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1.
Chemosphere ; 258: 127357, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947670

RESUMO

Diffusive isotope fractionation of non- and perdeuterated benzenes and toluenes in aqueous solution was investigated. The experimental method was based on a Stokes diaphragm cell. The isotope composition of diffusate and retentate was found to be identical within a range of uncertainty of ±5‰ for benzene and ±10‰ for toluene. These data are consistent with a previous fractionation study using phase-transition kinetics as the potentially fractionating step. The present study contributes to strengthening the data base for diffusive isotope fractionation of organic compounds in aqueous solution. According to the presented data, diffusion of naturally occurring, monodeuterated organic compounds does not significantly affect their hydrogen isotope pattern.


Assuntos
Hidrocarbonetos/química , Poluentes Químicos da Água/química , Benzeno , Isótopos de Carbono , Fracionamento Químico/métodos , Difusão , Hidrogênio , Isótopos , Cinética , Tolueno , Água
2.
Biosens Bioelectron ; 169: 112592, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32942143

RESUMO

Global health and food security constantly face the challenge of emerging human and plant diseases caused by bacteria, viruses, fungi, and other pathogens. Disease outbreaks such as SARS, MERS, Swine Flu, Ebola, and COVID-19 (on-going) have caused suffering, death, and economic losses worldwide. To prevent the spread of disease and protect human populations, rapid point-of-care (POC) molecular diagnosis of human and plant diseases play an increasingly crucial role. Nucleic acid-based molecular diagnosis reveals valuable information at the genomic level about the identity of the disease-causing pathogens and their pathogenesis, which help researchers, healthcare professionals, and patients to detect the presence of pathogens, track the spread of disease, and guide treatment more efficiently. A typical nucleic acid-based diagnostic test consists of three major steps: nucleic acid extraction, amplification, and amplicon detection. Among these steps, nucleic acid extraction is the first step of sample preparation, which remains one of the main challenges when converting laboratory molecular assays into POC tests. Sample preparation from human and plant specimens is a time-consuming and multi-step process, which requires well-equipped laboratories and skilled lab personnel. To perform rapid molecular diagnosis in resource-limited settings, simpler and instrument-free nucleic acid extraction techniques are required to improve the speed of field detection with minimal human intervention. This review summarizes the recent advances in POC nucleic acid extraction technologies. In particular, this review focuses on novel devices or methods that have demonstrated applicability and robustness for the isolation of high-quality nucleic acid from complex raw samples, such as human blood, saliva, sputum, nasal swabs, urine, and plant tissues. The integration of these rapid nucleic acid preparation methods with miniaturized assay and sensor technologies would pave the road for the "sample-in-result-out" diagnosis of human and plant diseases, especially in remote or resource-limited settings.


Assuntos
Doenças Transmissíveis/diagnóstico , Dispositivos Lab-On-A-Chip , Ácidos Nucleicos/isolamento & purificação , Doenças das Plantas , Sistemas Automatizados de Assistência Junto ao Leito , Betacoronavirus/isolamento & purificação , Fracionamento Químico/instrumentação , Fracionamento Químico/métodos , Doenças Transmissíveis/microbiologia , Doenças Transmissíveis/parasitologia , Doenças Transmissíveis/virologia , Infecções por Coronavirus/diagnóstico , Infecções por Coronavirus/virologia , Desenho de Equipamento , Humanos , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Técnicas de Amplificação de Ácido Nucleico/métodos , Ácidos Nucleicos/sangue , Ácidos Nucleicos/urina , Pandemias , Doenças das Plantas/microbiologia , Doenças das Plantas/parasitologia , Doenças das Plantas/virologia , Pneumonia Viral/diagnóstico , Pneumonia Viral/virologia
3.
Nat Protoc ; 15(8): 2568-2588, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32651564

RESUMO

RNA-protein interactions play a pivotal role in cell homeostasis and disease, but current approaches to study them require a considerable amount of starting material, favor the recovery of only a subset of RNA species or are complex and time-consuming. We recently developed orthogonal organic phase separation (OOPS): a quick, efficient and reproducible method to purify cross-linked RNA-protein adducts in an unbiased way. OOPS avoids molecular tagging or the capture of polyadenylated RNA. Instead, it is based on sampling the interface of a standard TRIzol extraction to enrich RNA-binding proteins (RBPs) and their cognate bound RNA. OOPS specificity is achieved by digesting the enriched interfaces with RNases or proteases to release the RBPs or protein-bound RNA, respectively. Here we present a step-by-step protocol to purify protein-RNA adducts, free protein and free RNA from the same sample. We further describe how OOPS can be applied in human cell lines, Arabidopsis thaliana, Schizosaccharomyces pombe and Escherichia coli and how it can be used to study RBP dynamics.


Assuntos
Fracionamento Químico/métodos , Proteoma/isolamento & purificação , Proteínas de Ligação a RNA/isolamento & purificação , RNA/isolamento & purificação , Transcriptoma , Linhagem Celular , Humanos , Proteoma/metabolismo , RNA/metabolismo , Proteínas de Ligação a RNA/metabolismo , Fluxo de Trabalho
4.
Food Chem ; 333: 127491, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32659672

RESUMO

A cascade process for the sequential recovery of proteins and feruloylated arabinoxylan from wheat bran is proposed, involving a protein isolation step, enzymatic destarching and subcritical water extraction. The protein isolation step combining lactic acid fermentation and cold alkaline extraction reduced the recalcitrance of wheat bran, thus improving the total yields of the subsequent subcritical water extraction. The time evolution of subcritical water extraction of feruloylated arabinoxylan was compared at two temperatures (160 °C and 180 °C). Longer residence times enhanced the purity of target feruloylated arabinoxylans, whereas higher temperatures resulted in faster extraction at the expense of significant molar mass reduction. The radical scavenging activity of the extracted feruloylated arabinoxylans was preserved after the initial protein isolation step. This study opens new possibilities for the cascade valorization of wheat bran into enriched protein and non-starch polysaccharide fractions, which show potential to be used as functional food ingredients.


Assuntos
Fracionamento Químico/métodos , Ácidos Cumáricos/química , Fibras na Dieta/análise , Proteínas de Plantas/isolamento & purificação , Xilanos/química , Xilanos/isolamento & purificação , Temperatura Alta , Peso Molecular
5.
Food Chem ; 333: 127488, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32682229

RESUMO

A mild mixed-solvent of n-hexane/isopropanol is proposed for extracting total mineral oil hydrocarbons (MOH) from commercial milk powder products. Unlike acid-hydrolysis, the mixed-solvent extraction was performed at ambient temperature and the low-boiling-point hydrocarbons were retained to the greatest extent. After extraction, total MOH was determined by on-line liquid chromatography-gas chromatography with a flame ionization detector (LC-GC-FID). The validation of the proposed extraction method revealed a recovery efficacy of 83.0-107.5% and a limit of quantification of 0.5 mg/kg. Then, the total MOH in ten commercial milk powders was determined and mineral oil saturated hydrocarbons (MOSH)/polyolefin oligomeric saturated hydrocarbons (POSH) were found to be within the range of 0.61-5.46 mg/kg. The comparison of the total and surface MOSH/POSH indicated that a major part of the contamination was derived from sources before packaging. The present study provides a robust method for the extraction and determination of total MOH in milk powders.


Assuntos
Fracionamento Químico/métodos , Contaminação de Alimentos/análise , Hidrocarbonetos/análise , Hidrocarbonetos/isolamento & purificação , Leite/química , Óleo Mineral/química , Solventes/química , Animais , Hidrocarbonetos/química , Pós
6.
Food Chem ; 333: 127447, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32688304

RESUMO

Quantification of the specific folate vitamers to estimate total folate in foods is not standardized. A collaborative study, including eight European laboratories, was conducted in order to determine the repeatability and reproducibility of the method for folate quantification in foods using the plant-origin γ-glutamyl hydrolase as part of the extraction procedure. The seven food samples analyzed represent the food groups; fruits, vegetables, dairy products, legumes, offal, fish, and fortified infant formula. The homogenization step was included, and six folate vitamers were analyzed using LC-MS/MS. Total folate content, expressed as folic acid equivalent, was 17-490 µg/100 g in all samples. Horwitz ratio values were within the acceptable range (0.60-1.94), except for fish. The results for fortified infant formula, a certified reference material (NIST 1869), confirmed the trueness of the method. The collaborative study is part of a standardization project within the Nordic Committee on Food Analysis (NMKL).


Assuntos
Fracionamento Químico/métodos , Ácido Fólico/análise , Análise de Alimentos/métodos , Espectrometria de Massas em Tandem/métodos , Animais , Cromatografia Líquida/métodos , Cromatografia Líquida/normas , Laticínios/análise , Grão Comestível/química , Produtos Pesqueiros/análise , Análise de Alimentos/normas , Alimentos Fortificados/análise , Frutas/química , Humanos , Lactente , Fórmulas Infantis/análise , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem/normas , Verduras/química
7.
Food Chem ; 333: 127534, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32673948

RESUMO

A new kind of multi-component membrane was prepared by combining gelatin solution, porogen and an inclusion complex of ionic liquid (IL) and beta-cyclodextrin (ß-CD) in a simple physical manner for selective separation of tea polyphenols (TPs) from green tea crude extracts. After screening, it was found that the resulting membrane containing the IL of dicationic N-vinylimidazole proline salt ([VIm]2C3[l-pro]2) had the excellent performance for the enrichment of the target molecules. Then the newly-developed film was comprehensively characterized by scanning electron microscopy, conductivity, thermogravimetry and spectral analysis. Under pressure driving, the adsorption from an aqueous solution of a mixture of TPs and theophylline on IL@ß-CD-Gel membrane showed that the adsorption capacity for TPs was 303.45 mg/g with removal percentages of 94.38%. The experimental data fit well with pseudo-second-order model and Freundlich model. By using this composite material, a new technology of membrane separation for selective adsorption of TPs was finally established.


Assuntos
Fracionamento Químico/métodos , Gelatina/química , Líquidos Iônicos/química , Membranas Artificiais , Polifenóis/isolamento & purificação , Chá/química , beta-Ciclodextrinas/química , Polifenóis/análise
8.
Anim Sci J ; 91(1): e13388, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32578273

RESUMO

Serum-based biomarkers hold propitious applications for addressing livestock health, and management. However, discovery of protein biomarkers in complex biological fluids like serum is wholly intractable due to the large dynamic range of protein concentrations; that is, ˜10-12 high abundance proteins constitute >90% of the total protein content and effectively mask proteomic detection of low-abundance biomarkers. Toward addressing this limitation, we test a continuous elution size-based fractionation method, and two approaches that use affinity interaction-based separation of proteins in preparing bovine serum, and compare liquid chromatography tandem mass spectrometry protein identification to neat serum. Our results identify the high-abundance proteins in bovine serum, and demonstrate dynamic range compression and improved protein identification with the different enrichment methods. Although these findings indicate the highest protein number identified in bovine serum (445 proteins, all methods combined), and by any single sample processing method (312 proteins) to date, they still remain lower than levels deemed necessary for biomarker discovery. As such, this investigation revealed limitations to resolving the bovine serum proteome, and the need for species-specific tools for immunodepleting high-abundance proteins. In concert, this study represents a step toward advancing sample preparation methods for bovine serum biomarker identification.


Assuntos
Proteínas Sanguíneas/análise , Fracionamento Químico/métodos , Cromatografia Líquida/métodos , Proteoma/análise , Soro/química , Espectrometria de Massas em Tandem/métodos , Animais , Biomarcadores/sangue , Bovinos , Feminino , Manejo de Espécimes/métodos
9.
Food Chem ; 326: 126965, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32413755

RESUMO

Natural deep eutectic solvents (NADES) were introduced for the extraction of free seleno-amino acids from lyophilized and powdered milk samples. Different NADES were evaluated, and lactic acid:glucose (LGH) showed the highest selenium recoveries. Selenium analysis was performed by inductively coupled plasma mass spectrometry (ICP MS). Se-NADES analysis in ICP MS was optimized according to the radio frequency power and nebulization gas flow rate. Se-NADES extraction was optimized by an experimental design. LGH dilution, LGH volume, sample quantity, and ultrasound time were factors influencing the extraction. Seleno-amino acids were determined by liquid chromatography-ICP MS. After optimization, the limits of detection obtained were 7.37, 8.63, and 9.64 µg kg-1 for selenocysteine, selenomethionine, and seleno-methyl-selenocysteine, respectively. The NADES-extraction is a green procedure with 2 penalty points in the EcoScale. The method was applied to the analysis of powdered milk, lyophilized Se-fortified sheep milk, and ERM-BD151 skimmed milk powder.


Assuntos
Análise de Alimentos/métodos , Leite/química , Selenocisteína/análogos & derivados , Selenocisteína/análise , Selenometionina/análise , Animais , Fracionamento Químico/métodos , Cromatografia Líquida , Feminino , Alimentos Fortificados/análise , Liofilização , Química Verde , Limite de Detecção , Espectrometria de Massas/métodos , Pós/química , Selênio/análise , Ovinos , Solventes/química
10.
Chemosphere ; 255: 126960, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388264

RESUMO

It was investigated that toxic metals (cadmium and lead) enhanced in coal gangue soil used for the reclamation of soil, creates adverse impacts on atmosphere. Presently the chemical fractionation of toxic metals in coal, inner and outer coal gangue soil samples of Lakhra coalfield were studied along with the impact on the orchard grass grown on coal gangue soil in a subside land of the coal mining area. The BCR sequential extraction scheme (BCR-SES) was carried out to determine the different chemical profiles of heavy metals in coal and coal gangue soil samples. For comparative purpose time saving conventional single step extraction (CSE) and vortex assisted single step extraction (VSE) schemes based on same working setting used BCR extraction scheme. The all three procedures were validated by a certified soil sample (BCR 483) and standard addition method in real samples. The total Cd and Pb in coal, soil and grass samples were determined prior to oxidize by acid mixture. The separation of each fraction of Cd, and Pb in all types of environmental samples by VSE could be completed in 30-120 s. The extracted Cd and Pb concentrations in reducible fractions by CSE and VSE extraction procedure were 2.5-5% higher than those values gained through BCR-SES. About 71 and 50% of Cd and Pb in coal samples were observed in acid soluble, reducible and oxidizable fraction, respectively, whilst rest of Cd and Pb (29 and 50%) were found in residual phase. The orchard grass (Dactylis glomerata) grown on land reclaimed with OSG was analysed, the bioaccumulate Cd and Pb may create adverse impacts on grazing cattle.


Assuntos
Monitoramento Ambiental , Metais Pesados/análise , Poluentes do Solo/análise , Animais , Cádmio/análise , Bovinos , Fracionamento Químico/métodos , Carvão Mineral/análise , Minas de Carvão , Dactylis/química , Solo
11.
J Environ Sci Health B ; 55(5): 477-483, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32449480

RESUMO

Pyraoxystrobin is a novel strobilurin fungicide that is widely used on many crops. The high log Kow of pyraoxystrobin implies that it tends to accumulate in aquatic organisms. This study optimized the sorbents of QuEChERS (quick, easy, cheap, effective, rugged, and safe) using 13C-labelled pyraoxystrobin as the internal standard (IS). It has been established a QuEChERS-LC-MS/MS IS method to study the bioconcentration and elimination of pyraoxystrobin in zebrafish (Danio rerio). The results indicated that the method had satisfactory linearity between 0.234 and 15 µg L-1 (R2 = 0.9996). The limits of detection (LOD) and quantification (LOQ) for pyraoxystrobin were 0.01 and 0.03 µg L-1, respectively. The LOQs of the method for water and zebrafish were 0.05 µg L-1 and 0.01 mg/kg, respectively. The mean recovery of pyraoxystrobin in zebrafish and water at fortification levels of 0.01-0.3 mg kg-1 and 0.05-1.5 µg L-1 ranged from 98.31 to 105.61% and 101.87 to 108.48%, respectively, with a % RSD (relative standard deviation) of 0.94-3.57%. The bioconcentration has been evaluated. The bioconcentration factors for pyraoxystrobin in zebrafish were 1,792 and 3,505 after exposure to 0.5 µg L-1 for 168 h and 0.05 µg L-1 for 216 h, respectively. The half-life of pyraoxystrobin in zebrafish was 9.0-9.5 d.


Assuntos
Acrilatos/análise , Acrilatos/farmacocinética , Fracionamento Químico/métodos , Pirazóis/análise , Pirazóis/farmacocinética , Peixe-Zebra , Acrilatos/toxicidade , Animais , Bioacumulação , Cromatografia Líquida , Ecotoxicologia/métodos , Fungicidas Industriais/análise , Fungicidas Industriais/farmacocinética , Fungicidas Industriais/toxicidade , Meia-Vida , Limite de Detecção , Pirazóis/toxicidade , Sensibilidade e Especificidade , Espectrometria de Massas em Tandem/métodos , Testes de Toxicidade Aguda , Poluentes Químicos da Água/análise
12.
J Food Sci ; 85(6): 1742-1751, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32449951

RESUMO

Coffee leaves contain various bioactive compounds that are beneficial for human health. However, there are very limited researches related to the extraction of the bioactive phytochemicals from coffee leaves. In the present study, the extraction conditions for bioactive components from coffee leaves were optimized using Taguchi design and response surface methodology (RSM). Taguchi design was used to screen significant factors that affected the yield of phytochemicals including trigonelline, caffeine, chlorogenic acids, mangiferin, and rutin, total phenolic content (TPC) and antioxidant activity. Sequentially, a Box-Behnken design (BBD) was used to optimize the extraction conditions. Three factors including Liquid-to-solid (L:S) ratio, ethanol concentration, and extraction temperature that significantly affected most of the phytochemical yields and antioxidant activity were selected from the six variables using Taguchi design. The optimal extraction conditions obtained from RSM were 30.3:1 L:S ratio, 54.5% ethanol, and 80 °C when simultaneously considered four responses, including TPC, the yields of mangiferin and 5-CQA and DPPH scavenging capacity. Under the optimal conditions, the experimental results for the above four responses were 62.1 mg gallic acid/g, 4.1 mg/g, 11.4 mg/g, and 356.9 µmol Trolox/g, respectively, which were close to the predicted values. About 97% of phytochemicals can be extracted in the first two times of extraction. In conclusion, the combination of Taguchi design and response surface methodology can be successfully used to screen and optimize the significant factors that affected the bioactive components extracted from coffee leaves. PRACTICAL APPLICATION: Coffee leaves, the byproducts of coffee plants, are considered no- or low-value although it has a long history for using them as tea-like beverage and ethnomedicine by locals in the coffee plant growing countries. Bioactive components extracted from coffee leaves can be used as ingredients in functional beverages, functional food, and natural health products. These applications will add values to coffee leaves as well as increase the incomes of coffee farmers and workers.


Assuntos
Fracionamento Químico/métodos , Extratos Vegetais/isolamento & purificação , Folhas de Planta/química , Ultrassom/métodos , Humanos , Fenóis/análise , Fenóis/isolamento & purificação , Compostos Fitoquímicos/análise , Compostos Fitoquímicos/isolamento & purificação , Extratos Vegetais/química
13.
Food Chem ; 322: 126765, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32311620

RESUMO

An efficient and sensitive analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated for the simultaneous determination of 42 pharmaceuticals belonging to different therapeutic classes (i.e. antibiotics, analgesics, anti-inflammatories, cardiovascular agents, anxiolytics and human indicators) in seafood samples. The very simple sample preparation included analytes extraction with acidified methanol, concentration by evaporation and filtration of the final extract prior to LC-MS/MS analysis. Analytical performances were evaluated in muscles of four commercial species (hake, red mullet, sole and shrimp) and showed good recoveries at two spiked concentration levels, with relative standard deviations below 45%. Limits of quantification ranged from 0.1 to 40.2 ng/g. This procedure has been successfully applied to the determination of the target analytes in seafood collected from the Bay of Biscay (Southern France) and 4 of these 42 pharmaceuticals were detected at low ng/g levels, suggesting a very limited contamination.


Assuntos
Cromatografia Líquida/métodos , Contaminação de Alimentos/análise , Preparações Farmacêuticas/análise , Alimentos Marinhos/análise , Espectrometria de Massas em Tandem/métodos , Fracionamento Químico/métodos , Análise de Alimentos/métodos , França , Músculos/química , Solventes , Poluentes Químicos da Água/análise
14.
Food Chem ; 322: 126767, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32330787

RESUMO

Due to the lack of innovative valorization strategies, berry pomaces are a poorly utilized as a cheap source of valuable nutrients and phytochemicals. An effective biorefining scheme was developed to recover functional components from lingonberry pomace by consecutive supercritical CO2 (SFE-CO2), pressurized liquid (PLE) and enzyme assisted (EAE) extractions. SFE-CO2 at optimized parameters yielded 11.8 g/100 g of lipophilic fraction, containing 43.3 and 37.4% of α-linolenic and linoleic fatty acids, respectively. The combined PLE with ethanol and water additionally recovered 61.8 g/100 g of polar constituents and reduced the antioxidant capacity of starting material by up to 94%. The major portion of the antioxidants (89-94% in different assays), anthocyanins (231 mg/100 g pomace) and proanthocyanidins (15.9 g/100 g pomace) was present in PLE-EtOH extract. Cyanidin-3-galactoside was the major anthocyanin (146.9 mg/100 g). High-pressure fractionation was more efficient for obtaining bioactive pomace constituents as compared with conventional and enzyme-assisted extractions.


Assuntos
Fracionamento Químico/métodos , Solventes/química , Vaccinium vitis-Idaea , Gerenciamento de Resíduos/métodos , Antocianinas/análise , Antocianinas/química , Antioxidantes/análise , Antioxidantes/química , Dióxido de Carbono/química , Etanol/química , Frutas/química , Galactosídeos/análise , Galactosídeos/química , Química Verde , Resíduos Industriais , Complexos Multienzimáticos/química , Complexos Multienzimáticos/metabolismo , Pressão , Proantocianidinas/análise , Proantocianidinas/química , Água
15.
Food Chem ; 321: 126727, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32283503

RESUMO

Alkenylbenzenes are natural toxins with genotoxic and carcinogenic effects in rodents, which are highly present in condiments frequently consumed. The aim of this study was the development of the first multi-analyte method for the determination of eight alkenylbenzenes (eugenol, methyl eugenol, acetyl eugenol, trans-isoeugenol, safrole, estragole, myristicin and trans-anethole) in different pepper varieties by gas chromatography coupled to high-resolution mass spectrometry (GC-HRMS-Q-Orbitrap) in combination with a simple ultrasound-assisted extraction method (UAE). The method was successfully validated, and it was applied for studying the presence of these analytes in peppers as well as to elucidate the effects of the berries' maturity and the geographical origin on alkenylbenzene contents. The analysis of the pepper samples showed that eugenol (10.5-120 mg/kg), trans-anethole (10.7-42.7 mg/kg) and estragole (2.2-45.7 mg/kg) tended to be the most detected alkenylbenzenes at high levels, whereas trans-isoeugenol (0.69-3.6 mg/kg) and safrole (0.20-3.0 mg/kg) were minor components. Estragole (PubChem CID: 8815); trans-anethole (PubChem CID: 637563); Myristicin (PubChem CID: 4276); Safrole (PubChem CID: 5144); Eugenol (PubChem CID: 3314); Methyl eugenol (PubChem CID: 7127); Acetyl eugenol (PubChem CID: 7136); trans-Isoeugenol (PubChem CID: 853433); Caffeine (PubChem CID: 2519); Dicyclohexylmethanol (PubChem CID: 78197).


Assuntos
Derivados de Benzeno/análise , Análise de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Piper nigrum/química , Anisóis/análise , Compostos de Benzil/análise , Fracionamento Químico/métodos , Dioxolanos/análise , Eugenol/análogos & derivados , Eugenol/análise , Piper nigrum/fisiologia , Pirogalol/análogos & derivados , Pirogalol/análise , Safrol/análise , Ultrassom
16.
Food Chem ; 318: 126473, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32143131

RESUMO

In this work is presented the development of a method for As and Se determination in crude palm oil samples by hydride generation atomic fluorescence spectrometry and Hg by cold vapor atomic fluorescence spectrometry after ultrasound-assisted emulsification and extraction induced by emulsion breaking (EIEB). The optimization of the method was carried out by multivariate designs. The developed method has presented limits of quantification (LOQ) of 0.72, 0.12, and 1.5 µg L-1 for As, Hg, and Se, respectively. The precisions of the proposed method expressed as repeatability were 0.92, 2.2, and 3.7% RSD for 2 µg L-1 (n = 10) of As, Hg and Se, respectively. The developed methodology was applied in palm oil samples collected in the Bahia State. Concentrations (µg L-1) found in the samples were between

Assuntos
Arsênico/análise , Emulsões/química , Análise de Alimentos/métodos , Mercúrio/análise , Óleo de Palmeira/análise , Selênio/análise , Fracionamento Químico/métodos , Análise de Alimentos/estatística & dados numéricos , Contaminação de Alimentos , Gases/química , Limite de Detecção , Análise Multivariada , Óleo de Palmeira/química , Espectrometria de Fluorescência/métodos , Espectrofotometria Atômica/métodos
17.
Food Chem ; 319: 126582, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32199144

RESUMO

An ultrasound-assisted supercritical carbon dioxide (USC-CO2) procedure was developed for the extraction of ursolic acid, oleanolic acid and oridonin from Rabdosia rubescens, with yields that were 9.84-10.46 and 15.43-21.10% higher than those of the conventional SC-CO2 and heat-reflux extractions, respectively. USC-CO2 uses a shorter extraction time (1.83-2.09 times) and less organic solvent (3.39-173.25 times) to operate at a lower extraction temperature (5-16 °C). The dominant component in the extract was oridonin, which may indicate that the kinetic behavior in the extraction system is predominated by that of oridonin. Furthermore, the USC-CO2 and conventional SC-CO2 dynamic extraction kinetics of oridonin from R. rubescens were well described by the second-order rate and Fick's second law models. The extraction rate constant, energy of activation for diffusion, Biot number and thermodynamic parameters were deduced from the data obtained. These results provide valuable insights into the USC-CO2 and conventional SC-CO2 procedures.


Assuntos
Fracionamento Químico/métodos , Diterpenos de Caurano/isolamento & purificação , Isodon/química , Ácido Oleanólico/isolamento & purificação , Triterpenos/isolamento & purificação , Dióxido de Carbono/química , Cromatografia Líquida de Alta Pressão , Diterpenos de Caurano/análise , Química Verde , Cinética , Ácido Oleanólico/análise , Extratos Vegetais/química , Plantas Medicinais/química , Reprodutibilidade dos Testes , Solventes/química , Espectrometria de Massas em Tandem , Triterpenos/análise , Ultrassom
18.
Chemosphere ; 251: 126345, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32169696

RESUMO

This study aimed at investigating whether stable isotopes can be used to monitor the progress of volatile organic compounds (VOCs) volatilization from contaminated sediment during venting. Batches of a dry aquifer sediment were packed into stainless steel HPLC columns, humidified with distilled water and later contaminated by either liquid toluene or propan-2-ol. The VOCs were then volatilized by a stream of gas at room temperature, and the concentrations and stable isotope ratios of gaseous VOCs were recorded by isotope-ratio mass spectrometry. During early stages of volatilization of toluene, the isotope ratios Δδ13C shifted to more negative values by about -3 to -5‰ and the Δδ2H by more than -40‰, while the concentration remained at or near initial saturated vapor concentration. Depletion of the isotope ratios in the gas was explained by the vapor-liquid fractionation process, which is amplified by successive self-partitioning steps of gaseous VOC into remaining liquid VOC. For propan-2-ol the carbon isotope shift was negative like for toluene, whereas the H shift was positive. Hydrogen bonding in the liquid propan-2-ol phase causes a normal vapor-liquid H isotope effect which was described already in classical literature. The isotope shifts in the present experiments are larger than previously reported shifts due to phase-change processes and reach the magnitude of shifts usually observed in kinetic isotope fractionation.


Assuntos
2-Propanol/química , Água Subterrânea/química , Tolueno/química , Carbono , Isótopos de Carbono/análise , Fracionamento Químico/métodos , Gases/análise , Hidrogênio/análise , Ligação de Hidrogênio , Areia , Tolueno/análise , Compostos Orgânicos Voláteis/análise , Volatilização
19.
J Food Sci ; 85(3): 673-681, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32078761

RESUMO

Soybeans, Glycine max (L.) Merr., are among the most important food crops worldwide. Isoflavones are major bioactive phytochemicals in soybeans, and have a variety of health benefits, including antioxidative, antiatherosclerotic, antiinflammatory, and weak estrogen-like effects. The isoflavone content and composition of soybeans vary according to the cultivar and the extraction solvent conditions. Therefore, we investigated the effects of three different solvent pHs (1.0, 5.5, and 10.0) on the isoflavone, total phenolic, and total flavonoid contents and antioxidant capacities of eight soybean cultivars developed in Korea. Twelve isoflavones in soybeans were efficiently separated and identified on a reversed-phase high-performance liquid chromatography (HPLC) system. The percentage distribution of isoflavones measured by HPLC in the eight soybean cultivars at various extraction pHs decreased as follows: malonyl isoflavones (67.2% to 81.3%) > isoflavone glucosides (16.2% to 29.0%; as nonacylated form) > acetyl isoflavones (1.6% to 5.9%). The highest contents of isoflavone glucosides, malonyl derivatives, and acetyl derivatives were extracted at solvent pHs of 10.0, 1.0, and 5.5, respectively. The solvent extraction at pH 1.0 yielded a lower total isoflavone content than those at pHs 5.5 and 10.0. However, the highest total phenolic and flavonoid contents were extracted from soybeans at pH 1.0. Soybeans extracted at pH 10.0 displayed the highest antioxidant capacities in the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical assay. Taken together, these results suggest that proper solvent pH adjustment is needed to maximize the extraction of targeted forms of isoflavones from soybeans. PRACTICAL APPLICATION: Soybeans contain a variety of bioactive compounds, including isoflavones, which function as antioxidants and weak phytoestrogens. Chemical and instrumental analyses can facilitate the selection of soybean cultivars with high amounts of isoflavones for soybean breeding and isoflavone-enriched product development. Proper solvent pH adjustment allows for the efficient extraction of high amounts of targeted isoflavone subgroups (acetyl and malonyl forms) from soybeans for functional food products.


Assuntos
Fracionamento Químico/métodos , Isoflavonas/análise , Isoflavonas/isolamento & purificação , Extratos Vegetais/análise , Extratos Vegetais/isolamento & purificação , Soja/química , Antioxidantes/análise , Antioxidantes/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Flavonoides/análise , Flavonoides/isolamento & purificação , Fenóis/análise , Fenóis/isolamento & purificação , República da Coreia , Sementes/química
20.
Chemosphere ; 248: 125975, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32007772

RESUMO

Stable isotopes have been widely used to monitor remediation of environmental contaminants over the last decades. This approach gives a good mechanistic description of natural or assisted degradation of organic pollutants, such as methyl tert-butyl ether (MTBE). Since abiotic degradation seems to be the most promising assisted attenuation method, the isotopic fractionation associated with oxidation and hydrolysis processes need to be further investigated in order to understand better these processes and make their monitoring more efficient. In this study, position-specific isotope effects (PSIEs) associated with permanganate oxidation and acid hydrolysis of MTBE were determined using isotope ratio monitoring by 13C Nuclear Magnetic Resonance Spectrometry (irm-13C NMR) combined with isotope ratio monitoring by Mass Spectrometry (irm-MS). The use of this Position-Specific Isotopic Analysis (PSIA) method makes it possible to observe a specific normal isotope effect (IE) associated with each of these two abiotic degradation mechanisms. The present work demonstrates that the 13C isotope pattern of the main degradation product, tert-butyl alcohol (TBA), depends on the chemical reaction by which it is produced. Furthermore, this study also demonstrates that PSIA at natural abundance can give new insights into reaction mechanisms and that this methodology is very promising for the future of modeling the remediation of organic contaminants.


Assuntos
Compostos de Manganês/química , Éteres Metílicos/química , Modelos Químicos , Óxidos/química , Poluentes Químicos da Água/química , Isótopos de Carbono/análise , Fracionamento Químico/métodos , Hidrólise , Oxirredução , Poluentes Químicos da Água/análise , terc-Butil Álcool
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