腐殖酸磁固相萃取与高效液相色谱-荧光检测联用测定食用油中的苯并芘

采用简单的混合研磨方法制备磁性腐殖酸(MHAS)复合材料,并将其作为磁固相萃取的吸附剂选择性分离和富集食用油脂中的苯并芘(BaP)。结合高效液相色谱-荧光检测法(HPLC-FLD),建立了食用油中BaP检测的新方法。该方法整个样品前处理过程在15min内即可完成,对目标物BaP的检测限低至0.04ng/g,在0.1~100ng/g范围内线性良好(R=0.999),日内(n=5)和日间(n=3)相对标准偏差分别小于3.5%和15.8%。将该方法应用于多种食用油中BaP的检测,每种食用油中均有不同含量的BaP被检出,对12种常见食用油的加标回收率在74.2%至120.6%之间,相对标准偏差小于11.0%。     

Facile synthesis of magnetic one-dimensional polyaniline and its application in magnetic solid phase extraction for fluoroquinolones in honey samples

In this work, we proposed a simple co-mixing method to fabricate magnetic one-dimensional polyaniline (denoted as 1D-PANIs/MNPs). One-dimensional polyanilines (1D-PANIs) and magnetic nanoparticles (MNPs) were prepared by chemical oxidation and solvothermal methods, respectively. When MNPs and 1D-PANIs (with mass ratio 4:1) were co-mixed and vortexed evenly in a solvent (e.g., ethanol, water, acetonitrile), they could assemble into 1D-PANIs/MNPs spontaneously and thus be magnetically separable. To testify the feasibility of 1D-PANIs/MNPs in sample preparation, it was applied as the sorbent for magnetic solid phase extraction (MSPE) of fluoroquinolones (FQs) in honey samples. Under optimized conditions, a rapid, convenient, and efficient method for the determination of four FQs in honey samples by 1D-PANIs/MNPs-based MSPE coupling with high performance liquid chromatography with fluorescence detection (HPLC-FLD) was established. The limits of detection (LODs) for four FQs ranged from 0.4 to 1.4 ng g⁻¹. The intra- and interday relative standard deviations (RSDs) were less than 17.6%. The recoveries of FQs for three spiked honey samples ranged from 86.3 to 121.3%, with RSDs of less than 16.3%.     

Surface Polymers on Multiwalled Carbon Nanotubes for Selective Extraction and Electrochemical Determination of Rhodamine B in Food Samples

In this study, we combine magnetic solid phase extraction (MSPE), with the screen-printed carbon electrode (SPCE) modified by a molecular imprinted polymer (MIP) for sensitive and selective extraction and electrochemical determination of Rhodamine B in food samples. A magnetic solid phase extraction (MSPE) was carried out using magnetic poly(styrene-co-divinylbenzene) (PS-DVB) and magnetic nanoparticles (MNPs) synthetized on the surface of multiwalled carbon nanotubes (MWCNTs). An MIP was prepared on the surface of MWCNTs in the presence of titanium oxide nanoparticles (TiO₂NPs) modifying the SPCE for the rapid electrochemical detection of Rhodamine B. The MIPs synthesis was optimized by varying the activated titanium oxide (TiO₂) and multiwalled carbon nanotubes (MWCNTs) amounts. The MSPE and electrochemical detection conditions were optimized as well. The present method exhibited good selectivity, high sensitivity, and good reproducibility towards the determination of Rhodamine B, making it a suitable method for the determination of Rhodamine B in food samples.     

Magnetic solid-phase extraction of sulfonylurea herbicides in environmental water samples by Fe3O4@dioctadecyl dimethyl ammonium chloride@silica magnetic particles

A magnetic solid phase extraction (MSPE) method coupled with high-performance liquid chromatography (HPLC) was proposed for the determination of five sulfonylurea herbicides (bensulfuron-methyl, prosulfuron, pyrazosulfuron-ethyl, chlorimuron-ethyl and triflusulfuron-methyl) in environmental water samples. The magnetic adsorbent was prepared by incorporating Fe₃O₄ nanoparticles and surfactant into a silica matrix according to a sol–gel procedure, which can provide surfactant free extracts during the eluting step to avoid chromatographic interference. The prepared adsorbent was used to extract the sulfonylurea herbicides in several kinds of water samples. The main factors affecting the extraction efficiency, including desorption conditions, extraction time, sample volume, and sample solution pH were optimized. Under the optimum conditions, good linearity was obtained within the range of 0.2–50.0 μg L⁻¹ for all analytes, with correlation coefficients ranging from 0.9993 to 0.9999. The enrichment factors were between 1200 and 1410, and the limits of detection were between 0.078 and 0.10 μg L⁻¹. The proposed method was successfully applied in the analysis of sulfonylurea herbicides in environmental samples (tap, reservoir, river, and rice field). The recoveries of the method ranged between 80.4% and 107.1%. This study reported for the first time the use of MSPE procedure in the preconcentration of sulfonylurea herbicides in environmental samples. The procedure proved to be efficient, environmentally friendly, and fast.     

磁固相萃取/气相色谱一质谱法分析水样中的16种邻苯二甲酸酯类化合物

合成了一种由Fe3 O4磁性纳米粒子(MNPs)和多壁碳纳米管(MWCNTs)组成的复合纳米材料,用于水样中16种邻苯二甲酸酯类化合物(PAEs)的磁固相萃取(MSPE),并结合气相色谱-质谱(GC - MS)法进行定量分析.合成的纳米材料用傅立叶变换红外光谱表征.为提高萃取效率,优化了解析溶剂的种类和用量、解析时间、...     

Effervescence assisted dispersive liquid–liquid microextraction with extractant removal by magnetic nanoparticles

In this article, effervescence assisted dispersive liquid–liquid microextraction with extractant removal by magnetic nanoparticles is presented for the first time. The extraction technique makes use of a mixture of 1-octanol and bare Fe₃O₄ magnetic nanoparticles (MNPs) in acetic acid. This mixture is injected into the sample, which is previously fortified with carbonate, and as a consequence of the effervescence reaction, CO₂ bubbles are generated making possible the easy dispersion of the extraction solvent. In addition, the MNPs facilitates the recovery of the 1-octanol after the extraction thanks to the interaction between hydroxyl groups present at the surface of the MNPs and the alcohol functional group of the solvent. The extraction mode has been optimized and characterized using the determination of six herbicides in water samples as model analytical problem. The enrichment factors obtained for the analytes were in the range 21–185. These values permit the determination of the target analytes at the low microgram per liter range with good precision (relative standard deviations lower than 11.7%) using gas chromatography (GC) coupled to mass spectrometry (MS) as analytical technique.     

Rapid and effective sample cleanup based on graphene oxide-encapsulated core–shell magnetic microspheres for determination of fifteen trace environmental phenols in seafood by liquid chromatography–tandem mass spectrometry

In this study, graphene oxide-encapsulated core–shell magnetic microspheres (GOE-CS-MM) were fabricated by a self-assemble approach between positive charged poly(diallyldimethylammonium) chloride (PDDA)-modified Fe₃O₄@SiO₂ and negative charged GO sheets via electrostatic interaction. The as-prepared GOE-CS-MM was carefully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer analysis (VSM), and X-ray photoelectron spectroscopy (XPS), and was used as a cleanup adsorbent in magnetic solid-phase extraction (MSPE) for determination of 15 trace-level environmental phenols in seafood coupled to liquid chromatography–tandem mass spectrometry (LC–MS/MS). The obtained results showed that the GOE-CS-MM exhibited excellent cleanup efficiency and could availably reduce the matrix effect. The cleanup mechanisms were investigated and referred to π–π stacking interaction and hydrogen bond between GOE-CS-MM and impurities in the extracts. Moreover, the extraction and cleanup conditions of GOE-CS-MM toward phenols were optimized in detail. Under the optimized conditions, the limits of detection (LODs) were found to be 0.003–0.06 μg kg⁻¹, and satisfactory recovery values of 84.8–103.1% were obtained for the tested seafood samples. It was confirmed that the developed method is simple, fast, sensitive, and accurate for the determination of 15 trace environmental phenols in seafood samples.     

Extraction of ammonia and nitrite using modified magnetite iron oxide nanoparticles before spectrophotometric determination in different water samples

A new analytical approach was developed for the extraction and determination of ammonia and nitrite in environmental water samples involving magnetic solid-phase extraction (MSPE) with magnetite nanoparticles (MNPs) as the adsorbent. The procedure is based on the derivatisation of ammonia based on Berthelot reaction. The obtained indophenol dye was extracted using MSPE and determined spectrophotometrically at 655 ± 3 nm. Nitrite ion is determined after its reduction to ammonia in the presence of Zn/HCl. The main factors that affected the extraction efficiency were studied and optimised. The method gave calibration curves for ammonia with good linearity in the range 10–550 µg L^?1, and correlation coefficients (r) higher than 0.99. The detection and quantification limit was found to be 3.1 and 10.2 µg L^?1, respectively. The method showed good precision and accuracy, with intra- and inter-assay precisions of less than 6.6% at all concentrations. The recoveries ranged 89–105% and 88–105%, for ammonia and nitrite determination, respectively. The method was applied to the determination of the target analytes in real samples.     

Rapid magnetic solid-phase extraction based on magnetite/silica/poly(methacrylic acid–co–ethylene glycol dimethacrylate) composite microspheres for the determination of sulfonamide in milk samples

A novel magnetic solid-phase extraction (MSPE) sorbent, magnetite/silica/poly (methacrylic acid–co-ethylene glycol dimethacrylate) (Fe₃O₄/SiO₂/P(MAA-co-EGDMA)), was developed. This MSPE material was prepared by distillation–precipitation polymerization of MAA and EGDMA in the presence of Fe₃O₄/SiO₂ microspheres with the surface containing abundant reactive double bonds. The resultant sorbent material was characterized by elemental analysis, electron microscopy, X-ray diffraction and Fourier-transformed infrared spectroscopy. In this work, eleven sulfonamides (SAs) were selected as model analytes to validate the extraction performance of this new MSPE sorbent. Noticeably, the extraction can be carried out quickly, the extraction time for the SAs onto Fe₃O₄/SiO₂/P(MAA-co-EGDMA) sorbent can be clearly shortened to 0.5 min. The desorption solution of SAs was analyzed by LC–MS/MS, and the results showed that the recoveries of these compounds were in the range of 87.6–115.6%, with relative standard deviations ranging between 0.9% and 10.8%; the limit of detection were in the range of 0.5–49.5 ng/L.     

Magnetic solid-phase extraction of triclosan using core-shell Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@MIL-100 magnetic nanoparticles,and its determination by HPLC with UV detection

The article describes the synthesis of core-shell magnetic nanoparticles (MNPs) of the type Fe₃O₄@MIL-100 (MIL standing for Material Institut Lavoisier), and their application as sorbent for magnetic solid-phase extraction (MSPE) of triclosan. The MNPs were prepared via circular self-assembly of ferric chloride and benzenetricarboxylic acid. The functionalized MNPs were characterized by transmission electron microscopy, FTIR and thermogravimetry. Following extraction, triclosan was eluted with ammoniacal methanol and then submitted to HPLC with UV detection. The amount of magnetic microspheres, sample pH and ionic strength, adsorption time, desorption time, desorption solvent and the volume of the eluent were optimized. Under optimum conditions, the method showed good linearity in the 0.1 to 50 mg·kg^?1 triclosan concentration range in toothpaste samples. Other features include (a) intra-day and inter-day relative standard deviations (RSD, for n = 4) of <5.5 %, (b) a 30 μg·kg^?1 limit of detection, and (c) extraction recoveries between 90.86 % and 101.1 %. The method was successfully applied to the determination of triclosan in children’s toothpaste.

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Graphical abstract The article describes the synthesis of core-shell magnetic nanoparticles (MNPs) of the type Fe₃O₄@MIL-100, and their application as sorbent for magnetic solid-phase extraction (MSPE) of triclosan.

     

Preparation of magnetite/poly(styrene-divinylbenzene) nanoparticles for selective enrichment-determination of fenitrothion in environmental and biological samples

In the present study, a cross-linked nano-sized spherical magnetic poly(styrene-divinylbenzene) is synthesized and used as an adsorbent for enrichment-determination of fenitrothion. A miniemulsion polymerization procedure was used to prepare the adsorbent. The magnetic adsorbent was characterized by FT-IR, SEM and TEM. The prepared magnetic adsorbent nanoparticles were mixed with magnetite nanoparticles for faster and more efficient magnetic precipitation. The reduced fenitrothion was coupled with 3-methyl-2-benzothiazolinone hydrazone and then the blue colored complex was extracted. The blue derivative of fenitrothion was eluted by a 1 mL aliquot of 1-propanol prior to spectrophotometry at 571 nm. Beer's law was obeyed in the range of 2–230 ng mL⁻¹ of fenitrothion with relative standard deviation and recovery in the ranges of 0.9–5.1% and 97.2–100.0%, respectively. Selectivity of the method was evaluated, and the method was successfully applied to the determination of fenitrothion in various water, soil, urine and human plasma samples.     

磁固相萃取-气相色谱-火焰光度检测联用测定果汁中的有机磷农药

制备了苯乙烯（St）和甲基丙烯酸（MAA）共聚物改性的磁性微球Fe₃O₄@P（St-co-MAA）,并将其作为磁固相萃取吸附剂,建立了磁固相萃取（MSPE）-气相色谱（GC）-火焰光度检测（FPD）联用分析有机磷农药（OPPs）残留的新方法。以5种有机磷农药（二嗪农、甲基毒死蜱、杀螟硫磷、毒死蜱和喹硫磷）为目标分析物,考察并优化了吸附和解吸条件,确定了最佳实验条件。在最优的实验条件下,方法对5种OPPs的检出限（S/N=3）为0.013~0.305 μg/L,方法的相对标准偏差（RSD,n=7）为3.1%~8.8%,富集倍数为406~951,线性范围达3个数量级。将该方法应用于新鲜番茄汁、草莓汁样品中的OPPs残留分析,加标回收率为85.4%~118.9%。该方法具有检出限低、分析速度快、富集倍数高等优点,为有机磷农药的残留分析提供了新的技术平台。     

Magnetic solid-phase extraction of malachite green using soluble eggshell membrane protein doped with magnetic graphene oxide nanocomposite

ABSTRACT

This study describes a new magnetic solid-phase extraction (MSPE) technique based on Fe₃O₄/graphene oxide-soluble eggshell membrane protein (Fe₃O₄/GO-SEP) for accurate measurement of malachite green (MG) residue in various water samples residues by UV-Vis spectroscopy. The morphology of the prepared adsorbent has been studied by scanning electron microscopy and atomic force microscopy in details. Parameters affecting the MSPE were optimised and determined with UV-Vis spectrophotometry thoroughly. Under the optimised extraction circumstances, the introduced method represented a wide linearity over the concentration of 0.5–250 ng mL^?1, a high enrichment factor of 83.3 and low detection limit of 0.2 ng mL^?1. The prepared Fe₃O₄/GO-SEP was successfully used for preconcentration and determination of MG in river and fish farming water samples with suitable precision and accuracy.     

Facile preparation of surface-exchangeable core@shell iron oxide@gold nanoparticles for magnetic solid-phase extraction: Use of gold shell as the intermediate platform for versatile adsorbents with varying self-assembled monolayers

The core@shell Fe₃O₄@Au nanoparticles (NPs) functionalized with exchangeable self-assembled monolayers have been developed for mode switching magnetic solid-phase extraction (MSPE) using high performance liquid chromatography with ultraviolet detection. The adsorbents were synthesized by chemical coprecipitation to prepare magnetic cores followed by sonolysis to produce gold shells. Functionalization of Fe₃O₄@Au NPs surface was realized through self-assembly of commercially available low molecular weight thiol-containing ligands using gold shells as intermediate platform and the dynamic nature of Au–S chemistry allowed substituent of one thiol-containing ligand with another simply by thiol exchange process. The resultant adsorbents were characterized by transmission electronic microscopy, Fourier transform infrared spectroscopy, elemental analysis, contact angle measurement, and vibrating sample magnetometry. To evaluate the versatile performance of the developed MSPE adsorbents, they were applied for normal-phase SPE followed by reversed-phase SPE. A few kinds of diphenols and polycyclic aromatic hydrocarbons (PAHs) were employed as model analytes, respectively. The predominant parameters affecting extraction efficiency were investigated and optimized. Under the optimum experimental conditions, wide dynamic linear range (6.25–1600 μg L⁻¹ for diphenols and 1.56–100 μg L⁻¹ for PAHs) with good linearity (r² ≥ 0.989) and low detection limits (0.34–16.67 μg L⁻¹ for diphenols and 0.26–0.52 μg L⁻¹ for PAHs) were achieved. The advantage of the developed method is that the Fe₃O₄@Au NPs could be reutilized for preconcentrating diverse target analytes in different SPE modes sequentially simply through treatment with desired thiol-containing ligands.     

Green tea-synthesized magnetic nanoparticles accelerate the microwave digestion of proteins analyzed by MALDI-TOF-MS

In present work, green tea is used for the synthesis of magnetic nanoparticles. During synthesis of MNPs, no additional reducing agents required because green tea extract itself contains polyphenols reducing agent, comparatively other reported methods. Surface of the green tea-synthesized nanoparticles is functionalized with tetraethyl orthosilicate and 3-aminopropyltriethoxysilane. Functionalized MNPs are applied for the microwave digestion of protein molecules. Functionalized MNPs contain negative charge, and thus adsorb peptide fragments after microwave digestion of protein molecules. The functionalized MNPs can assist, accelerate and effectively enhance the digestion efficiency, sequence coverage and detection sensitivity of peptides for the microwave-assisted tryptic digestion of proteins in matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). The reason is attributed to the fact that proteins or partially digested proteins are easily attracted or concentrated onto the surface of functionalized MNPs, resulting in higher efficiency of digestion reactions in the microwave experiments. Besides, the functionalized MNPs could act as a microwave absorber to accelerate and enrich the protein fragments in a short period of time (30–50 s). Various experimental conditions such as enzyme-to-protein ratio 1:30, MNPs concentration 600 µg, heating time 40 s and incubation time 15 min were investigated in the MALDI-TOF-MS. Thus, the current technique proves the suitability, cheapness and ecofriendly nature of MNPs and its utility for various biotechnological and proteome research in near future.     

A covalent organic framework-based magnetic sorbent for solid phase extraction of polycyclic aromatic hydrocarbons,and its hyphenation to HPLC for quantitation

Microchimica Acta - A novel covalent organic framework based magnetic adsorbent was developed for magnetic solid phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs). Covalent organic...     

One-Step Synthesis of Polyethylenimine-Coated Magnetic Nanoparticles and its Demulsification Performance in Surfactant-Stabilized Oil-in-Water Emulsion

In this study, polyethylenimine (PEI)-coated Fe₃O₄ magnetic nanoparticles (MNPs) were successfully synthesized via a one-step, solvo-thermal method. The synthetic PEI-coated MNPs were characterized by using multiple techniques and their demulsification efficiencies were evaluated in surfactant-stabilized, oil-in-water emulsions. The results showed that the synthesized MNPs successfully adsorbed to the emulsion’s O/W interfaces and, consequently, the oil droplets could be rapidly destabilized under an applied magnetic field. It was found that the demulsification efficiency was enhanced with the increased particle dosage. The opposite effect was found with the increase in pH value and surfactant concentration. The presence of electrolytes facilitated oil removal, presumably by reduction of the electrostatic repulsion or by altering the hydrophobicity of the MNPs. Recovery experiments at various pH levels indicated that the PEI-coated MNPs could be reused for up to ten times without significant reduction in demulsification efficiency. Altogether, the results suggested that the PEI-coated MNPs could provide a simple but powerful tool to remove emulsified oil from aqueous systems.     

Polythionine-decorated magnetic nanoparticles as a robust and highly effective sorbent for mercury determination in environmental water samples

Extraction, pre-concentration and determination of trace amounts of mercury ions from water samples were investigated by magnetic solid phase extraction (MSPE) method using Fe₃O₄ nanoparticles decorated with polythionine as an adsorbent. A simple chemical synthesis by catalytic reaction of thionine in the presence of FeCl₃ and hydrogen peroxide was used for preparation of the magnetic sorbent. Scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometer analysis and Fourier transform infrared spectroscopy were used to characterise the adsorbent. Mercury ions were determined by cold vapour atomic absorption spectrometry. The parameters for MSPE procedure, such as pH of the extraction solution, adsorption time, weight adsorbent, elution conditions (type, concentration and volume of the eluent), volume of the sample solution and effects of coexisting ions were investigated. The obtained optimal conditions were: sample pH of 4; sorbent amount of 4 mg; sorption time of 20 min; elution solvent of HNO₃ (0.3 mol L^?1)/thiourea (2% w/v) with volume of 2 mL, and breakthrough volume of 400 mL. A good linearity in the concentration range of 0.025–40 µg L^?1 (R² > 0.999) with the pre-concentration factor of 198 was obtained. The limits of detection and quantification were achieved as 0.008 and 0.025 µg L^?1, respectively. Furthermore, sea and river water samples were analysed and good recoveries (97.1–99.6%) were obtained.     

Magnetic functionalized graphene oxide combined with ultra-high performance liquid chromatography for trace detection of succinate dehydrogenase inhibitor fungicides in food

In this study, an efficient, sensitive, and convenient magnetic solid-phase extraction method combined with ultra-high performance liquid chromatography-tandem mass spectrometry (MSPE-UHPLC-MS/MS) was developed for the simultaneous determination of 19 succinate dehydrogenase inhibitor fungicide residues in six different food matrices The synthesized tetraethylenepentamine magnetic graphene oxide nanocomposite showed the advantages of good dispersibility, large specific surface area (113.93 m²/g) and large pore volume (0.25 cm³/g), making it an ideal succinate dehydrogenase inhibitor pretreatment adsorbent. The MSPE-UHPLC-MS/MS method showed linearity in the range of 5.0–800.0 μg/kg, with a correlation coefficient (R²) > 0.99, and a limit of quantification of 5 μg/kg. The recovery of succinate dehydrogenase inhibitor fungicides was in the range of 71.2%–119.4%. The MSPE method is simple, rapid, and efficient, making it an ideal alternative to sample pretreatment in the determination of trace succinate dehydrogenase inhibitor fungicides in complex matrices.     

Dual-color upconversion fluorescence and aptamer-functionalized magnetic nanoparticles-based bioassay for the simultaneous detection of Salmonella Typhimurium and Staphylococcus aureus

A sensitive luminescent bioassay for the simultaneous detection of Salmonella Typhimurium and Staphylococcus aureus was developed using aptamer-conjugated magnetic nanoparticles (MNPs) for both recognition and concentration elements and using upconversion nanoparticles (UCNPs) as highly sensitive dual-color labels. The bioassay system was fabricated by immobilizing aptamer 1 and aptamer 2 onto the surface of MNPs, which were employed to capture and concentrate S. Typhimurium and S. aureus. NaY_0.78F₄:Yb_0.2,Tm_0.02 UCNPs modified aptamer 1 and NaY_0.28F₄:Yb_0.70,Er_0.02 UCNPs modified aptamer 2 further were bond onto the captured bacteria surface to form sandwich-type complexes. Under optimal conditions, the correlation between the concentration of S. Typhimurium and the luminescent signal was found to be linear within the range of 10¹–10⁵ cfu mL⁻¹ (R² = 0.9964), and the signal was in the range of 10¹–10⁵ cfu mL⁻¹ (R² = 0.9936) for S. aureus. The limits of detection of the developed method were found to be 5 and 8 cfu mL⁻¹ for S. Typhimurium and S. aureus, respectively. The ability of the bioassay to detect S. Typhimurium and S. aureus in real water samples was also investigated, and the results were compared to the experimental results from the plate-counting methods. Improved by the magnetic separation and concentration effect of MNPs, the high sensitivity of UCNPs, and the different emission lines of Yb/Er- and Yb/Tm-doped NaYF₄ UCNPs excited by a 980 nm laser, the present method performs with both high sensitivity and selectivity for the two different types of bacteria.