Determination of testosterone in serum by magnetic molecularly imprinted polymer-coupled nano-ESI-MS.

Monitoring clinical biomarkers, such as testosterone in serum, is important for disease assessment. Due to the very low concentration of testosterone in serum, we have developed a new strategy for its enrichment in serum samples by magnetic molecularly imprinted polymers (MMIPs) technology and detection by nano-electrospray ionization mass spectrometry (Nano-ESI-MS). Testosterone was selectively extracted and enriched by the imprinted polymers on the surface of magnetic particles and the complex matrix was eliminated from the serum. The linear calibration curve was in the range of 0.1-10 µg/L and the limit of detection was 11.4 ng/L. The recovery and repeatability of the spiked serum were satisfactory. These results demonstrate that the proposed method is a promising approach for quantitative analysis of testosterone in serum.

A deep eutectic solvent magnetic molecularly imprinted polymer for extraction of laminarin from seaweeds.

Magnetic molecular imprinted polymers (MIPs) based on 4-vinylbenzyltrimethylammonium chloride (VBTAC) and 4-vinylbenzoic acid (VBA) deep eutectic solvent as dual functional monomers was successfully synthesized for the specific recognition of laminarin. The MIPs were characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and vibrating sample magnetometer analysis. The results showed that the MIPs were spheres of a uniform size, with the surface rich in cavities and excellent superparamagnetism properties. The adsorption experiments showed that MIPs conform to pseudo-second-order kinetics and Langmuir isotherm adsorption. The maximum adsorption capacity under optimal conditions was 322.58 µg·mg-1 and the imprinting factor was 2.13. Under the optimized conditions, the limit of detection (LOD) of the developed material was 6.6 µM. Linearity of the material was obtained within the range 20-800 µM with a coefficient of determination (r2) being better 0.999. Relative standard deviations (RSDs) were less than 3.96%, and satisfactory recoveries were between 94.55 and 97.39%. The actual sample analysis manifested that MIPs could effectively separate laminarin from Laminarin japonica Aiesch.

Magnetic Molecularly Imprinted Polymers for the Rapid and Selective Extraction and Detection of Methotrexatein Serum by HPLC-UV Analysis.

In this work, novel selective recognition materials, namely magnetic molecularly imprinted polymers (MMIPs), were prepared. The recognition materials were used as pretreatment materials for magnetic molecularly imprinted solid-phase extraction (MSPE) to achieve the efficient adsorption, selective recognition, and rapid magnetic separation of methotrexate (MTX) in the patients' plasma. This method was combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) to achieve accurate and rapid detection of the plasma MTX concentration, providing a new method for the clinical detection and monitoring of the MTX concentration. The MMIPs for the selective adsorption of MTX were prepared by the sol-gel method. The materials were characterized by transmission electron microscopy, Fourier transform-infrared spectrometry, X-ray diffractometry, and X-ray photoelectron spectrometry. The MTX adsorption properties of the MMIPs were evaluated using static, dynamic, and selective adsorption experiments. On this basis, the extraction conditions were optimized systematically. The adsorption capacity of MMIPs for MTX was 39.56 mgg-1, the imprinting factor was 9.40, and the adsorption equilibrium time was 60 min. The optimal extraction conditions were as follows: the amount of MMIP was 100 mg, the loading time was 120 min, the leachate was 8:2 (v/v) water-methanol, the eluent was 4:1 (v/v) methanol-acetic acid, and the elution time was 60 min. MTX was linear in the range of 0.00005-0.25 mg mL-1, and the detection limit was 12.51 ng mL-1. The accuracy of the MSPE-HPLC-UV method for MTX detection was excellent, and the result was consistent with that of a drug concentration analyzer.

Magnetic molecularly imprinted polymers for extraction of S-phenylmercapturic acid from urine samples followed by high-performance liquid chromatography.

In this study, magnetic molecularly imprinted polymers (MMIPs) were prepared and used as sorbents for extraction of S-phenylmercapturic acid (S-PMA) from urine samples, followed by high-performance liquid chromatography ultraviolet-visible (HPLC-UV/Vis) analysis. The MMIPs were synthesized by the copolymerization reaction of (phenylthio) acetic acid (template molecule), methacrylic acid (functional monomers) and ethylene glycol dimethacrylate (cross-linkers). The morphology, structure property and surface groups of the prepared MMIPs were characterized by scan electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray diffraction pattern, thermogravimetric analyses, Brunauer-Emmett-Teller and vibrating sample magnetometer. The selectivity of the MMIPs was investigated in the presence of interferents. Various parameters affecting the S-PMA extraction efficiency were investigated, including MMIPs amount, pH, sample volume, desorption solvent, as well as extraction and desorption time. The obtained optimal parameters were as follows: MMIPs amount (20 mg), pH (3.0), sample volume (5 mL), desorption solvent (methanol/acetic acid [9/1, v/v]), extraction time (30 minutes) and desorption time (2 minutes). The method was validated according to the Food and Drug Administration Guidance for Industry on Bioanalytical Method Validation. The calibration curve for the analyte was linear in the concentration range of 0.030-1.0 mg/L (r = 0.9995). The LOD and LOQ of the method were 0.0080 and 0.0267 mg/L, respectively. The enrichment factor of the MMIPs was 5. The relative standard deviations of intra- and inter-day tests were in the range of 3.8-5.1% and 3.9-6.3%, respectively. The recoveries at three different concentrations of 0.10, 0.50 and 0.80 mg/L ranged between 95.2% and 98.6%. In addition, the MMIPs could be reused for at least eight times. The proposed method was successfully applied to the determination of S-PMA in urine samples. In addition, this developed method could be used as a tool in the early screening and clinical diagnosis of benzene intoxication.

Development of hydrophilic magnetic molecularly imprinted polymers for the dispersive solid-phase extraction of sulfonamides from animal-derived samples before HPLC detection.

Highly hydrophilic magnetic molecularly imprinted polymers were prepared through a surface imprinting technique for dispersive solid-phase extraction coupled with high-performance liquid chromatography to detect trace levels of ten sulfonamides in animal-derived samples. The obtained imprinted polymers were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and adsorption experiments, which exhibited excellent specific adsorption for template sulfamethazine in aqueous solution. Moreover, the adsorption process could be completed within 25 min. Under the optimum conditions, the method exhibits good linear performance in the range of 5-to 10 mg/L, limits of detection ranging from 0.57 to 1.50 µg/L, and good recoveries of 85.09-110.93% in the spiked samples (chicken, cow milk, and goat milk). The proposed detection method not only avoids the use of organic solvents but also simplifies the pretreatment procedure via excellent magnetic properties. Furthermore, the method shows great potential for the rapid detection of drug residues.

Multi-functional magnetic molecular imprinting probe for visual detection of IgY antibodies.

Egg yolk antibodies (IgY) are an alternative to mammalian antibodies, which have been successfully applied in treatment of disease, as immunochemical reagents and as food additives. A fast, accurate, and easy-to-operate detection method for IgY antibodies is needed. Herein, we developed a rapid and cost-effective colorimetric assay for the ultrasensitive detection of anti-S. aureus IgY antibodies using multi-functional magnetic molecularly imprinted polymers (MMIPs). The prepared MMIPs can recognize, adsorb, and separate the analyte from the matrix efficiently, and oxidize TMB to generate a colorimetric signal within ~ 60 min. As low as 0.013 mg·mL-1 was able to be detected by using this method. The visual detection limit reached 0.02 mg·mL-1. By testing the IgY in milk samples, the feasibility was verified.

Magnetic Core-Shell Molecularly Imprinted Nano-Conjugates for Extraction of Antazoline and Hydroxyantazoline from Human Plasma-Material Characterization, Theoretical Analysis and Pharmacokinetics.

The aim of this study was to develop magnetic molecularly imprinted nano-conjugate sorbent for effective dispersive solid phase extraction of antazoline (ANT) and its metabolite, hydroxyantazoline (ANT-OH) in analytical method employing liquid chromatography coupled with mass spectrometry method. The core-shell material was characterized in terms of adsorption properties, morphology and structure. The heterogeneous population of adsorption sites towards ANT-OH was characterized by two Kd and two Bmax values: Kd (1) = 0.319 µg L-1 and Bmax (1) = 0.240 µg g-1, and Kd (2) = 34.6 µg L-1 and Bmax (2) = 5.82 µg g-1. The elemental composition of magnetic sorbent was as follows: 17.55, 37.33, 9.14, 34.94 wt% for Si, C, Fe and O, respectively. The extraction protocol was optimized, and the obtained results were explained using theoretical analysis. Finally, the analytical method was validated prior to application to pharmacokinetic study in which the ANT was administrated intravenously to three healthy volunteers. The results prove that the novel sorbent could be useful in extraction of ANT and ANT-OH from human plasma and that the analytical strategy could be a versatile tool to explain a potential and pharmacological activity of ANT and ANT-OH.

Magnetic Molecularly Imprinted Nano-Conjugates for Effective Extraction of Food Components-A Model Study of Tyramine Determination in Craft Beers.

In this paper, magnetic molecularly imprinted nano-conjugates were synthesized to serve as selective sorbents in a model study of tyramine determination in craft beer samples. The molecularly imprinted sorbent was characterized in terms of morphology, structure, and composition. The magnetic dispersive solid phase extraction protocol was developed and combined with liquid chromatography coupled with mass spectrometry to determine tyramine. Ten samples of craft beers were analyzed using a validated method, revealing tyramine concentrations in the range between 0.303 and 126.5 mg L-1. Tyramine limits of detection and quantification were 0.033 mg L-1 and 0.075 mg L-1, respectively. Therefore, the fabricated molecularly imprinted magnetic nano-conjugates with a fast magnetic responsivity and desirable adsorption performance could be an effective tool for monitoring tyramine levels in beverages.

Magnetic molecularly imprinted electrospun nanofibers for selective extraction of nilotinib from human serum.

A new magnetic molecularly imprinted nanofiber (MMIN) nanocomposite was prepared and used to the selective extraction of nilotinib. MMIN was constructed using a novel and general method including a combination of molecular imprinting and electrospinning technology. By electrospun precursor nanofibers containing polyacrylonitrile, Fe3O4 magnetic nanoparticles, and nilotinib as the template, molecularly imprinted nanofibers were produced with a mean diameter of 500 nm and lengths up to several millimeters. The microstructure and morphology of the prepared MMIN were thoroughly investigated using techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). The MMIN was then used to the extraction of nilotinib. The extracted nilotinib was re-extracted and determined spectrofluorimetrically at the excitation and emission wavelengths of 271 and 335 nm, respectively. The relation between fluorescence signal for the re-extracted solution and nilotinib concentration was linear in the range 0.01-10.0 mg L-1 (n = 9) and the RSD for the determination of 1.0 and 5.0 mg L-1 nilotinib 2.75% and 1.09% (n = 3), respectively. The detection limit of the method was obtained as 0.002 mg L-1 nilotinib. The results indicated that the proposed method can be successfully applied to the determination of nilotinib in human serum samples. Graphical abstract.

Preparation of porous magnetic molecularly imprinted polymers for fast and specifically extracting trace norfloxacin residue in pork liver.

Here, magnetic molecularly imprinted polymers were designed for norfloxacin via oil-in-water emulsifier-free emulsion method. It was prepared by simply mixing norfloxacin, methacrylic acid-co-ethylene glycol dimethacrylate copolymer, and Fe3 O4 together at room temperature. Characterized by multiple analytical tools, the particle size, pore size, pore volume, specific surface area, and saturation magnetization of the product were about 30 µm, 10-500 nm, 2.92 mL/g, 105.84 m2 /g, and 3.052 emu/g, respectively. And the adsorption capacity was high at 27.04 mg/g towards norfloxacin. Combined with ultra high performance liquid chromatography, it was used to determine norfloxacin in real samples. Average recoveries were above 77.44% with relative standard deviations between 1.21 and 6.85% at three spiked levels (n = 3) for lake water and pork liver. The determination was achieved for the most complex biosample pork liver spiked with norfloxacin low to 30 ng/g, about 100 times less than the maximum residue limit regulated by Commission of the European Communities. All evidences demonstrated that the magnetic molecularly imprinted polymers can be used in practice for monitoring norfloxacin either in environmental water or meat product with high accuracy and reliability.

Preparation of magnetic molecularly imprinted polymer for dispersive solid-phase extraction of valsartan and its determination by high-performance liquid chromatography: Box-Behnken design.

In this work, core/shell magnetic molecularly imprinted polymer nanoparticles were synthesized for extraction and pre-concentration of valsartan from different samples and then it was measured with high-performance liquid chromatography. For preparation of molecularly imprinted polymer nanoparticles, Fe3 O4 nanoparticles were coated with tetraethyl orthosilicate and then functionalized with 3-(trimethoxysilyl) propyl methacrylate. In the next step, molecularly imprinted polymer nanoparticles were synthesized under reflux and distillation conditions via polymerization of methacrylic acid, valsartan (as a template), azobisisobutyronitrile and ethylene glycol dimethacrylate as cross linking. The properties of molecularly imprinted polymer nanoparticle were investigated by FTIR spectroscopy, field emission scanning electron microscopy, and X-ray diffraction. Box-Behnken design with the aid of desirability function was used for optimizing the effect of variables such as the amounts of molecularly imprinted polymer nanoparticles, time of sonication, pH, and volume of methanol on the extraction percentage of valsartan. According to the obtained results, the affecting variables extraction condition were set as 10 mg of adsorbent, 16 min for sonication, pH = 5.5 and 0.6 mL methanol. The obtained linear response (r2  > 0.995) was in the range of 0.005-10 µg/mL with detection limit 0.0012 µg/mLand extraction recovery was in the range of 92-95% with standard deviation less than 6% (n = 3).

Magnetic solid phase extraction sorbents using methyl-parathion and quinalphos dual-template imprinted polymers coupled with GC-MS for class-selective extraction of twelve organophosphorus pesticides.

A novel magnetic dual-template molecularly imprinted polymer (DMIP) was prepared with methyl-parathion and quinalphos as templates. For comparison, a series of single-template polymers with only methyl-parathion (MPMIP) or quinalphos (QPMIP) as template as well as a non-imprinted polymer (NIP) in the absence of the template, were synthesized using the same procedure of DMIP. The obtained MIPs were characterized by scanning electron microscopy(SEM), Fourier transform infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM), and X-ray diffraction (XRD). The properties including kinetic effect, thermodynamic effect, selectivity, and reusability of MIPs were investigated . Only DMIP possessed high affinity and good recognition for all twelve OPPs including quinalphos, isazophos, chlorpyrifos-methyl, chlorpyrifos, methidathion, triazophos, profenofos, fenthion, fenitrothion, methyl-parathion, parathion, and paraoxon in comparison to MPMIP, QPMIP, or NIP. Moreover, DMIP was used as magnetic solid phase extraction (MSPE) sorbent for the pre-concentration of twelve OPPs in cabbage samples. The developed DMIP-MSPE-GC-MS method showed high sensitivity, low LODs (1.62-13.9 ng/g), fast adsorption equilibrium (10 min), and acceptable spiked recoveries (81.5-113.4%) with relative standard deviations (RSD) in the range 0.05-7.0% (n = 3). The calibration plots were linear in the range 10-800 ng/mL with coefficients of determination (R2) better 0.99 for all twelve compounds. These results suggest that the DMIP is applicable for rapid determination and high throughput analysis of multi-pesticide residues. Graphical abstract.

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.

A highly sensitive tetracycline sensor based on a combination of magnetic molecularly imprinted polymer nanoparticles and surface plasmon resonance detection.

A method is reported for in-situ detection of the antibiotic tetracycline (TC). It is based on a combination of extraction of TC by magnetic molecularly imprinted polymers nanoparticles (MMIPs NPs) and detection by surface plasmon resonance (SPR). The TC-captured MMIPs NPs were flowed over the surface of the SPR chip that was modified with mercaptoethylamine. The SPR signal undergoes a strong increase through the use of MMIPs NPs. It increases linearly in the 5.0-100 pg·mL-1 TC concentration range, and the detection limit is as low as 1.0 pg·mL-1 (at S/N = 3). This method shows selectivity to TC compared with structurally analogues. In order to demonstrate the power of the method, it was applied to the analysis of milk spiked with TC. These results were validated by comparing them to those of an enzyme-linked immunoassay. The average recovery is in the range of 95.7-104.6%. Graphical abstract Schematic representation of a surface plasmon resonance assay for the sensitive determination of tetracycline in milk using the magnetic molecularly imprinted polymers nanoparticles that can extract tetracycline and amplify the SPR signal.

Preparation of magnetic molecularly imprinted polymers for the rapid detection of diethylstilbestrol in milk samples.

BACKGROUND: Diethylstilbestrol (DES) residues are harmful to human health because of their potential carcinogenic properties. Therefore, it is important to develop a fast and efficient pretreatment method to prevent their harmful effects on human health and the environment. RESULTS: In this paper, two types of magnetic molecularly imprinted polymers (MMIPs) of DES were prepared by bulk polymerization and the sol-gel method, respectively. The synthetic materials were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. Adsorption capacities of the bulk and sol-gel MMIPs were investigated. A rapid detection method was developed using the two types of MMIPs as sorbents, coupled to high-performance liquid chromatography, for the determination of DES residues in milk samples. Under optimized conditions, the limit of detection (S/N = 3) of both methods for DES was 2.0 µg L-1 ; and the linear response range to DES was 0.1-500 mg L-1 . The milk samples were analyzed according to this method with good recoveries of 88.3-97.6 and 90.5-103.5% for the two types of MMIPs, respectively. CONCLUSIONS: The method described had high sensitivity and high selectivity, and could prove to be a new method for the rapid determination of DES residues in milk samples. © 2019 Society of Chemical Industry.

Magnetic molecularly imprinted polymers based on silica modified by deep eutectic solvents for the rapid simultaneous magnetic-based solid-phase extraction of Salvia miltiorrhiza bunge, Glycine max (Linn.) Merr and green tea.

Novel magnetic molecularly imprinted polymers (MMIPs) with multiple-template based on silica were modified by four types of deep eutectic solvents (DESs) for the rapid simultaneous magnetic solid-phase extraction (MSPE) of tanshinone Ⅰ, tanshinone ⅡA, and cryptotanshinone from Salvia miltiorrhiza bunge; glycitein, genistein, and daidzein from Glycine max (Linn.) Merr; and epicatechin, epigallocatechin gallate, and epicatechin gallate from green tea, respectively. The synthesized materials were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Single factor experiments were to explore the relationship between the extraction efficiency and four factors (the sample solution pH, amount of DESs for modification, amount of adsorbent, and extraction time). It was showed that the DES4-MMIPs have better extraction ability than the MMIPs without DESs and the other three DESs-modified MMIPs. The best extraction recoveries with DES4-MMIP were tanshinone Ⅰ (85.57%), tanshinone ⅡA (80.58%), cryptotanshinone (92.12%), glycitein (81.65%), genistein (87.72%), daidzein (92.24%), epicatechin (86.43%), epigallocatechin gallate (80.92%), and epicatechin gallate (93.64%), respectively. The novel multiple-template MMIPs materials modified by DES for the rapid simultaneous MSPE of active compounds were proved to reduce the experimental steps than single-template technique, and increase the extraction efficiency.

Synthesis and application of magnetic molecularly imprinted polymers in sample preparation.

Magnetic molecularly imprinted polymers (MMIPs) have superior advantages in sample pretreatment because of their high selectivity for target analytes and the fast and easy isolation from samples. To meet the demand of both good magnetic property and good extraction performance, MMIPs with various structures, from traditional core-shell structures to novel composite structures with a larger specific surface area and more accessible binding sites, are fabricated by different preparation technologies. Moreover, as the molecularly imprinted polymer (MIP) layers determine the affinity, selectivity, and saturated adsorption amount of MMIPs, the development and innovation of the MIP layer are attracting attention and are reviewed here. Many studies that used MMIPs as sorbents in dispersive solid-phase extraction of complex samples, including environmental, food, and biofluid samples, are summarized. Graphical abstract The application of magnetic molecularly imprinted polymers (MIPs) in the sample preparation procedure improves the analytical performances for complex samples. MITs molecular imprinting technologies.

Synthesis of cobalt-based magnetic nanoporous carbon core-shell molecularly imprinted polymers for the solid-phase extraction of phthalate plasticizers in edible oil.

In this work, cobalt magnetic nanoporous carbon (Co-MNPC) is employed as an alternative to intensively used Fe3O4 cores for the preparation of magnetic molecularly imprinted polymers (Co-MNPC@MIPs) for the first time. Co-MNPC was prepared by one-step carbonization of Zeolitic Imidazolate Framework-67 (ZIF-67). Compared with the traditional Fe3O4 core, Co-MNPC showed a high specific surface area and large pore volumes. The prepared adsorbents, which could be rapidly collected from a matrix by external magnetic field, were applied for solid-phase extraction of phthalate plasticizers in edible oil. Several requisite extraction parameters were optimized to achieve desired extraction performance. Under the optimum extraction conditions, Co-MNPC@MIPs displayed better performance than commercialized columns. An analysis method based on Co-MNPC@MIPs coupled with gas chromatography (GC) was established. The linear range was 1-150 µg mL-1, and the detection limit range was 0.010-0.025 µg mL-1. The spiked recovery rate of the five phthalate plasticizers was 81.6-102.2%, with a relative standard deviation of 3.25-12.02%. Finally, the proposed method showed good feasibility for phthalate plasticizer extraction from edible oil.

Selective extraction of morphine from biological fluids by magnetic molecularly imprinted polymers and determination using UHPLC with diode array detection.

The determination of morphine concentration in the blood and urine is necessary for patients and recruitment purposes. Herein, a magnetic molecularly imprinted polymer for selective and efficient extraction of morphine from biological samples was synthesized by using a core-shell method. Fe3 O4 nanoparticles were coated with SiO2 -NH2 . The molecularly imprinted polymer was coated on the Fe3 O4 /SiO2 -NH2 surface by the copolymerization of methacrylic acid and ethylene glycol dimethacrylate in the presence of morphine as the template molecule. The morphological and magnetic properties of the polymer were investigated. Field-emission scanning electron microscopy indicated that the prepared magnetic polymer is almost uniform. The saturation magnetization values of Fe3 O4 nanoparticles, Fe3 O4 /SiO2 -NH2 , and the magnetic polymer were 48.41, 31.69, and 13.02 emu/g, respectively, indicating that all the particles are superparamagnetic. Kinetics of the adsorption of morphine on magnetic polymer were well described by second-order kinetic and adsorption processes and well fitted by the Langmuir adsorption isotherm, in which the maximum adsorption capacity was calculated as 28.40 mg/g. The recoveries from plasma and urine samples were in the range of 84.9-105.5 and 94.9-102.8%, respectively. By using the magnetic molecularly imprinted polymer, morphine can selectively, reliably, and in low concentration be determined in biological samples with high-performance liquid chromatography and UV detection.

Ternary deep eutectic solvent magnetic molecularly imprinted polymers for the dispersive magnetic solid-phase microextraction of green tea.

Ternary deep eutectic solvent magnetic molecularly imprinted polymers grafted on silica were developed for the selective recognition and separation of theophylline, theobromine, (+)-catechin hydrate, and caffeic acid from green tea through dispersive magnetic solid-phase microextraction. A new ternary deep eutectic solvent was adopted as a functional monomer. The materials obtained were characterized by FTIR spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, NMR spectroscopy, and powder X-ray diffraction. The practical recovery of the theophylline, theobromine, (+)-catechin hydrate, and caffeic acid isolated with ternary deep eutectic solvent magnetic molecularly imprinted polymers in green tea were 91.82, 92.13, 89.96, and 90.73%, respectively, and the actual amounts extracted were 5.82, 4.32, 18.36, and 3.69 mg/g, respectively. The new method involving the novel material coupled with dispersive magnetic solid-phase microextraction showed outstanding recognition, selectivity and excellent magnetism, providing a new perspective for the separation of bioactive compounds.