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1.
Mikrochim Acta ; 191(7): 385, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38860988

RESUMO

A new polyether sulfone (PES) membrane modified with manganese-aluminum layered double hydroxide (Mn-Al LDH) was prepared and utilized in the membrane micro-solid phase extraction (M-µSPE) of acrylamide for the first time. The analyses were conducted using HPLC-UV. The extraction efficiency of the PES membrane was enhanced two-fold with the addition of LDH. The fabricated LDH@PES was characterized using ATR-FTIR, SEM, XRD, and nitrogen adsorption/desorption isotherms. The specific surface area, average pore diameter, thickness, cross-sectional channels, and LDH particle size of the LDH@PES membrane were determined. The extraction key factors including membrane composition, desorption conditions, sample pH, and salt concentration were studied. The method was validated by determining the limit of detection, the limit of quantification, linear range, r2, matrix effect, enrichment factor, and precision. Extraction recoveries ranged from 87.4 to 103.5% with RSD < 5.9%. Finally, the method's green features were assessed with the AGREE protocol. This is the first report on the application of LDH@PES for microfiltration/extraction of acrylamide in various chocolate and cocoa products.

2.
Environ Res ; 216(Pt 1): 114416, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36181897

RESUMO

In this study, an adsorbent made of alginate (Alg) caged magnesium sulfide nanoparticles (MgS) microbeads were used to treat lead ions (Pb2+ ions). The MgS nanoparticles were synthesized at low temperatures, and Alg@MgS hydrogel microbeads were made by the ion exchange process of the composite materials. The newly fabricated Alg@MgS was characterized by XRD, SEM, and FT-IR. The adsorption conditions were optimized for the maximum removal of Pb2+ ions by adjusting several physicochemical parameters, including pH, initial concentration of lead ions, Alg/MgS dosage, reaction temperature, equilibration time, and the presence of co-ions. This is accomplished by removing the maximum amount of Pb2+ ions. Moreover, the adsorbent utilized more than six times with a substantial amount (not less than 60%) of Pb2+ ions was eliminated. Considering the ability of sodium alginate (SA) for excellent metal chelation and controlled nanosized pore structure, the adsorption equilibrium of Alg@MgS can be reached in 60 min, and the highest adsorption capacity for Pb2+ was 84.7 mg/g. The sorption mechanism was explored by employing several isotherms. It was found that the Freundlich model fits the adsorption process quite accurately. The pseudo-second-order model adequately described the adsorption kinetics.


Assuntos
Nanopartículas , Poluentes Químicos da Água , Purificação da Água , Alginatos/química , Águas Residuárias , Magnésio , Microesferas , Chumbo , Poluentes Químicos da Água/análise , Espectroscopia de Infravermelho com Transformada de Fourier , Adsorção , Cinética , Sulfetos , Concentração de Íons de Hidrogênio
3.
J Sep Sci ; 45(5): 1106-1115, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34958521

RESUMO

A new green miniaturized quick, easy, cheap, effective, rugged, and safe approach was developed and used for the extraction of multiclass 16 pesticides in milk before gas chromatography analysis. The miniaturization of method reduced the consumption of chemical reagents and samples. Magnetic three-dimensional graphene was used as sorbent in the clean-up step. Choline chloride:lactic acid (1:2) natural deep eutectic solvent was used as desorption solvent. Temperature-assisted solidification of floating menthol drop was executed for preconcentration of analytes. The method parameters including sorbent, desorption solvent, sorption and desorption times, menthol amount, pH, and ionic strength were optimized. The limit of quantification and linear range were 0.03-0.38 and 0.03-250 µg/kg, respectively. The accuracy was assessed by recovery evaluation at the spike levels of 50 and 100 µg/kg, in the range of 61-119%, with relative standard deviations within 2.1-18.2%. The method was applied to the analysis of pasteurized low and high-fat bovine milk, and various pesticide residues were detected in the concentrations range of 1.24-4.68 µg/kg. Finally, the greenness of the procedure was evaluated using the Analytical Eco-Scale. This work represents the first application of hybrid miniaturized extraction/preconcentration using a natural deep eutectic solvent and menthol to analyze pesticides.


Assuntos
Microextração em Fase Líquida , Resíduos de Praguicidas , Animais , Microextração em Fase Líquida/métodos , Mentol/química , Leite/química , Resíduos de Praguicidas/análise , Temperatura
4.
J Sep Sci ; 44(19): 3626-3635, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34355865

RESUMO

Four new thymol-based ternary deep eutectic solvents were prepared and evaluated as the extractive phase in air-bubbles assisted dispersive liquid-liquid microextraction for extraction of tetracycline, doxycycline, and oxytetracycline from the water before high-performance liquid chromatography. The maximum extraction efficiencies were obtained using 400 µL of [choline chloride]:[thymol]:[nonanoic acid] in the molar ratio of 1:2:2 at pH = 5. The solvent was characterized by FTIR and NMR spectroscopy. The hydrophobicity of the deep eutectic solvent and its effect on the pH of water samples after mixing was also studied. Besides, the extraction efficiency of the ternary deep eutectic solvent was compared with that of two binary thymol-based deep eutectic solvents, including [choline chloride]:[thymol] and [thymol]:[nonanoic acid] at the same conditions. Under optimal conditions, limits of detection and quantification were 1.2-8.0 and 3.8-26.6 µg/L, respectively. The linear ranges were 18.2-500 µg/L for oxytetracycline, 26.6-500 µg/L for tetracycline, and 3.8-500 µg/L for doxycycline with the determination coefficients > 0.9912. Intra- and inter-day relative standard deviations were 1.2-3.8 and 7.7-11.2%, respectively. The developed method was applied to the analysis of tetracyclines in unspiked and spiked environmental water samples, and the obtained recoveries were 74.5-95.4% with relative standard deviations of 1.2-4.0%.


Assuntos
Solventes Eutéticos Profundos/química , Microextração em Fase Líquida/métodos , Tetraciclinas/análise , Timol/química , Cromatografia Líquida de Alta Pressão , Resíduos de Drogas/análise , Resíduos de Drogas/química , Resíduos de Drogas/isolamento & purificação , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes , Tetraciclinas/química , Tetraciclinas/isolamento & purificação , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
5.
J Sci Food Agric ; 101(6): 2304-2311, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33006378

RESUMO

BACKGROUND: Tetracycline antibiotics are employed for human and animal health and for speeding up growth rates. However, their presence in food products and environmental waters has been a concern for some years. Therefore, a variety of sample preparation methods have been developed for the analysis of tetracycline residues in these matrices. RESULTS: An electrochemically controlled solid phase microextraction based on a modified copper electrode with polyaniline/graphene oxide (PANI/GO) conductive nanocomposite was developed for the extraction of oxytetracycline, tetracycline and doxycycline before high-performance liquid chromatography-UV analysis. PANI/GO was synthesized by in situ chemical oxidative polymerization, characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy, and bound on the electrode using high purity conductive double-sided adhesive carbon glue. The significant factors affecting the performance of microextraction were investigated and optimized. Under the optimized conditions [sample, 15 mL; sorbent, 10 mg; pH, 3.0; electroextraction voltage, -0.9 V; electroextraction time, 20 min; eluent (MeOH/NH3 ), 500 µL; and desorption time, 5 min], the limits of detection for target analytes were in the ranges 0.32-1.01 and 2.42-7.59 µg L-1 in water and milk samples, respectively. The linear ranges were 1.06-750 µg L-1 for water and 8.05-750 µg L-1 for milk samples. The intra-day and inter-day precisions were 2.32-3.80 and 3.29-4.25, respectively. The method was applied to the determination of analytes in milk and water samples with different fat contents, and the recoveries were obtained in the range 71-104%. CONCLUSION: The developed electro-microextraction method provides a facile, rapid, cost-effective, sensitive and efficient promising procedure for the extraction of antibiotics in complex matrices. © 2020 Society of Chemical Industry.


Assuntos
Antibacterianos/isolamento & purificação , Leite/química , Microextração em Fase Sólida/métodos , Tetraciclinas/isolamento & purificação , Poluentes da Água/isolamento & purificação , Compostos de Anilina/química , Animais , Antibacterianos/análise , Bovinos , Cromatografia Líquida de Alta Pressão , Condutividade Elétrica , Contaminação de Alimentos , Grafite/química , Limite de Detecção , Nanocompostos/química , Polímeros/química , Microextração em Fase Sólida/instrumentação , Tetraciclinas/análise , Poluentes da Água/análise
6.
Anal Bioanal Chem ; 412(1): 129-138, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31773230

RESUMO

A novel lab-on-chip integrated microfluidic device for solid-phase extraction (SPE) and spectrophotometric detection of morphine (MOR), codeine (COD), and papaverine (PAP) was developed. The extracted analytes were analyzed with a miniature UV-Vis spectrophotometer. The SPE adsorptive phase composed of polyurethane/polyaniline (PU/PANI) nanofibers was fabricated by electrospinning and in situ oxidative polymerization techniques. The sorbent was characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The main factors of extraction such as desorption conditions, pH, salt effect, and extraction time were investigated. The partial least square (PLS) regression was applied to improve the quantification of analytes. The linear dynamic ranges (LDRs) for MOR, COD, and PAP were 4-240, 4-210, and 1-150 ng mL-1, respectively. Finally, the proposed method was successfully applied for the determination of MOR, COD, and PAP in human urine samples and the extraction recoveries were obtained in the range of 66.7-85.0% with RSDs < 8.3%.


Assuntos
Codeína/urina , Dispositivos Lab-On-A-Chip , Morfina/urina , Papaverina/urina , Extração em Fase Sólida/instrumentação , Espectrofotometria Ultravioleta/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Humanos , Microscopia Eletrônica de Varredura , Reprodutibilidade dos Testes
7.
J Sep Sci ; 43(11): 2115-2124, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32115813

RESUMO

This study describes the synthesis and application of a magnetic amino-functionalized hollow silica-titania microsphere as a new sorbent for magnetic dispersive micro-solid phase extraction of selected pesticides in coffee bean samples. The sorbent was fully characterized by Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, transition electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometry techniques. Significant extraction parameters affecting the proposed method, such as extraction time, sorbent amount, sample solution pH, salt amount, and desorption conditions (desorption solvent and time) were investigated and optimized. All the figures of merits were validated in coffee bean samples under the matrix-matched calibration method. Linear dynamic ranges were 5-250 µg/kg with the determination coefficients (R2 ) > 0.9980. The limits of detection for the pesticides of chlorpyrifos, malathion, hexaconazole, and atrazine were 1.42, 1.43, 1.35, and 1.33 µg/kg, respectively. Finally, the method was successfully applied for the determination of the pesticides in green and roasted coffee bean samples, and the obtained recoveries were in the range of 74-113% for spiked samples. The prepared sorbent could be used for the magnetic dispersive micro-solid phase extraction of pesticides in the plant-derived food matrix.


Assuntos
Café/química , Microesferas , Praguicidas/isolamento & purificação , Dióxido de Silício/química , Titânio/química , Adsorção , Atrazina/química , Atrazina/isolamento & purificação , Clorpirifos/química , Clorpirifos/isolamento & purificação , Fenômenos Magnéticos , Malation/química , Malation/isolamento & purificação , Tamanho da Partícula , Praguicidas/química , Porosidade , Propriedades de Superfície , Triazóis/química , Triazóis/isolamento & purificação
8.
J Sep Sci ; 43(22): 4216-4224, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32964564

RESUMO

Priority pollutants chlorophenols are broadly used chemicals that are persistent in the environment and causing serious human health hazards. The current study introduces a novel adsorbent for the extraction of chlorophenols from river water, surface water, and milk by headspace solid-phase microextraction coupled with gas chromatography. The adsorbent composite was prepared by blending polycaprolactam (nylon-6) mat and newly synthesized carbon nanotubes decorated with cadmium oxide nanoparticles followed by electrospinning technique to produce based nanofiber. The proposed nanofiber was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The main parameters that affect extraction efficiency, including ionic strength, extraction time, desorption time, and extraction temperature, were investigated and optimized. The linear range was 0.05-5 ng/mL; the limits of detection (signal/noise=3) were 0.02-0.04 ng/mL. The relative recoveries for real samples (river water, surface water, and milk) were in the range of 84-114%.


Assuntos
Compostos de Cádmio/química , Clorofenóis/análise , Nanofibras/química , Nanotubos de Carbono/química , Óxidos/química , Microextração em Fase Sólida , Poluentes Químicos da Água/análise , Animais , Caprolactama/química , Leite/química , Tamanho da Partícula , Polímeros/química , Água/química
9.
Mikrochim Acta ; 187(9): 541, 2020 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-32876845

RESUMO

This review (including 127 refs) summarizes applications of nanosorbent-based solid phase microextraction (SPME) for the cleanup, extraction, and quantification of Emerging Organic Contaminants (EOCs). SPME is the most widely used technique for the analysis of EOCs from water samples. The selection of sorbent material plays a key role in SPME applications. Here, we have collected information about recent developments in the application of nanosorbents in the SPME technique used for the extraction of EOCs from water and wastewater samples. In this review, the preparation, properties, advantages, and limitations of nanosorbents used in SPME applications are evaluated and discussed. Besides, the applications of these nanosorbents in SPME-based extraction techniques and their analytical characteristics for the determination of EOCs are reviewed. Graphical abstract.


Assuntos
Microextração em Fase Sólida/métodos , Águas Residuárias/química , Humanos
10.
J Sci Food Agric ; 100(3): 1048-1055, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31677164

RESUMO

BACKGROUND: Magnetic three-dimensional graphene-based nanoadsorbents have unique characteristics such as large surface area, good thermal and chemical stability, and high adsorption capacity that make them efficient materials in sorbent-based extraction techniques. In this study, four aflatoxins (AFs) were analyzed in bread samples using magnetic three-dimensional graphene as the adsorbent phase in dispersive micro solid-phase extraction. RESULTS AND CONCLUSIONS: In-syringe magnetic sheet solid-phase extraction based on magnetic three-dimensional graphene in tandem with dispersive liquid-liquid microextraction was used for the extraction and preconcentration of the target AFs. The effect of significant parameters of the method was investigated and the optimum conditions were determined as follows: adsorbent dosage, 20 mg; desorption/disperser solvent (methanol) volume, 700 µL; desorption solvent flow rate, 0.7 mL min-1 ; pH, neutral; salt (NaCl) concentration, 10% (w/v); extraction solvent (chloroform) volume, 250 µL; and centrifugation rate (and time), 4000 rpm (5 min). The limits of detection and quantification were in the ranges 0.043-0.083 and 0.14-0.28 µg kg-1 , respectively. The extraction method was followed by the HPLC technique with fluorescence detection and applied to the determination of the AFs in four different Iranian fresh and moldy bread samples. The relative recoveries were in the range 84-107% with relative standard deviations of 3.9-8.6%. © 2019 Society of Chemical Industry.


Assuntos
Aflatoxinas/isolamento & purificação , Pão/análise , Contaminação de Alimentos/análise , Microextração em Fase Líquida/métodos , Magnetismo/métodos , Extração em Fase Sólida/métodos , Adsorção , Aflatoxinas/análise , Cromatografia Líquida de Alta Pressão , Irã (Geográfico) , Extração em Fase Sólida/instrumentação , Seringas
11.
J Sci Food Agric ; 100(6): 2534-2543, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31975389

RESUMO

BACKGROUND: Pesticides are extensively used worldwide to control plant pathogens and prevent agricultural product damage. However, they can pollute the environment and endanger human health. So far, a variety of sample preparation methods have been developed for the analysis of pesticide residues. RESULTS: A hyphenated solid-liquid microextraction method based on a new adsorbent of magnetic graphene oxide functionalized by (3-glycidyloxypropyl)trimethoxysilane and a deep eutectic solvent (choline chloride/4-chlorophenol (1:2)) was developed for extraction/preconcentration of trace levels of pesticides. The sorbent was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. In-syringe magnetic dispersive solid-phase extraction in tandem with dispersive liquid-liquid microextraction followed by gas chromatography was applied for the analysis of the selected pesticides. The main parameters governing sample preparation efficiency, including adsorbent dosage, desorption conditions, pH, extraction time, deep eutectic solvent volume, and salt concentration, were investigated. The linear ranges were 0.024-500 µg L-1 with 0.9971-0.9999 linearity factor (R2 ). The limits of detection and quantification were 0.006-0.038 and 0.024-0.126 µg L-1 , respectively. The relative standard deviations were 0.5-4.2% for intra-day analysis and 2.7-4.6% for inter-day analysis. Enrichment factors were in the range 210-540. CONCLUSIONS: The method was successfully applied for the determination of malathion, heptachlor epoxide, endrin, dichlorodiphenyltrichloroethane, azinphos ethyl, cypermethrin, and deltamethrin in fruit juice samples (apple, pineapple, cherry, peach, and red and green grape juices) and the recoveries were within the range 71-115%. © 2020 Society of Chemical Industry.


Assuntos
Cromatografia Gasosa/métodos , Sucos de Frutas e Vegetais/análise , Resíduos de Praguicidas/análise , Adsorção , Grafite/química , Microextração em Fase Líquida/métodos , Fenômenos Magnéticos , Resíduos de Praguicidas/isolamento & purificação , Extração em Fase Sólida/métodos , Solventes/química
12.
Cells Tissues Organs ; 207(3-4): 177-186, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31775143

RESUMO

Wound healing is a complex process and some agents have been reported to accelerate it. The aim of this study was to evaluate the healing effect of Eucerin-based ointments of lemon, sesame and olive oils on infected full-thickness wounds in rats. Wounds were created on the dorsal surface of Male Albino Wistar rats (n = 12). Wounds were treated with an Eucerin-based ointment containing either of lemon, sesame or olive oils (33% w/w) twice a day for 14 days. Histopathology results showed that contraction of wounds treated with lemon and sesame oils was higher than in the olive oil and control groups on days 10 and 14. In the lemon- and sesame-oil treated groups, on day 14, 50% of rat lesions were completely healed. Total number of inflammatory cells in lemon oil treatment group was significantly smaller than that of others on day 14 (p < 0.001). Also, thickness of the epidermal layer and rejuvenation of the hair follicles and other skin appendages was normal in lemon and sesame oil treated groups. The lemon and sesame oil ointments accelerated the healing process of wounds in macroscopic, morphological and morphmetrical analyses. Therefore, lemon and sesame oil ointments could be considered as alternative dressings for infected full-thickness wounds because of improved wound healing characteristics.


Assuntos
Azeite de Oliva/uso terapêutico , Óleos de Plantas/uso terapêutico , Óleo de Gergelim/uso terapêutico , Cicatrização/efeitos dos fármacos , Animais , Lipídeos , Masculino , Bases para Pomadas , Pomadas , Azeite de Oliva/administração & dosagem , Óleos de Plantas/administração & dosagem , Ratos Wistar , Óleo de Gergelim/administração & dosagem
13.
Anal Bioanal Chem ; 411(16): 3631-3640, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31175397

RESUMO

In this research, electrospun polycaprolactam nanofibers were collected on a fine stainless steel mesh sheet without a binder, and a layer of conductive polyaniline was chemically deposited on the nanofibers. The polyaniline immobilized on the polycaprolactam nanofibers provided high electrical conductivity, acceptable mechanical stability, and a large surface area. This assembly was then used as a working electrode in electrochemically controlled solid-phase microextraction (EC-SPME), a fast and environmentally friendly method. The polymer layers were characterized by SEM and FTIR techniques. Significant factors affecting the EC-SPME efficiency were investigated, including the desorption conditions, the sorbent used, the pH of the sample solution, the extraction voltage, the extraction time, and the ionic strength. Under the optimum conditions, the limits of detection and quantification for the target analytes were 0.9-1.8 µg L-1 and 3.0-6.1 µg L-1, respectively. The linear dynamic range was 5-2000 µg L-1, with R2 > 0.993. The method was coupled with HPLC analysis and applied to the determination of angiotensin ΙΙ receptor antagonists (ARA-ΙΙs) in human plasma, and relative recoveries of 91.1-104.3% with RSDs of ≤8.3% were obtained.


Assuntos
Antagonistas de Receptores de Angiotensina/sangue , Compostos de Anilina/química , Caprolactama/química , Cromatografia Líquida de Alta Pressão/métodos , Técnicas Eletroquímicas/métodos , Nanofibras/química , Microextração em Fase Sólida/métodos , Adsorção , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Microscopia Eletrônica de Varredura , Concentração Osmolar , Reprodutibilidade dos Testes , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier
14.
J Sep Sci ; 42(8): 1500-1508, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30730108

RESUMO

A new composite nanofiber of polyacrylonitrile doped with copper benzene-1,3,5-tricarboxylate metal-organic framework was fabricated by electrospinning and used as a microsorbent in the solid-phase extraction of trace tetracycline. The chemical structure of the adsorbent was studied by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, and Barrett-Joyner-Halenda pore size and volume analysis techniques. The significant parameters of the method including desorption solvent kind and volume, adsorbent mass, pH, and salt percentage were investigated. At the optimized conditions, the linear range was 8-1000 µg/L with a determination coefficient (R2 ) of 0.9954. The limits of detection and quantification were 2.40 and 8.00 µg/L, respectively. The inter- and intraday precisions were 4.7 and 3.4%, respectively. The developed extraction method was followed by high-performance liquid chromatography and applied for the determination of tetracycline in human blood plasma, and good relative recoveries (97.3-104.5%) were obtained.


Assuntos
Antibacterianos/isolamento & purificação , Nanofibras/química , Extração em Fase Sólida/métodos , Tetraciclina/sangue , Tetraciclina/isolamento & purificação , Resinas Acrílicas/química , Adsorção , Antibacterianos/química , Cromatografia Líquida de Alta Pressão , Humanos , Estruturas Metalorgânicas/química , Microscopia Eletrônica de Varredura , Extração em Fase Sólida/instrumentação , Espectroscopia de Infravermelho com Transformada de Fourier
15.
Mikrochim Acta ; 186(4): 232, 2019 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-30852695

RESUMO

This review (with 115 refs) summarizes applications of 3-dimensional graphene (3DGs) and its derivatives in the fields of preconcentration, extraction, and sorption. Following an introduction into the field (including a definition of the materials treated here), the properties and synthetic strategies for 3DGs are described. The next section covers applications of 3DG-based adsorbents in solid phase extraction of organic species including drugs, phthalate esters, chlorophenols, aflatoxins, insecticides, and pesticides. Another section treats applications of 3DGs in solid phase microextraction of species such as polycyclic aromatic hydrocarbons, alcohols, and pesticides. We also describe how the efficiency of assays may be improved by using these materials as a sorbent. A final section covers conclusions and perspectives. Graphical abstract Graphical abstract contains poor quality and small text inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.Tiff file of graphical abstract was attached. Schematic presentation of synthesis of three-dimensional graphene (3DG) from two-dimensional graphene (2DG) with self-assembly, template-assisted and direct deposition methods. Application of 3DG-based nanoadsorbents in direct immersion-solid phase microextraction (DI-SPME), headspace-SPME (HS-SPME), magnetic-solid phase extraction (Magnetic-SPE), dispersive-SPE, and magnetic sheet-SPE.

16.
J Sep Sci ; 41(16): 3258-3266, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29956480

RESUMO

A new method named graphene-coated magnetic-sheet solid-phase extraction based on a magnetic three-dimensional graphene sorbent was developed for the extraction of aflatoxins prior to high-performance liquid chromatography with fluorescence detection. The use of a perforated magnetic-sheet for fixing the magnetic nanoparticles is a new feature of the method. Hence, the adsorbent particles can be separated from sample solution without using an external magnetic field. This made the procedure very simple and easy to operate so that all steps of the extraction process (sample loading, washing, and desorption) were carried out continuously using two lab-made syringe pumps. The factors affecting the performance of extraction procedure such as the extraction solvent, adsorbent dose, sample loading flow rate, ionic strength, pH, and desorption parameters were investigated and optimized. Under the optimal conditions, the obtained enrichment factors and limits of detection were in the range of 205-236 and 0.09-0.15 µg/kg, respectively. The relative standard deviations were <3.4 and 7.5% for the intraday (n = 6) and interday (n = 4) precisions, respectively. The developed method was successfully applied to determine aflatoxins B1 , B2 , G1 , and G2 in different soy-based food samples.


Assuntos
Aflatoxina B1/análise , Aflatoxinas/análise , Grafite/química , Extração em Fase Sólida/métodos , Adsorção , Cromatografia Líquida de Alta Pressão , Fluorescência , Fenômenos Magnéticos , Propriedades de Superfície
17.
J Sep Sci ; 41(7): 1567-1575, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29230971

RESUMO

A new type of adsorbent composed of magnetic three-dimensional graphene coated with silver nanoparticles was synthesized by an electroless technique and used in the magnetic solid-phase extraction of selected pesticides (fenitrothion, chlorpyrifos, and hexaconazole) before gas chromatography with a micro-electron capture detector. The adsorbent was characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometry, and field-emission scanning electron microscopy. The important extraction parameters such as pH, adsorbent dose, extraction time, and desorption conditions were investigated. Under the optimal conditions, the analytical figures of merit were obtained as: linear dynamic range of 0.1-5 ng/g with determination coefficients of 0.991-0.996; limit of detection of 0.07-0.13 ng/g; limit of quantification of 0.242-0.448 ng/g; and the intraday and interday relative standard deviations (C = 5 ng/g, n = 3) were 3.8-8.7 and 6.6-8.9%, respectively. The developed method was successfully applied for analysis of the selected pesticides in tomato and grape with extraction recoveries in the range of 72.8-109.6%.


Assuntos
Clorpirifos/análise , Fenitrotion/análise , Frutas/química , Inseticidas/análise , Triazóis/análise , Grafite/química , Campos Magnéticos , Nanopartículas Metálicas/química , Prata/química , Extração em Fase Sólida
18.
J Food Sci Technol ; 55(4): 1350-1359, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29606749

RESUMO

Saffron quality is commonly determined by three parameters: color, aroma, and taste. Several factors including harvesting and post-harvesting conditions, affect these parameters. In this study, the effect of storage time on saffron quality was evaluated. At first, the relative concentration of the saffron secondary metabolites in freshly dried and 2 years stored saffron samples prepared with ISO 3632 and UA-DLLME methods and then measured using UV-Vis and GC-FID techniques. In order to find saffron storage time biomarkers, the obtained data were subjected to several data analysis steps including data preprocessing, principal component analysis (PCA), partial least square discriminant analysis (PLS-DA) and variable selection methods. Based on the obtained main biomarkers and proposed molecule mechanism, it can be concluded that during the storage periods, the intensity of saffron color reduces, while its aroma increases, reflecting a negative correlation between them. Freshly dried samples have a higher level of the crocins as coloring agents, ß-isophorone, 4-hydroxy-3,5,5-trimethylcyclohex-2-enone and picrocrocin, while the stored samples were more abundant by safranal as the main saffron aroma agent.

19.
Bioorg Med Chem ; 25(9): 2577-2582, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28343756

RESUMO

A panel of 22 phenols was investigated as inhibitors of the ß-class carbonic anhydrase (CAs, EC 4.2.1.1) from the fungal parasite Malassezia globosa (MgCA), a validated anti-dandruff drug target. The displayed inhibitory activities were compared to the ones previously reported against the off-target widely distributed human (h) isoforms hCA I and II. All tested phenols possessed a better efficacy in inhibiting MgCA than the clinically used sulfonamide acetazolamide, with KIs in the range of 2.5 and 65.0µM. A homology-built model of MgCA was also used for understanding the binding mode of phenols to the fungal enzyme. Indeed, a wide network of hydrogen bonds and hydrophobic interactions between the phenol and active site residues were evidenced. The OH moiety of the inhibitor was observed anchored to the zinc-coordinated water, also making hydrogen bonds with Ser48 and Asp49. The diverse substituents at the phenolic scaffold were observed to interact with different portions of the hydrophobic pocket according to their nature and position. Considering the effective MgCA inhibitory properties of phenols, beside to the rather low inhibition against the off-target hCA I and II, this class of compounds might be of considerable interest in the cosmetics field as potential anti-dandruff drugs.


Assuntos
Inibidores da Anidrase Carbônica/farmacologia , Malassezia/enzimologia , Fenóis/farmacologia , Acetazolamida/farmacologia , Anidrase Carbônica I/antagonistas & inibidores , Inibidores da Anidrase Carbônica/química , Caspa/tratamento farmacológico , Humanos , Ligação de Hidrogênio , Simulação de Acoplamento Molecular , Fenóis/química , Relação Estrutura-Atividade
20.
J Sep Sci ; 40(17): 3383-3391, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28664592

RESUMO

An electrospun polyethylene terephthalate/graphene oxide nanofibrous mat was fabricated and used as an effective and novel membrane for the solid-phase extraction of tamoxifen in human blood plasma samples before detection by high-performance liquid chromatography. The membrane was characterized by some identification techniques, such as FTIR spectroscopy, X-ray diffraction, and scanning electron microscopy. The effective variables of the extraction procedure including desorption condition (type and volume of the eluent), adsorbent dose, pH of sample solution, salt concentration, and sample loading time were investigated and their optimum values were obtained using one factor at a time methodology. Under the optimized conditions, the results showed wide linear concentration range of 5-2000 ng/mL with a determination coefficient of 0.992. The limits of detection and limits of quantification were 1.3 and 5.0 ng/mL, respectively. The intra-day and inter-day precisions were 3.4 and 4.6%, respectively. The method was successfully applied to determination of tamoxifen in the blood plasma samples and satisfactory relative recoveries (92.6-98.3 %) were achieved.


Assuntos
Cromatografia Líquida de Alta Pressão , Nanofibras , Polietilenotereftalatos , Extração em Fase Sólida , Tamoxifeno/sangue , Grafite , Humanos , Óxidos
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