Determination of trace bisphenol A in environmental water by high-performance liquid chromatography using magnetic reduced graphene oxide based solid-phase extraction coupled with dispersive liquid–liquid microextraction

Removal and measurement of trace amounts of rhodamine B in aqueous samples based on the synthesis of a nanosorbent composed of Fe3O4 nanoparticles modified with SiO2 and polydopamine by magnetic solid phase extraction

Rhodamine B (RDB) dye is generally toxic and causes problems such as carcinogenic activities, neurological disorders, and respiratory tract irritations. However, some individuals still illegally use RDB as a food additive. Therefore, a simple and accurate method is needed to determine RDB in real samples such as food or cosmetic products. In this study, the magnetic solid phase extraction (MSPE) method was used to measure very low amounts of RDB dye in water samples. The advantages of this method include simplicity, good repeatability, high preconcentration factor, higher extraction efficiency, low organic solvent volume requirement, rapid separation, low cost, high sensitivity, and interference removal compared to other methods. Within this approach, iron oxide nanoparticles were synthesised, followed by the application of tetra ethoxy silane (TEOS) and polydopamine (PDA) coatings on the nanoparticle surface, resulting in the creation of the Fe3O4@SiO2@PDA nano-sorbent. This nano-sorbent was then utilized as the magnetic solid phase in MSPE. The characteristics of the synthesized compounds were investigated by various methods such as infrared Fourier transform spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and vibrating sample magnetometry (VSM). Response surface methodology (RSM) and Box-Behnken (BB) design were used to optimize the variables affecting the adsorption process and achieved high recovery percentages. Under optimal experimental conditions, the detection limit and quantification limit of the method were found to be 0.73 and 2.42 μg L-1 for RDB, respectively, with RSDs of ±0.32% and ±0.67%. Furthermore, the linear concentration range of the proposed method for solid phase extraction of RDB was determined to be 10.0-900.0 μg L-1. Moreover, the recovery rates for tap water, lake water, and well water samples ranged from 96.9% to 98.6%.

Preparation of dual recognition adsorbents based on molecularly imprinted polymers and aptamer for highly sensitive recognition and enrichment of ochratoxin A

In light of the significant risks that mycotoxins posed to public health and environmental safety, this research developed an adsorbent MIPs/Apt/AuNPs@ZIF-67 (MA-AZ) utilizing a dual-recognition approach combining molecularly imprinted polymers (MIPs) and aptamer (Apt). This innovative method enabled the effective and highly selective recognition and enrichment of ochratoxin A (OTA). ZIF-67 was utilized as a carrier with a substantial specific surface area, and gold nanoparticles (AuNPs) were loaded on its surface to fix the thiol-modified Apt on the surface of the carrier. Then, an initiator was used to initiate a polymerization reaction, and the generated MIPs coated Apt/AuNPs@ZIF-67, thereby synthesizing the MA-AZ with a "synergistic recognition" effect. The Apt significantly increased the number of recognition sites within the imprinted cavities, and MIPs played roles in identifying targets, fixing and protecting Apt. The combination of the both produced the effect of "1+1>2". The study on the adsorption performance of MA-AZ found that the adsorption capacity of MA-AZ could reach 65.1 mg/g, and the imprinted factor was 5.48. In addition, MA-AZ exhibited excellent stability, specificity, reusability and recovery rate. Thus, this study offers valuable insights for the recognition and enrichment of hazardous substances, and helps to promote the rapid development of safety detection.

Determination of phenytoin at trace levels in domestic wastewater and synthetic urine samples by gas chromatography-mass spectrometry after its preconcentration by simple liquid-phase microextraction

This work presents a sensitive and accurate analytical method for the determination of phenytoin at trace levels in domestic wastewater and synthetic urine samples by gas chromatography-mass spectrometry (GC-MS) after the metal sieve-linked double syringe liquid-phase microextraction (MSLDS-LPME) method. A metal sieve was produced in our laboratory in order to disperse water-immiscible extraction solvents into aqueous media. Univariate optimization studies for the selection of proper extraction solvent, extraction solvent volume, mixing cycle, and initial sample volume were carried out. Under the optimum MSLDS-LPME conditions, mass-based dynamic range, limit of quantitation (LOQ), limit of detection (LOD), and percent relative standard deviation (%RSD) for the lowest concentration in calibration plot were figured out to be 100.5-10964.2 μg kg-1, 150.6 μg kg-1, 45.2 μg kg-1, and 9.4%, respectively. Detection power was improved as 187.7-folds by the developed MSLDS-LPME-GC-MS system while enhancement in calibration sensitivity was recorded as 188.0-folds. In the final step of this study, the accuracy and applicability of the proposed system were tested by matrix matching calibration strategy. Percent recovery results for domestic wastewater and synthetic urine samples were calculated as 95.6-110.3% and 91.7-106.6%, respectively. These results proved the accuracy and applicability of the proposed preconcentration method, and the obtained analytical results showed the efficiency of the lab-made metal sieve apparatus.

Analytical application of flower-shaped nickel nanomaterial for the preconcentration of manganese in domestic wastewater samples

In this study, detection sensitivity of the conventional flame atomic absorption spectrophotometer (FAAS) for the determination of manganese (Mn2+) was enhanced by employing a preconcentration method from wastewater samples. Flower-shaped Ni(OH)2 nanomaterials were synthesized and used as sorbent material in preconcentration procedure. With the aim of attaining optimum experimental conditions, effective parameters of extraction method were optimized and these included pH of buffer solution, desorption solvent concentration and volume, mixing type and period, nanoflower amount, and sample volume. The detection limit of the optimized method was determined to be 2.2 μg L-1, and this correlated to about 41-fold enhancement in detection power relative to direct FAAS measurement. Domestic wastewater was used to test the feasibility of the proposed method to real samples by performing spike recovery experiments. The wastewater sample was spiked at four different concentrations of manganese, and the percent recoveries determined were in the range of 95-120%.

Speciation of trace amounts of Sb(III) and Sb(V) in environmental water using inductively coupled plasma mass spectrometry after magnetic solid-phase extraction with rGO/Fe3O4

We developed an approach of magnetic dispersive solid-phase extraction (MSPE) based on magnetic graphene nanocomposite rGO/Fe3O4 for the determination of trace Sb(III) and Sb(V) using inductively coupled plasma mass spectrometry (ICP-MS). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the sorbent. The adsorption behavior of Sb(III) and Sb(V) on rGO/Fe3O4 was investigated. The results showed that the adsorption capacity of Sb(V) was nearly zero at pH = 9, while Sb(III) could be well adsorbed on rGO/Fe3O4. The magnetic SPE parameters including pH, adsorbent dosage, eluent type, and volume were optimized. The detection limit of Sb(III) under ideal conditions was 6 ng L-1, and the relative standard deviation was 7.6% (c = 1 g L-1, n = 7). The technique was used to identify Sb(III) at trace levels in environmental water samples, and its validity was examined by recovery experiments and the examination of an approved reference material.

The green synthesis of magnesium oxide nanocomposite-based solid phase for the extraction of arsenic, cadmium, and lead from drinking water

Solid-phase extraction (SPE) has attracted the attention of scientists because it can increase the selectivity and sensitivity measurements of analytes. Therefore, this study is designed to synthesise magnesium oxide nanoparticles (D-MgO-NPs) by an eco-friendly method using biogenic sources Duranta erecta followed by fabricating its chitosan-based polymeric composite (D-MgO-NC) for the SPE of heavy metals (HMs), i.e., arsenic (As), cadmium (Cd), and lead (Pb) from drinking water. Various analytical techniques were used for the surface characterization of D-MgO-NPs and D-MgO-NC. FTIR findings confirmed the formation of D-MgO-NC based on MgO association with the -OH/-NH2 of the chitosan. D-MgO-NC showed the smallest size of particles with rough surface morphology, followed by the crystalline cubic structure of MgO in its nanoparticle and composites. The synthesised D-MgO-NC was used as an adsorbent for the SPE of HMs from contaminated water, followed by their detection by atomic absorption spectrometry. Various experimental parameters, including pH, flow rate, the concentration of HMs, eluent composition, and volume, were optimised for the preconcentration of HMs. The limits of detection for As, Cd, and Pb of the proposed D-MgO-NC-based SPE method were found to be 0.008, 0.006, and 0.012 μm L-1, respectively. The proposed method has an enrichment factor and relative standard deviation of >200 and <5.0%, respectively. The synthesised D-MgO-NC-based SPE method was successfully applied for the quantitative detection of As, Cd, and Pb in groundwater samples, which were found in the range of 18.3 to 15.2, 3.20 to 2.49, and 8.20 to 6.40 μg L-1, respectively.

Machine learning-driven 3D plasmonic cellulose sensor for in situ rapid SERS detection of bisphenol compounds in water sample

Rapid component separation and accurate identification of bisphenols compounds (BPs) in real water sample remain an attractive challenge due to the trace amounts and structural similarities of BPs, and complexity of real samples. Here, we designed and synthesized chemically modified cellulose p-toluenesulfonate (CTSA) to encapsulate octadecylamine-modified gold nanoparticles (Au-ODA), obtaining 3D plasmonic cellulose (Au@CTSA). Simultaneously, by virtue of the high surface area in the 3D network of CTSA and the solvent volatile deposition, BPs in water were in situ extracted and concentrated in Au@CTSA microspheres. Since the 3D network of Au@CTSA supports the formation of "hotspots", the number of "hotspots" available is greatly improved, enabling excellent SERS detection of BPs. Based on the collected SERS spectra, machine learning was utilized to analyze the overall profile of BPs, which eliminated the subjective judgment of the concentration by the Au@CTSA sensor using a single characteristic peak. In this way, the accuracy of identification of BPs was significantly improved. The machine learning-driven Au@CTSA sensor realized the detection of traces bisphenol A (BPA), bisphenol S (BPS), and bisphenol F (BPF) in water sample, pushing quantitative detection of different concentrations of BPs and contributing facile indicators for water quality monitoring.

An efficient 3D adsorbent foam based on graphene oxide/AgO nanoparticles for rapid vortex-assisted floating solid phase extraction of bisphenol A in canned food products

In this study, a three-dimensional adsorbent was developed based on graphene oxide/AgO nanoparticles over interconnected nickel foam (GO/AgO@Ni foam) for rapid and efficient vortex assisted floating solid phase extraction of bisphenol A in canned food products prior to high performance liquid chromatography with a fluorescence detector. The analytical techniques scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FT-IR) were used for characterization of the synthetized GO/AgO@Ni foam. The effect of proficiency factors including pH, foam size, vortexing time, salt addition, sample volume, desorption type and volume, and desorption time on the extraction efficiency of bisphenol A were explored through the matrix match method. Under the above experimental conditions, the figures of merit of the method were acquired as LODs (S/N = 3) of 0.18-0.84 μg kg^-1, LOQs of 0.61-2.81 μg kg^-1 (S/N = 10), linear ranges of 0.5-500 μg kg^-1, and enrichment factors of 235.5-244.9. The inter-day precision values (RSD%, n = 7) of 2.5-3.6 and the intra-day precision (%) of (5 days and seven replicates for each day) 2.8-3.8 were achieved for bisphenol A at a concentration of 50 μg kg^-1. The relative recoveries of 94.0% to 99.6% were obtained for the canned food samples.

Health risk assessment of endocrine disruptor bisphenol A leaching from plastic bottles of milk and soft drinks

Bisphenol A (BPA) is of major concern to public health due to its toxic potential and xenoestrogenic endocrine-disrupting effect. One of the major sources of BPA comes from the plastic bottles used to pack milk and soft drinks. The purpose of the present study was to assess and compare the risk associated with BPA transfer from plastic bottles to milk and soft drinks being stored in summer and winter conditions. A sensitive and reliable method of solid phase extraction cartridge packed with multi-walled carbon nanotubes (MWCNTs) was employed. In milk samples (supplied in plastic bottles) of winter season, BPA levels were 0.17-0.32 mg/ kg. In milk samples of summer season, BPA levels were 0.77-1.59 mg/ kg. In soft drink samples of winter, BPA levels were between 0.14 and 0.3 mg/kg. While in 4-month-aged summer soft drink samples, BPA levels were 0.7-1.02 mg/kg of food. The daily exposure dose (DED) of BPA in milk samples of winter season was 1.42-2.67 μg/kg which was below the standard tolerable daily intake (TDI) of 50 μg of BPA/kg of body weight as per USEPA. The DED of BPA in milk samples of summer season was 5.58-10 μg/kg of body weight which was also less than TDI. For soft drink samples, BPA from winter samples was ranged from 1.17 to 1.67 μg/kg of body weight while for summer 4-month-aged samples was 2.5-7.08 μg/kg of body weight. Both types of samples were still less than TDI of BPA.

Analysis of recycled rubber: Development of an analytical method and determination of polycyclic aromatic hydrocarbons and heterocyclic aromatic compounds in rubber matrices

Recycled crumb rubber (CR) is rich in compounds with unrecognized toxic potency; this study aims at the development of an analytical method that would allow identification and quantification of a very wide range of organic compounds extractable from the complex rubber matrix. The analytical set-up includes target analysis of polycyclic aromatic hydrocarbons (PAHs) and methyl-PAHs and suspect screening of raw extracts to tentatively identify primary organic compounds present, but not included in the standard target analysis of recycled rubber, followed by analytical method development and target analysis of identified compounds. Analyzed samples included weathered and new CR originating from football turf granulates, rubber mats, and end-of-life car tires (ELTs). The developed analytical method involves sonication extraction, followed by solid phase extraction (SPE) fractionation that enables simple and efficient separation of analytes with broad polarity scale. The application of SPE fractionation resolves coelution problems and simplifies the chromatograms. This analytical approach allowed to identify and quantify 46 sample specific compounds, including several heterocyclic PAHs like 2-methylthiobenzothiazole, benzonapthothiophenes, benzonaphthofuranes and aromatic amines like diphenylamine and N-phenyl-2-naphthylamine, which to our knowledge were not determined before. The PAHs concentrations determined in CR tiles purchased in Dutch and Spanish shops exceed the EU limits for articles marketed for use by the public. Furthermore, sets of methylated PAHs, dibenzothiazoles and aromatic amines were identified and quantified, and several other compounds were tentatively identified. The obtained results stress the need for expanding the list of target compounds analyzed in CR and the need for longitudinal studies on weathering processes taking place in CR.

An Effective Acid-Base-Induced Liquid-Liquid Microextraction Based on Deep Eutectic Solvents for Determination of Testosterone and Methyltestosterone in Milk

An environmentally friendly method for the determination of testosterone and methyltestosterone by acid-base-induced deep eutectic solvents liquid-liquid microextraction (DES-ABLLME) combining with high-performance liquid chromatography was established. The deep eutectic solvent (DES) consisting of menthol:lauric acid:decanoic acid (3:1:1) can act as both hydrogen bond donor and hydrogen bond acceptor. In this approach, ammonia solution (NH3•H2O) is used as an emulsifier to react with DESs in the extraction process to generate salt and form milky white solution, achieving high extraction efficiency. Hydrochloric acid was used as a phase separator to change the emulsification state and promote the separation of extraction agent from water phase. A series of parameters were optimized including the volume of DES and the emulsifying agent, glucose concentration as well as hydrochloric acid volume. The method was linear in the range 0.5-100 μg mL-1 with a correlation coefficient (R) of 0.9999, and the limits of detection were 0.067 and 0.2 μg mL-1 for testosterone and methyltestosterone, respectively. This method was applied to analyze testosterone and methyltestosterone in milk samples, and the recoveries were between 89.2 and 108.2%.

Preparation and characterization of molecularly imprinted polymers based on β-cyclodextrin-stabilized Pickering emulsion polymerization for selective recognition of erythromycin from river water and milk

Molecularly imprinted polymers were prepared via β-cyclodextrin-stabilized oil-in-water Pickering emulsion polymerization for selective recognition and adsorption of erythromycin. The synthesized molecularly imprinted polymers were spherical in shape, with diameters ranging from 20 to 40 µm. The molecularly imprinted polymers showed high adsorption capacity (87.08 mg/g) and adsorption isotherm data fitted well with Langmuir model. Adsorption kinetics study demonstrated that the molecularly imprinted polymers acted in a fast adsorption kinetic pattern and the adsorption features of molecularly imprinted polymers followed a pseudo-first-order model. Adsorption selectivity analysis revealed that molecularly imprinted polymers had a much better specificity for erythromycin than that for spiramycin or amoxicillin, and the relative selectivity coefficient values on the bases of spiramycin and amoxicillin were 3.97 and 3.86, respectively. The Molecularly imprinted polymers also showed a satisfactory reusability after four times of regeneration. In addition, molecularly imprinted polymers exhibited good adsorption capacities for erythromycin under complicated environment, that is, river water and milk. These results proved that the as-prepared molecularly imprinted polymers is a potent absorbent for selective recognition of erythromycin, and therefore it may be a promising candidate for practical applications, such as wastewater treatment and detection of erythromycin residues in food.

Magnetic Solid-Phase Extraction of Organic Compounds Based on Graphene Oxide Nanocomposites

Graphene oxide (GO) is a chemical compound with a form similar to graphene that consists of one-atom-thick two-dimensional layers of sp²-bonded carbon. Graphene oxide exhibits high hydrophilicity and dispersibility. Thus, it is difficult to be separated from aqueous solutions. Therefore, functionalization with magnetic nanoparticles is performed in order to prepare a magnetic GO nanocomposite that combines the sufficient adsorption capacity of graphene oxide and the convenience of magnetic separation. Moreover, the magnetic material can be further functionalized with different groups to prevent aggregation and extends its potential application. Until today, a plethora of magnetic GO hybrid materials have been synthesized and successfully employed for the magnetic solid-phase extraction of organic compounds from environmental, agricultural, biological, and food samples. The developed GO nanocomposites exhibit satisfactory stability in aqueous solutions, as well as sufficient surface area. Thus, they are considered as an alternative to conventional sorbents by enriching the analytical toolbox for the analysis of trace organic compounds.

Enhanced removal of As(Ⅲ) and As(Ⅴ) from aqueous solution using ionic liquid-modified magnetic graphene oxide

In this study, ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆])-modified magnetic graphene oxide (MGO-IL) was prepared for the first time, and was used to adsorb and remove arsenic (As(Ⅲ) and As(V)) ions from aqueous solution. MGO-IL was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and magnetization curves. Effects of ionic liquid type, solution pH, initial arsenic concentration and contact time on the adsorption performance of MGO-IL for As(Ⅲ) and As(V) were studied. The experimental results showed that the adsorption equilibrium was achieved within 30 min, with maximum adsorption capacities of 160.65 mg g^-1 for As(Ⅲ) and 104.13 mg g^-1 for As(V), respectively, and MGO-IL could be rapidly isolated from solution by applying a magnetic field. MGO-IL was reused for 5 times, without marked decrease in its adsorption capacities. Moreover, common coexisting anions did not interfere with the absorption of As(Ⅲ) and As(V). Compared with MGO, the sorption quantities of MGO-IL for As(Ⅲ) and As(V) were greatly enhanced, and the equilibrium time was significantly reduced. Therefore, MGO-IL can potentially serve as an excellent adsorbent for the simultaneous separation and removal of As(Ⅲ) and As(V) from water.

A green deep eutectic solvents microextraction coupled with acid-base induction for extraction of trace phenolic compounds in large volume water samples

A simple, effective and convenient method for determination of phenolic compounds by acid-base induced deep eutectic solvents (DESs) microextraction was developed. The binary and ternary DESs were prepared by a range of fatty acids (C₈-C₁₂), which can act as hydrogen bond donors and hydrogen bond acceptors simultaneously. The gas-assisted mixing customization provides excellent mixing performance and concentration efficiency through the bubble adsorption mechanism for the handling of large-volume aqueous sample. In extraction process, NH₃·H₂O can act as the emulsifier agent and reacted with DESs to form salts with a cloudy solution, which can obviously improve the extraction efficiency. HCl can act as the phase separation agent, and there is no need to centrifuge, which increases the efficiency of analysis procedure. The factors affected on extraction efficiency were carefully optimized. At optimum conditions and molar ratio of C₈:C₉:C₁₂ (3:2:1), the limit of detections (LODs), the preconcentration factor, the repeatability (RSDs%) were in the range of 0.22-0.53 μg L^-1, 235-244, and 2.6-6.7%, respectively. Finally, the proposed method was applied to analyze four phenolic compounds in real water samples and the recoveries were between 87.4% and 106.6%.

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.

C8-modified magnetic graphene oxide based solid-phase extraction coupled with dispersive liquid-liquid microextraction for detection of trace phthalate acid esters in water samples

Phthalate acid esters (PAEs) are extensively applied in plastic and plastic products, and have caused potential hazards on human and animal health. In this study, a highly sensitive method was proposed for trace detection of selected PAEs in water by gas chromatography-mass spectrometry, after solid-phase extraction (SPE) using octyl (C8)-modified magnetic graphene oxide (MGO-C8) as the adsorbent followed by dispersive liquid-liquid microextraction (DLLME). The prepared MGO-C8 was characterized by Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric analysis (TGA) and vibrating sample magnetometry (VSM). The recoveries of the PAEs using MGO-C8 as the adsorbent were found to be significantly higher those obtained by MGO. The influences of solution pH, adsorption and desorption time, eluent and extractant, and salt addition on the extraction efficiency of PAEs were investigated. Under the optimized conditions, limits of detection (LODs) of 0.5-1.0 ng L^-1 for PAEs, and related standard deviations (RSDs) of 4.8-7.5% were obtained. The proposed method was utilized in the detection of trace PAEs in real environmental water samples, with spiked recoveries of 89.5-112.3%, 91.5-105.0% and 98.0-110.0% for DBP, DEHP and DNOP, respectively.

Graphene oxide based molecularly imprinted polymers modified with β-cyclodextrin for selective extraction of di(2-ethylhexyl) phthalate in environmental waters

Graphene oxide based molecularly imprinted polymers modified with β-cyclodextrin were prepared as solid-phase extraction column sorbents for specific recognition and sensitive detection of di(2-ethylhexyl) phthalate in water samples. The morphology and composition of synthesized sorbents were characterized by scanning electron microscopy, thermo-gravimetric analysis, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The conditions affecting the performance of extraction procedures such as desorption solvent types and volume, sample pH and volume were investigated. The loading capacity (8.2 μg/mg) of the prepared sorbents increased eight times after modification with β-cyclodextrin. The developed extraction procedures coupled to high-performance liquid chromatography exhibited good linearity (0.2-500 μg/L), low limit of detection (0.052 μg/L), and good precision (relative standard deviation˂5.7%) under optimized conditions. The developed solid-phase extraction technique with prepared sorbents has been successfully applied in extracting trace di(2-ethylhexyl) phthalate from real natural waters with high efficiency, good selectivity, and desirable recoveries.

Efficient and selective separation of metronidazole from human serum by using molecularly imprinted magnetic nanoparticles

Magnetic molecularly imprinted nanoparticles were prepared through surface-initiated reversible addition fragmentation chain transfer polymerization by using metronidazole as a template. The molecularly imprinted magnetic nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry. The adsorption characteristics were also investigated and the kinetics of the adsorption of metronidazole on the imprinted nanoparticles were described by the second-order kinetic model with the short equilibrium adsorption time (30 min). The adsorption isotherm was well matched with the Langmuir isotherm in which the maximum adsorption capacity was calculated to be 40.1 mg/g. Furthermore, the imprinted magnetic nanoparticles showed good selectivity as well as reusability even after six adsorption-desorption cycles. The imprinted magnetic nanoparticles were used as a sorbent for the selective separation of metronidazole from human serum. The recoveries of metronidazole from human serum changed between 97.5 and 99.8% and showed similar sensitivity as an enzyme-linked immunoassay method. Therefore, the molecularly imprinted magnetic nanoparticles might have potential application for the selective and reliable separation of metronidazole from biological fluids in clinical applications.

Polypyrrole-modified magnetic multi-walled carbon nanotube-based magnetic solid-phase extraction combined with dispersive liquid–liquid microextraction followed by UHPLC-MS/MS for the analysis of sulfonamides in environmental water samples

Polypyrrole modified magnetic multi-walled carbon nanotubes were prepared and applied as an efficient adsorbent for magnetic solid-phase extraction.

Chemiluminescence determination of furazolidone in poultry tissues and water samples after selective solid phase microextraction using magnetic molecularly imprinted polymers

For the first time, a selective extraction method combined with chemiluminescence was developed for the determination of FZD in various samples.

Green synthesis of monolithic column incorporated with graphene oxide using room temperature ionic liquid and eutectic solvents for capillary electrochromatography

In this work, a hybrid monolith incorporated with graphene oxide (GO) was prepared in the first time with binary green porogens of deep eutectic solvents (DESs) and room temperature ionic liquids (RTILs). GO was modified with 3-(trimethoxysilyl) propylmethacrylate (γ-MPS), and the resultant GO-MPS can be incorporated into poly (methacrylic acid-co-butylmethacrylate-co-ethylene glycol dimethacrylate) monoliths covalently. A hybrid monolithic column with high permeability and homogeneity can be achieved due to good dispersion of GO-MPS in the green solvents. The GO-MPS incorporated monolith was characterized by transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis and nitrogen adsorption tests. The separation of small organic molecules of alkylphenones and alkylbenzenes was used to evaluate the performance of GO-MPS grafted monolith. The GO-MPS grafted monolith displayed the maximum column efficiency of 147,000 plates/m, about twice higher than the GO-free monolith. In addition, all of the retention and selectivity of small molecules of alkylphenones and alkylbenzenes increased due to the addition of GO-MPS. The results demonstrated that the use of DESs and RTILs is a powerful approach for the preparation of GO incorporated polymer monoliths. The monolith was further applied to the separation of tryptic digests from bovine serum albumin, and the result indicated its potential in the analysis of some complex samples.