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  1 / 1152 MEDLINE  
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[PMID]:27776641
[Au] Autor:Wang T; Yang H; Qiu R; Huang S
[Ad] Endereço:College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
[Ti] Título:Synthesis of novel chiral imidazolium stationary phases and their enantioseparation evaluation by high-performance liquid chromatography.
[So] Source:Anal Chim Acta;944:70-77, 2016 Nov 09.
[Is] ISSN:1873-4324
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Two novel chiral stationary phases (CSPs) were prepared by bonding chiral imidazoliums on the surface of silica gel. The chiral imidazoles were derivatized from chiral amines, 1-phenylethylamine and 1-(1-naphthyl)ethylamine. The obtained CSPs were characterized by Fourier Transform Infrared (FT-IR) spectroscopy and elemental analysis (EA), demonstrating the bonding densities of CSP 1 and CSP 2 were 0.43 mmol g and 0.40 mmol g , respectively. These two CSPs could be used to availably separate 8 pharmaceuticals, 7 mandelic acid/its derivatives, 2 1-phenylethylamine derivatives, 1 1,1'-bi-2-naphthol, and 1 camphorsulfonic acid in high-performance liquid chromatography (HPLC). It is found that CSP 1 could effectively enantioseparate most chiral analytes, especially the acidic components, while CSP 2 could enantiorecognize all chiral analytes, although a number of components did not achieve baseline separation. Additionally, the effects of mobile phase composition, mobile phase pH and salt content, chiral selector structures, and analyte structures on the enantiorecognitions of the two CSPs were investigated. It is found that high acetonitrile content in mobile phases was conducive to enantiorecognition. Mobile phase pH and salt content could alter the retention behaviors of different enantiomers of the same chiral compound, resulting in better enantioresolution. Moreover, both chiral selector structures and substituted groups of analytes played a significant role in the separation of chiral solutes.
[Mh] Termos MeSH primário: Imidazóis/síntese química
Imidazóis/isolamento & purificação
[Mh] Termos MeSH secundário: Aminas/química
Técnicas de Química Sintética
Cromatografia Líquida de Alta Pressão
Custos e Análise de Custo
Concentração de Íons de Hidrogênio
Imidazóis/química
Modelos Moleculares
Conformação Molecular
Dióxido de Silício/química
Estereoisomerismo
Ácido Trifluoracético/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Amines); 0 (Imidazoles); 7631-86-9 (Silicon Dioxide); 7GBN705NH1 (imidazole); E5R8Z4G708 (Trifluoroacetic Acid)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180116
[Lr] Data última revisão:
180116
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161026
[St] Status:MEDLINE


  2 / 1152 MEDLINE  
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[PMID]:29189771
[Au] Autor:Tang S; Zuo C; Huang DL; Cai XY; Zhang LH; Tian CL; Zheng JS; Liu L
[Ad] Endereço:Department of Chemistry, Tsinghua-Peking Center for Life Sciences, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Tsinghua University, Beijing, China.
[Ti] Título:Chemical synthesis of membrane proteins by the removable backbone modification method.
[So] Source:Nat Protoc;12(12):2554-2569, 2017 Dec.
[Is] ISSN:1750-2799
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Chemical synthesis can produce membrane proteins bearing specifically designed modifications (e.g., phosphorylation, isotope labeling) that are difficult to obtain through recombinant protein expression approaches. The resulting homogeneously modified synthetic membrane proteins are valuable tools for many advanced biochemical and biophysical studies. This protocol describes the chemical synthesis of membrane proteins by condensation of transmembrane peptide segments through native chemical ligation. To avoid common problems encountered due to the poor solubility of transmembrane peptides in almost any solvent, we describe an effective procedure for the chemical synthesis of membrane proteins through the removable-backbone modification (RBM) strategy. Two key steps of this protocol are: (i) installation of solubilizing Arg4-tagged RBM groups into the transmembrane peptides at any primary amino acid through Fmoc (9-fluorenylmethyloxycarbonyl) solid-phase peptide synthesis and (ii) native ligation of the full-length sequence, followed by removal of the RBM tags by TFA (trifluoroacetic acid) cocktails to afford the native protein. The installation of RBM groups is achieved by using 4-methoxy-5-nitrosalicyladehyde by reduction amination to incorporate an activated O-to-N acyl transfer auxiliary. The Arg4-tag-modified membrane-spanning peptide segments behave like water-soluble peptides to facilitate their purification, ligation and mass characterization.
[Mh] Termos MeSH primário: Proteínas de Membrana/síntese química
Peptídeos/síntese química
Técnicas de Síntese em Fase Sólida/métodos
[Mh] Termos MeSH secundário: Sequência de Aminoácidos
Fluorenos/síntese química
Fluorenos/química
Proteínas de Membrana/química
Peptídeos/química
Ácido Trifluoracético/síntese química
Ácido Trifluoracético/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (9-fluorenylmethoxycarbonyl); 0 (Fluorenes); 0 (Membrane Proteins); 0 (Peptides); E5R8Z4G708 (Trifluoroacetic Acid)
[Em] Mês de entrada:1712
[Cu] Atualização por classe:171219
[Lr] Data última revisão:
171219
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171201
[St] Status:MEDLINE
[do] DOI:10.1038/nprot.2017.129


  3 / 1152 MEDLINE  
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[PMID]:28714592
[Au] Autor:Reinhard S; Zhang W; Wagner E
[Ad] Endereço:Department of Pharmacy, Pharmaceutical Biotechnology, Center of Nanoscience, CeNS, Ludwig-Maximilians-Universität, Butenandtstr. 5-13, 81377, München, Germany.
[Ti] Título:Optimized Solid-Phase-Assisted Synthesis of Oleic Acid Containing siRNA Nanocarriers.
[So] Source:ChemMedChem;12(17):1464-1470, 2017 Sep 07.
[Is] ISSN:1860-7187
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:Cationic lipo-oligomers containing unsaturated oleic acid are potent siRNA carriers based on electrostatic and hydrophobic lipo-polyplex formation and endosomal membrane destabilization. Lipo-oligomers can be produced by solid-phase-supported synthesis in sequence-defined form. However, the trifluoroacetic acid (TFA)-mediated removal of acid-labile protecting groups and cleavage from the resin can be accompanied by side products caused by the addition of TFA to the double bonds of oleic acid. Under aqueous conditions, these TFA adducts of oleic acid are converted into hydroxystearic acid derivatives. The cleavage protocol was optimized to decrease TFA adducts. The pure oleic acid (C18:1) containing lipo-oligomer was compared with analogous structures containing saturated or modified hydrophobic moieties (stearic acid (C18:0), hydroxystearic acid, and 8-nonanamidooctanoic acid). The structure containing intact oleic acid shows favorable pH dependency of lytic activity, efficient gene silencing, and excellent cell tolerability relative to its counterparts.
[Mh] Termos MeSH primário: Ácido Oleico/síntese química
RNA Interferente Pequeno/administração & dosagem
Técnicas de Síntese em Fase Sólida/métodos
[Mh] Termos MeSH secundário: Animais
Linhagem Celular Tumoral
Genes Reporter
Hemólise
Seres Humanos
Camundongos
Ácido Oleico/química
Interferência de RNA
RNA Interferente Pequeno/genética
Transfecção/métodos
Ácido Trifluoracético/síntese química
Ácido Trifluoracético/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (RNA, Small Interfering); 2UMI9U37CP (Oleic Acid); E5R8Z4G708 (Trifluoroacetic Acid)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170922
[Lr] Data última revisão:
170922
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170718
[St] Status:MEDLINE
[do] DOI:10.1002/cmdc.201700350


  4 / 1152 MEDLINE  
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[PMID]:28419898
[Au] Autor:Luo C; Dong W; Gu Y
[Ad] Endereço:Harbin Institute of Technology Shenzhen Graduate School, Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control, Shenzhen 518055, China.
[Ti] Título:Theory-guided access to efficient photodegradation of the simplest perfluorocarboxylic acid: Trifluoroacetic acid.
[So] Source:Chemosphere;181:26-36, 2017 Aug.
[Is] ISSN:1879-1298
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:The photodegradation approaches of perfluorocarboxylic acids have attracted considerable attention and have been developed extensively. However, the reaction channels along which the perfluorocarboxylic acid molecules dissociate remain to be deciphered by means of the quantum chemical method at the electronically excited state level of theory until now. Here we report the photodissociation mechanism of the simplest perfluorocarboxylic acid, trifluoroacetic acid, using the complete active space self-consistent field (CASSCF) and the multi-configurational second-order perturbation (CASPT2) methods. The CC and CO α bond fission channels were both taken into account. Based on the constructed potential energy surfaces, it is concluded that the CC α bond fission, which would probably account for further degradations and mineralizations, may mainly take place in the triplet manifolds via intersystem crossing from the S state. Thus, taking the computational results of the simple member of perfluorocarboxylic acids as a rational clue, strategies to enhance intersystem crossing process efficiencies of the photodegradation of perfluorocarboxylic acids can be developed.
[Mh] Termos MeSH primário: Modelos Teóricos
Fotólise
Ácido Trifluoracético/efeitos da radiação
[Mh] Termos MeSH secundário: Elétrons
Teoria Quântica
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
E5R8Z4G708 (Trifluoroacetic Acid)
[Em] Mês de entrada:1707
[Cu] Atualização por classe:170727
[Lr] Data última revisão:
170727
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170419
[St] Status:MEDLINE


  5 / 1152 MEDLINE  
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[PMID]:28371732
[Au] Autor:Guo J; Zhai Z; Wang L; Wang Z; Wu J; Zhang B; Zhang J
[Ad] Endereço:State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China.
[Ti] Título:Dynamic and thermodynamic mechanisms of TFA adsorption by particulate matter.
[So] Source:Environ Pollut;225:175-183, 2017 Jun.
[Is] ISSN:1873-6424
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Trifluoroacetic acid (TFA) in the atmosphere is produced by degradation of hydrochlorofluorocarbons and hydrofluorocarbons. In recent years, TFA has attracted global attention because of increased environmental concentrations, biological toxicity and accumulation in aqueous environments. This study focused on the mechanisms underlying the adsorption of TFA by particulate matter to identify the appropriate descriptive model for this process and thus improve estimation of TFA adsorption in future environmental monitoring. Onsite gas and particle phase sampling in Beijing, China, and subsequent measurement of TFA concentrations indicated that the TFA concentration in the gas phase (1396 ± 225 pg m ) was much higher than that in the particle phase (62 ± 8 pg m ) and that monthly concentrations varied seasonally with temperature. Based on the field results and analysis, an adsorption experiment of TFA on soot was then conducted at three different temperatures (293, 303, and 313 K) to provide parameters for kinetic and thermodynamic modelling. The proportion of atmospheric TFA concentration in the gas phase increased with temperature, indicating that temperature affected the phase distribution of TFA. The subsequent kinetic and thermodynamic modelling showed that the adsorption of TFA by soot could be described well by the Bangham kinetic model. The adsorption was controlled by diffusion, and the key mechanism was physical adsorption. The adsorption behavior can be well described by the Langmuir isotherm model. The calculated thermodynamic parameters ΔG° (-2.34, -1.25, and -0.15 kJ mol at 293, 303, and 313 K, respectively), ΔH° (-34.34 kJ mol ), and ΔS° (-109.22 J mol K ) for TFA adsorption by soot were negative, indicating that adsorption was a spontaneous, exothermic process.
[Mh] Termos MeSH primário: Modelos Químicos
Ácido Trifluoracético/química
Poluentes Químicos da Água/química
[Mh] Termos MeSH secundário: Adsorção
Pequim
China
Monitoramento Ambiental
Substâncias Húmicas
Concentração de Íons de Hidrogênio
Cinética
Material Particulado
Fuligem
Temperatura Ambiente
Termodinâmica
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Humic Substances); 0 (Particulate Matter); 0 (Soot); 0 (Water Pollutants, Chemical); E5R8Z4G708 (Trifluoroacetic Acid)
[Em] Mês de entrada:1707
[Cu] Atualização por classe:170727
[Lr] Data última revisão:
170727
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170404
[St] Status:MEDLINE


  6 / 1152 MEDLINE  
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[PMID]:28366568
[Au] Autor:Ragab MA; El-Kimary EI
[Ad] Endereço:Faculty of Pharmacy, Department of Pharmaceutical Analytical Chemistry, University of Alexandria, El-Messalah, Alexandria 21521, Egypt. Electronic address: marmed_2001@yahoo.com.
[Ti] Título:High performance liquid chromatography with photo diode array for separation and analysis of naproxen and esomeprazole in presence of their chiral impurities: Enantiomeric purity determination in tablets.
[So] Source:J Chromatogr A;1497:110-117, 2017 May 12.
[Is] ISSN:1873-3778
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:A stereoselective high performance liquid chromatographic method with diode array detection (HPLC-DAD) was introduced for S-naproxen and esomeprazole determination in tablets. The separation was achieved on a Kromasil Cellucoat chiral column using a mobile phase consisting of hexane: isopropanol: trifluoroacetic acid (TFA) (90:9.9:0.1 v/v/v). The proposed system was found to be suitable for the enantioseparation of naproxen and omeprazole biologically active isomers. After optimization of the chromatographic conditions, resolution values of 3.84 and 2.17 could be obtained for naproxen and omeprazole isomers, respectively. The method was fully validated for the determination of S-isomers of each drug in their dosage form. Also, the enentiomeric purity was determined in commercial tablet containing S-naproxen and esomeprazole. The enantiomeric purity was calculated for each drug and the chiral impurities (R-isomers) could be determined at 1% level. The method was validated and good results with respect to linearity, precision, accuracy, selectivity and robustness were obtained. The limits of detection (LOD) and quantification (LOQ) were 2.00, 6.50 and 0.10, 0.35µgmL for S-naproxen and esomeprazole, respectively.
[Mh] Termos MeSH primário: Cromatografia Líquida de Alta Pressão
Esomeprazol/análise
Naproxeno/análise
Comprimidos/química
[Mh] Termos MeSH secundário: 2-Propanol/química
Hexanos/química
Limite de Detecção
Omeprazol/análise
Reprodutibilidade dos Testes
Estereoisomerismo
Ácido Trifluoracético/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Hexanes); 0 (Tablets); 57Y76R9ATQ (Naproxen); E5R8Z4G708 (Trifluoroacetic Acid); KG60484QX9 (Omeprazole); N3PA6559FT (Esomeprazole); ND2M416302 (2-Propanol)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170516
[Lr] Data última revisão:
170516
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170404
[St] Status:MEDLINE


  7 / 1152 MEDLINE  
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[PMID]:28363419
[Au] Autor:Åsberg D; Langborg Weinmann A; Leek T; Lewis RJ; Klarqvist M; Lesko M; Kaczmarski K; Samuelsson J; Fornstedt T
[Ad] Endereço:Department of Engineering and Chemical Sciences, Karlstad University, SE-651 88 Karlstad, Sweden.
[Ti] Título:The importance of ion-pairing in peptide purification by reversed-phase liquid chromatography.
[So] Source:J Chromatogr A;1496:80-91, 2017 May 05.
[Is] ISSN:1873-3778
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:The adsorption mechanism for three peptides was studied under overloaded conditions through adsorption isotherm measurements in the presence of an ion-pairing reagent, trifluoroacetic acid (TFA), on an end-capped C -bonded stationary phase. The overall aim of the study was to obtain a better understanding of how the acetonitrile and the TFA fractions in the eluent affected the overloaded elution profiles and the selectivity between peptides using mechanistic modelling and multivariate design of experiments. When studying the effect of TFA, direct evidence for ion pair formation between a peptide and TFA in acetonitrile-water solutions was provided by fluorine-proton nuclear Overhauser NMR enhancement experiments and the adsorption of TFA on the stationary phase was measured by frontal analysis. The adsorption isotherms for each peptide were then determined by the inverse method at eight TFA concentrations ranging from 2.6mM to 37.3mM (0.02-0.29vol-%) in isocratic elution. The equilibrium between the peptide ion and the peptide-TFA complex was modelled by coupling the mass-balance to reaction kinetics and determining separate adsorption isotherms for the two species. We found that a Langmuir isotherm described the elution profile of peptide-TFA complex well while the peptide ion was described by a bi-Langmuir adsorption isotherm since it exhibited strong secondary interactions. The elution profiles had an unfavorable shape at low TFA concentrations consisting of a spike in their front and a long tailing rear due to the secondary interactions for the peptide ion having very low saturation capacity. The acetonitrile dependence on the adsorption isotherms was studied by determination of adsorption isotherms directly from elution profiles obtained in gradient elution which enabled a broad acetonitrile interval to be studied. Here, it was found that the column saturation capacity was quickly reached at very low acetonitrile fractions and that there were significant variations in adsorption with the molecular weight. Finally, practical implications for method development are discussed based on an experimental design where gradient slope and TFA concentrations are used as factors.
[Mh] Termos MeSH primário: Cromatografia de Fase Reversa/métodos
Peptídeos/química
Peptídeos/isolamento & purificação
[Mh] Termos MeSH secundário: Acetonitrilos/química
Adsorção
Íons/química
Cinética
Espectroscopia de Ressonância Magnética
Ácido Trifluoracético/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Acetonitriles); 0 (Ions); 0 (Peptides); E5R8Z4G708 (Trifluoroacetic Acid); Z072SB282N (acetonitrile)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170512
[Lr] Data última revisão:
170512
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170402
[St] Status:MEDLINE


  8 / 1152 MEDLINE  
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[PMID]:28259841
[Au] Autor:Papastavrou N; Chatzopoulou M; Ballekova J; Cappiello M; Moschini R; Balestri F; Patsilinakos A; Ragno R; Stefek M; Nicolaou I
[Ad] Endereço:Department of Pharmaceutical Chemistry, School of Pharmacy, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54214 Thessaloniki, Greece.
[Ti] Título:Enhancing activity and selectivity in a series of pyrrol-1-yl-1-hydroxypyrazole-based aldose reductase inhibitors: The case of trifluoroacetylation.
[So] Source:Eur J Med Chem;130:328-335, 2017 Apr 21.
[Is] ISSN:1768-3254
[Cp] País de publicação:France
[La] Idioma:eng
[Ab] Resumo:Aldose reductase (ALR2) has been the target of therapeutic intervention for over 40 years; first, for its role in long-term diabetic complications and more recently as a key mediator in inflammation and cancer. However, efforts to prepare small-molecule aldose reductase inhibitors (ARIs) have mostly yielded carboxylic acids with rather poor pharmacokinetics. To address this limitation, the 1-hydroxypyrazole moiety has been previously established as a bioisostere of acetic acid in a group of aroyl-substituted pyrrolyl derivatives. In the present work, optimization of this new class of ARIs was achieved by the addition of a trifluoroacetyl group on the pyrrole ring. Eight novel compounds were synthesized and tested for their inhibitory activity towards ALR2 and selectivity against aldehyde reductase (ALR1). All compounds proved potent and selective inhibitors of ALR2 (IC = 0.043-0.242 µΜ, Selectivity index = 190-858), whilst retaining a favorable physicochemical profile. The most active (4g) and selective (4d) compounds were further evaluated for their ability to inhibit sorbitol formation in rat lenses ex vivo and to exhibit substrate-specific inhibition.
[Mh] Termos MeSH primário: Aldeído Redutase/antagonistas & inibidores
Pirazóis/farmacologia
Pirróis/farmacologia
[Mh] Termos MeSH secundário: Acetilação
Animais
Inibidores Enzimáticos/química
Inibidores Enzimáticos/farmacologia
Cristalino/metabolismo
Pirazóis/química
Pirróis/química
Ratos
Sensibilidade e Especificidade
Sorbitol/antagonistas & inibidores
Ácido Trifluoracético/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Enzyme Inhibitors); 0 (Pyrazoles); 0 (Pyrroles); 506T60A25R (Sorbitol); E5R8Z4G708 (Trifluoroacetic Acid); EC 1.1.1.21 (Aldehyde Reductase)
[Em] Mês de entrada:1703
[Cu] Atualização por classe:170322
[Lr] Data última revisão:
170322
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170306
[St] Status:MEDLINE


  9 / 1152 MEDLINE  
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[PMID]:28110166
[Au] Autor:Van Wanseele Y; Viaene J; Van den Borre L; Dewachter K; Vander Heyden Y; Smolders I; Van Eeckhaut A
[Ad] Endereço:Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information (FASC), Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium. Electronic address: yannick.van.wanseele@vub.ac.be.
[Ti] Título:LC-method development for the quantification of neuromedin-like peptides. Emphasis on column choice and mobile phase composition.
[So] Source:J Pharm Biomed Anal;137:104-112, 2017 Apr 15.
[Is] ISSN:1873-264X
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:In this study, the separation of four neuromedin-like peptides is investigated on four different core-shell stationary phases. Moreover, the effect of the mobile phase composition, i.e. organic modifier (acetonitrile and methanol) and additive (trifluoroacetic acid, formic acid, acetic acid, ammonium formate and ammonium acetate) on the chromatographic performance is studied. An improvement in chromatographic performance is observed when using the ammonium salt instead of its corresponding acid as additive, except for the column containing a positively charged surface (C18+). In general, the RP-Amide column provided the highest separation power with different mobile phases. However, for the neuromedin-like peptides of interest, the C18+ column in combination with a mobile phase containing methanol as organic modifier and acetic acid as additive provided narrower and higher peaks. A three-factor, three-level design is applied to further optimize the method in terms of increased peak height and reduced solvent consumption, without loss in resolution. The optimized method was subsequently used to assess the in vitro microdialysis recovery of the peptides of interest. Recovery values between 4 and 8% were obtained using a perfusion flow rate of 2µL/min.
[Mh] Termos MeSH primário: Cromatografia Líquida/métodos
Peptídeos/química
[Mh] Termos MeSH secundário: Acetatos/química
Ácido Acético/química
Acetonitrilos/química
Formiatos/química
Metanol/química
Solventes/química
Ácido Trifluoracético/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Acetates); 0 (Acetonitriles); 0 (Formates); 0 (Peptides); 0 (Solvents); 0YIW783RG1 (formic acid); E5R8Z4G708 (Trifluoroacetic Acid); Q40Q9N063P (Acetic Acid); RRE756S6Q2 (ammonium acetate); Y4S76JWI15 (Methanol); Z072SB282N (acetonitrile)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170608
[Lr] Data última revisão:
170608
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170123
[St] Status:MEDLINE


  10 / 1152 MEDLINE  
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[PMID]:28069167
[Au] Autor:McCalley DV
[Ad] Endereço:Centre for Research in Biosciences, University of the West of England, Frenchay, Bristol BS16 1QY, UK. Electronic address: David.Mccalley@uwe.ac.uk.
[Ti] Título:Effect of mobile phase additives on solute retention at low aqueous pH in hydrophilic interaction liquid chromatography.
[So] Source:J Chromatogr A;1483:71-79, 2017 Feb 03.
[Is] ISSN:1873-3778
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Trifluoracetic acid (TFA) added to the aqueous acetonitrile mobile phase induces some unexpected changes in the ionic component of retention in hydrophilic interaction separations when using Type B silica and amide-bonded silica columns. TFA use results in anion exchange properties which contrast with the cation exchange typically found with ammonium salt buffers. The significant cation exchange properties of silica hydride columns are also moderated by TFA. Similar behaviour was shown in a metal- free amide column operated on a system washed with a metal complexing agent, suggesting that adsorbed metal cations were not responsible for this anion exchange behaviour. Both suppression of silanol ionisation at low pH and ion pairing of bases with TFA could contribute to this effect. It is also possible that the column surface acquires some positive charges at the low pH of TFA. A surprising reversal of the properties of the columns back to predominately cation exchange behaviour was shown using methanesulfonic acid (MSA), which appears to be a stronger acid than TFA in high concentrations of acetonitrile. MSA maintains sufficient ionic strength in the mobile phase even at low concentrations, giving good peak shape, which could be useful for mass spectrometry detection. Besides giving different selectivity to TFA, MSA also gives different selectivity to that of ammonium salt buffers, suggesting it may be useful in manipulating the selectivity of a separation. Similar changes to the selectivity with TFA could be achieved by adding neutral methylsulfonate salts to the TFA mobile phase. While it is possible that methylsulfonate ions are retained on the stationary phase surface, experiments using ion pair reagents of opposite charge yielded the same results as MSA salts. It therefore seems more likely that the higher ionic strength of these solutions negates the influence of charges that may be formed in TFA solutions. Ion pairing effects with MSA are expected to be limited.
[Mh] Termos MeSH primário: Acetonitrilos/química
Cromatografia Líquida/métodos
Interações Hidrofóbicas e Hidrofílicas
Ácido Trifluoracético/química
Água/química
[Mh] Termos MeSH secundário: Adsorção
Amidas/química
Tampões (Química)
Cátions
Cromatografia Líquida de Alta Pressão/métodos
Concentração de Íons de Hidrogênio
Mesilatos/química
Metais/química
Concentração Osmolar
Sais/química
Dióxido de Silício/química
Soluções
Termodinâmica
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Acetonitriles); 0 (Amides); 0 (Buffers); 0 (Cations); 0 (Mesylates); 0 (Metals); 0 (Salts); 0 (Solutions); 059QF0KO0R (Water); 12EH9M7279 (methanesulfonic acid); 7631-86-9 (Silicon Dioxide); E5R8Z4G708 (Trifluoroacetic Acid); Z072SB282N (acetonitrile)
[Em] Mês de entrada:1703
[Cu] Atualização por classe:170817
[Lr] Data última revisão:
170817
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170111
[St] Status:MEDLINE



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