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1.
Plant Mol Biol ; 104(3): 327-337, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32761540

RESUMO

KEY MESSAGE: Psoralen synthase and angelicin synthase responsible for the formation of psoralen and angelicin in Peucedanum praeruptorum Dunn were identified and functionally characterized, respectively. Furanocoumarins were reported to possess several activities such as anticancer, anti-inflammatory and neuroprotective, and function as phytotoxin and allelochemical in plants. Furanocoumarins are the main bioactive ingredient in P. praeruptorum which is a commonly used traditional Chinese medicine. Phenylalanine ammonia lyase (PAL), 4-coumarate: CoA ligase (4CL), p-coumaroyl CoA 2'-hyfroxylase (C2'H) were cloned previously to elucidate the biosynthetic mechanism of coumarin lactone ring. However, the genes involved in complex coumarins in P. praeruptorum have not been explored. Herein, putative psoralen synthase CYP71AJ49 and angelicin synthase CYP71AJ51 were cloned from P. praeruptorum. In vivo and in vitro yeast assays were conducted to confirm their activities. Furthermore, the results of High Performance Liquid Chromatography-Electrospray Ionization Mass Spectrometry (HPLC-ESI-MS) verified that CYP71AJ49 catalyzed the conversion of marmesin to psoralen, and CYP71AJ51 catalyzed columbianetin to angelicin. Subsequently, the expression profile showed that CYP71AJ49 and CYP71AJ51 were easily affected by environmental conditions, especially UV and temperature. The genes tissue-specific expression and compounds tissue-specific distribution pattern indicated the existence of substance transport in P. praeruptorum. Phylogenetic analysis was conducted with 27 CYP71AJs, CYP71AJ49 and CYP71AJ51 were classified in I-4 and I-2, respectively. These results provide further insight to understand the biosynthetic mechanism of complex coumarins.


Assuntos
Apiaceae/enzimologia , Apiaceae/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Furocumarinas/metabolismo , Proteínas de Plantas/metabolismo , Apiaceae/genética , China , Cromatografia Líquida de Alta Pressão/métodos , Coenzima A Ligases/genética , Cumarínicos/metabolismo , Sistema Enzimático do Citocromo P-450/química , Sistema Enzimático do Citocromo P-450/genética , Furocumarinas/química , Furocumarinas/genética , Regulação da Expressão Gênica de Plantas , Cinética , Medicina Tradicional Chinesa , Fenilalanina Amônia-Liase/genética , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/isolamento & purificação , Espectrometria de Massas por Ionização por Electrospray/métodos , Transcriptoma
2.
PLoS One ; 15(8): e0227528, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32841235

RESUMO

The morphology and physiology of diaspores play crucial roles in determining the fate of seeds in unpredictable habitats. In some genera of the Brassicaceae different types of diaspores can be found. Lepidium appelianum produces non-dormant seeds within indehiscent fruits while in L. campestre dormant seeds are released from dehiscent fruits. We investigated whether the allocation of relevant defence compounds into different tissues in different Lepidium species may be related to the diverse dispersal strategy (indehiscent and dehiscent) and seed physiology (non-dormant and dormant). Total glucosinolate concentration and composition were analysed in immature and mature seeds and pericarps of L. appelianum and L. campestre using high-performance liquid chromatography. Moreover, for comparison, transgenic RNAi L. campestre lines were used that produce indehiscent fruits due to silencing of LcINDEHISCENCE, the INDEHISCENCE ortholog of L. campestre. Total glucosinolate concentrations were lower in immature compared to mature seeds in all studied Lepidium species and transgenic lines. In contrast, indehiscent fruits of L. appelianum maintained their total glucosinolate concentration in mature pericarps compared to immature ones, while in dehiscent L. campestre and in indehiscent RNAi-LcIND L. campestre a significant decrease in total glucosinolate concentrations from immature to mature pericarps could be detected. Indole glucosinolates were detected in lower abundance than the other glucosinolate classes (aliphatic and aromatic). Relatively high concentrations of 4-methoxyindol-3-ylmethyl glucosinolate were found in mature seeds of L. appelianum compared to other tissues, while no indole glucosinolates were detected in mature diaspores of L. campestre. The diaspores of the latter species may rather depend on aliphatic and aromatic glucosinolates for long-term protection. The allocation patterns of glucosinolates correlate with the morpho-physiologically distinct fruits of L. appelianum and L. campestre and may be explained by the distinct dispersal strategies and the dormancy status of both species.


Assuntos
Glucosinolatos/metabolismo , Lepidium/fisiologia , Sementes/metabolismo , Brassicaceae/fisiologia , Cromatografia Líquida de Alta Pressão/métodos , Ecossistema , Frutas/metabolismo , Frutas/fisiologia , Germinação/fisiologia , Lepidium/crescimento & desenvolvimento , Dormência de Plantas , Sementes/fisiologia , Água
3.
J Chromatogr A ; 1626: 461279, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797811

RESUMO

We report on a comparative study of the basic separation kinetics of commercial packed bed columns and a micro-pillar array column (µPAC) working in the 1-10µL/min flow rate range, i.e., operating in the area of capillary flow LC. This is done using a basic test mixture of 8 alkylphenones under both isocratic and gradient separation conditions. Care was taken the µPAC and the packed bed columns have similar volumes (around 10µL) and hence also similar t0-times when compared at the same flow rate. In addition, the isocratic mobile phase composition and gradient programs were selected such to have similar elution windows (in absolute times) for all 4 column types. It was found that the µPAC produces significantly more theoretical plates (up to 3 times) in the 1-4µL/min range, while, the packed bed columns perform better at the higher flow rates because of the relatively large inter-pillar distance in the µPAC. Under gradient conditions, the µPAC produces a clearly higher peak capacity than any of the three packed bed columns over the entire range of investigated flow rates, albeit that this is also partly to be owed to the steeper gradient that needed to be used in the µPAC in order to maintain a similar elution window on all columns.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cinética , Pressão
4.
J Chromatogr A ; 1626: 461319, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797815

RESUMO

The aim of this study is to model, describe and predict the mass transfer of IgG as a function of the agarose concentration in the protein A stationary phase, taking into account the influence of adsorption on the pore size. Therefore, particle size distribution, bed and bead porosities were examined by light microscopy, pressure-flow behavior and iSEC. Three agarose protein A stationary phases (2 wt%, 4 wt%, 6 wt%) were investigated. The pore size decreased from 116 nm for 2 wt% to 54 nm for 6 wt% and the porosity for the target molecule IgG was reduced by 25%. A shrinking core model approach was used to assess the influence of IgG adsorption on the pore size of the stationary phase and the diffusivity of IgG. Due to IgG adsorption, the pore diameter reduced by 24 nm, which is approximately two times its hydrodynamic diameter. Effective pore diffusivities of IgG were obtained by fitting the general rate model to breakthrough curves. They were in the range between 3.96·10-12m2/s and 6.5·10-12m2/s, decreasing as the agarose concentration increased. The DBC1% has a maximum for the 4 wt% agarose gel, showing optimal tradeoffs between accessibility, specific surface and diffusive mass transfer for IgG. A simple geometrical model was developed to describe the change in pore and filament diameters due to adsorption. The diffusion measured in protein A agarose beads can be described by a modification of the Ogston model. This enables the diffusion measured in protein A agarose networks to be predicted.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Sefarose/química , Adsorção , Cromatografia em Gel , Difusão , Imunoglobulina G/metabolismo , Tamanho da Partícula , Porosidade , Ligação Proteica , Proteína Estafilocócica A/metabolismo
5.
J Chromatogr A ; 1626: 461366, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797845

RESUMO

An alternative method for efficient synthesis of urea-functionalized silanes was proposed on the basis of an N, N'-carbonyldiimidazole-mediated acyl-transfer reaction between various amino-containing building blocks. The employment of different parent aminosilanes and alkylamines afforded an array of urea-containing silanes, which were subsequently immobilized onto silica gel to form corresponding urea-embedded alkyl stationary phases for high-performance liquid chromatography. The different substituents on the silicon core of the derivatized silane were found to significantly influence the final chromatographic behaviors. The comparative chromatographic characterization of thus-prepared silica packings with conventional octadecyl (C18) stationary phases revealed that the urea group was beneficial to suppress silanol activity towards basic probes, as well as to increase the water-compatibility of the alkyl stationary phases. The combination of a polar urea moiety and a non-polar long alkyl chain was favorable for an enhanced steric selectivity towards shape-constrained isomers. The polarizability-sensitive feature of such stationary phases made them good candidates for efficient separation of nitro-containing polar substances.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Silanos/química , Ureia/química , Isomerismo , Silanos/síntese química , Sílica Gel/química , Dióxido de Silício/química
6.
J Chromatogr A ; 1626: 461266, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797862

RESUMO

The search for biomarkers allowing the assessment of disease by early diagnosis is facilitated by liquid chromatography. However, it is not clear how many components are lost due to being present in concentrations below the detection limit and/or being obscured by chromatographic peak overlap. First, we extend the study of missing components undertaken by Enke and Nagels, who employed the log-normal probability density function (pdf) for the distribution of signal intensities (and concentrations) of three mixtures. The Weibull and exponential pdfs, which have a higher probability of small-concentration components than the log-normal pdf, are also investigated. Results show that assessments of the loss of low-intensity signals by curve fitting are ambiguous. Next, we simulate synthetic chromatograms to compare the loss of peaks from superposition (overlap) with neighboring peaks to the loss arising from lying below the limit of detection (LOD) imposed by a finite signal-to-noise ratio (SNR). The simulations are made using amplitude pdfs based on the Enke-Nagels data as functions of relative column efficiency, i.e., saturation, and SNR. Results show that at the highest efficiencies, the lowest-amplitude peaks are lost below the LOD. However, at small and medium efficiencies, peak overlap is the dominant loss mechanism, suggesting that low-level components will not be found easily in liquid chromatography with single channel detectors regardless of SNR. A simple treatment shows that a multichannel detector, e.g., a mass spectrometer, is necessary to expose more low-level components.


Assuntos
Biomarcadores/análise , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Razão Sinal-Ruído
7.
J Chromatogr A ; 1627: 461394, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823099

RESUMO

The early identification of unstable glass objects in museum collections is essential for their conservation, but as yet cannot be accomplished straightforwardly. Accordingly, this paper describes the development and validation of a simple protocol for quantitative determination of ions characteristic of the chemical decay of historic glass, using surface swabbing combined with ion-exchange chromatography. The establishment of a robust protocol is an important step in the development of an early warning system for the chemical deterioration of unstable glass. Using a model system, the protocol was validated for specificity, linearity, accuracy, precision, limits of detection, and limits of quantification for 10 anionic species (fluoride, acetate, formate, chloride, nitrite, bromide, nitrate, carbonate, sulfate and phosphate) and 6 cationic species (lithium, sodium, ammonium, potassium, magnesium and calcium). Good validation parameters (R2 > 0.995; RSD < 5%; Recovery 90-100%) were obtained for acetate, formate, nitrite, nitrate, phosphate, lithium, sodium, potassium, magnesium and calcium. Chloride (R2 = 0.934; RSD = 13.6%; recovery 71.4%) and carbonate (R2 = 0.993; RSD = 10.3%; recovery 120%) had poor validation parameters. Sulfate had low recovery (78.2%), but high reproducibility (RSD = 4.32%) with R2 = 0.997. Limits of quantification were below 1 mg/L for all analytes, which is satisfactory for the study of unstable glass in museum collections. The validated sampling protocol was trialled using artificially aged unstable glass fragments, which resulted in a high relative standard deviation (between 1 and 30%). The ability to achieve improved care of historic glass by application of the validated protocol in museum collections is discussed in the context of a pilot study undertaken at the Rijksmuseum, Amsterdam.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Vidro/química , Íons/análise , Cloretos/análise , Cromatografia por Troca Iônica , Fluoretos/análise , Íons/química , Limite de Detecção , Metais/análise , Metais/química , Museus , Nitratos/análise , Reprodutibilidade dos Testes , Propriedades de Superfície
8.
J Chromatogr A ; 1627: 461395, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823100

RESUMO

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


Assuntos
Líquidos Iônicos/química , Estruturas Metalorgânicas/química , Preparações Farmacêuticas/isolamento & purificação , Extração em Fase Sólida/métodos , Antagonistas Adrenérgicos beta/análise , Antagonistas Adrenérgicos beta/isolamento & purificação , Atenolol/análise , Atenolol/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Cobre/química , Metoprolol/análise , Metoprolol/isolamento & purificação , Preparações Farmacêuticas/análise , Propranolol/análise , Propranolol/isolamento & purificação , Solventes/química , Estereoisomerismo
9.
J Chromatogr A ; 1627: 461399, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823104

RESUMO

Citrinin is a toxic small organic molecule produced as a secondary metabolite by fungi types Penicillium, Monascus and Aspergillus and is known to contaminate various food commodities during postharvest stages of food production. During the last 10 years, most reported methods for citrinin analysis employed enzyme-linked immunosorbent assays or high-performance liquid chromatography. Over this same time period, liquid extraction, solid-phase extraction, dispersive liquid-liquid microextraction and QuEChERS were the most cited sample preparation and clean-up methods. In this review the advantages and disadvantages of the various sample preparation, separation and detection methods for citrinin analysis over the last decade are evaluated. Furthermore, current trends, emerging technologies and the future prospects of these methods are discussed.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Citrinina/análise , Espectrometria de Massas em Tandem/métodos , Aspergillus/metabolismo , Citrinina/isolamento & purificação , Citrinina/urina , Ensaio de Imunoadsorção Enzimática , Contaminação de Alimentos/análise , Humanos , Microextração em Fase Líquida , Monascus/metabolismo , Extração em Fase Sólida
10.
J Chromatogr A ; 1627: 461402, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823107

RESUMO

Surfactants are used in various applications: cosmetics, pharmaceuticals, petrochemicals, environmental, etc. Many of these compounds are polydisperse, and because of this intrinsic polydispersity, it is essential to have a universal detector with a uniform response to quantify them in a simple way. Indeed, Charged Aerosol Detector (CAD) was presented as a universal detector with a uniform response. Thus, in the present study, the CAD response, in a High-Performance Liquid Chromatography - CAD configuration (HPLCCAD), was evaluated using purified alcohol ethoxylated surfactants. A semi-preparative liquid chromatography step using a Hydrophilic interaction chromatography (HILIC) bare silica column (150 mm, 4.6 mm, 2.6 µm) was implemented to prepare eleven homologues of BrijC10, a nonionic surfactant. These homologues differed only by the number of ethylene oxide units. BrijC10 homologues were analyzed by HPLCCAD, using a HILIC bare silica column (150 mm, 2.1 mm, 2.6 µm) to determine the HPLCCAD response factors of purified homologues. From the calibration curves (from 100 to 500 mg.kg-1), their response factors were estimated: differences in response factors were observed and a maximum difference in response factors of 3.6 was obtained. Thus, it could be concluded that CAD hyphenated to HILIC separation did not present a uniform response for this homologue's distribution.


Assuntos
Aerossóis/química , Cromatografia Líquida de Alta Pressão/métodos , Calibragem , Cromatografia Líquida de Alta Pressão/normas , Etil-Éteres/química , Interações Hidrofóbicas e Hidrofílicas , Dióxido de Silício/química , Tensoativos/química
11.
J Chromatogr A ; 1626: 461328, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797818

RESUMO

Ferric oxide/carbon (Fe2O3@C) was fabricated via direct carbonization of metal-organic framework of iron (MOF-235) under argon atmosphere. The magnetic Fe2O3 nanoparticles are evenly embedded in porous carbon matrix, while original morphology of MOF-235 was well-maintained. The synthesized Fe2O3@C was used as magnetic sorbent for extracting five benzoylurea insecticides (BUs). The materials exhibited excellent extraction performance, which benefited not only from the strong π-π interaction and hydrophobic interaction (π-conjugated system), but also to the abundant adsorption sites and flexible transport channel (the interconnected 3D porous structure). A three-factor-three-level Box-Behnken design (BBD) was selected to optimize three greatly influential parameters: amount of adsorbent (A), desorption time (B) and volume of desorption solvent (C) by response surface methodology. The established method coupled to HPLC-UV detection showed wide linearity with the range of 0.2-450 µg•L-1, relatively low limits of detection (0.05-0.10 µg•L-1) with the relative standard deviation (RSD) (n = 7) lower t than 5.47%. Moreover, the proposed method was successfully applied to analyze BUs in tea samples and investigate the removal effect of different washing on BUs residues from tea leaf. These results indicated that the synthesized Fe2O3@C is a promising adsorbent material for magnetic solid phase extraction of BUs at trace concentrations from tea samples.


Assuntos
Inseticidas/análise , Nanopartículas de Magnetita/química , Estruturas Metalorgânicas/química , Chá/química , Ureia/análise , Adsorção , Carbono/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida de Alta Pressão/normas , Compostos Férricos/química , Inseticidas/isolamento & purificação , Inseticidas/normas , Limite de Detecção , Porosidade , Padrões de Referência , Extração em Fase Sólida , Espectrofotometria Ultravioleta , Chá/metabolismo , Ureia/análogos & derivados , Ureia/isolamento & purificação , Ureia/normas
12.
J Chromatogr A ; 1626: 461341, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797822

RESUMO

The recognition and separation of polar chiral compounds are important technological challenges in separation science. Taking full advantage of the intrinsically chiral environment and multiple interactions featured by macrocycles, we designed the first example of porous methylated cyclodextrins-containing polymers (MP-CDPs) with three-dimensional (3D) chiral channels. The enantioselective recognition of (R)/(S)-1-phenylethylamine mixtures was realized with enantiomer excess (e.e.) >73% in only 3 min by using MP-CDPs as the adsorbent. The obtained MP-CDPs also serve as highly efficient liquid chromatographic stationary phases for separation of polar chiral compounds. The stationary phase can separate racemic alcohols and acids successfully. These chiral compounds can be separated within 8 min under normal-phase mode, and the resolution (RS) range from 1.76 to 3.00. Molecular simulations suggest that chiral recognition is a cooperative interaction based on multiple effects such as host-guest interaction, H-bond and size selection. These findings will provide novel chiral stationary phases for recognition and separation of polar chiral compounds in the fields of separation science and pharmaceutical industry.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Polímeros/química , beta-Ciclodextrinas/química , Álcoois/química , Ligação de Hidrogênio , Porosidade , Estereoisomerismo
13.
J Chromatogr A ; 1626: 461346, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797826

RESUMO

A molecularly imprinted polymer was synthesized and characterized to be used as solid-phase extraction sorbent for simultaneous chlorpyrifos and diazinon and their oxon derivatives. Several imprinted polymers were prepared and evaluated in a retention study of these analytes compared with a non-printed polymer. Several parameters affecting the extraction of imprinted polymer such as washing solvent, composition and volume of the eluting solvent and sample volume, were also investigated. Under the optimum conditions, the developed method provided satisfactory limits of detection ranging between 0.07 µg L-1 to 0.12 µg L-1 and the material showed an excellent reusability (> 50 reuses). The method was applied to the extraction and preconcentration of these analytes in water samples. The average recoveries ranged from 79 ± 6 to 104 ± 3 %.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Impressão Molecular , Praguicidas/análise , Clorpirifos/análise , Clorpirifos/isolamento & purificação , Diazinon/análise , Diazinon/isolamento & purificação , Água Doce/análise , Limite de Detecção , Praguicidas/isolamento & purificação , Polímeros/química , Extração em Fase Sólida , Espectrofotometria Ultravioleta
14.
PLoS One ; 15(8): e0236297, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32780750

RESUMO

Naproxen is a widely used non-steroidal anti-inflammatory drug for the control of postoperative inflammatory signs and symptoms in dentistry. Its association with esomeprazole has been widely studied and has yielded good results for the control of acute pain, even with the delayed absorption of naproxen owing to the presence of esomeprazole. To further understand the absorption, distribution, and metabolism of this drug alone and in combination with esomeprazole, we will analyze the pharmacokinetic parameters of naproxen and its major metabolite, 6-O-desmethylnaproxen, in saliva samples. A rapid, sensitive, and selective liquid chromatography-tandem mass spectrometric method for the simultaneous determination of naproxen and 6-O-desmethylnaproxen in saliva will be developed and validated. Sequential saliva samples from six patients will be analyzed before and 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 6 8, 11, 24, 48, 72, and 96 h after the ingestion of one naproxen tablet (500 mg) and esomeprazole-associated naproxen tablets (500 + 20 mg), at two different times. After liquid-liquid extraction with ethyl acetate and HCl, the samples will be analyzed using an 8040 Triple Quadrupole Mass Spectrometer (Shimadzu, Kyoto, Japan). Separation of naproxen and its major metabolic products will be performed using a Shim-Pack XR-ODS 75Lx2.0 column and C18 pre-column (Shimadzu, Kyoto, Japan) at 40°C using a mixture of methanol and 10 mM ammonium acetate (70:30, v/v) with an injection flow of 0.3 mL/min. The total analytical run time will be 5 min. The detection and quantification of naproxen and its metabolite will be validated, which elucidate the pharmacokinetics of this drug, thereby contributing to its proper prescription for the medical and dental interventions that cause acute pain.


Assuntos
Anti-Inflamatórios não Esteroides/farmacocinética , Monitoramento de Medicamentos/métodos , Esomeprazol/farmacocinética , Naproxeno/análogos & derivados , Saliva/química , Administração Oral , Adolescente , Adulto , Anti-Inflamatórios não Esteroides/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Esomeprazol/administração & dosagem , Esomeprazol/isolamento & purificação , Feminino , Absorção Gastrointestinal , Humanos , Masculino , Metanol/química , Pessoa de Meia-Idade , Naproxeno/administração & dosagem , Naproxeno/isolamento & purificação , Naproxeno/farmacocinética , Dor Processual/tratamento farmacológico , Reprodutibilidade dos Testes , Comprimidos , Espectrometria de Massas em Tandem/métodos , Adulto Jovem
15.
J Chromatogr A ; 1626: 461358, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797837

RESUMO

In this study, the in-situ conversion of the synthesized Co-Al layered double hydroxide (Co-Al LDH) nanosheets to three dimensional hierarchical zeolitic imidazolate framework-67 (3D HZIF-67) was presented as a cost-effective, highly efficient, flexible and robust sorbent to carry out the microextraction process. In the first stage, the anodized aluminum foil was prepared electrochemically. Then, the Co-Al LDH precursor was constructed on the surface of the previously-prepared anodized Al foil applying in-situ formation approach. The procedure is followed by the conversion of the prepared Co-Al LDH film to 3D HZIF-67 film via a facile solvothermal method without adding cobalt salt. The in-situ prepared 3D HZIF-67-anodized Al was used for the thin film microextraction (TFME) of caffeine. The effective factors in TFME procedure were investigated and optimized through applying Central Composite Design (CCD). In the obtained optimal condition, the calibration curves for TFME-HPLC-UV of caffeine were linear in the range of 1-200 µg L-1 with the coefficient of determination (r2) higher than 0.9915. The limits of detection were 0.33 and 0.38 µg L-1, in water and urine matrices, respectively. Moreover, the enrichment factors (EFs) and absolute recoveries (%AR) were also calculated as 173-198 and 57.1%-65.3%, respectively. The inter-day relative standard deviations (RSDs) were evaluated as the method precision for 20 and 200 µg L-1 of spiked sample and were between 4.9-6.1%. The repeatability of the preparation step was investigated as batch-to-batch reproducibility and it was found to be 4.9%; as a result, the reproducibility of the presented film was approved. Finally, the proposed method was utilized to determine caffeine (as the model analyte) from different types of real samples including urine, coffee, beverage (Pepsi) and shampoo. The obtained recoveries (higher than 88%) confirmed the capability of the method for real sample analysis.


Assuntos
Alumínio/química , Cafeína/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Cobalto/química , Hidróxidos/química , Imidazóis/química , Raios Ultravioleta , Zeolitas/química , Adsorção , Eletrodos , Limite de Detecção , Microscopia de Força Atômica , Porosidade , Reprodutibilidade dos Testes , Solventes/química , Propriedades de Superfície
16.
J Chromatogr A ; 1626: 461427, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32739066

RESUMO

The physicochemical properties of small molecules that can be determined by retention measurements in reversed-phase liquid chromatography include solvent-based properties inferred from equilibrium processes occurring predominantly in the mobile phase and sorption properties for materials which can be used as stationary phases inferred from solute-stationary phase interactions. In addition, physicochemical properties can be estimated from correlation models based on surrogate chromatographic systems with a similar capability for intermolecular interactions to the chemical or biological system. Examples of properties determined by direct methods include molecular descriptors (solvation parameter model), acid dissociation constants, formation constants, and surface properties of solids determined by inverse liquid chromatography. Examples of properties estimated by indirect methods include hydrophobicity, lipophilicity, n-octanol-water partition constant, soil-water sorption constant, non-specific toxicity to fish and microorganisms, and permeation coefficients for the blood-brain and skin-water barriers. Since all approaches depend on an accurate measurement of chromatographic retention parameters typical operational and mechanistic problems are discussed from the perspective of data quality. Fundamentally the accuracy of direct methods is limited by stationary phase heterogeneity and indirect methods by the limited number of suitable surrogate chromatographic models.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa , Interações Hidrofóbicas e Hidrofílicas , Membranas Artificiais , Octanóis/química , Solo/química , Solventes/química , Água/química
17.
J Chromatogr A ; 1626: 461371, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797850

RESUMO

Effect of mobile phase (water-methanol) composition on the enantioseparation of dipeptides on the chiral stationary phase Chirobiotic R was investigated using Ala-Ala, Leu-Leu, Gly-Leu, and Leu-Gly as case studies. The lipophilicity of dipeptides was found to be an essential factor in the dependence of their retention on the methanol percentage, the retention factor of lipophobic dipeptides increasing monotonously and that of lipophilic dipeptides changing according to an asymmetric U-shaped trajectory as methanol concentration increases. The behavior of enantioselectivity as a function of the methanol content also depends on the lipophilicity of dipeptide. For lipophilic Leu-Leu, the dependence has a dome-like shape, and for more lipophobic dipeptides, Ala-Ala and Gly-Leu, it is an increasing function of the methanol concentration. The importance of solvation equilibria in the bulk liquid and on the surface of the stationary phase for the total retention is discussed from the thermodynamic point of view. Special consideration is given to the adsorption of the water-methanol mixture on the surface of the Chirobiotic R stationary phase.


Assuntos
Antibacterianos/química , Cromatografia Líquida de Alta Pressão/métodos , Dipeptídeos/química , Metanol/química , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Estereoisomerismo , Termodinâmica
18.
J Chromatogr A ; 1626: 461374, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797852

RESUMO

This work demonstrates the development of a compact, modular, cost-effective separation system configured to address a specific separation problem. The principles of the separation are based on gradient capillary liquid chromatography where the system consists of precision stepper motor-driven portable syringe pumps with interchangeable glass syringes (100 µL to 1000 µL). Excellent flow-rate precision of < 1% RSD was achieved with typical flow-rates ranging from 1 µL/min to 100 µL/min, which was ideal for capillary columns. A variable external loop volume and electrically actuated miniature injection valve was used for sample introduction. Detection was based upon a commercial Z-type UV absorbance flow-cell housed within a custom-built cooling enclosure (40 mm x 40 mm) which also contained a UV-LED light-source and a photodiode. System and chromatographic performance was evaluated using linear gradient elution, with day to day repeatability of <1.5% RSD (n = 6) for peak area, and < 0.4% RSD (n = 6) for retention time, for the separation of a 5 component mixture using a 50 mm X 530 µm ID C18 3 µm particle capillary column. The system can run any commercial or in-house packed columns from 50 mm to 100 mm length with IDs ranging from 200 to 700 µm. The developed portable system was operated using custom-built windows-based chromatography software, complete with data acquisition and system control.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cafeína/análise , Carbamazepina/análise , Análise Custo-Benefício , Limite de Detecção , Miniaturização , Sistemas Automatizados de Assistência Junto ao Leito , Reprodutibilidade dos Testes , Espectrofotometria Ultravioleta , Sulfametazina/análise
19.
J Chromatogr A ; 1626: 461377, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797853

RESUMO

This study reports the use ofa natural deep eutectic solvent (NADES) with hollow fiber-microporous membrane liquid-liquid microextraction (HF-MMLLE) for the multiclass determination of 11 compounds classified as emerging contaminantsin water. Different deep eutectic solvents were synthetized and Thymol: Camphor (1:1 molar fraction) wasused as extraction solvent. The Thymol:Camphor was impregnated into the polypropylene membrane porous for 10 min, replacing commonly used solvents (ex. hexane and octanol). The optimized parameters were obtained by multi and univariate models. Extractions were carried out for 50 min using 1.5 mL of water sample at pH 6 and without addition of salt while desorption was made in a mixture of acetone: methanol (3:1, v/v) for 15 min. Separation/quantification was conducted by HPLC with a diode array detection (DAD)and calibration curves were obtained for each analyte. Determination coefficients higher than 0.9906 and limits of detection ranged from 0.3 to 6.1 µg L-1. Intraday precision (n = 3) ranged from 1.6 to 18.4% and inter day from 5.0 to 21.3%. Relative recoveries were performed in tap and stream water and ranged from 64 to 123%.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Microextração em Fase Líquida/métodos , Solventes/química , Poluentes Químicos da Água/análise , Calibragem , Cromatografia Líquida de Alta Pressão/normas , Interações Hidrofóbicas e Hidrofílicas , Membranas Artificiais , Polipropilenos/química , Porosidade , Espectrofotometria , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/normas
20.
J Chromatogr A ; 1626: 461384, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797857

RESUMO

More and more various chemical media are being applied in enantioseparation; among them, ionic liquids (ILs) have attracted the long-term attention in this decade as green designable solvents. This paper provides comprehensive overview for the applications of ILs in chiral extraction, gas chromatography, liquid chromatography, capillary electrophoresis and other techniques for enantioseparation. Additionally, the important resolution mechanisms based on ILs have also been summarized and discussed. This review focuses on the latest development of enantioseparation methods by using ILs in various modes, leading to meaningful and valuable information to related fields and thus promotes further research and application of reported methods.


Assuntos
Cromatografia Gasosa/métodos , Cromatografia Líquida de Alta Pressão/métodos , Eletroforese Capilar/métodos , Líquidos Iônicos/química , Ligantes , Extração Líquido-Líquido , Extração em Fase Sólida , Estereoisomerismo
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