Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 135
Filtrar
1.
Food Chem ; 355: 129523, 2021 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-33780796

RESUMEN

A method for simultaneous determination of carbendazim and tebuconazole residues in cabbage was developed and validated in LC-MS/MS. Samples were extracted and purified following the modified QuEChERS procedure, which enabled the elution of carbendazim and tebuconazole at 0.96 and 5.31 min, respectively. LOD and LOQ were 0.0005 and 0.0015 mg kg-1, respectively. Mean recovery was in the range of 78.94 to 104.89% for carbendazim and 76.07 to 98.62% for tebuconazole. The field samples recorded residues of 0.274 and 0.481 mg kg-1; and 0.194 and 0.392 mg kg-1 at single and double dose for carbendazim and tebuconazole, respectively. Half-life values were 2.17 and 2.99 for carbendazim and 2.74 and 2.81 for tebuconazole at single and double dose, respectively. Decontamination with saltwater wash followed by cooking and lemon water wash found superior in the removal of residues more than 90%.


Asunto(s)
Brassica/química , Descontaminación , Análisis de los Alimentos/métodos , Contaminación de Alimentos/análisis , Residuos de Plaguicidas/análisis , Residuos de Plaguicidas/aislamiento & purificación , Bencimidazoles/análisis , Bencimidazoles/aislamiento & purificación , Carbamatos/análisis , Carbamatos/aislamiento & purificación , Cromatografía Liquida , Semivida , Espectrometría de Masas en Tándem , Factores de Tiempo , Triazoles/análisis , Triazoles/aislamiento & purificación
2.
Food Chem ; 342: 128336, 2021 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-33077280

RESUMEN

Polypyrrole magnetic microspheres were synthesized and used to extract carbaryl, carbofuran, and methomyl before analysis by a high-performance liquid chromatography with diode array detection. Under optimal conditions, four times the preconcentration was achieved with the use of only 1.2 mL of sample. Good linearity with ranges of 3.0-7.5 × 103, 6.0-4.5 × 103, and 15-3.0 × 103 ng kg-1 and limits of detection of 1.37 ± 0.10, 4.7 ± 1.2, and 10.1 ± 5.7 ng kg-1 were obtained, respectively. Good reproducibility (RSDs < 5%) was achieved over 24 cycles of extraction and regeneration. Good accuracy (recoveries 81.6 ± 1.5%-108.3 ± 2.2%) and good precision (RSDs 0.11%-4.5%) were obtained. Carbaryl was detected in apple (2.75 ± 0.23 ng kg-1), carbofuran in tomato (11.34 ± 0.61 ng kg-1), and methomyl in watermelon (34.7 ± 1.7 ng kg-1). The relative expanded uncertainty of the measurement method was less than 14% for all three pesticides.


Asunto(s)
Carbonato de Calcio/química , Carbamatos/aislamiento & purificación , Citrullus/química , Imanes/química , Microesferas , Plaguicidas/aislamiento & purificación , Solanum lycopersicum/química , Carbamatos/química , Técnicas de Química Sintética , Límite de Detección , Plaguicidas/química , Polímeros/química , Pirroles/química , Reproducibilidad de los Resultados
3.
Food Chem ; 337: 127755, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32777567

RESUMEN

Since the beginning of the widespread use of pesticides, their removal from food has become a serious concern. In this study, the removal of residual pesticides (malathion and carbosulfan) from pak choi via treatment with ozonated water was investigated. Under the optimal treatment conditions, i.e., 2.0 mg/L ozonated water and a treatment duration of 15 min, malathion and carbosulfan were degraded by 53.0 and 33.0%, respectively, without any significant changes in color. Even though there was a slight decrease in vitamin C content (~7.9 mg/100 g) following the treatments, a significant decrease in the microbial colonies on the vegetables was observed. Additionally, the pesticide degradation mechanism showed good fitting with a "first + first"-order kinetic model (R2 > 0.9), and the slope (k) indicated that ozone had a more prominent degradation effect on malathion than on carbosulfan. Therefore, this study provides a theoretical basis for controlling agricultural pesticide residues in household applications.


Asunto(s)
Brassica rapa/química , Carbamatos/química , Carbamatos/aislamiento & purificación , Malatión/química , Malatión/aislamiento & purificación , Ozono/química , Contaminación de Alimentos , Residuos de Plaguicidas/química , Residuos de Plaguicidas/aislamiento & purificación , Verduras/química
4.
J Basic Microbiol ; 60(11-12): 983-993, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33103250

RESUMEN

This study investigates the anticancer cytotoxic mechanism of action of benzoyloxy-ethyl-carbamic acid (BECA) produced by Streptomyces globosus VITLGK011. Flow cytometry analysis confirmed that BECA (at IC50 : 3.12 µg/ml) treatment for 24 h induced apoptosis in 60% of cells. Schrodinger Maestro tools such as QikProp and DFT were used to confirm that BECA is an eligible drug-like molecule, with suitable physiochemical properties. Glide XP tool was used to perform induced-fit docking between BECA and 30 cancer drug target proteins. The highest significance was observed for VEGFR2 protein (-6.7 kcal/mol). GROMACS tool was used to perform molecular dynamic simulation between BECA and VEGFR2 protein for 40 ns. Root mean square deviation, root mean square fluctuation, H-bond, and trajectory analysis, confirmed that BECA is a suitable inhibitor of VEGFR2 protein. Results conclude that BECA is a valid VEGFR2 inhibitor, and it thus exerts the observed anticancer cytotoxicity against MCF-7 cells.


Asunto(s)
Antineoplásicos/química , Carbamatos/química , Streptomyces/metabolismo , Receptor 2 de Factores de Crecimiento Endotelial Vascular/química , Antineoplásicos/aislamiento & purificación , Antineoplásicos/metabolismo , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Carbamatos/aislamiento & purificación , Carbamatos/metabolismo , Carbamatos/farmacología , Humanos , Células MCF-7 , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Estructura Molecular , Receptor 2 de Factores de Crecimiento Endotelial Vascular/antagonistas & inhibidores
5.
J Chromatogr A ; 1626: 461360, 2020 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-32797839

RESUMEN

Conjugated microporous polymers (CMPs) with uniform morphology have shown fascinating application in the separation science. In this study, metal-free Knoevenagel condensation was adopted to prepare spherical sp2 carbon-conjugated microporous polymers, which used tetrakis(4-formylphenyl)methane and 1,4-phenylenediacetonitrile as monomers. Due to the remarkable extraction capability for carbamate pesticides (CPs), the as-synthesized CMPs were fabricated as the coating for solid-phase microextraction (SPME). After optimized SPME parameters (adsorption time, salt concentration, sample pH, adsorption temperature, desorption time, desorption solvent and desorption volume), ten CPs in water samples were quantified by ultrahigh performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Linearity in the range 0.005-100 ng mL-1 with low detection limits of 0.00060-0.017 ng mL-1 was obtained. The intra-day and inter-day precisions expressed as relative standard deviations were 1.5-8.1% and 1.1-8.0%, respectively. Fiber-to-fiber reproducibility was below 7.3%. The CMPs-SPME-UPLC-MS/MS method was applied to detect trace CPs in real water samples with relative recoveries from 91.8% to 108%.


Asunto(s)
Carbamatos/análisis , Microextracción en Fase Sólida/métodos , Contaminantes Químicos del Agua/análisis , Adsorción , Carbamatos/aislamiento & purificación , Cromatografía Líquida de Alta Presión , Plaguicidas/análisis , Plaguicidas/aislamiento & purificación , Polímeros/química , Porosidad , Reproducibilidad de los Resultados , Espectrometría de Masas en Tándem , Contaminantes Químicos del Agua/aislamiento & purificación
6.
Carbohydr Res ; 492: 108021, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32388218

RESUMEN

Solvent-free melts of unprotected d-ribose and urea generated mainly C1- substituted ribosyl products. The remarkable resolving power of a graphitised-carbon HPLC column allowed products of the reaction formed over a range of heating times and temperatures to be monitored. Heating an uncatalysed mixture of d-ribose and urea at temperatures between 75 °C and 90 °C resulted in complex mixtures of compounds; after 19 h heating at 90 °C, up to ten components could be resolved. At shorter heating times and lower temperatures, the composition and distribution of products varied. By manipulation of the reaction time and temperature, and with the addition of an acid catalyst, it was possible to optimise the yields of selected products. Thus, the acid-catalysed reaction after 1-2 h at 80 °C gave optimal yields of α- and ß-d-ribopyranosyl urea, whereas the uncatalysed reaction after 22 h at 75-78 °C in addition produced significant amounts of α-d-ribofuranosyl-1,2- cyclic carbamate [glyco-1,2-oxazolidin-2-one] plus the α- and ß-ribofuranosyl ureas. The five compounds were isolated and characterised, demonstrating the significant advantages of this approach; its simplicity, and the ability to produce multiple compounds of biological interest in a single step. LC/MS was used to identify tentatively several other components of the reaction mixture. The unprotected title compounds were prepared, isolated and characterised with water as the only solvent.


Asunto(s)
Carbamatos/aislamiento & purificación , Carbohidratos/química , Ribosa/aislamiento & purificación , Urea/aislamiento & purificación , Carbamatos/química , Conformación de Carbohidratos , Ribosa/química , Urea/análogos & derivados , Urea/química
7.
J Agric Food Chem ; 68(12): 3703-3710, 2020 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-32125839

RESUMEN

Application of biochar in soils can affect the soil properties and, in turn, the fate of pesticides. Batch experiments were conducted to investigate the effect of sewage sludge-derived biochars on the dissipation of a fungicide carbendazim in soil, and the transformation of carbendazim in soil was also studied. Results showed that the dissipation of carbendazim was fastest in a loamy soil SD with a half-life of 11.0 d among the three kinds of soils tested in this study. A dual effect (both acceleration and inhibition) of sewage sludge-derived biochars on carbendazim degradation in soil was reported. The addition of 10% biochars produced at 700 °C (BC 700) in soil could accelerate the carbendazim degradation, but an inhibitory effect was observed for 10% BC 300 or BC 500. Degradation of carbendazim was significantly inhibited when 0.5 or 5% BC 700 was added in soil but accelerated when the amendment ratio of BC 700 was increased to 10%. Such complex effects of the sewage sludge biochar should be taken into consideration in risk assessment of pesticides and the biochar effects on soil remediation. Eight metabolites of carbendazim were characterized, seven of which were reported in unamended soil for the first time. The metabolic pathways of carbendazim in soil are proposed.


Asunto(s)
Bencimidazoles/aislamiento & purificación , Carbamatos/aislamiento & purificación , Carbón Orgánico/química , Fungicidas Industriales/aislamiento & purificación , Aguas del Alcantarillado/química , Contaminantes del Suelo/aislamiento & purificación , Suelo/química , Restauración y Remediación Ambiental
8.
ACS Appl Mater Interfaces ; 12(14): 16216-16226, 2020 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-32149501

RESUMEN

The rapid development of electrochemical sensors holds great promise to serve as next generation point-of-care safety devices. However, the practical performances of electrochemical sensors are cruelly limited by stability, selectivity, and sensitivity. These issues have been well addressed by introducing rational designs into the modified electrode for achieving the required performances. Herein, we demonstrate the gadolinium oxide nanorods embedded on the graphene aerogel (GdO NRs/GA) for a highly selective electrochemical detection of carbendazim (CDM). The GdO NRs/GA nanocomposite was characterized using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field emission gun scanning electron microscopy, transmission electron microscopy with elemental mapping, and energy-dispersive spectrometry. The GdO NRs/GA-modified electrode shows a much improved electrochemical performance compared to other electrodes. Interestingly, the GdO NRs are strongly anchored in the GA matrix, which provides a more sufficient pathway for the rapid electron and ion transportation. On the basis of these findings, our proposed sensor achieves a wide detection range from 0.01 to 75 µM with a correlation coefficient of 0.996 and a low detection limit of 3.0 nM. Most markedly, the real-time monitoring of the proposed electrochemical sensor was proved by the successful determination of CDM in environmental samples. Our research work has opened a novel way to the rationale for the construction of highly efficient practical electrochemical sensors.


Asunto(s)
Bencimidazoles/aislamiento & purificación , Técnicas Biosensibles , Carbamatos/aislamiento & purificación , Fungicidas Industriales/aislamiento & purificación , Nanotubos/química , Bencimidazoles/efectos adversos , Carbamatos/efectos adversos , Técnicas Electroquímicas , Fungicidas Industriales/efectos adversos , Gadolinio/química , Geles/química , Grafito/química , Humanos , Límite de Detección
9.
Chem Biodivers ; 17(4): e1900717, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32069384

RESUMEN

Considering the increase in agricultural production in Brazil, the use of pesticides for this production, and that there are no studies on pesticides in the region, the presence of carbamates and thiocarbamates was investigated in different environmental compartments of the Formoso River, TO, Brazil, by UHPLC/MS/MS. The collections were made on the banks of this river, in the area of influence of the agricultural project. The active principles were not found in the soil and sediment samples, only the propoxur principle was found in the water, reaching values of up to 0.025 µg L-1 . It was found that the biodiversity of the Tocantinense savannah is under threat, because even though only one of the substances surveyed, propoxur and its derivatives, has been detected, they are substances of high toxicity and tendency to contaminate surface and groundwater to varying degrees and irreversible damage to different species.


Asunto(s)
Carbamatos/análisis , Sedimentos Geológicos/química , Ríos/química , Contaminantes del Suelo/química , Tiocarbamatos/análisis , Contaminantes Químicos del Agua/química , Brasil , Carbamatos/aislamiento & purificación , Cromatografía Líquida de Alta Presión , Plaguicidas/análisis , Plaguicidas/química , Contaminantes del Suelo/análisis , Contaminantes del Suelo/aislamiento & purificación , Extracción en Fase Sólida , Espectrometría de Masas en Tándem , Tiocarbamatos/aislamiento & purificación , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/aislamiento & purificación
10.
J Sep Sci ; 43(6): 1145-1153, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31869501

RESUMEN

Considering the importance of developing a new analytical approach for pesticide residue detection for the sake of ensuring food safety, a ß-cyclodextrin based molecularly imprinted polymer was prepared for selective determination of carbendazim. The polymers consist of a porous and hollow structure demonstrating the selective abundant adsorption sites for carbendazim molecule. The selectivity and adsorption capacity of the imprinted polymers were analyzed with dispersive solid-phase extraction and analyzed with high performance liquid chromatography coupled with ultraviolet. The results of imprinted polymers were higher than non-imprinted polymers with the maximum adsorption capacity of 3.65 mg/g within 30 min of total adsorption time. The reusability of the imprinted polymers was determined to evaluate its effectiveness and stability, which proved that the polymers lost 10% efficiency within seven consecutive recycles. The developed method displayed good linearity over the concentration range of 0.05-2.0 mg/L. The recovery percentage of 81.33-97.23 with relative standard deviations of 1.49-4.66% was obtained from spiked apple, banana, orange, and peach samples with a limit of detection of 0.03 mg/L and a limit of quantification of 0.10 mg/L (signal to noise ratio = 3/10). The overall performance of the proposed method evident that this technique provided a desirable outcome and it can be used as a convenient approach, as it qualifies the analytical standards.


Asunto(s)
Bencimidazoles/aislamiento & purificación , Carbamatos/aislamiento & purificación , Frutas/química , Fungicidas Industriales/aislamiento & purificación , Impresión Molecular , Polímeros/química , beta-Ciclodextrinas/química , Adsorción , Bencimidazoles/química , Carbamatos/química , Cromatografía Líquida de Alta Presión , Fungicidas Industriales/química , Estructura Molecular , Tamaño de la Partícula , Extracción en Fase Sólida , Propiedades de Superficie , Rayos Ultravioleta
11.
J Chromatogr Sci ; 58(2): 109-116, 2020 Jan 23.
Artículo en Inglés | MEDLINE | ID: mdl-31711217

RESUMEN

A multiresidue method for determining 12 carbamate pesticides in purple cabbage, orange, watermelon, cucumber, cowpea and Lactuca sativa L. employing multi-plug filtration cleanup (m-PFC) and ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) was developed. M-PFC was carried out by cleanup at dispersive solid phase extraction (d-SPE), one m-PFC tip-filtration, two m-PFC tip-filtration and other methods (1-3 m-PFC cleanups). Results demonstrated that filtration simplified the cleanup method compared with d-SPE and other m-PFC methods (1-3 m-PFC cleanups). The method validation results showed that the method was linear, selective and accurate. The limits of quantification (LOQs) were 0.05-5.0 µg/kg, and the recoveries were in the range of 70.1-119.9% in different matrices. Although matrix effects were observed, they were successfully compensated using matrix-matched calibration. Finally, the developed method was successfully applied to detect pesticides in real samples.


Asunto(s)
Carbamatos/química , Cromatografía Líquida de Alta Presión/métodos , Frutas/química , Insecticidas/química , Residuos de Plaguicidas/química , Espectrometría de Masas en Tándem/métodos , Verduras/química , Carbamatos/aislamiento & purificación , Filtración , Contaminación de Alimentos/análisis , Insecticidas/aislamiento & purificación , Residuos de Plaguicidas/aislamiento & purificación , Extracción en Fase Sólida
12.
Molecules ; 24(16)2019 Aug 12.
Artículo en Inglés | MEDLINE | ID: mdl-31408943

RESUMEN

A multi-residue method for the determination of 107 pesticide residues in wolfberry has been developed and validated. Similar pretreatment approaches were compared, and the linearity, matrix effect, analysis limits, precision, stability and accuracy were validated, which verifies the satisfactory performance of this new method. The LODs and LOQs were in the range of 0.14-1.91 µg/kg and 0.46-6.37 µg/kg, respectively. The recovery of analytes at three fortification levels (10 µg/kg, 50 µg/kg, 100 µg/kg) ranged from 63.3-123.0%, 72.0-118.6% and 67.0-118.3%, respectively, with relative standard deviations (RSDs) below 15.0%. The proposed method was applied to the analysis of fifty wolfberry samples collected from supermarkets, pharmacies and farmers' markets in different cities of Shandong Province. One hundred percent of the samples analyzed included at least one pesticide, and a total of 26 pesticide residues was detected in fifty samples, which mainly were insecticides and bactericide. Several pesticides with higher detection rates were 96% for acetamiprid, 82% for imidacloprid, 54% for thiophanate-methyl, 50% for blasticidin-S, 42% for carbendazim, 42% for tebuconazole and 36% for difenoconazole in wolfberry samples. This study proved the adaptability of the developed method to the detection of multiple pesticide residues in wolfberry and provided basis for the research on the risks to wolfberry health.


Asunto(s)
Extracción Líquido-Líquido/métodos , Lycium/química , Residuos de Plaguicidas/aislamiento & purificación , Bencimidazoles/aislamiento & purificación , Carbamatos/aislamiento & purificación , Cromatografía Líquida de Alta Presión/métodos , Humanos , Neonicotinoides/aislamiento & purificación , Nitrocompuestos/aislamiento & purificación , Nucleósidos/aislamiento & purificación , Residuos de Plaguicidas/clasificación , Espectrometría de Masas en Tándem/métodos , Tiofanato/aislamiento & purificación , Triazoles/aislamiento & purificación
13.
J Chromatogr A ; 1602: 178-187, 2019 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-31301797

RESUMEN

A magnetic porous covalent triazine-based organic polymer (M-PCTP) was synthesized by co-precipitation method. The M-PCTP combined both the properties of the PCTP and the magnetism of Fe3O4 nanoparticles, possessing highly porous structure and good magnetism. It was used as a magnetic solid phase extraction (MSPE) adsorbent to extract carbamate pesticides (propoxur, carbaryl, isoprocarb, fenobcarb and diethofencarb) from lemonade and grape juice samples prior to high performance liquid chromatography-mass spectrometric detection. Under the optimal conditions, a good linearity for the real samples was received in the range from 0.10-0.90 to 80.00 ng mL-1 with the correlation coefficients of 0.9882-0.9983. The method recoveries for the five carbamates were 86.3-108.0%. The limits of detection were 0.02-0.20 ng mL-1 for lemonade sample, and 0.04-0.30 ng mL-1 for grape juice sample. The M-PCTP also demonstrated good extraction capabilities for other different kinds of organic compounds including chlorophenols and polycyclic aromatic hydrocarbons.


Asunto(s)
Carbamatos/aislamiento & purificación , Cromatografía Líquida de Alta Presión , Análisis de los Alimentos/métodos , Espectrometría de Masas , Plaguicidas/análisis , Extracción en Fase Sólida , Jugos de Frutas y Vegetales/análisis , Magnetismo , Hidrocarburos Policíclicos Aromáticos/análisis , Polímeros/química , Porosidad
14.
J Chromatogr A ; 1596: 69-78, 2019 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-30837161

RESUMEN

Amino acids play an important role in cellular processes and are building blocks for peptides and proteins, which take part in regulatory processes within each organism. Hence a large variety of biotechnologically or synthetically produced therapeutic drugs are peptides and proteins. Due to the chiral nature of amino acids and the large variety of common, uncommon and newly synthesized amino acid type compounds, stereoselective separation tools combined with mass spectrometric detection are important in research as well as purity control of therapeutics in industry. Since structural isomers and epimers of common amino acids are isobaric to each other, stereoselective separation is key to their identification. For this purpose zwitterionic quinine and quinidine type chiral stationary phases Chiralpak ZWIX(+) and Chiralpak ZWIX(-) were investigated for their separation performance for underivatized and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC; AccQ) derivatized proteinogenic amino acids, uncommon amino acids and their isobaric analogs such as allo-threonine, homoserine, allo-isoleucine and homocysteine by HPLC-ESI-QTOF-MS. Cystine and homocystine were reduced with dithiothreitol and S-alkylated with iodoacetic acid and iodoacetamide. In general, derivatization with AQC and thiol alkylation increased the detection sensitivity and resolution of acidic, basic and polar amino acids significantly (e.g. separation factor of Asp increased from 1.00 to 2.29 for Asp-AQC). In addition, throughout this study a u-13C15N-L-amino acid metabolomics mixture was added to the DL-amino acid test solution and used as a co-eluting peak assignment standard to identify the corresponding u-12C14N-L-amino acid peak and hence determine the elution order of the enantiomer pairs for complex mixtures within a single run, employing the same separation conditions for underivatized and AQC-derivatized amino acids and their isobaric analogs.


Asunto(s)
Aminoácidos/aislamiento & purificación , Aminoquinolinas/química , Carbamatos/química , Técnicas de Química Analítica/métodos , Cromatografía Líquida de Alta Presión , Quinidina/química , Quinina/química , Espectrometría de Masas en Tándem , Aminoácidos/química , Aminoquinolinas/aislamiento & purificación , Carbamatos/aislamiento & purificación , Técnicas de Química Analítica/instrumentación , Cinchona/química , Estereoisomerismo
15.
Analyst ; 144(9): 2872-2880, 2019 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-30830135

RESUMEN

Modern process research and development can often be hampered by the tedious method development required to chromatographically resolve mixtures of chemical species with very similar physical properties. Herein, we describe a simple approach for the development and implementation of an efficient ultra-high performance liquid chromatography (UHPLC) assay that is extensively applied to the separation and analysis of multicomponent reaction mixtures of closely related pharmaceutical intermediates and impurities. Methods are optimized using multi-column and multi-solvent UHPLC screening in conjunction with chromatography simulation software (ACD Labs/LC Simulator). This approach is implemented to enable the separation, identification, mapping and control of impurities formed within the process chemistry optimization of the dimeric catalyst used in the synthesis of new drug substances. The final method utilized a sub-2 µm C18 stationary phase (2.1 mm I.D. × 50 mm length, 1.7 µm particle size ACQUITY UPLC BEH C18) with a non-conventional chaotropic mobile phase buffer (35 mM potassium hexafluorophosphate in 0.1% phosphoric acid/acetonitrile) in order to achieve baseline separation of all reaction components. The chromatographic simulation and modeling strategy served to generate 3D resolution maps with robust separation conditions that match the outcome of subsequent experimental data (overall ΔtR < 0.35%). Our multi-column UHPLC screening with computer-assisted chromatographic modeling is a great addition to the toolbox of synthetic chemists and can be a powerful tool for streamlining process chemistry optimization in organic chemistry laboratories across both academic and industrial sectors.


Asunto(s)
Carbamatos/aislamiento & purificación , Cromatografía Líquida de Alta Presión/métodos , Compuestos Heterocíclicos con 2 Anillos/aislamiento & purificación , Cromatografía Líquida de Alta Presión/instrumentación , Simulación por Computador
16.
J Environ Sci Health B ; 54(4): 226-236, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30633640

RESUMEN

Spent coffee grounds (SCG) have been used for the production of activated carbon (AC) by impregnation with different ratios of phosphoric acid at 600 °C, Xp (H3PO4/coffee): 3:130%, 4:130%, 3:150% and 4:150%. The obtained AC was characterized by BET, FTIR and SEM. BET surface area corresponds to 803.422 m2 g-1. The influences of the main parameters such as contact time, the pesticides initial concentration, adsorbent dose, pH and temperature on the efficiency of separation process were investigated during the batch operational mode. Results were modeled by adsorption isotherms: Langmuir, Freundlich and Temkin isotherms, which gave satisfactory correlation coefficients. The maximum adsorption capacities calculated from the Langmuir isotherms were 11.918 mg g-1 for carbendazim and 5.834 mg g-1 for linuron at room temperature. Adsorption kinetics of carbendazim and linuron have been studied by the pseudo-first-order, the pseudo-second-order and the intraparticle diffusion model. The results of adsorption kinetics have been fitted the best by pseudo-second-order model. The resulted data from FTIR characterization pointed to the presence of many functional groups on the AC surface. SCG adsorbent, as an eco-friendly and low-cost material, showed high potential for the removal of carbendazim and linuron from aqueous solutions.


Asunto(s)
Bencimidazoles/aislamiento & purificación , Carbamatos/aislamiento & purificación , Carbón Orgánico/química , Café/química , Linurona/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Bencimidazoles/química , Carbamatos/química , Cinética , Linurona/química , Ácidos Fosfóricos/química , Soluciones/química , Espectroscopía Infrarroja por Transformada de Fourier , Temperatura , Termodinámica , Agua/química , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación
17.
Nat Prod Res ; 33(5): 695-700, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-29212359

RESUMEN

One new and three known compounds were isolated from the ethanol extract of Psychotria prainii aerial parts. By means of spectroscopic methods, their structures were elucidated to be deacetylasperulosidic acid 6-ethyl ether (1), asperulosidic acid (2), asperuloside (3) and obtucarbamates C (4). The isolated compounds were evaluated for their inhibitory effect on NO production in LPS-stimulated RAW264.7 cells. Among them, compounds 2 and 4 exhibited strong effect with the IC50 values of 5.75 ± 0.85 and 6.92 ± 0.43 µM, respectively. This is the first report for the chemical composition and biological activity of P. prainii.


Asunto(s)
Antiinflamatorios/farmacología , Carbamatos/farmacología , Glicósidos/farmacología , Psychotria/química , Animales , Antiinflamatorios/aislamiento & purificación , Carbamatos/aislamiento & purificación , Monoterpenos Ciclopentánicos , Glucósidos , Glicósidos/aislamiento & purificación , Ratones , Estructura Molecular , Fitoquímicos/aislamiento & purificación , Fitoquímicos/farmacología , Componentes Aéreos de las Plantas/química , Extractos Vegetales/química , Piranos , Células RAW 264.7 , Vietnam
18.
Anal Chim Acta ; 1045: 117-122, 2019 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-30454566

RESUMEN

In this work, a novel molecularly imprinted stir-bar was developed for the stir-bar sorptive extraction (SBSE) of thiabendazole (TBZ) and carbendazim (CBZ) from orange samples. Magnetic nanoparticles were surface modified with oleic acid and then encapsulated by a silica shell using a conventional sol-gel procedure. Subsequently, nanoparticles were functionalized with methacrylate functionalities by grafting onto the particles surface. Finally, the modified magnetic nanoparticles were entrapped in a polymer monolith synthetized by copolymerization with the imprinting polymerization mixture using a glass vial insert as a mold. Variables affecting the polymerization and rebinding conditions of target analytes were optimized. The uptake capacity for the template (TBZ) was evaluated as well as the cross-reactivity for the related compound CBZ by rebinding experiments. Finally, the proposed magnetic imprinted monolith was applied to the SBSE of TBZ and CBZ from orange sample extracts providing a remarkable clean-up ability. The calculated detection limit were 0.13 and 0.10 mg kg-1 for CBZ and TBZ respectively, low enough to satisfactory analysis of both compounds in orange samples according to current European Union regulations.


Asunto(s)
Bencimidazoles/aislamiento & purificación , Carbamatos/aislamiento & purificación , Citrus sinensis/química , Nanopartículas de Magnetita/química , Impresión Molecular , Polímeros/química , Tiabendazol/aislamiento & purificación , Adsorción , Bencimidazoles/química , Carbamatos/química , Polímeros/síntesis química , Tiabendazol/química
19.
Anal Bioanal Chem ; 410(27): 7185-7193, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30167743

RESUMEN

A hierarchically porous structured composite monolith sorbent of polypyrrole-coated graphene oxide and octadecyl silica incorporated in chitosan cryogel (PPY/GOx/C18/chitosan) was synthesized and used as solid-phase extraction sorbent for the determination of carbamate pesticides. Various factors affecting the characteristics of the adsorbents (chemistry of the sorbent, polymerization time, concentrations of graphene oxide and octadecyl silica) and the extraction efficiency using the prepared sorbents, such as sample loading, desorption conditions, sample volume, sample flow rate, sample pH, and ionic strength, were investigated and optimized. Under the optimal conditions of sorbent preparation and extraction, the developed composite monolith sorbent provided wide linear responses from 1.0 to 500 µg L-1 for carbofuran and diethofencarb, from 0.5 to 500 µg L-1 for carbaryl, and from 2.0 to 500 µg L-1 for isoprocarb. The limits of detection using HPLC-UV at 203, 220, and 208 nm were in the range of 0.5-2.0 µg L-1. When the composite monolith sorbent was applied for the pre-concentration and determination of carbamate in fruit juices, good recoveries (84.1-99.5%) were achieved. The developed sorbents were porous and exhibited low back pressure enabling their use at high flow rates during sample loading. Extraction and clean-up were highly efficient, and the good physical and chemical stability of the sorbent enables reuse up to 13 times. Graphical abstract ᅟ.


Asunto(s)
Carbamatos/aislamiento & purificación , Quitosano/química , Criogeles/química , Jugos de Frutas y Vegetales/análisis , Grafito/química , Plaguicidas/aislamiento & purificación , Polímeros/química , Pirroles/química , Adsorción , Carbamatos/análisis , Cromatografía Líquida de Alta Presión/métodos , Análisis de los Alimentos/métodos , Límite de Detección , Plaguicidas/análisis , Porosidad , Reproducibilidad de los Resultados , Extracción en Fase Sólida/métodos
20.
Antiviral Res ; 157: 140-150, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-30031760

RESUMEN

Infection with Junín virus (JUNV) is currently being effectively managed in the endemic region using a combination of targeted vaccination and plasma therapy. However, the long-term sustainability of plasma therapy is unclear and similar resources are not available for other New World arenaviruses. As a result, there has been renewed interest regarding the potential of drug-based therapies. To facilitate work on this issue, we present the establishment and subsequent optimization of a JUNV minigenome system to a degree suitable for high-throughput miniaturization, thereby providing a screening platform focused solely on factors affecting RNA synthesis. Using this tool, we conducted a limited drug library screen and identified AVN-944, a non-competitive inosine monophosphate dehydrogenase (IMPDH) inhibitor, as an inhibitor of arenavirus RNA synthesis. We further developed a transcription and replication competent virus-like particle (trVLP) system based on these minigenomes and used it to screen siRNAs against IMPDH, verifying its role in supporting arenavirus RNA synthesis. The antiviral effect of AVN-944, as well as siRNA inhibition, on JUNV RNA synthesis supports that, despite playing only a minor role in the activity of ribavirin, exclusive IMPDH inhibitors may indeed have significant therapeutic potential for use against New World arenaviruses. Finally, we confirmed that AVN-944 is also active against arenavirus infection in cell culture, supporting the suitability of arenavirus lifecycle modelling systems as tools for the screening and identification, as well as the mechanistic characterization, of novel antiviral compounds.


Asunto(s)
Antivirales/aislamiento & purificación , Carbamatos/aislamiento & purificación , Inhibidores Enzimáticos/aislamiento & purificación , IMP Deshidrogenasa/metabolismo , Virus Junin/efectos de los fármacos , Virus Junin/crecimiento & desarrollo , Compuestos de Fenilurea/aislamiento & purificación , Animales , Antivirales/farmacología , Carbamatos/farmacología , Línea Celular , Evaluación Preclínica de Medicamentos/métodos , Inhibidores Enzimáticos/farmacología , Humanos , IMP Deshidrogenasa/antagonistas & inhibidores , Virus Junin/genética , Compuestos de Fenilurea/farmacología , Genética Inversa/métodos , Transcripción Genética/efectos de los fármacos , Cultivo de Virus , Replicación Viral/efectos de los fármacos
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...