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1.
J Chromatogr A ; 1627: 461387, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823095

RESUMO

A simple and efficient magnetic solid-phase extraction (MSPE) method was established with magnetic covalent organic framework (COF) as adsorbent to enrich organophosphorus pesticides from fatty milk samples, followed by the sensitive determination via LC-MS/MS. The key parameters influencing the MSPE efficiency were comprehensively investigated to afford an optimized procedure. All the target analytes could be captured directly by magnetic COF from milk without protein precipitation, making the pretreatment rapid and convenient. Systematic method validation demonstrated its satisfactory linearity, recoveries (80.0-105 %), and precision (RSDs <12.3 %). The method limits of quantification were 0.2-0.5 µg L-1. A comparison experiment to the reported solid-phase extraction fully verified the present MSPE more rapid, accurate, and environment-friendly. Furthermore, FT-IR and XPS analysis were performed to reveal the adsorption mechanisms of magnetic COF to organophosphorus pesticides, which could offer guidance on the rational design of COF adsorbent for various target analytes.


Assuntos
Fenômenos Magnéticos , Estruturas Metalorgânicas/química , Leite/química , Compostos Organofosforados/análise , Praguicidas/análise , Extração em Fase Sólida/métodos , Acetonitrilos/análise , Adsorção , Animais , Limite de Detecção , Espectroscopia Fotoeletrônica , Padrões de Referência , Reprodutibilidade dos Testes , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier
2.
J Chromatogr A ; 1627: 461390, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823096

RESUMO

A dispersive solid phase extraction method was combined with deep eutectic solvent-based solidification of floating organic drop-dispersive liquid-liquid microextraction and used for the extraction/preconcentration of some organophosphorus pesticides residues from edible oil samples. The extracted analytes were quantified with gas chromatography-nitrogen phosphorous detector. In this procedure, the sample lipids are saponified with a sodium hydroxide solution and then the analytes are adsorbed onto a primary secondary amine sorbent. After that the analytes are desorbed with acetone as an elution/dispersive solvent and mixed with choline chloride: 3,3-dimethyl butyric acid deep eutectic solvent and the mixture is rapidly dispersed into deionized water. Then, the obtained cloudy solution is centrifuged and placed into an ice bath. The extraction solvent is solidified on the top of the solution. Finally, it is removed and dissolved in acetonitrile, and 1 µL of the solution is injected into the separation system. Validation of the method showed that limits of detection and quantification were in the ranges of 0.06-0.24 and 0.20-0.56 ng mL-1, respectively. Enrichment factors and extraction recoveries of the analytes ranged from 170-192 and 68-77%, respectively. The method had an acceptable precision with relative standard deviations less than ≤9.2% for intra- (n=6) and inter-day (n=6) precisions at four concentrations (3, 10, 50, and 250 ng mL-1, each analyte). Finally the method was used for determination of the analytes in five edible oil samples.


Assuntos
Microextração em Fase Líquida/métodos , Compostos Organofosforados/análise , Praguicidas/análise , Óleos Vegetais/química , Extração em Fase Sólida/métodos , Solventes/química , Acetonitrilos/química , Reprodutibilidade dos Testes , Hidróxido de Sódio/química , Soluções , Sonicação , Fatores de Tempo
3.
Ecotoxicol Environ Saf ; 204: 111042, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32738626

RESUMO

Paralytic shellfish poisoning (PSP) toxins have received considerable attention in recent years because of their adverse effects on marine breeding industries and human health. In this study, a reliable method for the analysis of extracellular PSP toxins in the culture medium of marine toxic dinoflagellates was developed for the first time using graphitized carbon black-solid-phase extraction and hydrophilic interaction liquid chromatography-high-resolution mass spectrometry. The limit of quantification of typical PSP toxins in algal culture medium ranged from 0.072 µg/L to 0.151 µg/L under optimal conditions. Satisfactory absolute recoveries (87.5%-102.4%), precision (relative standard deviation ≤ 7.6%), and linearity (R2 ≥ 0.9998) were also achieved. In addition, the proposed method was applied to screen and determine the extracellular PSP toxins of two typical toxigenic dinoflagellates, Alexandrium minutum and Alexandrium tamarense. The total concentrations of the extracellular PSP toxins in A. minutum and A. tamarense over the whole growth period were within 2.0-735.5 and 2.0-19.2 µg/L, respectively. The concentrations of extracellular PSP toxins varied remarkably in the different growth stages of A. minutum and A. tamarense, and the contents of some extracellular PSP toxins were substantially higher than those of intracellular PSP toxins. Therefore, the extracellular PSP toxins released by toxigenic red tide algae cannot be ignored, and their environmental fate, bioavailability, and potential harm to aquatic environment need to be investigated in future studies.


Assuntos
Cromatografia Líquida/métodos , Meios de Cultura/química , Dinoflagelados/metabolismo , Toxinas Marinhas/análise , Espectrometria de Massas/métodos , Extração em Fase Sólida/métodos , Interações Hidrofóbicas e Hidrofílicas , Intoxicação por Frutos do Mar , Fuligem/química
4.
J Anal Toxicol ; 44(7): 708-717, 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-32808043

RESUMO

An analytical method for the detection of 40 benzodiazepines, (±)-zopiclone, zaleplon and zolpidem in blood and urine by solid-phase extraction liquid chromatography-tandem mass spectrometry was developed and validated. Twenty-nine of 43 analytes were quantified in 0.5 mL whole blood for investigating postmortem, drug-facilitated sexual assault (DFSA) and driving under the influence of drugs cases (DUID). The four different dynamic ranges of the seven-point, linear, 1/x weighted calibration curves with lower limits of quantification of 2, 5, 10 and 20 µg/L across the analytes encompassed the majority of our casework encountered in postmortem, DFSA and DUID samples. Reference materials were available for all analytes except α-hydroxyflualprazolam, a hydroxylated metabolite of flualprazolam. The fragmentation of α-hydroxyflualprazolam was predicted from the fragmentation pattern of α-hydroxyalprazolam, and the appropriate transitions were added to the method to enable monitoring for this analyte. Urine samples were hydrolyzed at 55°C for 30 min with a genetically modified ß-glucuronidase enzyme, which resulted in >95% efficiency measured by oxazepam glucuronide. Extensive sample preparation included combining osmotic lysing and protein precipitation with methanol/acetonitrile mixture followed by freezing and centrifugation resulted in exceptionally high signal-to-noise ratios. Bias and between-and within-day imprecision for quality controls (QCs) were all within ±15%, except for clonazolam and etizolam that were within ±20%. All 29 of the 43 analytes tested for QC performance met quantitative reporting criteria within the dynamic ranges of the calibration curves, and 14 analytes, present only in the calibrator solution, were qualitatively reported. Twenty-five analytes met all quantitative reporting criteria including dilution integrity. The ability to analyze quantitative blood and qualitative urine samples in the same batch is one of the most useful elements of this procedure. This sensitive, specific and robust analytical method was routinely employed in the analysis of >300 samples in our laboratory over the last 6 months.


Assuntos
Benzodiazepinas/metabolismo , Hipnóticos e Sedativos/metabolismo , Detecção do Abuso de Substâncias/métodos , Alprazolam/análogos & derivados , Compostos Azabicíclicos/sangue , Compostos Azabicíclicos/metabolismo , Compostos Azabicíclicos/urina , Benzodiazepinas/sangue , Benzodiazepinas/urina , Cromatografia Líquida/métodos , Diazepam/análogos & derivados , Toxicologia Forense , Humanos , Hipnóticos e Sedativos/análise , Hipnóticos e Sedativos/sangue , Hipnóticos e Sedativos/urina , Limite de Detecção , Piperazinas/sangue , Piperazinas/metabolismo , Piperazinas/urina , Medicamentos Indutores do Sono/sangue , Medicamentos Indutores do Sono/metabolismo , Medicamentos Indutores do Sono/urina , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Zolpidem/sangue , Zolpidem/metabolismo , Zolpidem/urina
5.
J Chromatogr A ; 1626: 461359, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797838

RESUMO

The enantiomeric determination of chiral drugs in the environment is of emerging concern since their enantiomers often exhibit stereoselectivity in environmental occurrence, fate and toxicity. In this study a method based on solid-phase extraction followed by chiral liquid chromatography and high-resolution mass spectrometry has been developed for the enantiomeric determination of a group of cathinones in river water and effluent wastewater. The enantioseparation was carried out using a Chiralpak CBH column in reversed-phase mode, and optimised by evaluating the effects of flow rate, buffer concentration and organic modifier. Under optimal conditions, good enantioseparations (Rs ≥1.2) were achieved for all the analytes. Two mixed-mode cation-exchange sorbents (Oasis WCX and Oasis MCX) in solid-phase extraction were evaluated in river water. Oasis MCX sorbent showed better performance with apparent recoveries ranging from 57 to 91% and matrix effect ranging from -10 to 15%. It is worth noting that a shifting of retention times and loss of enantioresolutions in environmental water samples was observed for all the analytes when the Oasis WCX sorbent was used. The method was validated with river water and effluent wastewater samples and its overall performance was satisfactory. The method quantification limits for all the analyte enantiomers ranged from 1.0 to 2.9 ng/L in river water, and from 2.3 to 6.0 ng/L in effluent wastewater. The repeatability and reproducibility values, expressed as% relative standard deviation (n = 5) were less than 15%. The method was then applied to the analysis of river water and effluent wastewater. The racemic methylone and methedrone (EF=0.49 and 0.46, respectively) were detected at low ng/L in some of the river water samples.


Assuntos
Alcaloides/análise , Cromatografia Líquida/métodos , Espectrometria de Massas/métodos , Alcaloides/química , Alcaloides/isolamento & purificação , Reprodutibilidade dos Testes , Rios/química , Extração em Fase Sólida/métodos , Estereoisomerismo , Águas Residuárias/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
6.
J Chromatogr A ; 1626: 461362, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797841

RESUMO

Exploring new material as adsorbent for the efficient enrichment of pollutants is always of great significance in analytical chemistry. In this work, a magnetic azobenzene framework (labeled as MAzo) was constructed as a magnetic solid phase extraction (MSPE) adsorbent by a simple and environmentally benign strategy. The MAzo exhibited the attractive features of strong magnetism, outstanding adsorption performance, as well as good reusability. Combining MAzo-based MSPE with high performance liquid-phase chromatography, a simple and effective method was developed for simultaneous determination of four phenylurea herbicides in pear juice and apple juice samples. Under optimized experimental conditions, the method offered low limits of detection of 0.05-0.15 ng mL-1, high recoveries of 86.7-109.2% with RSD less than 7%. Density functional theory calculation indicated that the good adsorption performance of MAzo for PUHs can be ascribed to the strong H-bonding forces and weak π-π interactions. The facile, green, low-cost synthesis method together with the excellent adsorption performance endows the MAzo great application prospect in sample preparation.


Assuntos
Compostos Azo/química , Poluentes Ambientais/análise , Herbicidas/análise , Compostos de Fenilureia/análise , Extração em Fase Sólida/métodos , Adsorção , Cromatografia Líquida de Alta Pressão , Poluentes Ambientais/isolamento & purificação , Sucos de Frutas e Vegetais/análise , Herbicidas/isolamento & purificação , Fenômenos Magnéticos , Malus , Estruturas Metalorgânicas , Compostos de Fenilureia/isolamento & purificação , Pyrus
7.
J Chromatogr A ; 1626: 461364, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797843

RESUMO

A new type of restricted access media-imprinted nanomaterials (RAM-MIPs) were successfully prepared on the surface of metal-organic framework by reversible addition fragmentation chain transfer polymerization technology. Then it was applied as a dispersed solid phase extraction (DSPE) material in analysis of fluoroquinolones (ofloxacin, pefloxacin, norfloxacin, enrofloxacin and gatifloxacin) in untreated milk and river water by HPLC-UV detection. The resulted material has a good binding amounts (60.81 mg g-1), rapid binding kinetic (15 min) and satisfactory selectivity as well as has a good ability to eliminate matrix interference. Several major factors affecting DSPE efficiency, pH of sample solution, dosage of RAM-MIPs, adsorption time and volume ratios of elution solvent were primarily optimized. In optimization conditions, RAM-MIPs-DSPE was combined with HPLC-UV to enrich fluoroquinolones in untreated milk and river water, achieving satisfactory linear correlation (R2 > 0.9988), good limits of detection (LOD, 1.02-3.15 µg L-1 for milk and 0.93-2.87 µg L-1 for river water) and better recoveries (80.7-103.5% and 85.1-105.9% with relative standard deviation (RSD) of not higher than 5.3% and 4.7% for milk and river water samples, respectively). The research results illustrate that it provides a simple and efficient method for the direct detection of FQs in complex samples.


Assuntos
Antibacterianos/análise , Fluoroquinolonas/análise , Estruturas Metalorgânicas/química , Leite/química , Nanoestruturas/química , Rios/química , Extração em Fase Sólida/métodos , Adsorção , Animais , Antibacterianos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Fluoroquinolonas/isolamento & purificação , Impressão Molecular , Polimerização
8.
J Chromatogr A ; 1626: 461348, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797828

RESUMO

Solid-phase extraction (SPE) is a widely-used and very well-established sample preparation technique for liquid samples. An area of on-going focus for innovation in this field concerns the development of new and improved SPE sorbents that can enhance the sensitivity and/or the selectivity of SPE processes. In this context, mixed-mode ion-exchange sorbents have been developed and commercialised, thereby allowing enhanced capacity and selectivity to be offered by one single material. The ion-selectivity of these materials is such that either anion-exchange or cation-exchange is possible, however one limitation to their use is that more than one sorbent type is required to capture both anions and cations. In this paper, we disclose the design, synthesis and exploitation of a novel SPE sorbent based on microporous polymer microspheres with amphoteric character. We show that it is possible to switch the ion-exchange retention mechanism of the sorbent simply by changing the pH of the loading solution; anion-exchange dominates at low pH, cation-exchange dominates at high pH, and both mechanisms can contribute to retention when the polymer-bound amphoteric species, which are based on the α-amino acid sarcosine (N-methylglycine), are in a zwitterionic state. This is an interesting and useful feature, since it allows distinctly different groups of analytes (acids and bases) to be fractionated using one single amphoteric sorbent with dual-functionality. The sarcosine-based sorbent was applied to the SPE of acidic, basic and amphoteric analytes from ultrapure water, river water and effluent wastewater samples. Under optimised conditions (loading 100 mL of sample at pH 6, washing with 1 mL of MeOH and eluting with an acidic or basic additive in MeOH) the recoveries for most of the compounds were from 57% to 87% for river water and from 61% to 88% for effluent wastewater. We anticipate that these results will lay the basis for the development of a new family of multifunctional sorbents, where two or more separation mechanisms can be embedded within one single, bespoke material optimised for application to challenging chemical separations to give significant selectivity advantages over essentially all other state-of-the-art SPE sorbents.


Assuntos
Ácidos/química , Microesferas , Polímeros/química , Extração em Fase Sólida/métodos , Adsorção , Cátions , Concentração de Íons de Hidrogênio , Troca Iônica , Porosidade , Rios/química , Solventes/química , Águas Residuárias/química , Poluentes Químicos da Água/análise
9.
J Chromatogr A ; 1628: 461437, 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32822977

RESUMO

During stoppers production, large amounts of cork by-products (CBPs) are generated, being used as low-value material. This project aims to turn CBPs into smart, natural and sustainable materials (sorbent) for solid-phase extraction (SPE) of pesticides from water. The study describes the use of CBPs for the extraction of 17 fungicides (metalaxyl, cyprodinil, tolylfluanid, procymidone, folpet, fludioxonil, myclobutanil, kresoxim methyl, iprovalicarb, benalaxyl, trifloxystrobin, fenhexamid, tebuconazole, iprodione, pyraclostrobin, azoxystrobin and dimethomorph) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. The most critical parameters affecting SPE were optimized by experimental design methodology. Under the optimal conditions, the method was successfully validated in terms of linearity, repeatability, and intermediate precision. Fungicide recovery was assessed in different real water samples including river, fountain, rainwater and spring water at 3 concentration levels (0.1, 0.5 and 10 µg L-1). Recoveries ranged between 70-118% with RSD values lower than 20%, and matrix effects were not observed. Finally, the method was applied to samples from irrigation, rain, and river water, all collected in vineyards areas, revealing the presence of 10 of the 17 fungicides, at concentration up to hundreds of µg L-1. The use of CBPs seems to be a promising low-cost and ecofriendly alternative to be employed as sorbent in SPE techniques to extract fungicides from the aquatic environment.


Assuntos
Fungicidas Industriais/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/análise , Adsorção , Análise de Variância , Tamanho da Partícula , Chuva , Rios/química , Espectrometria de Massas em Tandem/métodos , Água/química
10.
J Chromatogr A ; 1627: 461395, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823100

RESUMO

Nowadays, enantioseparation of racemic pharmaceuticals in preparations is a prime concern by drug authorities across the globe. In the present work, it was attempted to develop novel enantioselective extraction method for five clinically used drugs (atenolol, propranolol, metoprolol, racecadotril, and raceanisodamine in their tablets) as racemates. The enantioselective solid-liquid extraction of these racemic drugs was carried out successfully by the use of chiral ionic liquid (CIL) in combination with a metal organic framework (MOF) for the first time. The composite CIL@MOF was synthesized from tropine based chiral ionic liquids with L-proline anion ([CnTr][L-Pro], n=3-6) and HKUST-1 type MOF, which was comprehensively characterized before being used as sorbent for enantioselective dispersive solid-liquid extraction. Preliminary selection of appropriate CIL was carried out on thin layer chromatography (TLC); under the joint participation of copper ion in the developing reagent, [C3Tr][L-Pro] ionic liquid showed better resolution performance with ΔRf value of 0.35 between the enantiomers was obtained for racemic atenolol. Moreover, the effect of copper salt dosage, amount of CIL, soli-liquid ratio and extraction time were investigated. The optimal conditions were obtained after thorough investigations; i.e. sample solution: ethanol, elution solvent: methanol, solid-liquid ratio: 12.5 mg:50 mL, amount of copper salt: 8 mg L-1, amount of impregnated CIL: 30% and extraction time of 30 min. As a result, enantiomeric excess values are 90.4%, 95%, 92%, 81.6% and 83.2% for atenolol, propranolol, metoprolol, racecadotril and raceanisodamine, respectively. The developed enantioselective method was validated following ICH guidelines and it was proved to be simple, effective and enantioselective way for separation of racemic pharmaceuticals with similar behaviors.


Assuntos
Líquidos Iônicos/química , Estruturas Metalorgânicas/química , Preparações Farmacêuticas/isolamento & purificação , Extração em Fase Sólida/métodos , Antagonistas Adrenérgicos beta/análise , Antagonistas Adrenérgicos beta/isolamento & purificação , Atenolol/análise , Atenolol/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Cobre/química , Metoprolol/análise , Metoprolol/isolamento & purificação , Preparações Farmacêuticas/análise , Propranolol/análise , Propranolol/isolamento & purificação , Solventes/química , Estereoisomerismo
11.
J Chromatogr A ; 1625: 461275, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709327

RESUMO

Efficient extraction of polar sulfonamides antibiotics from aqueous samples and food is very challenging, because they are hydrophilic, their concentration is very low, and the matrix is complex. Covalent organic frameworks (COFs), a novel porous organic material, have attracted great attention. In this work, the spherical triphenylbenzene-dimethoxyterephthaldehyde-COFs (TPB-DMTP-COFs) were synthesized by a simple room temperature method, and due to their attractive properties, such as high outstanding acid-base stability, large specific surface area, low skeletal density, inherent porosity and high crystallinity, so TPB-DMTP-COFs as ideal solid phase extraction adsorbents showed excellent adsorption performance for trace polar sulfonamides in food and water. TPB-DMTP-COFs were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction, and so on. The important parameters were optimized to improve the extraction efficiency of TPB-DMTP-COFs toward sulfonamides. Analysis of sulfonamides was performed by liquid chromatography-tandem mass spectrometry. The developed method based on TPB-DMTP-COFs material achieved low limits of detection (0.5-1.0 ng L-1), wide linearity (5-1000 ng L-1), and good repeatability (2.5%-8.7%). The possible extraction mechanism was also discussed. Finally, the method was successfully applied to the enrichment and detection of sulfonamides in environmental water samples and food samples. The present study indicated that TPB-DMTP-COFs had splendid prospects in highly sensitive analysis of other pollutants in complex matrix.


Assuntos
Análise de Alimentos , Estruturas Metalorgânicas/química , Extração em Fase Sólida/métodos , Sulfonamidas/análise , Espectrometria de Massas em Tandem/métodos , Poluentes Químicos da Água/análise , Adsorção , Animais , Cromatografia Líquida , Contaminação de Alimentos/análise , Leite/química , Carne de Porco/análise , Porosidade , Sulfonamidas/química , Água/química
12.
J Chromatogr A ; 1625: 461307, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709350

RESUMO

In this study, the ultrasonic-assisted dispersive solid phase extraction (UA-d-SPE) method coupled to gas chromatography-mass spectrometry (GC-MS) was applied for the analysis of phthalate esters in drinking water and distilled herbal beverages (Rosa, Mentha, Cichorium). A new nanocomposite based on layered double hydroxide supported on graphene oxide was synthesized and modified by sulfonated polyaniline via a simple one-pot in-situ polymerization method. The structure and morphology of the nanocomposite was confirmed by means of complementary techniques: Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy. The effects of key parameters including adsorbent mass, type and amount of back extraction solvent, extraction and desorption time, pH of the solution and ionic strength were optimized and good precision and sensitivity were achieved. Under the optimum conditions, the limits of detection were between 0.06-0.3 ng mL-1 in aqueous solutions. The hybrid nanomaterial exhibited good adsorption ability toward phthalates in drinking water and distilled herbal beverages. The relative standard deviations (RSD%) for beverage samples varied from 0.1% to 9.9% (n = 3). The relative recoveries varied from 54.5% to 112.6%.


Assuntos
Compostos de Anilina/química , Bebidas/análise , Grafite/química , Hidróxidos/química , Ácidos Ftálicos/isolamento & purificação , Extração em Fase Sólida/métodos , Ácidos Sulfônicos/química , Ultrassom/métodos , Adsorção , Ésteres/análise , Cromatografia Gasosa-Espectrometria de Massas , Concentração de Íons de Hidrogênio , Nanocompostos/química , Concentração Osmolar , Ácidos Ftálicos/análise , Preparações de Plantas/química , Reprodutibilidade dos Testes , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , Difração de Raios X
13.
J Chromatogr A ; 1625: 461337, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709361

RESUMO

Monitoring the levels of perfluorinated compounds (PFCs) in the environment is of vital importance, owing to their sustained environmental presence, extensive distribution, and associated health risks. The development of cost-effective and efficient sorbents for the establishment of sensitive analytical methods is critical for achieving trace-level detection. In this study, a graphitic carbon nitride (g-C3N4)-based sorbent is synthesized by a facile sonication-assisted method exfoliated by zeolitic imidazolate framework-67 (ZIF-67) in situ. The novel ZIF-67/g-C3N4 composites were systematically characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and N2 adsorption-desorption analysis, exhibiting good dispersity and a large surface area. Moreover, molecular dynamics simulations indicated that g-C3N4 structures can be effectively exfoliated by the introduced ZIF-67 molecules. The hybrid material was successfully utilized as a dispersive solid-phase extraction sorbent, and the extraction factors were systematically optimized by response surface methodology. Under optimal conditions, the synthesized sorbent exhibited desirable linear correlations (R2 > 0.99), a low detection limit (0.3-2 ng L-1), and good repeatability (relative standard deviation <15%, n = 6). The developed method was applied for the analysis of natural and spiked water samples. The study demonstrated that the ZIF-67/g-C3N4 composites are promising materials for pollutant adsorption from drinking water samples.


Assuntos
Água Potável/química , Fluorcarbonetos/análise , Grafite/química , Estruturas Metalorgânicas/química , Compostos de Nitrogênio/química , Extração em Fase Sólida/métodos , Sonicação , Poluentes Químicos da Água/análise , Adsorção , Simulação de Dinâmica Molecular
14.
Ecotoxicol Environ Saf ; 203: 110995, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678763

RESUMO

In the present study, silver (Ag) atoms were chemically deposited on γ-alumina (Al2O3) nanospheres to be further functionalized with trithiocyanuric acid (TTC). The result was Al2O3@Ag@TTC composites, which were used for the selective extraction and preconcentration of Fe (III) and Pb (II) ions in seawater and river water samples. TTC is a potent scavenger of heavy metal ions with multiple nitrogen- and sulfur-containing functional groups. The concentrations of analytes were determined by flame atomic absorption spectrometry, and the structure of the synthetic adsorbent was characterized by spectral and microscopic techniques. Furthermore, the fundamental parameters influencing the extraction and desorption of the target ions were evaluated. Under optimized conditions, the calibration curve was linear in the range of 10-100 ng mL-1 for both analytes. The detection limits of the proposed method for Fe (III) and Pb (II) ions were 1.5 ng mL-1 and 0.8 ng mL-1, respectively, with a relative standard deviation of less than 6.1% (n = 7). Moreover, the proposed method tolerated salinities of up to 50.0 g L-1 without exhibiting any decrease in selectivity or recovery. The developed method was successfully applied to extract Fe (III) and Pb (II) ions from seawater and river water samples. The extraction recovery rates of the spiked ions were at least 93% for Fe (III) and 97 % for Pb (II).


Assuntos
Óxido de Alumínio/química , Ferro/análise , Chumbo/análise , Nanoconjugados/química , Prata/química , Triazinas/química , Poluentes Químicos da Água/análise , Água Doce/química , Concentração de Íons de Hidrogênio , Íons , Água do Mar/química , Extração em Fase Sólida/métodos
15.
Food Chem ; 333: 127504, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32679416

RESUMO

The aim of this study is to extract zinc and manganese from foods and vegetables using an amphiphilic copolymer adsorbent, poly(styrene)-co-2-vinylpyridine which was synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization from styrene and 2-vinyl pyridine in the presence of a trithiocarbonate and 2,2'-azo-bis isobutyro nitrile (AIBN) in toluene solution under argon at 80 °C. Fourier Transform Infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy were used in the characterization of the obtained copolymer. Under the optimum conditions, several validation variables such as uncertainty measurement, selectivity, robustness, precisions, matrix effects and accuracy were investigated. Taking an adsorption time of 15 min, detection limits of 0.04 µg L -1 and 0.2 µg L-1and 7.9 µg L-1and enrichment factors of 145 and 110 were obtained for Mn(II) and Zn(II), respectively.The method was successfully applied to the analysis of Mn(II) and Zn(II) in foods and vegetables.


Assuntos
Manganês/isolamento & purificação , Poliestirenos/química , Polivinil/química , Extração em Fase Sólida/métodos , Verduras/química , Zinco/isolamento & purificação , Adsorção , Espectroscopia de Ressonância Magnética , Manganês/análise , Polimerização , Extração em Fase Sólida/instrumentação , Espectroscopia de Infravermelho com Transformada de Fourier , Zinco/análise
16.
Food Chem ; 333: 127516, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32683261

RESUMO

Benzotriazoles (BTRs) and benzothiazoles (BTs) are two groups of emerging concern and high production volume contaminants. Via the biomagnification of the food web, they could jeopardize human health. In this work, rapid determining the presence of five BTRs and two BTs in marketed fish was performed by a novel double-vortex-ultrasonic assisted matrix solid-phase dispersion (DVUA-MSPD) and UHPLC-electrospray ionization (+)-quadrupole time-of-flight mass spectrometry detection. Unlike traditional MSPD, we simplified the method without the use of mortar/pestle and SPE-column procedures. The DVUA-MSPD factors were screened by a multilevel categorical design, and then optimized by Box-Behnken Design plus with response surface methodology. The limits of quantification were 0.15-2 ng g-1 (dry weight). The satisfactory average recovery ranged from 70% to 93% with RSDs less than 9%. The developed method was successfully applied for the rapid determination of selected BTRs and BTs in fish samples at trace-level.


Assuntos
Benzotiazóis/química , Peixes/metabolismo , Extração em Fase Sólida/métodos , Animais , Benzotiazóis/análise , Benzotiazóis/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Reprodutibilidade dos Testes , Espectrometria de Massas por Ionização por Electrospray , Ultrassom
17.
Food Chem ; 332: 127427, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32619936

RESUMO

A magnetic porous organic framework (M-POF) was rationally designed and served as a sorbent for magnetic solid-phase extraction of six nitroimidazoles from chicken meat prior to their assay by high-performance liquid chromatography with diode array detection. The M-POF exhibited good magnetic responsiveness and outstanding affinity to nitroimidazoles with large adsorption capacity up to 36 mg g-1. Under optimal conditions, the developed method offered good linearity (r greater than 0.992) in the range of 1.5-100.0 ng g-1, low limits of detection (S/N = 3) of 0.5-0.8 ng g-1, low limits of quantification of 1.5-2.5 ng g-1 and high enrichment factors of 80-175 for the nitroimidazoles. The method was successfully applied to analyze nitroimidazoles in chicken meat. The recoveries were 80.2-118% with relative standard deviations lower than 12%. The adsorption mechanism was further explored and the results showed that the M-POF exhibited adsorption potential for compounds with strong polar interactions.


Assuntos
Antibacterianos/isolamento & purificação , Contaminação de Alimentos/análise , Magnetismo/métodos , Carne/análise , Estruturas Metalorgânicas/química , Nitroimidazóis/isolamento & purificação , Extração em Fase Sólida/métodos , Adsorção , Animais , Antibacterianos/análise , Bioensaio , Galinhas , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Magnetismo/instrumentação , Músculo Esquelético/química , Nitroimidazóis/análise , Porosidade , Extração em Fase Sólida/instrumentação
18.
Food Chem ; 332: 127390, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32603922

RESUMO

Revalorization of mushroom by-product (stalks of A. bisporus) by extracting its components is proposed. The extraction kinetics at 25 °C of ergosterol, phenolic compounds and antioxidant activity by mechanical agitation (at 130 rpm) and ultrasound assistance (at 182 and 321 W/L) in 70 and 96% v/v ethanol/water solutions during 30 min were evaluated and satisfactorily modelled, using the Weibull model (mean relative error ≤ 7.8%). The effect of the ethanol concentration was high in the ergosterol extraction yield (2 times higher yields in 96% than in 70%) but slight in those of phenolic compounds and antioxidant activity. Ultrasound assistance promoted considerable yield increases (up to 2 times higher in ergosterol, 46% in phenolic compounds and 25% in antioxidant activity) depending on the ethanol concentration and ultrasound power density. The residues after extraction were characterized and constituted a potential source of high value polysaccharides as ß-glucans (average 12.2 ± 1.7g/100 g dm).


Assuntos
Agaricales/química , Antioxidantes/química , Ergosterol/química , Extração em Fase Sólida/métodos , beta-Glucanas/química , Agaricales/metabolismo , Antioxidantes/isolamento & purificação , Ergosterol/isolamento & purificação , Etanol/química , Modelos Teóricos , Fenóis/química , Sonicação
19.
Food Chem ; 333: 127529, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32679419

RESUMO

A solid-phase extraction (SPE) method for enriching and purifying estrogenic disrupting compounds (EDCs) based on the estrogen response element was established. The estrogen receptor was used for molecular recognition, as it specifically binds EDCs. An estrogen response element was used to maintain the activity of the estrogen receptor. High-performance liquid chromatography (HPLC) was used to quantify the EDCs. This method combined with HPLC was applied to detect three kinds of EDCs, such as bisphenol A (BPA), 17ß-estradiol, and diethylstilbestrol in a liquid milk matrix, with recoveries of 84.1 ± 8.2% to 113.6 ± 2.9%. The limits of detection and quantification of the established method were 1 × 10-6 mg·mL-1 and 5 × 10-6 mg·mL-1. The method was further applied to analyze market samples, including liquid milk, fermented milk, and milk powder. Only BPA was detected from one brand of liquid milk and it was below the regulatory level.


Assuntos
Disruptores Endócrinos/isolamento & purificação , Estrogênios/metabolismo , Elementos de Resposta , Extração em Fase Sólida/métodos , Animais , Cromatografia Líquida de Alta Pressão , Disruptores Endócrinos/análise , Leite/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
20.
Food Chem ; 333: 127540, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32682226

RESUMO

A novel of magnetic dummy-template molecularly imprinted polymers (mag-MWCNTs-DMIPs) were prepared by surface molecular imprinting technique. The structure of polymers were characterized and the binding properties were assessed by adsorption experiments. The synthetic mag-MWCNTs-DMIPs exhibit satisfying adsorption capacity, excellent selectivity and fast adsorption rate toward phenoxy carboxylic acid (PCA) herbicides. Afterwards, a reliable analytical method for selective separation and determination of trace PCA herbicides in cereals was established by using magnetic solid-phase extraction (mag-MWCNTs-DMIPs as magnetic adsorbent) and UPLC-MS/MS detection. A series of requisite factors were optimized in detail to achieve expected extraction performance. Under the optimum MSPE parameters, the mean spiked recoveries for analytes in different cereals ranged from 86.7% to 95.2% with intra- and inter-day precision not greater than 8.5% and 10.6%, respectively. At last, the developed method was successfully utilized for determination the four PCA herbicides in actual cereals.


Assuntos
Ácidos Carboxílicos/análise , Ácidos Carboxílicos/isolamento & purificação , Grão Comestível/química , Herbicidas/química , Impressão Molecular , Nanotubos de Carbono/química , Extração em Fase Sólida/métodos , Adsorção , Ácidos Carboxílicos/química , Contaminação de Alimentos/análise , Imãs/química , Polímeros/síntese química , Polímeros/química , Fatores de Tempo
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