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.

Lipase-based MIL-100(Fe) biocomposites as chiral stationary phase for high-efficiency capillary electrochromatographic enantioseparation.

A novel chiral porous column was fabricated by lipase immobilized MIL-100(Fe) biocomposites as chiral stationary phase through covalent coupling and applied to capillary electrochromatographic enantioseparation. MOF-based lipase biocomposites not only enhance stereoselective activities but also improve the stability and applicability of the enzyme. The functionalized porous columns were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and powder X-ray diffraction. The performance of the porous column was evaluated by enantioseparating amino acid enantiomers, affording high resolution over 2.0. Besides, the enantio-resolutions of phenylephrine, phenylsuccinic acid, chloroquine, and zopiclone were also greater than 2.0. The relative standard deviations of run-to-run, intra-, and inter-day repeatability were within 4.0% in terms of resolution and retention time, exhibiting excellent stability of the column. Conceivably, the results show that MOF-based lipase composites as chiral stationary phase offer a highly efficient means for enantioseparation in capillary electrochromatography, attributing to the enhanced enantioselective activities of lipase by highly ordered frameworks.

Preparation of magnetic nitrogen-doped porous carbon by incomplete combustion with solvothermal synthesis for magnetic solid-phase extraction of benzoylurea insecticides from environmental water.

In this work, magnetic nitrogen-doped porous carbon (Fe3O4@N-PC) was prepared via incomplete combustion coupled with solvothermal synthesis for extraction of four benzoylureas (BUs) insecticides. Among them, nitrogen-doped porous carbon was produced through incomplete combustion of filter paper loaded with mixture formed by Zn(NO3)2·6H2O and polyethyleneimine solution, and magnetic nanoparticles were further introduced by solvothermal method. Compared with magnetic porous carbon (Fe3O4@PC), the surface hydrophilicity of Fe3O4@N-PC was improved by virtue of the doping of nitrogen atoms, and the dispersion of Fe3O4 was more uniform, which greatly exposed the adsorption site. The characterization of Fe3O4@N-PC were carried out by TEM, XRD, elemental analysis, XPS, BET and magnetic hysteresis curve. Besides, Fe3O4@N-PC was successfully used as magnetic solid-phase extraction (MSPE) adsorbent, which showed excellent enrichment factors and extraction recoveries toward polar BUs insecticides due to the polar surface and introduction of Lewis-basic nitrogen. The optimum amount of Fe3O4@N-PC adsorbent, extraction time, pH value, desorption solvent, desorption time and PEI concentration for BUs insecticides extraction were determined to be 3 mg, 10 min, 8, acetone/acetic acid (19:1, V/V), 6 min and 60 g L-1, respectively. Under this experimental condition, the enrichment factors ranged from 182 to 192 with good intra- and inter-day relative standard deviations (RSDs). The calibration lines were linear over the concentration in the range of 1-800 µg L-1, the limit of detection (LOD) and limit of quantification (LOQ) were 0.3 µg L-1 as well as 1 µg L-1, respectively. The recoveries for spiked sample ranged from 90.7 to 107.3% in spiked Yellow River water with the RSDs less than 7.0%. The results showed that the established MSPE strategy based on Fe3O4@N-PC could be used for the detection of trace BUs in complex samples.

Utilization of ionic deep eutectic solvent as sustainable mobile phase additive in high-performance liquid chromatography for improving the separation of biogenic amines.

Biogenic amines are present in large quantities in fermented foods and are a key marker for assessing food safety. This paper proposes a novel method for high-performance liquid chromatography analysis of biogenic amines using deep eutectic solvent as a mobile phase additive. After screening eight synthetic deep eutectic solvents and comparing them with several common additives, deep eutectic solvents based on choline chloride and ethylene glycol showed significant effects in improving the separation of biogenic amines. A Box-Behnken design of 17 runs was used to screen and optimize the key chromatographic parameters, resulting in an expected composition of the mobile phase of 0.73% deep eutectic solvent, 65% acetonitrile, and a column temperature of 28°C. The proposed method exhibited excellent linearity (0.1-50 µg/ml, R2 ≥ 0.9987), limit of detection (0.007-0.031 µg/ml), precision (1.28%-5.34%) and accuracy (87.2%-110.6%). The method can be applied successfully to the separation and analysis of biogenic amines in cooking wine samples.

The Separation of Chlorobenzene Compounds from Environmental Water Using a Magnetic Molecularly Imprinted Chitosan Membrane.

In this work, a magnetic molecularly imprinted chitosan membrane (MMICM) was synthesized for the extraction of chlorobenzene compounds in environmental water using the membrane separation method. The optimal extraction amount for chlorobenzene (9.64 mg·L-1) was found to be a 1:2 solid to liquid ratio, with a 20 min extraction time and 35 °C extraction temperature. This method proved to be successfully applied for the separation and trace quantification of chlorobenzene compounds in environmental water, with the limit of detection (LOD) (0.0016-0.057 ng·L-1), limit of quantification (LOQ) (0.0026-0.098 ng·L-1), and the recoveries ranging (89.02-106.97%).

Enantioseparation by simultaneous biphasic recognition using mobile phase additive and chiral stationary phase in capillary electrochromatography.

Biphasic chiral recognition was first applied for the enantioseparation acidic drugs in capillary electrochromatography. The biphasic recognition system was composed of mobile phase additive (ß-cyclodextrin) and monolithic chiral stationary phase (proteins). The pretreated silica-fused capillary was treated with 3-trimethoxysilyl propyl methacrylate to attach double bond ligand onto the surface. The mixed monolithic chiral stationary phase was constructed with bovine serum albumin and pepsin using one-pot polymerization by chemical covalent coupling, while dimethyl sulfoxide and methanol were used as the progenic solvents. The effects of the type and concentration of ß-cyclodextrin additive as well as pH value of the mobile phase on the separation efficiency were optimized. The performance of the biphasic recognition system was validated by separating acidic drugs (such as ketoprofen, ibuprofen, loxoprofen, flurbiprofen and carprofen) in capillary electrochromatography, achieving outstanding separation efficiency. In terms of migration time and resolution, the run-to-run, intra-day, and inter-day repeatability through relative standards deviation were within 5.0%, exhibiting excellent stability of the biphasic recognition system. Conceivably, the experimental result reveals that biphasic chiral recognition capillary electrochromatography offers a promising prospect for enantioseparation of chiral compounds in a highly efficient manner.

Multienzyme mimetic activities of holey CuPd@H-C3N4 for visual colorimetric and ultrasensitive fluorometric discriminative detection of glutathione and glucose in physiological fluids.

Nanozymes with multiple activities have drawn immense interest owing to their great prospect in biochemical analysis. Fabricating nanomaterials-based artificial enzymes for multiple-enzyme mimetic activity is a significant challenge. This paper reports a sensitive biosensing platform to mimic the peroxidase, oxidase, and catalase-like activity by bimetallic CuPd embedded holey carbon nitride (CuPd@H-C3N4). Owing to the combination of porous H-C3N4 and bimetallic CuPd nanoparticles, the CuPd@H-C3N4 exhibited a large specific surface area, extremely high mobility and catalytic activity of electrons, resulting in remarkable triple-enzyme mimetic activity. Owing to the excellent oxidase/peroxidase-like activities of CuPd@H-C3N4, a visual colorimetric and ultrasensitive fluorometric biosensing platform was established for the discriminatory detection of glutathione (linear range: 2-40 µM) and glucose (linear range: 0.1-40 µM) in physiological fluids, respectively. The fluorescence detection system showed ultrahigh sensitivity toward H2O2, with a linear range of 30-1500 nM. In addition, a one-step glucose detection strategy was proposed to replace the traditional, complicated two-step detection method, which simplifies the operation steps and improves the detection efficiency. The assay presented in this paper offers an effective multiple-enzymes mimicking detection platform that broaden its promising applications in biomedicine analysis and monitoring.

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.

Imidazole-modified C6 -chitosan derivatives used to extract ß-sitosterol from edible oil samples with a microwave-assisted solid phase extraction method.

ß-Sitosterol is a major bioactive constituent in plants with potent anticancer effects against many human cancer cells, but its bioavailability and therapeutic efficacy are limited by its poor solubility in water. In this study, C6 -imidazole chitosan, C6 -1-methylimidazole chitosan, C6 -1-ethylimidazole chitosan, C6 -1-vinylimidazole chitosan, C6 -1-allylimidazole chitosan, and C6 -1-butylimidazole chitosan were prepared to extract ß-sitosterol from edible oil samples via ultrasonic-assisted solid liquid extraction. The structures and properties of the newly synthesized products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and elemental analysis. The extraction abilities of the derivatives were tested in the experiment with high-performance liquid chromatography (limit of detection 0.21 µg/g and limit of quantification 0.67 µg/g), and the % relative standard deviation (<3.25%) and recovery values of the prepared chitosan derivatives toward ß-sitosterol (average: 100.20%) were acceptable. The spiked interday and intraday recoveries of ß-sitosterol were 102.60 ± 2.78 and 103.90 ± 3.04%, respectively. The actual amounts of ß-sitosterol extracted from three real samples using C6 -imidazole chitosan according to the solid phase extraction method were 3302.40, 901.70, and 2045.60 mg/kg for corn oil, olive oil, and pea oil, respectively.

Growth of two-layer copolymer as the stationary phase with very high separation efficiency for separating peptides in capillary electrochromatography.

Open tubular CEC (OT-CEC) column with a very high separation efficiency was prepared for peptides separation. A pretreated silica-fused capillary was reacted with 3-(methacryloxy) propyltrimethoxysilane followed by vinylbenzyl chloride and divinylbenzene to produce first thin monolithic monolayer. The second copolymer layer was formed on thin monolithic monolayer of the capillary by reversible addition-fragmentation transfer polymerization of N-phenylacrylamide and styrene. The key parameters including buffer pH value and organic modifier were systematically evaluated to provide the optimal chromatographic condition. The resultant OT-CEC columns were validated by separating a synthetic mixture of peptides and cytochrome C tryptic digest in capillary electrochromatography. The number of theoretical plates as high as 2.4 million per column was achieved for synthetic mixture peptides. In addition, the fabricated OT-CEC column also resolved more than 18 high-efficiency digestion peptides from a mixture containing tryptic digest of cytochrome C. The column to column and inter- to intraday repeatabilities of OT-CEC column through RSD% were found better than 3.0%, exhibiting satisfactory stability and repeatability of the two-layer deposited OT-CEC column. The results reveal that the open tubular capillary column modified with two-layer copolymer shows the great prospect for the separation of proteins in capillary electrochromatography.

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%).

Deep eutectic solvents cross-linked molecularly imprinted chitosan microsphere for the micro-solid phase extraction of p-hydroxybenzoic acid from pear rind.

A visual, rapid, and sensitive micro-solid phase extraction method was developed for the detection of p-hydroxybenzoic acid using molecularly imprinted chitosan microspheres based on deep eutectic solvents, both as a functional monomer and template. The parameters were optimized by using the response surface methodology strategy. The extraction capacity of p-hydroxybenzoic acid from pear rind under the optimized conditions using response surface methodology was 46.32 mg/g, when the pH of the extract solution (2), extraction time (35 min), extraction temperature (30°C), and adsorbent dosage (2 mg). The molecularly imprinted chitosan microspheres produced higher selectivity and extraction capacity than the traditional materials.

Preparation of levofloxacin-imprinted nanoparticles using designed deep eutectic solvents for the selective removal of levofloxacin pollutants from environmental waste water.

A deep eutectic solvent (DES) was prepared from choline chloride (ChCl) and methacrylic acid (MAA) and used as an eco-friendly surfactant and functional monomer. The process of producing DES and its free energy of formation (ΔG = -37.225 kcal mol-1) were evaluated theoretically by density-functional theory. The designed DES (ChCl-MAA) was introduced as a novel eco-friendly functional monomer (MAA as the control group) during the preparation of levofloxacin-imprinted nanoparticles (LINs) based on molecular imprinting technology. The nanoparticles were characterized using a range of techniques. The nanoparticles were applied as an adsorbing material to the selective removal of levofloxacin from environmental waste water. The selective removal and adsorption capacity of the adsorbing material were evaluated by high-performance liquid chromatography. Based on the introduction of DES, DES-LINs had better adsorption capacity for levofloxacin than common LINs. This method had the simple operation, rapid adsorption and efficient decontamination.

Solid-Phase Extraction of Catechins from Green Tea with Deep Eutectic Solvent Immobilized Magnetic Molybdenum Disulfide Molecularly Imprinted Polymer.

A type of molecular-imprinted polymer with magnetic molybdenum disulfide as a base and deep eutectic solvent as a functional monomer (Fe3O4@MoS2@DES-MIP) was prepared with surface molecular imprinting method. It was applied as the adsorbent for the selective recognition and separation of (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate in green tea in the process of magnetic solid-phase extraction (MSPE) combined with high-performance liquid chromatography (HPLC). The structure of Fe3O4@MoS2@DES-MIP was characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The adsorption properties and selective recognition ability on (-)-epigallocatechin gallate and the other four structural analogues were examined and compared. The results show that the polymer has excellent selective recognition ability for (-)-epigallocatechin gallate, and its adsorption capacity was much higher than that of structural analogues. The Fe3O4@MoS2@DES-MIP not only has the special recognition ability to template a molecule, but also can be separated by magnets with high separation efficiency and can be used in MSPE.

Multi-phase extraction of ephedrine from Pinellia ternata and herbal medicine using molecular imprinted polymer coated ionic liquid-based silica.

INTRODUCTION: Ephedrine is a typical compound found in lots of plant species that is used in several medicines for the treatment of asthma and bronchitis. However, excess amounts are harmful to humans, so it needs to be removed. OBJECTIVE: This study developed a multi-phase extraction (MPE) method with a molecular imprinted polymer (MIP) coated ionic liquid (IL)-based silica (SiO2 @IL@MIP) to simultaneously extract and separate ephedrine from Pinellia ternata, 10 medicines, and urine samples. METHODS: IL was immobilized on silica. Subsequently, the IL was combined with the functional monomer, followed by the addition of the crosslinker and template. The resulting sorbent was applied to the MPE, and the extraction, washing and elution solvents were evaluated. RESULTS: Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) confirmed the synthesis of SiO2 @IL@MIP. A maximum adsorption amount of 5.76 mg/g was obtained at 30°C at a neutral pH. In MPE, 10.00 mL of methanol could extract all the ephedrine from Pinellia ternata. The interference was removed by washing with 4.00 mL of water, ethanol, and acetonitrile. Finally, 8.00 mL of methanol/acetic acid (99:1, v/v) was applied as the elution solvent. The following were extracted: 5.50 µg/g of ephedrine from Pinellia ternata, 0.00-46.50 µg/g from the 10 herbal medicines, and 68.70-102.80 µg/mL in the urine samples. CONCLUSION: The proposed method was applied successfully to the simultaneously extraction and separation of ephedrine from plants and medicines. These results are expected to provide important data for the development of new methods for the separation and purification of bioactive compounds.

Deep eutectic solvents skeleton typed molecularly imprinted chitosan microsphere coated magnetic graphene oxide for solid-phase microextraction of chlorophenols from environmental water.

Novel molecularly imprinted chitosan microspheres were prepared on the surface of magnetic graphene oxide, with deep eutectic solvents both as a functional monomer and template. The prepared molecularly imprinted chitosan microspheres-magnetic graphene oxide was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller surface area, thermogravimetric analysis were subsequently combined with solid-phase micro-extraction for simultaneous separation and enrichment of the extraction of chlorophenols from environmental water. Factors affecting the extraction efficiency of chlorophenols were optimized using response surface methodology. The actual extraction capacities under the optimal conditions (liquid to solid ratio = 3, cycles of adsorption/desorption = 5, 40°C extraction temperature, and extraction time for 35 min) were 86.90 mg/g. Compared to the traditional materials, the molecularly imprinted chitosan microspheres-magnetic graphene oxide produced higher selectivity and extraction capacity.

Preparation of deep eutectic solvent-based hexagonal boron nitride-molecularly imprinted polymer nanoparticles for solid phase extraction of flavonoids.

Hexagonal boron nitride (h-BN) is introduced as a 2D scaffold during the preparation of molecularly imprinted polymers (MIPs). The MIPs were prepared from deep eutectic solvents (DES) or from DES containing h-BN, crosslinking agent (ethylene glycoldimethacrylate), initiator (AIBN), porogen (methanol), and template (quercetin). The recognition site of the monomer is protected by the hydrogen bond of the DES before the MIP is polymerized. The formation of the final MIP was analyzed theoretically using density-functional theory. The nanoparticles were characterized by scanning electron microscopy, nitrogen sorption analysis, thermogravimetry and Fourier transform infrared spectroscopy. The introduction of h-BN resulted in an increase in the surface area of the nanoparticles. They were applied as a solid phase extraction sorbent for the extraction of flavonoids (specifically of quercetin, isorhamnetin and kaempferol) from Ginkgo biloba leaves. Following extraction with ethanol, they were quantified by HPLC. The new sorbent has distinctly improved recognition capability for flavonoids compared to conventional MIP nanoparticles. Graphical abstractDeep eutectic solvent (DES)-based molecularly imprinted polymer (MIP) was polymerized on the surface of hexagonal boron nitride (h-BN). The h-BN-MIP nanoparticles were applied as a solid phase extraction sorbent for the specific recognition of flavonoids.

Determination of Heavy Metal Ions and Organic Pollutants in Water Samples Using Ionic Liquids and Ionic Liquid-Modified Sorbents.

Water pollution, especially by inorganic and organic substances, is considered as a critical problem worldwide. Several governmental agencies are listing an increasing number of compounds as serious problems in water because of their toxicity, bioaccumulation, and persistence. In recent decades, there has been considerable research on developing analytical methods of heavy metal ions and organic pollutants from water. Ionic liquids, as the environment-friendly solvents, have been applied in the analytical process owing to their unique physicochemical properties. This review summarizes the applications of ionic liquids in the determination of heavy metal ions and organic pollutants in water samples. In addition, some sorbents that were modified physically or chemically by ionic liquids were applied in the adsorption of pollutants. According to the results in all references, the application of new designed ionic liquids and related sorbents is expected to increase in the future.

Synthesis and characterization of deep eutectic solvents (five hydrophilic and three hydrophobic), and hydrophobic application for microextraction of environmental water samples.

Hydrophilic and hydrophobic deep eutectic solvents (DESs) as "green" solvents were applied in this study for the microextraction of environmental samples. A series of DESs (five hydrophilic and three hydrophobic) were synthesized and characterized by Fourier transform infrared spectroscopy. Physicochemical property parameters of eight DESs including water solubility, density, conductivity, and freezing point were assessed. Compared with the performance of five hydrophilic DESs in water phase, the three hydrophobic DESs were more suitable for application in dispersive liquid-liquid microextraction for the determination of sulfonamides in water sample. In dispersive liquid-liquid microextraction process, analytical parameters including type and volume of extraction solvent, extraction time, and pH of water sample were investigated. Under optimum conditions, 60 µL of hydrophobic DESs was used for extraction for 2 min in pH = 7.0 sample. The linear ranges were 0.05-5.0 µg/mL for the four sulfonamides with the correlation coefficients in the range of 0.9991-0.9999. The limits of detection were in the range of 0.0005-0.0009 µg/mL and the limits of quantification were in the range of 0.0019-0.0033 µg/mL. The recoveries of the analytes of the proposed method for the spiked samples were 80.17-93.5%, with the relative standard deviation less than 6.31%. The results indicated that three hydrophobic DESs showed commendable performance for extraction of sulfonamides, and hydrophobic DES-based microextraction method was successfully applied for monitoring sulfonamides in water samples. Graphical abstract.

Hydrophilic Molecularly Imprinted Chitosan Based on Deep Eutectic Solvents for the Enrichment of Gallic Acid in Red Ginseng Tea.

Hydrophilic molecularly imprinted chitosan (HMICS) were synthesized based on hydrophilic deep eutectic solvents (DESs) and the DESs was used as both a template and functional monomer for the enrichment of gallic acid (GA) from red ginseng tea using a solid phase microextraction (SPME) method. Using the response surface methodology (RSM) strategy, the optimal extraction amount (8.57 mg·g-1) was found to be an extraction time of 30 min, a solid to liquid ratio of 20 mg·mL-1, and five adsorption/desorption cycles. Compared to traditional methods, the produced HMICS-SPME exhibited the advantages of simplicity of operation, higher recovery and selectivity, improved analytical characteristics and reduced sample and reagent consumption, and it is expected to promote the rapid development and wide applications of molecular imprinting.