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1.
Molecules ; 25(10)2020 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-32429453

RESUMO

The chemical composition of the volatile fraction from Galium verum L. (leaves and flowers) and Cruciata laevipes Opiz (whole plant), Rubiaceae, was investigated. Samples from these two plant species were collected at full bloom in Val di Susa (Western Alps, Turin, Italy), distilled in a Clevenger-type apparatus, and analyzed by GC/FID and GC/MS. A total of more than 70 compounds were identified, making up 92%-98% of the total oil. Chemical investigation of their essential oils indicated a quite different composition between G. verum and C. laevipes, both in terms of the major constituents and the dominant chemical classes of the specialized metabolites. The most abundant compounds identified in the essential oils from G. verum were 2-methylbenzaldheyde (26.27%, corresponding to 11.59 µg/g of fresh plant material) in the leaves and germacrene D (27.70%; 61.63 µg/g) in the flowers. C. laevipes essential oils were instead characterized by two sesquiterpenes, namely ß-caryophyllene (19.90%; 15.68 µg/g) and trans-muurola-4(15),5-diene (7.60%; 5.99 µg/g); two phenylpropanoids, benzyl alcohol (8.30%; 6.71 µg/g), and phenylacetaldehyde (7.74%; 6.26 µg/g); and the green-leaf alcohol cis-3-hexen-1-ol (9.69%; 7.84 µg/g). The ecological significance of the presence of such compounds is discussed.


Assuntos
Flores/química , Galium/química , Folhas de Planta/química , Rubiaceae/química , Compostos Orgânicos Voláteis/isolamento & purificação , Acetaldeído/análogos & derivados , Acetaldeído/química , Acetaldeído/isolamento & purificação , Altitude , Benzaldeídos/química , Benzaldeídos/isolamento & purificação , Álcool Benzílico/química , Álcool Benzílico/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas , Hexanóis/química , Hexanóis/isolamento & purificação , Humanos , Itália , Extração Líquido-Líquido/métodos , Óleos de Plantas/química , Sesquiterpenos Policíclicos/química , Sesquiterpenos Policíclicos/isolamento & purificação , Sesquiterpenos de Germacrano/química , Sesquiterpenos de Germacrano/isolamento & purificação , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/classificação
2.
J Oleo Sci ; 63(11): 1195-201, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25354879

RESUMO

In this paper, the volatiles emitted by flowers and various parts of the flower of a rare spontaneous Italian red (peel and flesh) apple named "Pelingo", were analyzed by SPME with the aim of identifying the contribution of each one to the whole aroma profile. Linalool was the most abundant volatile of flowers: from 43.0% in the flower buds, to 17.6% in the stylus and stigma headspace. The second most represented volatile was (E,E)-α-farnesene mainly emitted by the mature flowers (32.2%). Benzenoid compounds also have been identified: benzyl-alcohol is the most representative (1.0-16.5%) in all the samples except flower buds, while benzyl acetate (5.7%) and methyl salicylate (7.7%) are mainly present in the calyx and in the mature flowers respectively but not in the flower buds. Benzenoid compounds are the attractors for pollinator, probably for this reason were not detected in the headspace of flower buds.


Assuntos
Álcool Benzílico/isolamento & purificação , Ácidos Graxos Insaturados/isolamento & purificação , Flores/química , Malus , Monoterpenos/isolamento & purificação , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/isolamento & purificação , Monoterpenos Acíclicos , Compostos de Benzil/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas , Itália , Polinização , Salicilatos/isolamento & purificação
3.
Immunopharmacol Immunotoxicol ; 36(5): 349-54, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25090632

RESUMO

On the search for anti-inflammatory compounds from natural Korean medicinal sources, a bioassay-guided fractionation and chemical investigation of the MeOH extract from the fruiting bodies of Hericium erinaceum resulted in the isolation and identification of five benzyl alcohol derivatives (1-5). In this study, their anti-inflammatory effects on lipopolysaccharide (LPS)-induced production of pro-inflammatory mediators were examined using RAW 264.7 macrophage cells. The structures of isolates were identified by comparing their spectroscopic data with previously reported values. The analysis of their inhibitory activities on LPS-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production in RAW 264.7 macrophage cells showed that erinacerin B (2) and hericenone E (4) decreased the levels of NO and PGE2 production in a concentration-dependent manner. Next, this study was performed to examine their mechanism of action on the regulation of NO and PGE2 production. Compounds 2 and 4 were found to block the LPS-induced phosphorylation of two major inflammatory transcription factors, NF-κB (p65/p50) and AP-1 (c-Jun and c-Fos). Taken together, these results suggest that down-regulation of LPS-induced NO and PGE2 production by compounds 2 and 4 is mediated through the modulation of NF-κB and AP-1 activation in macrophage cells. These results impact the development of potential health products for preventing and treating inflammatory diseases.


Assuntos
Agaricales/química , Anti-Inflamatórios/farmacologia , Álcool Benzílico/isolamento & purificação , Álcool Benzílico/farmacologia , Inflamação/induzido quimicamente , Inflamação/prevenção & controle , Lipopolissacarídeos/antagonistas & inibidores , NF-kappa B/efeitos dos fármacos , Fator de Transcrição AP-1/efeitos dos fármacos , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Dinoprostona/biossíntese , Camundongos , Óxido Nítrico/biossíntese
4.
BMC Complement Altern Med ; 12: 12, 2012 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-22380404

RESUMO

BACKGROUND: Litchi chinensis is regarded as one of the 'heating' fruits in China, which causes serious inflammation symptoms to people. METHODS: In the current study, the effects of isolates of litchi on prostaglandin E(2) (PGE(2)) and nitric oxide (NO) production in J774 murine macrophage cells were investigated. RESULTS: The AcOEt extract (EAE) of litchi was found effective on stimulating PGE(2) production, and three compounds, benzyl alcohol, hydrobenzoin and 5-hydroxymethyl-2-furfurolaldehyde (5-HMF), were isolated and identified from the EAE. Benzyl alcohol caused markedly increase in PGE(2) and NO production, compared with lipopolysaccharide (LPS) as positive control, and in a dose-dependent manner. Hydrobenzoin and 5-HMF were found in litchi for the first time, and both of them stimulated PGE(2) and NO production moderately in a dose-dependent manner. Besides, regulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) mRNA expression and NF-κB (p50) activation might be involved in mechanism of the stimulative process. CONCLUSION: The study showed, some short molecular compounds in litchi play inflammatory effects on human.


Assuntos
Dinoprostona/biossíntese , Inflamação/induzido quimicamente , Litchi/efeitos adversos , Macrófagos/efeitos dos fármacos , Óxido Nítrico/biossíntese , Extratos Vegetais/efeitos adversos , Animais , Benzoína/efeitos adversos , Benzoína/análogos & derivados , Benzoína/isolamento & purificação , Álcool Benzílico/efeitos adversos , Álcool Benzílico/isolamento & purificação , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Relação Dose-Resposta a Droga , Frutas , Furanos/efeitos adversos , Furanos/isolamento & purificação , Inflamação/metabolismo , Lipopolissacarídeos , Litchi/química , Macrófagos/metabolismo , Camundongos , NF-kappa B/metabolismo , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Extratos Vegetais/química , RNA Mensageiro/metabolismo
5.
Chem Pharm Bull (Tokyo) ; 59(4): 499-501, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21467683

RESUMO

The biological transformation of the biologically active chlorogentisyl alcohol (1), isolated from the marine-derived fungus Aspergillus sp., was studied. Preparative-scale fermentation of chlorogentisyl alcohol with marine-derived fungus Chrysosporium synchronum resulted in the isolation of a new glycosidic metabolite, 1-O-(α-D-mannopyranosyl)chlorogentisyl alcohol (2). The stereostructure of the new metabolite obtained was assigned on the basis of detailed spectroscopic data analyses, chemical reaction, and chemical synthesis. Compounds 1 and 2 exhibited significant radical-scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) with IC(50) values of 1.0 and 4.7 µM, respectively. The compounds 1 and 2 were more active than the positive control, L-ascorbic acid (IC(50), 20.0 µM).


Assuntos
Álcoois/química , Organismos Aquáticos/microbiologia , Álcool Benzílico/química , Álcoois Benzílicos/química , Chrysosporium/metabolismo , Manose/análogos & derivados , Manose/química , Álcoois/isolamento & purificação , Álcoois/farmacologia , Ácido Ascórbico/farmacologia , Álcool Benzílico/isolamento & purificação , Álcool Benzílico/farmacologia , Álcoois Benzílicos/farmacologia , Chrysosporium/química , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/metabolismo , Sequestradores de Radicais Livres/farmacologia , Manose/isolamento & purificação , Manose/farmacologia , Estereoisomerismo
6.
Biotechnol Bioeng ; 107(4): 633-41, 2010 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-20552670

RESUMO

The biotransformation of benzaldehyde and glucose to L-phenylacetylcarbinol (PAC) using Candida utilis was demonstrated in a solid-liquid two-phase partitioning bioreactor (TPPB) with the aim of reducing substrate, product, and by-product toxicity via sequestration. Previous work in the field had used octanol as the sequestering phase of liquid-liquid TPPBs but was limited by the toxic effects of octanol on C. utilis. To improve solvent selection in any future studies, the critical log P of C. utilis was determined in the current study to be 4.8 and can be used to predict biocompatible solvents. Bioavailability tests showed alkanes and alkenes to be non-bioavailable. As polymers are biocompatible and non-bioavailable, a wide range of commercially available polymers was screened and it was demonstrated that polymer softness plays a key role in absorptive capability. The polymer Hytrel G3548L was selected as the second phase to sequester benzaldehyde, PAC, and benzyl alcohol, with partition coefficients of 35, 7.5, and 10, respectively. With a 9% by volume partitioning phase, 13.6 g/L biomass of C. utilis achieved an overall PAC concentration of 11 g/L, a 1.9-fold improvement over the single-phase case. Benzyl alcohol concentration was 4.5 g/L, a 1.6-fold reduction. The volumetric productivity was 0.85 g/L h, a 1.2-fold improvement over the single-phase system. These results demonstrate a promising starting point for solid-liquid TPPBs for PAC production.


Assuntos
Acetona/análogos & derivados , Benzaldeídos/metabolismo , Biotecnologia/métodos , Candida/metabolismo , Acetona/isolamento & purificação , Acetona/metabolismo , Benzaldeídos/isolamento & purificação , Álcool Benzílico/isolamento & purificação , Reatores Biológicos , Biotransformação , Glucose/metabolismo , Poliésteres/metabolismo
7.
Molecules ; 14(8): 2717-28, 2009 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-19701118

RESUMO

Volatile organic compounds of Amorpha fruticosa honey samples were isolated by headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE), followed by gas chromatography and mass spectrometry analyses (GC, GC-MS), in order to obtain complementary data for overall characterization of the honey aroma. The headspace of the honey was dominated by 2-phenylethanol (38.3-58.4%), while other major compounds were trans- and cis-linalool oxides, benzaldehyde and benzyl alcohol. 2-Phenylethanol (10.5-16.8%) and methyl syringate (5.8-8.2%) were the major compounds of ultrasonic solvent extracts, with an array of small percentages of linalool, benzene and benzoic acid derivatives, aliphatic hydrocarbons and alcohols, furan derivatives and others. The scavenging ability of the series of concentrations of the honey ultrasonic solvent extracts and the corresponding honey samples was tested by a DPPH (1,1-diphenyl-2-picrylhydrazyl) assay. Approximately 25 times lower concentration ranges (up to 2 g/L) of the extracts exhibited significantly higher free radical scavenging potential with respect to the honey samples.


Assuntos
Fabaceae/química , Sequestradores de Radicais Livres/análise , Mel/análise , Compostos Orgânicos Voláteis/análise , Monoterpenos Acíclicos , Benzaldeídos/análise , Benzaldeídos/química , Benzaldeídos/isolamento & purificação , Álcool Benzílico/análise , Álcool Benzílico/química , Álcool Benzílico/isolamento & purificação , Compostos de Bifenilo/química , Cromatografia Gasosa , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas , Monoterpenos/análise , Monoterpenos/química , Monoterpenos/isolamento & purificação , Álcool Feniletílico/análise , Álcool Feniletílico/química , Álcool Feniletílico/isolamento & purificação , Picratos/química , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/isolamento & purificação , Volatilização
8.
J Chromatogr A ; 1216(50): 8787-92, 2009 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-19345365

RESUMO

Predictable scale-up from test tube derived distribution ratios and analytical-scale sample loading optimisation is demonstrated using a model sample system of benzyl alcohol and p-cresol in a heptane:ethyl acetate:methanol:water phase system with the new 18 L Maxi counter-current chromatography centrifuge. The versatility of having a liquid stationary phase with its high loading capacity and flexible operating modes is demonstrated at two different scales by separating and concentrating target compounds using a mixture of caffeine, vanillin, naringenin and carvone using a quasi-continuous technique called intermittent counter-current extraction.


Assuntos
Distribuição Contracorrente/instrumentação , Álcool Benzílico/isolamento & purificação , Centrifugação , Cresóis/isolamento & purificação , Projetos Piloto
10.
J Chromatogr A ; 1137(1): 36-41, 2006 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-17056050

RESUMO

A bi-dimensional (non-orthogonal) chromatographic system made of two columns of different length (longer along the first direction and shorter on the second) but packed with identical (or similar) materials has been employed to perform automated on-line fraction analysis and peak deconvolution of multicomponent overloaded band profiles. Multicomponent overloaded peaks, eluted from the first column, are sampled through a remotely-controlled switching valve and fractions are injected, under analytical conditions, directly into the second direction. This set-up serves a twofold purpose. First of all, it has been possible to use linear calibration curves for detector calibration (DC). Secondly, since single component peaks were resolved on the second direction, individual concentration profiles have been obtained beneath the envelop of overlapping bands. All the information necessary to operate the bi-dimensional system can be achieved by analyzing the chromatographic behavior of the mixture on the shorter column under linear conditions. Therefore, solutions of unknown concentration can be prepared and their composition reconstructed with a simple chromatographic run. Two- and three-component overloaded mixtures have been employed to validate the system.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Sistemas On-Line/instrumentação , Automação , Álcool Benzílico/isolamento & purificação , Calibragem , Cromatografia Líquida de Alta Pressão/instrumentação , Fenol/isolamento & purificação , Álcool Feniletílico/isolamento & purificação
11.
Electrophoresis ; 27(20): 3981-7, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16983634

RESUMO

Nonporous silica spheres (1 microm) were synthesized and bonded with octadecylsilane functionality. These stationary phase particles were packed electrokinetically into fused-silica capillaries with 100 microm id for a length of 20 cm, which was evaluated by using pressurized CEC (pCEC). The efficiency of the C18 RP column was characterized through the theoretical plates of thiourea, benzyl alcohol, toluene, styrene, and naphthalene. The effects of experimental parameters such as the applied voltage, sample size, pump flow rate, pH value and the concentration of the buffer solution, and the content of methanol in the mobile phase, on-column efficiency were evaluated. Column efficiency as high as 200 000 theoretical plates per meter for naphthalene was obtained with the optimal condition of 70% v/v methanol and 30% v/v of 10 mmol/L phosphate buffer (pH 7.8) at an applied voltage of 10 kV and a supplementary pressure of 500 psi.


Assuntos
Eletrocromatografia Capilar/métodos , Silanos/química , Dióxido de Silício/síntese química , Álcool Benzílico/isolamento & purificação , Soluções Tampão , Eletrocromatografia Capilar/instrumentação , Concentração de Íons de Hidrogênio , Naftalenos/isolamento & purificação , Reprodutibilidade dos Testes , Estireno/isolamento & purificação , Tioureia/isolamento & purificação , Tolueno/isolamento & purificação
12.
Ophthalmic Surg Lasers Imaging ; 37(2): 162-4, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16583642

RESUMO

Purification of commercially available formulations of triamcinolone acetonide is important to avoid potential toxic effects of the vehicle for intravitreal use. In 2004, a simple and rapid method to remove most of the vehicle with a centrifuge was reported. The aim of this article is to study the degree to which benzyl alcohol can be eliminated with this method. By means of a gas chromatographic procedure, it has been proven that centrifugation is suitable for removing most benzyl alcohol (ie, up to 95.5% at 10,000 rpm, 5 minutes), and it is better at modifying the concentration of the drug than other proposed methods (ie, decantation, filtering methods, or both).


Assuntos
Álcool Benzílico/isolamento & purificação , Glucocorticoides/química , Triancinolona Acetonida/química , Centrifugação com Gradiente de Concentração , Cromatografia Gasosa , Filtração , Humanos , Suspensões
13.
Br J Ophthalmol ; 89(9): 1112-4, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16113361

RESUMO

BACKGROUND: Intravitreal triamcinolone has increasingly been used for the treatment of oedematous and neovascular diseases and purification of triamcinolone suspension may be important in order to avoid the potential toxic effects of the vehicle. The aim was to evaluate different techniques used to reduce the solvent agent benzyl alcohol (9.9 mg/ml) from a commercially prepared triamcinolone acetonide suspension. METHODS: Different techniques were used to reduce the solvent agent benzyl alcohol: filter techniques using 0.22 mum or 5 mum pore size, and non-filter techniques using sedimentation or centrifugation. Quantification of triamcinolone acetonide and benzyl alcohol was performed by high pressure liquid chromatography (HPLC). RESULTS: Benzyl alcohol concentration was decreased significantly in all the techniques used compared with the original commercial suspension (p<0.05), with no significant differences among them. The reduction was approximately one tenth of its original concentration. However, triamcinolone acetonide concentration differed significantly depending on the method used. Centrifugation method showed no differences versus the original commercial solution; sedimentation technique reduced the expected dose only 25%; the filter technique using a 5 mum pore size membrane reduced the expected dose to one fourth, while the filter technique using a 0.22 mum pore size membrane reduced the expected dose to 45%. CONCLUSIONS: All the different techniques employed effectively reduced the concentration of benzyl alcohol. However, the final concentration of triamcinolone was much lower than expected using the filter techniques. The pore size membrane inversely influenced the final concentration, with part of the triamcinolone crystals probably being entrapped in the filter. Centrifugation is recommended as the best way of administering the drug.


Assuntos
Anti-Inflamatórios/isolamento & purificação , Álcool Benzílico/isolamento & purificação , Solventes/isolamento & purificação , Triancinolona Acetonida/isolamento & purificação , Anti-Inflamatórios/química , Centrifugação com Gradiente de Concentração , Filtração , Humanos , Injeções , Estatísticas não Paramétricas , Triancinolona Acetonida/química , Corpo Vítreo
14.
Z Naturforsch C J Biosci ; 58(11-12): 797-803, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-14713153

RESUMO

Volatile constituents of various solvent extracts (n-hexane, CH2Cl2, H2O) of 15 different organs (leaves, flowers, fruits) of five Rhododendron species (Ericaceae) growing in Turkey were trapped with headspace solid-phase microextraction (HS-SPME) technique and analyzed by GC-MS. A total of 200 compounds were detected and identified from organic extracts, while the water extracts contained only traces of few volatiles. The CH2Cl2 extract of the R. luteum flowers was found to exhibit the most diverse composition: 34 compounds were identified, with benzyl alcohol (16.6%), limonene (14.6%) and p-cymene (8.4%) being the major compounds. The CH2Cl2-solubles of R. x sochadzeae leaves contained only phenyl ethyl alcohol. This study indicated appreciable intra-specific variations in volatile compositions within the genus. Different anatomical parts also showed altered volatile profiles. This is the first application of HS-SPME-GC-MS on the volatiles of Rhododendron species.


Assuntos
Álcool Benzílico/química , Monoterpenos/química , Rhododendron/química , Terpenos/química , Álcool Benzílico/isolamento & purificação , Cicloexenos , Cimenos , Flores/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Limoneno , Monoterpenos/isolamento & purificação , Folhas de Planta/química , Rhododendron/classificação , Terpenos/isolamento & purificação , Turquia , Volatilização
15.
J Agric Food Chem ; 50(20): 5552-7, 2002 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-12236678

RESUMO

Enzymatic synthesis of aroma compound xylosides was performed by Trichoderma longibrachiatum xylanase. Information concerning the nature of xylosides present in the reaction medium was obtained by GC-EI-MS, by GC-NCI-MS of TFA derivatives, and by positive FAB-MS of the reaction mixtures. Moreover, the structures of isolated benzyl beta-D-xylopyranoside and 4-O-beta-xylopyranosyl-beta-D-xylopyranoside were established by (1)H and (13)C NMR and heteronuclear two-dimensional ((1)H-(13)C) chemical shift correlation. The results obtained for hexyl and benzyl alcohol xylosides indicated that a reaction implying a transfer of one to two or three xylose units from xylan was involved. The enzyme was able to recognize xylobiose, xylotriose, and xylan as xylose donors. Benzyl xyloside, produced independently of xylobioside and xylotrioside, was found as the major kinetic product of the reaction. Benzyl xyloside was produced in higher quantities and at a higher rate than that obtained for the di- and trixyloside derivatives. The maximum production for benzyl xyloside, 1.29 g/L, was obtained in the presence of hexane (50%) used as cosolvent. Xylosides and xylobiosides of several aroma compounds, (Z)-hex-3-en-1-ol, heptan-2-ol, geraniol, nerol, and citronellol, were synthesized in different amounts, from 850 mg/L for (Z)-hex-3-en-1-yl xylosides to 1.5 mg/L for citronellyl xylosides. No synthesis occurred when menthol, linalool, and eugenol were used as acceptors.


Assuntos
Glicosídeos/biossíntese , Odorantes , Trichoderma/enzimologia , Xilosidases/metabolismo , Álcoois/síntese química , Álcool Benzílico/química , Álcool Benzílico/isolamento & purificação , Cromatografia Gasosa , Cromatografia Gasosa-Espectrometria de Massas , Hexanóis/química , Cinética , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Solventes , Espectrometria de Massas de Bombardeamento Rápido de Átomos , Xilano Endo-1,3-beta-Xilosidase , Xilanos/química , Xilose/química
16.
Se Pu ; 20(3): 237-40, 2002 May.
Artigo em Chinês | MEDLINE | ID: mdl-12541945

RESUMO

The separation mechanism for neutral solutes on a cyano column in capillary electrochromatography (CEC) was investigated and the effects of components of mobile phases and the kinds of buffers on retention of samples were studied. In comparing the separation behavior of samples on CN column with reversed-phase ODS column and normal phase SI column, the peak order was different on CN column under different experimental conditions, and the characteristics of CN column having both reversed and normal phase mechanisms were obvious. The migration velocities for neutral solutes of different polarity on CN column were very different by the effects of two mechanisms under different operating conditions. It is easy to change peak order and to adjust selectivity.


Assuntos
Cianetos/química , Eletroforese Capilar/instrumentação , Tioureia/isolamento & purificação , Álcool Benzílico/isolamento & purificação , Eletroquímica , Mecânica , Naftalenos/isolamento & purificação , Soluções/análise
17.
Electrophoresis ; 22(3): 544-51, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11258767

RESUMO

A mode of capillary electrochromatography (CEC), based on the dynamical adsorption of surfactants on the uncharged monolithic stationary phases has been developed. The monolithic stationary phase, obtained by the in situ polymerization of butyl methacrylate with ethylene dimethacrylate, was dynamically modified with an ionic surfactant such as the long-chain quaternary ammonium salt of cetyltrimethylammonium bromide (CTAB) and long-chain sodium sulfate of sodium dodecyl sulfate (SDS). The ionic surfactant was adsorbed on the surface of polymeric monolith by hydrophobic interaction, and the ionic groups used to generate the electroosmotic flow (EOF). The electroosmotic mobility through these capillary columns increased with increasing the content of ionic surfactants in the mobile phase. In this way, the synthesis of the monolithic stationary phase with binary monomers can be controlled more easily than that with ternary monomers, one of which should be an ionic monomer to generate EOF. Furthermore, it is more convenient to change the direction and magnitude of EOF by changing the concentration of cationic or anionic surfactants in this system. An efficiency of monolithic capillary columns with more than 140000 plates per meter for neutral compounds has been obtained, and the relative standard deviations observed for to and retention factors of neutral solutes were about 0.22% and less than 0.56% for ten consecutive runs, respectively. Effects of mobile phase composition on the EOF of the column and the retention values of the neutral solutes were investigated. Simultaneous separation of basic, neutral and acidic compounds has been achieved.


Assuntos
Compostos de Cetrimônio , Eletroforese Capilar/métodos , Dodecilsulfato de Sódio , Tensoativos , Ânions , Álcool Benzílico/isolamento & purificação , Cátions , Cetrimônio , Eletroforese Capilar/instrumentação , Nitrilas/isolamento & purificação , Piridinas/isolamento & purificação
18.
Electrophoresis ; 20(12): 2360-5, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10499326

RESUMO

Capillary columns have been packed for capillary electrochromatography (CEC) using centripetal forces. The packed columns were maintained under wet conditions or they were dried with nitrogen gas prior to forming the retaining frits. Upon fabrication of the retaining frits, the dried columns were resolvated with the mobile phase. The performance of the columns was evaluated to determine the effect of the drying step during the packing procedure. The columns submitted to the drying step showed improved separation efficiencies and stronger retention characteristics than those kept under wet conditions. The drying step allows the silica-based packing material to be better accommodated inside the capillary column. Upon solvation, the packing material "swells," resulting in a greater packing density, which allows for a stronger retention and improved separation efficiencies. The drying step led to a 13% increase in retention on columns packed with isopropanol. An increase of 15-20% in theoretical plates for the most retained compounds was also observed in such columns.


Assuntos
2-Propanol , Acetona , Cromatografia Líquida de Alta Pressão/métodos , Eletroforese Capilar/métodos , Álcool Benzílico/isolamento & purificação , Compostos de Bifenilo/isolamento & purificação , Naftalenos/isolamento & purificação , Pentanos/isolamento & purificação , Solventes , Tioureia/isolamento & purificação
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