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1.
Food Chem ; 303: 125369, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31442902

RESUMO

A well-designed yolk-shell Fe3O4@graphitic carbon (YS-Fe3O4@GC) submicroboxes with a tunable internal cavity were constructed by one-step pyrolysis strategy followed by partially etching, in which the Fe3O4 magnetic core was well confined in compartment of GC submicroboxes. The suitable internal cavity, graphitic carbon shell and large specific surface area, play great roles in improving mass transfer of analytes. Compared to its core-shell structure, the YS-Fe3O4@GC submicroboxes as dispersive magnetic solid-phase extraction (d-MSPE) materials exhibited superior enrichment performance for sulfonamides (SAs). Thus, it was applied to sensitive/simultaneous detection of trace SAs in milk and meat samples, combing with high performance liquid chromatography (HPLC). Under optimized conditions, limits of detection (LODs, 0.11-0.25 µg L-1 for milk and 0.46-2.24 µg kg-1 for meat) and recoveries (77.2-118.0%) were obtained. This work not only offers a facile strategy for the tunable fabrication of yolk-shell architecture, but also successfully affords its exploration as d-MSPE materials.


Assuntos
Análise de Alimentos , Grafite/química , Extração em Fase Sólida/métodos , Sulfonamidas/isolamento & purificação , Animais , Cromatografia Líquida de Alta Pressão , Compostos de Ferro/química , Limite de Detecção , Magnetismo , Carne/análise , Leite/química , Sulfonamidas/análise
2.
Anal Bioanal Chem ; 411(23): 6189-6202, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31414155

RESUMO

It is a challenge to expand the metabolome coverage of liquid chromatography (LC)-electrospray ionization (ESI) mass spectrometry (MS) based untargeted metabolomics analysis. The limited coverage is attributed to the weak signal of hydroxyl and carboxyl groups in ESI-MS and the limited capacity of LC separation for metabolites with a wide range of polarities. Here a new sample preparation procedure is proposed to solve these problems. Mixed-mode (reversed-phase and anion-exchange) solid-phase extraction sorbents were used to separate metabolites into hydrophilic amine, hydrophobic amine/alcohol, and organic acid groups. Then, alcohols and carboxylic acids in separated groups were tagged with pyridine with use of two derivatization systems for signal enhancement. Finally, hydrophilic amines were analyzed by LC-MS with a hydrophilic interaction LC column, and the two hydrophobic compound groups were analyzed by LC-MS with a C18 column. From the results for standard samples, the detection limits of the new method are lower than those of the classic solvent extraction-protein precipitation method by 3.3-70 times for five amino acids and by 65-1141 times for five fatty acids. Moreover, the detection limit of this new method is 125 ng mL-1 for cholesterol, which has no signal with the classic method even at 10 µg mL-1. In seminal plasma samples, 110 more metabolites were identified by this new method than by the traditional solvent extraction-protein precipitation method in positive-mode ESI (new method vs traditional method, 65 vs 22 identified by comparing MS/MS spectra with those of standards, 203 vs 136 identified by searching MS spectra in a published database). Among them, 53 carboxylic acids and 21 alcohols were identified only by the new method, and more hydrophilic amine metabolites, such as amino acids and nucleosides, were identified by the new method than by the classic method. Finally, in application to the study of male infertility, more potential biomarkers of oligoasthenoteratospermic infertility were found with the new method (46 potential biomarkers) than with the classic method (19 potential biomarkers) and previously reported methods (10-30 potential biomarkers). Thus, it is demonstrated that this new sample preparation method expands the detection coverage of LC-MS-based untargeted metabolomics methods and has application potential in biological research.


Assuntos
Infertilidade Masculina/metabolismo , Metaboloma , Metabolômica/métodos , Sêmen/metabolismo , Biomarcadores/metabolismo , Humanos , Masculino , Sêmen/química , Extração em Fase Sólida/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos
3.
Food Chem ; 300: 125180, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31325753

RESUMO

An isonicotinic acid hydrazide (INAH) chemically modified fumed silica, as a novel adsorbent, was designed for the preconcentration and determination of Hg (II) ions in fish samples via the solid phase extraction followed by the hydride generation atomic absorption spectrometry (HG-AAS). In this work, the efficiency of the synthesized adsorbent was investigated to determine its ability for the extraction of the Hg (II) ions from the aqueous solutions. The extraction efficiency was investigated by optimizing of different experimental conditions, such as pH, sample volume, flow rate, adsorbent dosage, and eluent type. Under the optimal conditions, a linear calibration curve for the solid phase extraction method was obtained in the range of between 0.12 and 16.5 µg L-1. The obtained detection limit and preconcentration factor were 0.018 µg L-1 and 25, respectively (RSD > 3%). The proposed optimized method was successfully applied to fish samples.


Assuntos
Produtos Pesqueiros/análise , Mercúrio/análise , Nanopartículas/química , Extração em Fase Sólida/métodos , Espectrofotometria Atômica/métodos , Adsorção , Animais , Contaminação de Alimentos/análise , Concentração de Íons de Hidrogênio , Limite de Detecção , Mercúrio/isolamento & purificação , Dióxido de Silício/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
4.
J Chromatogr A ; 1602: 350-358, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31257039

RESUMO

This work describes development of a quick and accurate online solid-phase extraction (SPE) liquid chromatography tandem mass spectrometry method for simultaneous determination of 87 emerging organic compounds, including 22 per- and polyfluoroalkyl substances, 58 pharmaceuticals and personal care products, and 7 organophosphorus flame retardants, in diverse water matrices. Considering the wide range of physicochemical properties for the target contaminants, efficient analysis in one injection is challenging. Thus, key extraction and analytical parameters, including online SPE sorbent, mobile phase additives, sample pH, loading solvent pH and composition, injection volume, and valve-switching time, were systematically optimized. The final conditions, namely a polymeric reversed-phase column with alkaline samples and an acidic loading solvent, provided satisfactory results for all target analytes compared to conventional methods that employ acidic samples for multi-residue analysis. The method detection limits (MDLs) ranged from 0.16 to 5.13 ng L-1 with 85% of MDLs lower than 2 ng L-1 for sample volumes of just 1.8 mL. The method also demonstrated satisfactory accuracy with 82% of analytes exhibiting 70-130% recovery. Importantly, only 30 min was required per sample. The optimized method was successfully applied to investigate the removal efficiency of emerging contaminants in a drinking water treatment plant and to analyze the environmental occurrence of target analytes. The method is sensitive, reliable, labor-saving, and cost effective, and therefore has the potential to advance large-scale environmental monitoring programs.


Assuntos
Cromatografia Líquida/métodos , Retardadores de Chama/análise , Fluorcarbonetos/análise , Produtos Domésticos/análise , Preparações Farmacêuticas/análise , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Poluentes Químicos da Água/análise , Automação , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Internet , Limite de Detecção , Solventes/química , Fatores de Tempo
5.
Food Chem ; 300: 125204, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31336275

RESUMO

Analytical chromatographic techniques for mycotoxins control are well established, but they often depend on costly immunoaffinity sample clean-up. Serum albumins, particularly that from bovine origin (BSA), have stable binding affinity towards some mycotoxins, and can be cheaper alternative receptors for sample clean-up due to their wide availability. Thus, this work used BSA immobilized in agarose beads as a novel solid-phase extraction method for quantification of ochratoxin A (OTA) in wine. Constructed BSA-agarose columns could extract OTA efficiently from red wine after its dilution (4-fold) in 0.1 M Tris pH 8.0. The method was linear (R2 = 0.9999) in the OTA concentration range studied (0.05 to 3.0 µg L-1), with recovery rates above 98%. It also showed low detection (0.017 µg L-1) and quantification (0.051 µg L-1) limits. The efficacy of the BSA-based method was further validated by direct comparison with commercial immunoaffinity columns. Portuguese wines analyzed by both methods had agreeing results.


Assuntos
Contaminação de Alimentos/análise , Ocratoxinas/análise , Soroalbumina Bovina/química , Extração em Fase Sólida/métodos , Vinho/análise , Cromatografia Líquida de Alta Pressão/métodos , Concentração de Íons de Hidrogênio , Limite de Detecção , Micotoxinas/análise , Reprodutibilidade dos Testes , Extração em Fase Sólida/instrumentação
6.
Anal Chim Acta ; 1078: 78-89, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358231

RESUMO

Based on a one-step combustion fabrication approach, a novel magnetic porous carbon (MPC) was fabricated using filter paper as porous carbon source and iron salts as magnetic precursors. The textural properties of the MPC were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), vibration sample magnetometer (VSM) and nitrogen absorption-desorption isotherms. The as-prepared MPC possessed a high specific surface area, a microstructure comprised of mesopores and strong magnetic response. It was employed as a magnetic solid-phase extraction (MSPE) adsorbent for the determination of three non-steroidal anti-inflammatory drugs (NSAIDs) in environmental water and biological samples coupled with high performance liquid chromatography (HPLC). The main parameters affecting extraction efficiency were investigated in detail and a satisfactory performance was obtained under the optimal conditions. The calibration curves were linear over the concentration ranging from 1 to 1200 µg L-1 for ketoprofen (KET) and 2-1200 µg L-1 for naproxen (NAP) and diclofenac (DCF) with determination coefficients (R2) between 0.9995 and 0.9997. The limits of detection (LODs) were in the range of 0.2-0.4 µg L-1. The intra- and inter-day relative standard deviations (RSDs) were less than 4.03% and 8.72%, respectively. The recoveries ranged from 84.67% to 113.73% with RSDs less than 7.76%. The satisfactory results confirmed the great potential of the novel MPC adsorbent for the extraction of NSAIDs from complex sample matrices.


Assuntos
Anti-Inflamatórios não Esteroides/análise , Carbono/química , Diclofenaco/análise , Cetoprofeno/análise , Naproxeno/análise , Adsorção , Anti-Inflamatórios não Esteroides/sangue , Anti-Inflamatórios não Esteroides/urina , Diclofenaco/sangue , Diclofenaco/urina , Química Verde/métodos , Cetoprofeno/sangue , Cetoprofeno/urina , Limite de Detecção , Nanopartículas de Magnetita/química , Naproxeno/sangue , Naproxeno/urina , Porosidade , Rios/química , Extração em Fase Sólida/instrumentação , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/análise
7.
J Food Sci ; 84(7): 1992-2002, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31264718

RESUMO

A simple, fast, and efficient method, "enhanced matrix removal of lipids" (EMR-lipid), was proposed, optimized, and validated for identifying five polar heterocyclic amines (HCAs) in meat samples that ranged from high-protein (beef and chicken) to high-fat (pork bacon) matrices. The protocol involves an initial solid-liquid phase extraction followed by a rapid dispersive solid-phase extraction using EMR-lipid sorbents and salting-out partitioning. Acetonitrile containing formic acid at two levels (1% and 2%) efficiently extracted HCAs from different meat matrices. Liquid chromatography-tandem mass spectrometry (MS/MS) with selective reaction monitoring mode was developed for qualitative and quantitative analysis. The highest MS/MS responses and better peak separation of analytes were achieved by adjusting mobile phases to pH 3.0 with instrumental detection limits between 0.01 and 0.05 ng/mL. Good linearity of standard curves was obtained in both pure solvents and postspiked meat extracts between 0.5 and 50.0 ng/mL. The validation results showed good precision, accuracy, and sensitivity for detecting HCAs in spiked meat samples. Satisfactory recoveries of four HCAs were achieved: 65% to 111% in beef, 71% to 106% in bacon, and 42% to 77% in chicken. Matrix effects were also assessed and showed less than -20% of ion suppression in bacon extract, while a medium to high signal suppression was observed in beef (-37% to -55%) and chicken (-28% to -52%). This optimized EMR-lipid method provides acceptable results and advantages for determining trace level HCAs in complex meat matrices.


Assuntos
Aminas/análise , Aminas/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Extração Líquido-Líquido/métodos , Carne/análise , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Animais , Bovinos , Galinhas , Contaminação de Alimentos/análise , Suínos
8.
Food Chem ; 299: 125146, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31302427

RESUMO

Matrix effects in complex tea matrices remains a great challenge to rapid quantitative analysis of multi-residue pesticides by analysis of mass spectrometry. Herein, a mixed-mode polymer cationic exchange based dispersive solid-phase extraction (DSPE) procedure was established to eliminate matrix effects of tea for a rapid target alkaline multi-residue pesticides analysis. One-step DSPE procedure can eliminate matrix interferences from the tea extract without additional dilution or tedious cleanup operations. Liquid chromatography-high resolution mass spectrometry using pre-column dilution injection mode was used as the detection technique, while eliminating solvent effects of target analytes and improving the detection sensitivity. Based on this effective analytical method, the results of absolute matrix effects were within 0.77-1.08 for quantitation of the 68 alkaline pesticides, and superior relative matrix effects were also achieved with RSD values below 9.8%. Finally, this method was validated and applied to the alkaline pesticides analysis of the 123 tea samples.


Assuntos
Cromatografia Líquida/métodos , Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Extração em Fase Sólida/métodos , Chá/química , Cafeína/isolamento & purificação , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Resíduos de Praguicidas/química , Polifenóis/isolamento & purificação , Reprodutibilidade dos Testes
9.
Food Chem ; 299: 125136, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31302429

RESUMO

Glycerophospholipids (GPLs) constitute a chemical family within the saponifiable fraction of vegetable oils. GPLs have been scarcely studied in edible oils owing to the lack of sensitive and selective analytical methods. We have developed a method for identification, confirmation and relative quantitation of GPLs in vegetable oils. The method is based on solid-phase extraction (SPE) for isolation of GPLs and determination by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). As proof of concept, the approach has been applied to characterize GPLs in different olive oil categories, thus revealing compositional changes, which could be explained by factors such as the quality of fruits and the extraction process. Families such as glycerophosphatidic acids and phosphatidylglycerides are remarkable because of their capability to discriminate virgin olive oils from the rest of categories. These results open a door to additional studies targeted at the identification of olive oil quality by monitoring these lipids.


Assuntos
Cromatografia Líquida/métodos , Glicerofosfolipídeos/análise , Azeite de Oliva/química , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Análise de Alimentos/métodos , Glicerofosfolipídeos/isolamento & purificação , Óleos Vegetais/química
10.
Food Chem ; 299: 125144, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31323440

RESUMO

Magnetic nanoparticles were synthesised to extract Sudan dyes from chilli powders. The adsorbents used were magnetic ferroferric oxide nanoparticles coated with polystyrene. The extraction procedures for Sudan dyes comprised liquid-solid extraction and magnetic solid phase extraction. The conditions were optimised to achieve efficient magnetic solid phase extraction, including extraction and desorption time, type and volume of the desorption solvent, and the mass of the adsorbents. Repeatability tests showed satisfactory recovery rates of 80.2-115.8%, with a relative standard deviation <3.8%. The results suggested that the proposed extraction method was effective and efficient to extract Sudan dyes from chilli powders. The extraction process was simpler compared with traditional approaches because the adsorbents can be rapidly removed from the sample matrix using a permanent magnet. The use of recyclable adsorbents decreased the cost greatly. Chilli powder samples collected from local markets in Singapore were tested using the proposed method under optimum conditions.


Assuntos
Capsicum/química , Corantes/análise , Contaminação de Alimentos/análise , Nanopartículas de Magnetita/química , Compostos Azo/análise , Fracionamento Químico/métodos , Cromatografia Líquida de Alta Pressão , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Pós/química , Reprodutibilidade dos Testes , Singapura , Extração em Fase Sólida/instrumentação , Extração em Fase Sólida/métodos
11.
Environ Pollut ; 252(Pt B): 1574-1581, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31277026

RESUMO

The bioavailability of a pollutant is usually evaluated based on its freely dissolved concentration (Cfree), which can be measured by negligible-depletion equilibrium extraction that is commonly suffered from long equilibration time. Herein, metal-organic framework (MOF) composites (Fe3O4@MIL-101), consists of a magnetic Fe3O4 core and a MIL-101 (Cr) MOF shell, is developed as sorbents for negligible-depletion magnetic solid-phase extraction (nd-MSPE) of freely dissolved polyaromatic hydrocarbons (PAHs) in environmental waters. The freely dissolved PAHs in 1000 mL water samples are extracted with 1.5 mg MOF composites, and desorbed with 0.9 mL of acetonitrile under sonication for 5 min. The MOF composites exclude the extraction of dissolved organic matter (DOM) and DOM-associated PAHs by size exclusion. Additionally, the combined interactions (hydrophobic, π-π and π-complexation) between PAHs and composites markedly reduced the extraction equilibration time to < 60 min for all the studied PAHs with logKOW up to 5.74. Moreover, the porous coordination polymers property of the MOFs makes the proposed nd-MSPE based on the partitioning of PAHs and thus excludes the competitive adsorption of coexisting substances. The developed nd-MSPE approach provides low detection limits (0.08-0.82 ng L-1), wide linear range (1-1000 ng L-1) and high precision (relative standard deviations (RSDs) (3.3-4.8%) in determining Cfree of PAHs. The measured Cfree of PAHs in environmental waters are in good agreement with that of verified method. Given the large diversity in structure and pore size of MOFs, various magnetic MOFs can be fabricated for task-specific nd-MSPE of analytes, presenting a prospective strategy for high-efficiency measuring Cfree of contaminants in environments.


Assuntos
Nanopartículas de Magnetita/química , Estruturas Metalorgânicas/química , Nanocompostos/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/análise , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Solubilidade
12.
J Chromatogr A ; 1603: 83-91, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31288928

RESUMO

In the acidic environment of the stomach, nitrosatable pesticide residues may react with nitrite to form potentially carcinogenic pesticide-associated N-nitroso compounds (PANOCs). The objective of this study was to develop a method for the analysis of 10 nitrosatable pesticides and breakdown products in human serum and urine. Three sample preparation methods were evaluated for extraction of target analytes from the biomatrices. Deproteinization by methanol for 300-µL aliquots of serum with a final extract volume of 225 µL resulted in excessive ion enhancement of some analytes and suppression of others. Three types of solid-phase extraction cartridges were tested for optimal analyte retention from 200-µL aliquots of serum with a final extract volume of 400 µL; this approach resulted in significant analyte loss for some compounds. The Quick, Easy, Cheap, Effective, Rugged, and Safe approach resulted in a suitable method for extraction of the analytes from each biomatrix. Biofluid samples (500 µL) were spiked to 100 µg L-1 with analytical standards and extracted using 500 µL of acetonitrile (ACN) with 4% acetic acid (AcOH) for serum and 0.1% AcOH in ACN for urine. For extraction, 200 mg magnesium sulfate (MgSO4) and 50 mg sodium acetate were added for serum and 200 mg MgSO4 and 50 mg sodium chloride were added for urine. Final extract volumes for both biomatrices using the QuEChERS method was 400 µL after dilution. Samples were analyzed via ultra-high pressure liquid chromatography/high-resolution accurate mass orbital ion trap mass spectrometry. Mean recoveries for target analytes in serum and urine ranged between 74 and 120% (%RSD < 12) and 96 to 116% (%RSD ≤ 10), respectively. These methods may be used in large-scale biomonitoring studies to analyze PANNs and their parent compounds in human serum and urine.


Assuntos
Cromatografia Líquida/métodos , Compostos Nitrosos/análise , Resíduos de Praguicidas/análise , Soro/metabolismo , Extração em Fase Sólida/métodos , Manejo de Espécimes/métodos , Espectrometria de Massas em Tandem/métodos , Humanos , Soro/química , Urinálise/métodos
13.
Anal Bioanal Chem ; 411(23): 6129-6139, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31278554

RESUMO

Antibiotics may be present in agricultural soils through the application of organic amendments as fertilizers or by irrigation of fields with recycled water. As a result of these agricultural practices, antibiotics in soil can lead to their uptake by plants, entering in this way the food chain. Studies on the levels of antibiotics in cereal samples are scarce in the available literature. In this work, an analytical method was developed for the determination of 19 antibiotics (fluoroquinolones, sulfonamides, tetracyclines, and lincosamides) in four types of cereal grains (wheat, barley, rice, and oat). Ultrasound-assisted matrix solid-phase dispersion was selected as extraction technique with recoveries of target analytes ranging from 73 to 127% for the four cereals analyzed. Limits of quantification obtained ranged from 0.8 to 5.8 ng g-1. Compared with methods described for the analysis of antibiotics in cereals, the developed method uses a lower volume of extraction solvent and very good recoveries were obtained for all compounds. The validated method was applied to the analysis of different types of cereals samples, harvested from agricultural fields or purchased from local supermarkets. The analysis of the five cereal samples grown in fields with 3 years of consecutive organic amendments revealed that none of the nineteen antibiotics selected were found in any sample. Eleven commercial samples of cereals of different types and presentations were analyzed and enrofloxacin was detected in one rice sample; the presence of enrofloxacin in cereals or its incorporation into crops from soil or water not previously reported. Graphical abstract.


Assuntos
Antibacterianos/análise , Resíduos de Drogas/análise , Grão Comestível/química , Contaminação de Alimentos/análise , Espectrometria de Massas em Tandem/métodos , Cromatografia Líquida/métodos , Fluoroquinolonas/análise , Limite de Detecção , Lincosamidas/análise , Extração em Fase Sólida/métodos , Sulfonamidas/análise , Tetraciclinas/análise
14.
J Agric Food Chem ; 67(28): 8035-8044, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31282154

RESUMO

The simultaneous detection of multiple mycotoxins is important due to the increased toxic effects of combined mycotoxins in grains. In this research, a combination of modified QuEChERS with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used for simultaneous detection of 20 mycotoxins in grains. A series of different types of magnetic (Fe3O4) nanoparticles modified with multiwalled carbon nanotubes (Fe3O4-MWCNTs) were designed as modified QuEChERS adsorbents for facile and efficient purification and for target interferences removal in the matrices. When there is an external magnetic field, the proposed modified QuEChERS method uses a shorter pretreatment time compared with the traditional QuEChERS method, which makes it possible to conduct high-throughput analyses. To optimize the QuEChERS process, the extraction solvent and the type and amount of the Fe3O4-MWCNTs were investigated. Under optimal conditions, the method was validated and showed satisfactory linearity (r2 ≥ 0.9965), good recovery (73.5-112.9%), good precision (1.3-12.7%), and excellent sensitivity (ranging from 0.0021 to 5.4457 ng g-1), which indicates that this method can be used for detecting multiple mycotoxins in real samples.


Assuntos
Carbono/química , Cromatografia Líquida de Alta Pressão/métodos , Grão Comestível/química , Micotoxinas/química , Micotoxinas/isolamento & purificação , Nanotubos/química , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Adsorção , Magnetismo , Extração em Fase Sólida/instrumentação
15.
Anal Bioanal Chem ; 411(23): 6173-6187, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31324926

RESUMO

A simple, rapid and efficient solid-phase extraction method based on synthesized carbon nanodots was developed for the preconcentration and extraction of personal care products and organophosphorus pesticides in environmental matrices. Factorial (screening) and central composite designs were employed for the optimization of experimental conditions that could potentially influence the percentage recoveries of the target analytes. The experimental variables, including sample pH, mass of adsorbent, eluent volume and sample volume, were examined. Under the optimized conditions, the developed method was validated, and acceptable analytical results obtained showed good performance. The method accuracy carried out at two spiking levels (10 and 100 µg L-1) in different sample matrices ranged between 63 and 120%. The method precision based on relative standard deviation (% RSD) was < 10%. The linear range studied had a determination coefficient of (R2 > 0.995). The limits of detection (LOD) and limit of quantification (LOQ) established varied between 0.015-0.125 and 0.05-0.415 µg L-1 ,respectively. The ensuing method was applied successfully in the determination of the five multi-class organic compounds under study, in influent and effluent wastewater matrices, sampled from a municipal wastewater treatment plant located in Pretoria, South Africa.


Assuntos
Carbono/química , Cosméticos/isolamento & purificação , Nanotubos/química , Compostos Organofosforados/isolamento & purificação , Praguicidas/isolamento & purificação , Águas Residuárias/análise , Poluentes Químicos da Água/isolamento & purificação , Cromatografia Líquida/métodos , Limite de Detecção , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Purificação da Água/métodos
16.
Anal Chim Acta ; 1074: 108-116, 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31159930

RESUMO

As an important "food and drug dual-use" product, chrysanthemums are widely used in both botanical medicine and food applications. However, the misuse of pesticides during chrysanthemum cultivation makes pesticide residue monitoring crucial. The aim of the present work was to address this practical demand for the simultaneous determination of multiple pesticide residues in various species of chrysanthemums. Both the sample pre-treatment and instrumental methods were systematically investigated. Seven chrysanthemum samples were extracted using acetonitrile and purified by dispersive solid-phase extraction with amino-modified multi-walled carbon nanotubes (MWCNTs-NH2) and C18 as the cleanup co-adsorbents. After optimizing the amounts of MWCNTs-NH2 and C18, matrix effects could not be avoided during LC-MS/MS analysis of 112 pesticides, although satisfactory recoveries were obtained. The use of SFC-MS/MS was evaluated, which demonstrated the significant positive role of SFC-MS/MS in reducing the matrix effects during pesticide residue analysis. In addition, the use of SFC-MS/MS permitted a shorter run time and afforded greater analytical efficiency. Method validation was further performed to evaluate the linearity, sensitivity, recovery, and precision of the developed method. Good linearity was observed for 92% of the analytes in the concentration range of 2-250 µg L-1 for all seven of the chrysanthemum samples. The LODs of the 112 pesticides ranged from 0.01 to 31.41 µg L-1, depending on the sample, while the mean recoveries of all of the spiked pesticides ranged from 81.8% to 102% for concentrations of 20, 50, and 200 µg kg-1. These results clearly demonstrate the applicability of the developed method for the simultaneous determination of multi-pesticides in various chrysanthemum samples.


Assuntos
Cromatografia com Fluido Supercrítico/métodos , Chrysanthemum/química , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Acetonitrilos/química , Adsorção , Contaminação de Medicamentos/prevenção & controle , Contaminação de Alimentos/análise , Limite de Detecção , Nanotubos de Carbono/química , Extração em Fase Sólida/métodos
17.
Food Chem ; 297: 124926, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253318

RESUMO

Sand was studied as a solid support in ultrasound-assisted matrix solid-phase dispersion (UA-MSPD) for the extraction of different pesticide classes, including organophosphates, carbamates, triazoles and pyrethroids from fruits and vegetables, with determination by GC-MS and LC-MS/MS. The performance of sand was compared with that of different types of classic solid supports and alternative natural materials from renewable sources. The best results were obtained using 0.5 g sample, 1 g sand as a solid support, 20 mg activated charcoal and 5 mL ethyl acetate as elution solvent. Recoveries ranged from 55 to 140% with an RSD ≤ 20%. LOQs varied from 0.005 to 0.5 mg kg-1 for all analytes. Thiamethoxam, captan, chlorpyrifos, dimethoate and pyrimethanil were found in strawberry samples at concentrations from 0.01 to 0.06 mg kg-1. Acephate and tebuconazole were found in a tomato sample at concentrations of 0.45 and 0.30 mg kg-1, respectively. The method developed was efficient, simple, cheap, robust, and environmentally friendly.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Resíduos de Praguicidas/análise , Extração em Fase Sólida/métodos , Verduras/química , Cromatografia Líquida de Alta Pressão , Dimetoato/química , Frutas/química , Frutas/metabolismo , Limite de Detecção , Resíduos de Praguicidas/isolamento & purificação , Piretrinas/química , Sonicação , Espectrometria de Massas em Tandem , Triazóis/química , Verduras/metabolismo
18.
J Chromatogr A ; 1602: 107-116, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31182304

RESUMO

Polystyrene is one of the best candidates as the extracting medium due to its high stability in different media and acceptable extraction capability. However, the hydrophobic nature and low wettability of polystyrene limits its application to non-polar analytes. To resolve this limitation, in this project, amine groups were chemically attached to the surface of magnetic polystyrene. The resulting hydrophilic magnetic particles were expected to be capable of extracting both polar and non-polar analytes. Non-steroidal anti-inflammatory drugs (NSAIDs) were chosen for testing the applicability of modified magnetic polystyrene according to the importance of their analysis and also their wide polarity range. Major parameters associated with the extraction procedure were optimized using central composite design (CCD) method and pH 3, extraction time of 15 min, desorption volume of 350 µL and desorption time of 4 min were chosen as optimized values. Under these conditions, figures of merit were calculated including: linear dynamic range (0.5-1000 µg L-1), linear equation and limits of detection (0.1-3 µg L-1). To investigate the method precision, inter-day, intra-day and synthesis-to-synthesis relative standard deviation (RSD) were studied (<12%). All studies were conducted using blank urine samples spiked with aspirin, salicylic acid, ibuprofen, diclofenac and mefenamic acid. Naproxen was chosen as the internal standard and high-performance liquid chromatography-UV-Vis (HPLC-UV) was employed for the subsequent determination after extraction. To evaluate the applicability of the method for real sample analysis, urine samples from patients under treatment were analyzed and acceptable results were obtained. The aminated magnetic polystyrene revealed superior extraction efficiency, much higher than polystyrene before functionalization. In addition, hospital wastewater sample was tested and acceptable extraction efficiencies were obtained.


Assuntos
Aminas/química , Magnetismo , Preparações Farmacêuticas/isolamento & purificação , Preparações Farmacêuticas/urina , Poliestirenos/química , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/urina , Diclofenaco/química , Diclofenaco/urina , Humanos , Ibuprofeno/química , Ibuprofeno/urina , Limite de Detecção , Reprodutibilidade dos Testes , Extração em Fase Sólida/métodos , Espectroscopia de Infravermelho com Transformada de Fourier , Águas Residuárias/química
19.
Food Chem ; 293: 226-232, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31151605

RESUMO

Iprodione is a fungicide widely used in viticulture in most agricultural countries. It was banned recently in the European community because of its carcinogenic and endocrine disrupting characters. In this work, a cheap analytical method able to monitor iprodione in a white wine was developed. Molecularly imprinted sol-gel polymers (MIS) specific to iprodione and using green solvents were synthesized. An experimental design having the following factors (solvent volume and crosslinker quantity) was used to prepare an optimal MIS. In terms of selectivity, the optimal MIS showed the best partition coefficient towards iprodione in a white wine containing four other competing fungicides (procymidone, pyrimethanil, azoxystrobin and iprovalicarb). A solid phase extraction method using the optimal MIS was optimized and applied to analyse iprodione in a white wine. Low detection and quantification limits were reached 11.7 and 39.1 µg/L respectively.


Assuntos
Aminoimidazol Carboxamida/análogos & derivados , Fungicidas Industriais/análise , Hidantoínas/análise , Impressão Molecular , Polímeros/química , Solventes/química , Vinho/análise , Aminoimidazol Carboxamida/análise , Aminoimidazol Carboxamida/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Fungicidas Industriais/isolamento & purificação , Géis/química , Química Verde , Hidantoínas/isolamento & purificação , Extração em Fase Sólida/métodos
20.
J Environ Sci Health B ; 54(7): 569-579, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31164032

RESUMO

This study reports on the development and application of solid phase extraction (SPE) and ultrasonic extraction (UE) methods for the analysis of triazine herbicides in water, soil and sediment samples. The extraction parameters such as conditioning solvent, sample loading volume, eluting solvent, extraction time and sample mass were optimized due to their influence on the extraction efficiency of the analytes. To assess the applicability of the SPE and UE methods, spiked distilled water or soil samples were extracted and analyzed using an LC-PDA instrument. The recoveries obtained under optimum conditions were between 65-94% and 75-100% for SPE and UE, respectively. The relative standard deviations obtained were less than 0.36% for SPE and less than 4.6% for UE. The limit of detection (LOD) ranged from 0.026-0.084 µg/L for SPE and 0.0028-0.0083 mg/kg for UE. The limit of quantification (LOQ) was between 0.088-0.28 µg/L for SPE and 0.0089-0.028 mg/kg for UE. The concentrations of triazines were found to be between 0.96-7.4 µg/L and 0.79-15 µg/L in river water and wastewater effluent samples, respectively. In sediment samples, the triazine concentrations were found to be between 0.032-0.93 mg/kg, while in soil samples they were between 0.12-1.03 mg/kg.


Assuntos
Herbicidas/análise , Poluentes do Solo/análise , Extração em Fase Sólida/métodos , Triazinas/análise , Poluentes Químicos da Água/análise , Fracionamento Químico , Cromatografia Líquida/métodos , Sedimentos Geológicos/análise , Limite de Detecção , Solventes/química , África do Sul , Águas Residuárias/análise , Água/análise
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