxic solvents in the concept of green chemistry, the development and utilization of new green extraction techniques have become a research hotspot. Phenolic compounds in edible oils have good antioxidant activity, but due to their low content and complex matrix, it is difficult to achieve a high extraction rate in a green and efficient way. This paper reviews the current research status of novel extraction materials in solid-phase extraction, including carbon nanotubes, graphene and metal-organic frameworks, as well as the application of green chemical materials in liquid-phase extraction, including deep eutectic solvents, ionic liquids, supercritical fluids and supramolecular solvents. The aim is to provide a more specific reference for realizing the green and efficient extraction of polyphenolic compounds from edible oils, as well as another possibility for the future research trend of green extraction technology.

Chemiluminescence method based on the KIO4 -K2 CO3 -Mn2+ reaction for rapid and sensitive determination of forchlorfenuron in dried fruit

Forchlorfenuron is a low-toxic phenylurea plant growth regulator. Excessive intake of forchlorfenuron can lead to metabolic disorders of the matrix and be harmful to human health. The chemiluminescence intensity of the KIO4 -K2 CO3 -Mn2+ reaction decreased in the presence of forchlorfenuron. Based on this result, a rapid and sensitive chemiluminescence method was established to determine forchlorfenuron by combining it with a batch injection static device. The injection speed, injection volume and reagent concentration of the forchlorfenuron-KIO4 -K2 CO3 -Mn2+ chemiluminescence reaction were optimized. Under these optimized conditions, the linear range of the method was 1.0-200.0 μg/L, and the limit of detection was 0.29 μg/L (S/N = 3). The chemiluminescence method for the determination of forchlorfenuron could be completed in 10 s. The method was applied to detect the residual forchlorfenuron in dried fruit samples, and the results are consistent with high-performance liquid chromatography-mass spectrometry. This method has the advantages of high sensitivity, rapid response, less reagent consumption, and convenient operation. It will provide a new perspective for chemiluminescence for the rapid and sensitive determination of forchlorfenuron in various complex samples.

Production of a Monoclonal Antibody for the Detection of Forchlorfenuron: Application in an Indirect Enzyme-Linked Immunosorbent Assay and Immunochromatographic Strip

In this study, a monoclonal antibody (mAb) specific to forchlorfenuron (CPPU) with high sensitivity and specificity was produced and designated (9G9). To detect CPPU in cucumber samples, an indirect enzyme-linked immunosorbent assay (ic-ELISA) and a colloidal gold nanobead immunochromatographic test strip (CGN-ICTS) were established using 9G9. The half-maximal inhibitory concentration (IC₅₀) and the LOD for the developed ic-ELISA were determined to be 0.19 ng/mL and 0.04 ng/mL in the sample dilution buffer, respectively. The results indicate that the sensitivity of the antibodies prepared in this study (9G9 mAb) was higher than those reported in the previous literature. On the other hand, in order to achieve rapid and accurate detection of CPPU, CGN-ICTS is indispensable. The IC₅₀ and the LOD for the CGN-ICTS were determined to be 27 ng/mL and 6.1 ng/mL. The average recoveries of the CGN-ICTS ranged from 68 to 82%. The CGN-ICTS and ic-ELISA quantitative results were all confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with 84-92% recoveries, which indicated the methods developed herein are appropriate for detecting CPPU in cucumber. The CGN-ICTS method is capable of both qualitative and semiquantitative analysis of CPPU, which makes it a suitable alternative complex instrument method for on-site detection of CPPU in cucumber samples since it does not require specialized equipment.

TiO2@MOF-919(Fe-Cu) as a sorbent for the extraction of benzoylurea pesticides from irrigation water and fruit juices

The TiO₂@MOF-919(Fe-Cu) solid-phase extraction material was prepared by growing MOF-919(Fe-Cu) in situ on three-dimensional radial TiO₂ microspheres by a simple solvothermal method. This combination drew on both the resources of good single dispersion and extraction rate, which made it a better extraction material. It was accompanied with high-performance liquid chromatography (SPE-HPLC) for the separation and determination of four benzoylurea pesticides (triflumuron, chlorbenzuron, teflubenzuron and diflubenzuron) in afforestation irrigation water and juice samples (grape, peach and apple juices). Under the optimal conditions, the linearity of the method ranged from 1 to 400 μg L^-1 with a correlation coefficient (R²) ≥ 0.9994, while the detection limit was in the range of 0.40-0.56 μg L^-1 for the four pesticides. The adopted material showed good reusability and can be used no less than 10 times. The intra-day and inter-day precision were in the range of 1.78-3.24% and 4.06-5.08%, respectively. The proposed method was then successfully applied for the detection of benzoylurea pesticides in the spiked samples with good recoveries (72.3-108.4%) and good precision (5.15%) due to π-π and hydrophobic interactions between the analytes and adsorbent. The results show that the composite had the potential to be used as a SPE adsorbent for the enrichment and extraction of benzene ring structures containing imide groups in actual samples.

Green synthesis of phloroglucinol-urotropine porous polymer: Ingenious miniaturized solid phase extraction for efficient purification and determination of polycyclic aromatic hydrocarbons in lotus roots

Polycyclic aromatic hydrocarbons (PAHs) posed a serious threat to food safety and human health due to long-term emission. In this work, a new method was established using phloroglucinol-urotropine porous polymer (PU-PP) in a pipette tip for solid phase extraction (PT-SPE) for the first time and used prior to determination of four PAHs (phenanthrene, anthracene, fluoranthene, and pyrene) in lotus roots. Synthesis of the PU-PP adsorbent was green compared with alternatives; urotropine was used as a cross-linker and ethanol-water as the solvent. PU-PP-based PT-SPE had the advantages of low solvent consumption, good purification, practicability, stability, and low-cost. The proposed pre-purification method offered low limits of detection (0.09-0.28 ng/g) and good recoveries (84.6-114.3 %, RSDs ≤ 5.6 %) for determination of the four PAHs, which were detected at trace concentrations in samples. This new method provides an alternative for monitoring trace pollutants in aquatic plant ingredients.

Ionic Liquid Modified Porous Polymer as a Dispersive Filter Extraction Adsorbent for Simple, Sensitive, and Efficient Determination of Chlorotriazine Herbicides in Irrigation Water

Triazine herbicides (TRZHs) are widely used in agricultural production, but their improper use can threaten the environment and organisms. Herein, rapid extraction of four chlorotriazine herbicides (Cl-TRZHs) in irrigation water was achieved using an ionic liquid modified porous m-aminophenol formaldehyde resin (IL-MAPFR) as a dispersive filter extraction (DFE) adsorbent. The IL-MAPFR shows excellent adsorption performance for four Cl-TRZHs (simazine, cyanazine, atrazine, and terbuthylazine), with a large specific surface area (158.1 m² g^-1) and fast mass transfer (2 min). The adsorption process conforms to the pseudo-second-order kinetics and Freundlich isotherm models. The four Cl-TRZHs were concentrated 12-16-fold after the IL-MAPFR-DFE method. Coupled with high-performance liquid chromatography, an accurate and sensitive determination method for four Cl-TRZHs in irrigation water was established, with low detection limit (0.11-0.20 ng mL^-1), high recoveries (91.5-110%), and excellent precision (relative standard deviations (RSDs) ≤ 8.4%). This method provides technical support for agricultural irrigation water quality monitoring and has great application potential in water safety, especially pesticide residues.

A Sensitive Monoclonal-Antibody-Based ELISA for Forchlorfenuron Residue Analysis in Food Samples

In this study, forchlorfenuron (CPPU) was coupled with succinic anhydride to yield a CPPU hapten (CPPU-COOH), and a high-affinity monoclonal antibody (mAb) that can specifically recognize CPPU was produced. Using this mAb as a recognition reagent, a sensitive indirect competitive enzyme-linked immunosorbent assay (icELISA) for CPPU was optimized, which exhibits an IC50 of 1.04 ng/mL, a limit of detection of 0.16 ng/mL, and a linear range of 0.31–3.43 ng/mL for CPPU. Cross-reactivity percentages with six analogues were all below 6%. The average recovery rates for cucumber and orange samples were from 85.23% to 119.14%. The analysis results of this icELISA showed good consistency with those from liquid chromatography mass spectrometry. These results suggest that the proposed icELISA provides a sensitive, specific, and reliable strategy for CPPU detection in food samples.

Hydrophilic deep eutectic solvents modified phenolic resin as tailored adsorbent for the extraction and determination of levofloxacin and ciprofloxacin from milk

A reliable and efficient method for the simultaneous extraction and determination of antibiotics of ciprofloxacin and levofloxacin from milk was developed with solid phase extraction based on tailored adsorbent materials of deep eutectic solvents modified phenolic resin (DES-R-SPE). Six types of polyhydric alcohol-based hydrophilic DESs were prepared to modify the phenolic resin with the compositions of 3-aminophenol as a functional monomer, glyoxylic acid as a crosslinker, and polyethylene glycol 6000 as a porogen. And the prepared DES-Rs showed better extraction capacities for the target analytes than the unmodified phenolic resin because of more hydrogen bonding and electrostatic interactions supplied by DESs. The choline chloride-glycerol-based resin (DES¹-R) with the highest adsorption amounts was selected and the adsorption behavior of it was studied with static adsorption and the dynamic adsorption performance; the adsorption process followed Freundlich isotherm (R² ≥ 0.9337) and pseudo-second-order (R² ≥ 0.9951). The present DES¹-R-SPE method showed good linear range from 0.5 to100 μg mL^-1 (R² ≥ 0.9998), good recoveries of spiked milk samples (LEV, 96.7%; CIP, 101.5%), and satisfied repeatability for intra-day and inter-day (LEV, RSD≤5.4%; CIP, RSD≤4.6%).

Dissipation behavior, residue dynamics, and dietary risk assessment of forchlorfenuron in postharvest kiwifruits during simulated cold chain logistics and store shelf life

Forchlorfenuron (CPPU) is often applied during the cultivation of kiwifruit to produce larger fruit. To address degradation patterns of CPPU during simulated cold chain logistics and simulated shelf life of the fruit after harvest, appropriate storage methods and safe consumption behavior can be investigated. In this study, an ultra-high-performance liquid chromatography-tandem mass spectrometry method was adopted to detect CPPU residues under different conditions. CPPU in kiwifruit stored at 6 °C had a half-life of 40.8-77.0 days. However, when kiwifruit was stored at 0 °C under simulated cold chain storage conditions, the half-life of CPPU was 63.0-115.5 days, implying that lower storage temperatures can reduce the degradation rate of CPPU. The residues of CPPU in kiwifruit pulp declined with time, and the reduction followed the first-order kinetics equation. More CPPU residues were present in the pulp of postharvest kiwifruit treated with exogenous ethylene than in the pulp of untreated kiwifruit. Thus, using exogenous ethylene for artificial ripening after harvest is not recommended. We determined that the appropriate cold chain storage temperature is 6 °C. It is recommended that the public select kiwifruit stored for at least 2 weeks. The estimated chronic and acute dietary risk quotients of CPPU are ≤ 0.79% and ≤ 0.11%, respectively. Therefore, it is highly unlikely that consumers will be poisoned by CPPU due to kiwifruit consumption. Our results provide scientific evidence regarding the adoption of appropriate kiwifruit storage methods and consumption behavior to enhance consumption safety.

[Research progress in application of immobilized ionic liquid materials to separation by solid-phase extraction]

Ionic liquids are low-temperature molten salts with almost no vapor pressure, and they are composed of organic cations and inorganic anions. Ionic liquids are characterized by the properties of good chemical stability, high solubility, designable structure, high conductivity and so on. The physicochemical properties of an ionic liquid depend on the nature and size of the cation and anion, which confer unique characteristics; hence, these reagents are also termed "designed extractants." As a new class of green solvents, ionic liquids are potential replacements to traditional volatile organic solvents used for extraction; for this reason, ionic liquids have attracted the attention of scientists. Research on the methods of preparation and applications of ionic liquids is being diversified, and they are extensively used in catalytic chemistry, photoelectron chemistry, materials chemistry, analytical chemistry, etc. By functional guiding design, the structures of ionic liquids, especially the imidazole ring cations, can be easily grafted with active groups such as hydroxyl, amino, carboxyl, and cyano groups, so that interactions between the ionic liquids and target molecules can be promoted via the formation of π-π bonds, hydrogen bonds, ionic bonds, and van der Waals forces. In addition, ionic liquids can be readily immobilized on solid carriers by physical or chemical means in order to obtain a new solid material with ionic liquids embedded internally or decorated on the surface. Furthermore, ionic liquids could be converted into ionic liquid-immobilized composite materials by impregnation, grafting, etc. The resulting composites not only suffer minimal loss of ionic liquids but also retain the typical characteristics of the ionic liquids and solid materials, thus showing improved mass transfer performance and better adsorption performance. Immobilized materials are characterized by high enrichment efficiency, high adsorption capacity, good stability, and strong extraction selectivity, as well as the presence of numerous recognition sites and high utilization rate of ionic liquids. In recent years, they have been widely used as solid-phase extraction adsorption materials for the separation of small organic molecules. This review introduces common immobilization methods and the characteristics of ionic liquid-immobilized materials, as well as their application in solid-phase extraction. In this paper, methods for the immobilization of ionic liquids with solid carriers such as silica gel, molecular sieves, molecularly imprinted polymers, graphene oxide, and magnetic nanomaterials are summarized, and the application of ionic liquid-immobilized materials in solid-phase extraction is reviewed. The target substances include alkaloids, flavonoids, polyphenols, and other natural active components as well as common drug molecules, organic pesticides, and other organic small molecular compounds. The properties, applications, and separation mechanisms of ionic liquids immobilized with various carriers are systematically introduced. Literature survey shows that the distribution of the binding active sites of ionic liquid-immobilized materials to the target molecules is more uniform, which increases the adsorption capacity of the materials. The adsorption efficiency of ionic liquid-immobilized materials is related to the type of ionic liquid, amount of adsorption material, concentration of the sample solution, adsorption temperature, solution pH, flow rate of the eluent, and type and amount of the eluting solvent. The existing disadvantages of ionic liquids, such as simple structures, insufficient basic theoretical research, and unsatisfactory extraction degree in complex matrixes would also be discussed. The corresponding solutions would be presented with the aim of providing guidance for the application of ionic liquid-immobilized materials in the separation and analysis of targets in complex matrices, thus paving the way for a new direction in the field of extraction and separation.

Enhanced extraction of organophosphorus pesticides from fruit juices using magnetic effervescent tablets composed of the NiFe2O4@SiO2@PANI-IL nanocomposites

The reported ionic liquid (IL)-based magnetic effervescent tablets are a result of direct addition of ILs and magnetic nanoparticles (MNPs). In effervescent reaction-enhanced microextraction procedures, the dissociation between ILs and MNPs easily leads to loss of ILs due to aqueous solubility, thereby decreasing the extraction efficiency. Herein, we attached a hydrophilic IL ([BMIM]Br) onto the surface of NiFe₂O₄@SiO₂@polyaniline (NiFe₂O₄@SiO₂@PANI-IL) to prepare novel core–shell-like multi-layer nanocomposites. Magnetic effervescent tablets were composed of Na₂CO₃ as an alkaline source, tartaric acid as an acidic source and as-synthesized nanocomposites as an extractant. The nanocomposites were used in an effervescent reaction-enhanced magnetic solid-phase extraction (ERMSE) for the extraction of four organophosphorus pesticides (OPPs) in fruit juices prior to HPLC-DAD detection. Under optimized conditions, this method provided low limits of detection (0.06–0.17 μg L⁻¹), high recoveries (80.6–97.3%) and excellent precision (1.1–5.2%) for OPP quantification in five fruit juices. Notably, the three-layer core–shell nanocomposites were efficiently recycled for at least eight extraction cycles with a recovery loss of <10%. The novelty of this study lies in: (1) for the first time, the ILs-based hybrid magnetic nanocomposites were prepared with appropriate pore size/volume and more active sites for OPPs; (2) the combination of the nanocomposites with effervescent tablets realizes rapid dispersion of CO₂ bubbles, and convenient magnetic separation/collection into one synchronous step; and (3) due to there being no requirement of electrical power, it is feasible for use in field conditions. Thus, the ERMSE method has excellent potential for conventional monitoring of trace-level OPPs in complex fruit juice matrices.

The reported ionic liquid (IL)-based magnetic effervescent tablets are a result of direct addition of ILs and magnetic nanoparticles (MNPs).

Thermally Driven Separation of Perfluoroalkyl Substances with High Efficiency

Perfluoroalkyl substances (PFASs), such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), can contaminate the surface and groundwater. Common treatment strategies and adsorbents have low adsorption efficiencies and poor selectivity toward PFASs because of the extremely low surface energy of these compounds. This paper reports the use of a phenolic resin (PR) modified with perfluoroalkyl (PFA) segments and thermally sensitive poly(ethylene glycol) (PEG) segments (PR-PEG-PFA) to remove PFOA and PFOS from water. The modified PR microspheres captured >90% of PFASs and were insensitive to common anionic surfactants. By treating simulated wastewater six times with this material, the PFOA concentration in water was reduced from 1 ppm to 43 ppt (43 ng L^-1), showing that PR-PEG-PFA is a promising adsorbent for PFAS separation, recovery, and recycling.