3D hierarchical magnetic hollow sphere-like CuFe2O4 combined with HPLC for the simultaneous determination of Sudan I–IV dyes in preserved bean curd

Constructing N,S co-doped network biochar confined CoFe2O4 magnetic nanoparticles adsorbent: Insights into the synergistic and competitive adsorption of Pb2+ and ciprofloxacin

To solve the problem of biochar lack of adsorption sites for heavy metal ions and the difficulty of recycling, CoFe2O4 magnetic nanoparticles confined in nitrogen, sulfur co-doped 3D network biochar matrix (C-CoFe2O4/N,S-BC) was designed and fabricated successfully. The obtained C-CoFe2O4/N,S-BC displays remarkable adsorption performance for both Pb2+ and ciprofloxacin (CIP) removal at the single or binary system due to the role of N,S as metal ion anchoring compared to the N,S-free sample (CoFe2O4/BC). N,S co-doped BC not only participates in adsorption reaction but also effectively inhibites the agglomeration of CoFe2O4 nanoparticles and increases the active sites as a carrier at the same time. In the single system, CoFe2O4/N,S-BC demonstrates a fast adsorption rate (equilibrium time: 30 min) and high adsorption capacity (224.77 mg g-1 for Pb2+, 400.11 mg g-1 for CIP) towards Pb2+ and CIP. The adsorption process is befitted pseudo-second-order model, and the equilibrium data are in great pertinence with Langmuir model. In the binary system, the maximum adsorption capacity of CoFe2O4/N,S-BC for Pb2+ and CIP is 244.80 mg g-1 (CIP: 10.00 mg L-1) and 418.42 mg g-1 (Pb2+: 10.00 mg L-1), respectively. The adsorption mechanism is discussed based on the experimental results. Moreover, C-CoFe2O4/N,S-BC shows good practical water treatment capacity, anti-interference ability and stable reusability (the removal efficiency＞80% after eight cycles). The rapid, multifunctional, reusable, and easily separable adsorption properties make C-CoFe2O4/N,S-BC promising for efficient environmental remediation. This study also offers a viable method for the construction of adsorption material for complex wastewater treatment.

Application of electrochemical sensors based on nanomaterials modifiers in the determination of antipsychotics

At present, the content of antipsychotics in samples is always analyzed by traditional detection methods, including mass spectrometry (MS), spectrophotometry, fluorescence, capillary electrophoresis (CE). However, conventional methods are cumbersome and complex, require a large sample volume, many pre-processing steps, long analysis cycles, expensive instruments, and need well-trained detection capabilities personnel. In addition, patients with schizophrenia require frequent and painful blood collection procedures, which adds additional treatment costs and time burdens. In view of these factors, electrochemical methods have become the most promising candidate technology for timely analysis due to their low cost, simple operation, excellent sensitivity and specificity. As we all know, nanomaterials play an extremely important role in electrochemical sensing applications. As the sensor modifiers, nanomaterials enable electrochemical analysis to overcome the time-consuming and labor-intensive shortcomings of traditional detection methods, and greatly reduce the research cost. Nanomaterials modified electrodes can be used as sensors to determine the concentration of antipsychotics in organisms quickly and accurately, which is a bright spot in the application of nanomaterials. The combination of different nanomaterials can even form a nanocomposite with a synergistic effect. This paper firstly reviews the application of nanomaterials-modified sensors on the basis of research in the past ten years, reviews the use of nanomaterial-modified sensors to quickly and accurately determine the concentration of antipsychotics in biological samples, and demonstrates a new idea of using nanomaterials sensors for drug monitoring and determination. At the end of this review, a brief overview is given of the limitations and the future prospects of nanomaterial sensors for the determination of antipsychotics concentrations.

Designed new magnetic functional three-dimensional hierarchical flowerlike micro-nano structure of N-Co@C/NiCo-layered double oxides for highly efficient co-adsorption of multiple environmental pollutants

In order to eliminate multiple coexisting pollutants in environmental wastewater, a magnetic three-dimensional hierarchical porous flower-like N, Co-doped graphitic carbon nano-polyhedra decorated NiCo-layered double oxides (N-Co@C/NiCo-LDOs) adsorption material was synthesized, which consisted of two-dimensional LDOs nanosheets with functionalized surfaces (N, Co-doped graphitic carbon loaded on both sides of NiCo-LDOs nanosheets). The adsorption properties of N-Co@C/NiCo-LDOs for five types of typical pollutants (cationic dyes: rhodamine b, methylene blue; pesticides: ethofenprox, bifenthrin; anionic dyes: methyl orange, congo red; inorganic cations: Cr²⁺, Cd²⁺, Pb²⁺, Zn²⁺, inorganic anions: Cr₂O₇^2-, AsO₃^3-) were investigated systematically in single and coexisting systems. Combined with the results of FTIR and zeta potential, the adsorption mechanism was discussed. By virtue of its hierarchical porous architecture and the combined effect of functionalized surfaces and LODs supporter, the as-prepared N-Co@C/NiCo-LDOs demonstrates excellent adsorption performance towards five types of typical pollutants with fast adsorption rate, high adsorption capacity and good co-adsorption performance. More importantly, the N-Co@C/NiCo-LDOs showed satisfactory removal efficiency, stability and reusability in model wastewater. The broad-spectrum, rapid, easily separable, and reusable adsorption properties make N-Co@C/NiCo-LDOs promising for highly efficient wastewater treatments. This work also provides a feasible way for the preparation of adsorption materials for the treatment of complex wastewater systems.

Fabricating multifunctional low-toxicity ratiometric fluorescent probe for individual detection of Cu2+/glutamate and continuous sensing for glutamate via Cu2+-based platform

Herein, a multifunctional ratiometric fluorescent (RF) probe Fe-MIL-88NH₂@RhB was fabricated for individual detection of Cu^2+/Glu and continuous sensing of Glu based on unique coordination principle by encapsulating RhB into the porous of metal-organic-framework-Fe-MIL-88NH₂. Designed Fe-MIL-88NH₂@RhB platform could selectively identify Cu(II)/Glu accompanying a turn-off/turn-on fluorescent behavior with good linearity. Moreover, if the Fe-MIL-88NH₂@RhB/Cu²⁺ is treated with Glu continuously, the quenching fluorescence of this platform (after Cu²⁺ sensing at blue emission) would be further in turn restored. Utilizing Fe-MIL-88NH₂@RhB probe, the imaging of intracellular Cu(II) and Glu in living A549 cells was successful conducted through divisional channels with a satisfactory low cytotoxicity, meanwhile, the sensing results of Glu in serum by the molecular logic gate was also superior, which may use for development of an medical occupational tool for amyotrophic lateral sclerosis tentative diagnosis. In addition, the MOF shows di-modal response (color and lumescence) to Cu²⁺ and Glu with excellent selectivity against a wide range of other interference analytes, and the corresponding portable low-toxicity on-line test strips for Cu²⁺ and Glu recognize has exhibited a remarkable visually chromogenic phenomena, which may utilize for monitoring these contaminants in real water sample. Finally, the feasibility of probe to monitor Cu²⁺ and Glu in foodstuffs was also evaluated.

Preparation of Polyamidoamine Dendrimer Modified Magnetic Nanoparticles and Its Application for Reliable Measurement of Sudan Red Contaminants in Natural Waters at Parts-Per-Billion Levels

The health threat from Sudan red dyes has been the subject of much attention in recent years and is crucial to design and establish reliable measurement technologies. In the present study, a new magnetic nanomaterial, polyamidoamine dendrimer-modified magnetic nanoparticles (Gn-MNPs), was synthesized and characterized. The nanomaterials had good adsorption capacity for Sudan dyes from natural waters. G1.5-MNPs possessed excellent adsorption capacity and a linear adsorption relationship over the range from 0.02 to 300 μg L⁻¹ of Sudan dyes with relative coefficients all larger than 0.996. The sensitivity of the proposed method was excellent with detection limits over the range from 1.8 to 5.5 ng L⁻¹ and the precision was less than 3.0%. G1.5-MNPs showed a remarkable application potential for the enrichment of trace environment pollutants in aqueous samples and the developed method based on this nanomaterial could be a robust and reliable alternative tool for routine monitoring of such pollutants.

Electromagnetic dispersive solid-phase extraction based on polyaniline-coated magnetite/silica materials for the determination of Sudan red I in drinks

By replacing the permanent magnet with an electromagnet, traditional magnetic solid-phase extraction was developed into electromagnetic dispersive solid-phase extraction. A simple operation of power on and off can realize the separation of adsorbents from solutions easily. The improvement makes it possible for the automation of the determination of Sudan Red I by high-performance liquid chromatography. After series of optimization, a trace amount of Sudan red I was well-determined, and excellent linearity was achieved in the range of 0.005 to 1 mg/L with the correlation coefficient (R² ) = 0.997. The limit of detection with a signal-to-noise ratio of 3 was found to be 0.001 mg/L. The spiked recoveries of Sudan red I for the samples ranged from 93.6 to 104.9%. Moreover, the adsorbent could be recycled at least ten times. The results show that the electromagnetic dispersive solid-phase extraction combined with high-performance liquid chromatography is a rapid, eco-friendly, effective, and sensitive determination method with fascinating automation potential and high practical applicability.

Separation and Enrichment of Sudan III Using Surface Modified Hollow Glass Microspheres and Colorimetric Detection

BACKGROUND

Sudan III has been shown to be carcinogenic to human beings due to the azo chemical structure. A simple, highly selective, and environmentally friendly pretreatment method is usually required before the analysis of Sudan III in complex practical samples due to low concentration and matrix interference.

OBJECTIVE

The aim of this research was to prepare buoyant adsorbents, octyl trimethoxysilane caped hollow glass microspheres (HGMs), and establish a new pretreatment method for the detection of Sudan III in real samples.

METHOD

HGMs were activated and transferred to a flask containing 80 mL ethanol solution (9:1, v/v) and 0.9 mL ammonia. The octyl trimethoxysilane was added to the slurry and covalently coupled on the surface of the HGMs. The modified HGMs were used as adsorbents for the enrichment of Sudan III. After adsorption and desorption, the UV-Vis absorption spectrum was recorded under excitation at 506 nm.

RESULTS

Under the optimum conditions, the linear range and detection limit were 0.10-4.0 mg/L and 0.048 mg/L, respectively. The proposed method was successfully employed to detect Sudan III in chili products with acceptable recoveries of spikes (90.7-102%).

CONCLUSIONS

The adsorbent, which could be separated by flotation, provided a new solid phase extraction method for the pretreatment of complex samples.

HIGHLIGHTS

A new solid phase extraction method was provided for the pretreatment of complex samples. In addition, the adsorbents with high enrichment efficiency can be easily separated by flotation and repeatedly used for separation and enrichment of Sudan III.

Modification of screen-printed gold electrode with 1,4-dithiothreitol: application to sensitive voltammetric determination of Sudan II

Objectives

The aim of this study is to investigate the electrochemical behavior of Sudan II (SuII) using a screen-printed gold electrode (SPGE) modified with 1,4-dithiothreitol (DTT) and to determine the amount of Sudan II by voltammetry.

Materials and Methods

A DTT-modified screen-printed gold electrode (DTT/SPGE) was fabricated and its application for differential pulse voltammetric (DPV) determination of SuII was reported. Fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry and electrochemical impedance spectroscopy were used for the characterization of the modified electrode. The effects of instrumental and chemical parameters were optimized for the determination of SuII. The fabricated electrode was used for the analysis of SuII in fortified and real samples. High-performance liquid chromatography was preferred as a reference method for the evaluation of the obtained voltammetric results.

Results

The electrochemical studies and FT-IR demonstrated that the SPGE was modified with DTT. The obtained peak current at DTT/SPGE was 6.67 times higher than that recorded with SPGE. At the optimized conditions of DPV in pH = 2.5 of H2SO4, the oxidation peak current of SuII was proportional to its concentration in range: 0.001–1.500 μmol l–1 with a detection limit of 0.0002 μmol l–1 (S/N = 3). For the analysis of SuII, 101.67%–104.33% of recovery percentage was obtained.

Conclusions

A new electrode was successfully improved for the determination of SuII. This highly selective and sensitive electrode supplied the fast determination of SuII in ketchup, chili sauce and salsa dip sauce. In addition, voltammetric and chromatographic results are found to be consistent.

In-situ fabrication of 3D hierarchical flower-like β-Bi2O3@CoO Z-scheme heterojunction for visible-driven simultaneous degradation of multi-pollutants

Development of an efficient heterojunction catalyst with a superior visible-light driven activity is regarded as a promising strategy to decontaminate organic wastewater. Herein, a novel direct Z-scheme β-Bi₂O₃@CoO heterojunction was well designed and successfully fabricated by in situ incorporating the two energy band-matched semiconductors. The obtained β-Bi₂O₃@CoO hybrid presented a unique 3D hierarchical structure with a mass of open channels and mesoporous, which afforded not only rapid mass transfer of targets but also good light-harvesting in view of the multiple reflections. Compared to the pristine β-Bi₂O₃ and CoO, the β-Bi₂O₃@CoO hybrid exhibited remarkably improved photocatalytic activity towards the simultaneous degradation of chlorotetracycline (CTC), tetracycline hydrochloride (TCH), oxytetracycline (OTC) and nitrobenzene (NB) under visible-light irradiation. The possible intermediates and degradation pathways were also tracked by mass spectra (MS) analysis. Moreover, a direct Z-scheme charge transfer mechanism in the intimate contact interface between β-Bi₂O₃ and CoO was verified for the improved catalytic activity, endowing the effective separation/transportation of the photo-excited charge carriers and maintenance of the strong redox ability in β-Bi₂O₃@CoO heterojunction. The present work affords a simple approach to design and construct 3D hierarchical direct Z-scheme photocatalysts with promising applications in water environment remediation.

Fabrication of starch-salicylaldehyde based polymer nanocomposite (PNC) for the removal of pollutants from contaminated water

In the present study, we have fabricated magnetic nanocomposite based on the starch and salicylaldehyde resin embedded with magnetic Fe₃O₄ nanoparticles (SS@Fe₃O₄). The fabricated nanocomposite was characterized using various analytical methods including XRD, SEM, FTIR, TGA, TEM, BET and XPS. As-fabricated nanocomposite was used for the adsorption of Pb(II) and Cd(II) from aqueous solution. The adsorption results revealed that the maximum adsorption capacity was found to be 265.4 and 247.2 mg/g for Pb(II) and Cd(II) respectively at pH 6 and room temperature. The adsorption kinetic results support that the adsorption of both the toxic metals was carried out via second order reaction and the rate constants were found to be 6.31 × 10^-5 and 7.18 × 10^-5 g·mg^-1·min^-1 for Pb(II) and Cd(II) respectively. The adsorption isotherm displays the Langmuir adsorption isotherm and supports the monolayer and mainly chemisorption with poor physisorption. Additionally, the thermodynamic parameters were evaluated and the adsorption came true in exothermically and spontaneously with both Pb(II) and Cd(II). As-fabricated starch based magnetic nanocomposite displays excellent adsorption as well as outstanding reusability. Therefore, these outcomes support that the SS@Fe₃O₄ nanocomposite can be used as a promising adsorbent for industrial application.

Improved performance of 3D hierarchical NiAl-LDHs micro-flowers via a surface anchored ZIF-8 for rapid multiple-pollutants simultaneous removal and residues monitoring

In this paper, we report a new type of 3D ZIF-8@NiAl-LDHs micro-flowers material consisting of sandwich-like structured 2D nanopetals (highly compact ZIF-8 film anchored on both sides of petals). ZIF-8 was successfully incorporated into NiAl-LDHs (ZIF-8@NiAl-LDHs) via seeding strategy directed growth of ZIFs on the surface of LDHs nanopetals. The coating of ZIF-8 significantly increased the adsorption ability to organic pollutants and inorganic cation. 3D ZIF-8@NiAl-LDHs with excellent enrichment and filtration properties has been exploited for the application in water purification, and exhibit superior high adsorption rate and adsorption efficiency of organic (nonsteroidal anti-inflammatory drugs: ketoprofen, flurbiprofen, indometacin and ibuprofe; anionic dyes: congo red, orange g; cationic dyes: methylene blue, rhodamine b) and inorganic cation (Cu²⁺, Pb²⁺) residues due to their novel hierarchical and submicroscopic structures. Further, 3D ZIF-8@NiAl-LDHs as filter membrane to extraction four kind of trace anti-inflammatory drugs followed by direct quantification detection of targets with HPLC was demonstrated. The validated method was successfully applied for analysis of four anti-inflammatory drugs in environmental water and human urine samples. This work provided a feasible way to design and construct purification materials for wastewater treatment and contaminant detection.

A novel "turn-on" fluorescent probe based on hydroxy functionalized naphthalimide as a logic platform for visual recognition of H2S in environment and living cells

A novel hydroxy functionalized naphthalimide-based fluorescent probe (denoted SP2)was successfully designed and synthesized for monitoring of H₂S in living cells and environmental. In particular, SP2 can detect the H₂S without assistance of organic solvent or surfactant. When H₂S is present, the azide group in SP2 was reduced to amine group, resulting in a turn-on fluorescence signal. This remarkable properties of SP2 enable its applications in monitoring ex/endogenous H₂S in HepG-2 cells and hydrogen sulfide release in laboratories or chemical plants through visual recognition by optical color change. The probe displays highly selective and sensitive recognition to H₂S, with a low detection limit of 50.8 nM. Futhermore, this work presents the possibility of using naphthalimide-based "logic gate" platform for monitoring H₂S in biological and environmental samples.

Assembling 3D hierarchical hollow flower-like Ni@N-doped graphitic carbon for boosting simultaneously efficient removal and sensitive monitoring of multiple sulfonamides

The excessive accumulation of sulfonamides (SAs) drugs makes it imperative to develop novel materials for boosting simultaneously efficient removal and precise monitoring of multiple SAs. Herein, three-dimensional hollow flower-like Ni@nitrogen-doped graphitic carbon (3DHFNi@NGC) was designed/fabricated via a facile one-pot hydrothermal route and subsequent pyrolysis. The resultant 3DHFNi@NGC exhibits a unique 3D hollow hierarchical architecture assembled by a layer-by-layer interlacing of corrugated nanosheets subunits, thereby affording numerous interconnected channels, available internal/external surfaces as well as suitable interior cavities. By virtue of its special architecture and in-situ generated N-doped graphitic carbon along with good magnetism, the 3DHFNi@NGC demonstrates superior sorption performance towards SAs, accompanied by high total saturated adsorption capacity, fast sorption rate and easy magnetic recycling. It is noteworthy that as-constructed 3DHFNi@NGC also exhibits high-sensitive/simultaneous detection of trace multiple SAs combined high performance liquid chromatography (HPLC), together with a low detection limit (0.035-0.071 ng mL^-1) and a broad linear range (0.2-100 ng mL^-1) as well as high enrichment factors (252 < EFs < 291). These indicate that the smart 3DHFNi@NGC could be a promising candidate for the synchronous remediation and sensitive detection of multiple SAs in aqueous systems, presenting a viable option for sewage treatment and water quality monitoring.

A dual mode photoelectrochemical sensor for nitrobenzene and L-cysteine based on 3D flower-like Cu2SnS3@SnS2 double interfacial heterojunction photoelectrode

In this work, 3D hierarchical Cu₂SnS₃@SnS₂ flower assembled from nanopetals with sandwich-like Cu₂SnS₃-SnS₂-Cu₂SnS₃ double interfacial heterojunction was successfully designed and synthesized on fluoride doped tin oxide (FTO) for photoelectrochemical (PEC) sensor by in situ electrodeposition p-type Cu₂SnS₃ nanoparticles on both inner and outer surfaces of n-type SnS₂ nanopetals. The unique double interfacial heterojunction simultaneously combines 3D flower-like architectures to drastically increase the light trapping and absorption in visible-near infrared range (Vis-NIR), and dramatically inhibites the charge carrier recombination, which is crucial for boosting the PEC activity. Benefitting from the shape and compositional merits, the Cu₂SnS₃@SnS₂ heterojunction possess dual-mode signal by controlling the electrodeposition time to manipulate the composition ratio of Cu₂SnS₃ and SnS₂. The Cu₂SnS₃@SnS₂/FTO electrode not only exhibits excellent photoeletro-reduction capacity for ultra-sensitive sensing trace persistent organic pollutant (nitrobenzene, NB), but also presents photoeletro-oxidization activity for high selective detection of L-cysteine (L-Cys) without any auxiliary enzyme under the light illumination. Dual mode sensor displayed superb performance for the detection of NB/L-Cys, showing a wide linear range from 100 pM to 300 μM/10 nM to 100 μM and a low detection limit (3S/N) of 68 pM/8.5 nM, respectively. Such a tunable double interfacial heterojunction design opened up new avenue for constructing multifunction PEC sensing platform.

Fabrication of WO2/W@C core-shell nanospheres for voltammetric simultaneous determination of thymine and cytosine

Pomegranate-like multicore WO₂/W nanocrystals wrapped with layers of multiporous carbon were fabricated via carbonization of a copper(II)-organic framework host and a tungsten-based polyoxometalates guest, and subsequent etching off the metallic copper. The WO₂/W@C core-shell nanospheres were employed to modify an electrode for the analysis of the DNA bases thymine (T) and cytosine (C) by differential pulse voltammetry. The WO₂/W@C exhibited strongly increased oxidation signal of T and C. Under optimized conditions, the enhanced peak current represented excellent analytical performance for determination of T and C. This is attributed to the synergic effects of the porous multicore-shell microstructure and the use of tungsten-based materials with their excellent electrocatalytic activity for T and C, with typical peaks voltages near 1.26 V and 1.44 V. The calibration plots for T and C extend from 1 to 4000 μM and from 1 to 3000 μM, respectively, and both detection limits are 0.2 μM. The method was successfully applied to the determination of T and C in spiked blood and urine samples, and the recoveries are form 97.3 to 105.0%. Graphic abstractCore-shell nanospheres of type WO2/W-carbon were prepared for highly sensitive simultaneous voltammetric determination of thymine and cytosine.

Simultaneous determination of 20 disperse dyes in foodstuffs by ultra high performance liquid chromatography-tandem mass spectrometry

A reasonable, high sensitive and accurate analytical method for the determination of 20 allergenic disperse dyes in foodstuffs was developed and validated. The obtained results showed that an ultra high liquid performance chromatography system - equipped with tandem quadrupole mass spectrometry (UHPLC-MS/MS) proved to be ideal for the selected method enabling multidimensional processing of the samples. Under optimized conditions, validation results showed excellent linearity (5-1000 µg/L, r² ≥ 0.997), limits of detection (LODs, 1.1-10.8 μg/kg), recoveries (60.2-110.3%) and precision (RSDs ≤ 12.6%) for the twenty disperse dyes under investigation. The developed method was successfully applied to the analysis of 20 disperse dyes in real foodstuffs demonstrating the validity and applicability of the current method for continuing monitoring of the selected dyes. The proposed UHPLC-MS/MS is thus proved to be a convenient, effective, sensitive and timesaving method for the isolation and determination of allergenic disperse dyes in edible packaging and other foodstuffs.

Magnetic hyperbranched molecularly imprinted polymers for selective enrichment and determination of zearalenone in wheat proceeded by HPLC-DAD analysis

A novel magnetic surface molecular imprinted polymers with 2, 4, 6-trisacrylamido-3, 5-triazine (TAT) as a functional monomer was successfully synthesized and used for the enrichment and determination of zearalenone. The molecular imprinting is reported herein at first time for application of zearalenone in wheat. The magnetic imprinted materials possessed excellent magnetism and uniform appearance, which were characterized by fourier transform infared spectroscopy and transmission electron microscope. The results proved the magnetic molecular imprinted polymers was successfully prepared. The magnetic molecular imprinted polymers exhibited satisfactory sensitivity, stability and potential reusability. The binding affinity was investigated by selectivity experiment, which possessed high selectivity. To obtain the optimal application conditions, the amount of adsorption, extraction time, elution solvent and time were optimized. The limited detection of zearalenone was 0.55 ng g^-1 and the recoveries of zearalenone were 92.1-96.0%. The relative standard deviation was lower than 5.4%. This indicated that a simple, efficient and low-cost method was established and successfully applied in spiked wheat sample.

Novel functionalized magnetic ionic liquid green separation technology coupled with high performance liquid chromatography: A rapid approach for determination of estrogens in milk and cosmetics

Several magnetic ionic liquids (MILs), [P_6,6,6,14⁺][FeCl₄^-], [P_6,6,6,14⁺]₂[MnCl₄^2-], [P_6,6,6,14⁺]₂[CoCl₄^2-] and [P_6,6,6,14⁺]₂[NiCl₄^2-] were synthesized and applied for the extraction of six estrogens (estrone, estradiol, 17-α-hydroxyprogesterone, chloromadinone 17-acetate, megestrol 17-acetate and medroxyprogesterone 17-acetate) in dispersive liquid-liquid microextraction (DLLME). The [CoCl₄^2-]-based MIL was selected as extraction solvent for the separation and concentration of estrogens from milk and cosmetics due to its visual recognition, no sign of hydrolysis, solution acquisition easier and the highest extraction capacity. In addition, the [CoCl₄^2-]-based MIL with low UV absorbance allows direct analysis of the extraction solvent by HPLC-UV. The influence of the mass of MIL, extraction time, salt concentration, and the pH of the sample solution was investigated to obtain optimized extraction efficiency. Besides, extraction conditions including salt concentration, mass of MIL and extraction time were further optimized by the Box-Behnken design through the response surface method. Under optimized conditions, the limits of detection (LODs) of all estrogens were ranged from 5 ng mL^-1 to 15 ng mL^-1. The recoveries ranging from 98.5% to 109.3% in milk and from 96.3% to 111.4% in cosmetics were also studied, respectively. Furthermore, the proposed method were statistically compared with the reported conventional IL-DLLME method and the National standard methods of food safety and cosmetics. The experimental results showed that the functionalized MIL could successfully applied for extraction, separation and pretreatment of estrogens in milk and cosmetics.

Acrylic Acid-Functionalized Metal-Organic Frameworks for Sc(III) Selective Adsorption

The increasing demand for rare-earth elements (REEs) due to their extensive high-tech applications has encouraged the development of new sustainable approaches for REE recovery and separation. In this work, a series of acrylic acid-functionalized metal-organic framework materials (named as y-AA- x@MIL-101s) were prepared and used for selective adsorption of Sc(III). The adsorbent was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption, X-ray photoelectron spectroscopy, and zeta potential and surface functional-group titration. The adsorption isotherm and kinetics data were accurately described by the Langmuir and pseudo-second-order models. The adsorption capacity of the material for Sc(III), Nd(III), Gd(III), and Er(III) was 90.21, 104.59, 58.29, and 74.94 mg g^-1, respectively. Importantly, the adsorbent was better for selective recovery of Sc(III) not only from the 16 REE mixed system but also the Cu(II), Zn(II), Mn(II), Co(II), and Al(III) coexistence solution. Except for Sc(III), the material displayed high affinity for Nd(III) in the light rare-earth mixture and for Gd(III) in the middle rare-earth mixture. All in all, this study provides a new method for separation and recovery of REEs, which makes this work highly significant in separation and enrichment.

A highly efficient vortex-assisted liquid–liquid microextraction based on natural deep eutectic solvent for the determination of Sudan I in food samples

A natural deep eutectic solvent (NADES) composed of choline chloride (ChCl) and sesamol was successfully employed in the vortex-assisted liquid–liquid microextraction (VALLME) of food toxicant Sudan I (1-phenylazo-2-naphthalenol) in food samples for HPLC-UV analysis. Sesamol-based NADESs exhibited better Sudan I extraction abilities than other deep eutectic solvents and conventional organic solvents. ¹H NMR and 2D NOESY spectra were used to characterize the sesamol-based NADESs, indicating that hydrogen bonds were formed between ChCl and sesamol. The developed VALLME method showed a high extraction efficiency (near 100%) within 60 s at room temperature. Under the optimized extraction conditions, this established method showed good linearity (r² = 1.000) and a low limit of detection (LOD) of 0.02 mg kg⁻¹. The recoveries were in the range of 93–118%, and the intra-day and inter-day precisions were less than 4.5%. The developed method was successfully applied to the determination of Sudan I in various food samples, including chili oil, chili sauce, and duck egg yolk. This method gave a higher recovery than that of the EU recommended method when applied to sample analysis.

A highly efficient vortex-assisted liquid–liquid microextraction based on natural deep eutectic solvent was developed for the determination of Sudan I.

3D hollow porous CdFe2O4 microspheres as viable materials for magnetic solid-phase extraction of azo colorants

3D magnetic hollow porous CdFe₂O₄ microspheres (3D MHPS-CdFe2O4) were prepared by a one-step and template-free hydrothermal method. The material was applied for magnetic solid phase extraction of three azo colorants (Acid Red, Congo Red, Sunset Yellow). Compared to conventional CdFe₂O₄ nanoparticles, the new 3D material exhibits superior extraction capability because of its unique hollow porous structure, high specific surface area, and the strong interaction between 3D microspheres and the colorants. A magnetic solid phase extraction (MPSE) combined with HPLC was established for simultaneous detection of the three azo colorants in food samples. Under optimum conditions, the detection limits are 0.54-1.00 ng mL^-1, and good recoveries of 87.0-100.7% were obtained with spiked samples, with relative standard deviation of ≤ 3.8%. The combination of using the new 3D material and MPSE-HPLC results in an efficient, sensitive and inexpensive method for simultaneous determination of such colorants. Graphical abstract Schematic of the preparation of 3D magnetic hollow porous CdFe₂O₄ microspheres as solid phase extractant for simultaneous trace detection of three azo colorants in real samples.