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1.
J Chromatogr A ; 1629: 461487, 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-32823013

RESUMO

A graphene oxide-molybdenum disulfide (GO-MoS2) composite was synthesized and utilized as the highly efficient stationary phase of open-tubular capillary electrochromatography (OT-CEC). The characterization results indicated that GO-MoS2 composite was successfully synthesized. The GO-MoS2-coated capillary column was prepared by covalent immobilization method for the determination of seven sulfonamides. The baseline separation of seven sulfonamides was achieved by GO-MoS2-coated capillary column. The linear range was 0.05-100 µg/mL for sulfisomidine, sulfathiazole, sulfamerazine, phthalylsulfathiazole and sulfacetamide, 0.1-100 µg/mL for sulfamonomethoxine and sulfachloropyridazine with a satisfactory correlation coefficients (R2) > 0.9994. This developed OT-CEC method was successfully applied to determinate of seven sulfonamides in environmental water and milk samples with good recoveries of 85.77% - 109.10% and 80.03% - 109.97%, respectively. These results indicated that GO-MoS2-coated capillary column possessed good stability and repeatability.


Assuntos
Eletrocromatografia Capilar/métodos , Dissulfetos , Grafite , Molibdênio , Sulfonamidas/análise , Sulfonamidas/isolamento & purificação
2.
J Chromatogr A ; 1629: 461497, 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-32858454

RESUMO

Allylglycine, a conventional amino acid derivative, possesses typical zwitterionic and hydrophilic functionalities deriving from the carboxyl and amino groups in its structure. A novel monolithic column poly(allylglycine-co-1, 3, 5-triacryloylhexahydro-1, 3, 5-triazine) (AGly-co-TAT) with powerful hydrophilic selectivity and obvious zwitterionic feature was synthesized successfully with the monomer allyglycine and the cross-linker 1, 3, 5-triacryloylhexahydro-1, 3, 5-triazine through in-situ copolymerization for capillary electrochromatography. The obtained monolithic column has good permeability. Due to the zwitterionic functional groups of allylglycine, the poly(AGly-co-TAT) monolithic column can generate a cathodic and anodic electroosmotic flow (EOF) by changing the mobile phase pH, which is beneficial to expand its application range. The separations of different series of polar analytes, thioureas, xanthines, phenols, peptides and acidic compounds are achieved on this hydrophilic monolithic column due to the powerful hydrophilic, electrostatic and hydrogen bond interactions. Using this monolithic column, hydrophilic separations are achieved even at a lower level of 50% organic solvent. The separation efficiency up to 1.41 × 105 N m-1 and 1.19 × 105 N m-1 is achieved for the separation of theophylline and phenol, respectively. For a real sample, cytochrome C digestion, the monolithic column shows good separation performance, which offers the potential application of the monolithic column on proteomics study.


Assuntos
Eletrocromatografia Capilar/métodos , Eletro-Osmose , Glicina , Interações Hidrofóbicas e Hidrofílicas , Polímeros/química , Eletricidade Estática
3.
J Chromatogr A ; 1628: 461436, 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32822976

RESUMO

In recent years, mussel-inspired polydopamine (PDA) based materials have been widely used as stationary phases for open-tubular capillary electrochromatography (OT-CEC) because of their various excellent properties. Nevertheless, the traditional synthesis routes of functionalized PDA-based capillary columns usually are time-consuming and limited in aqueous solutions. Herein, we report a facile and rapid route to prepare octadecylamine (ODA) functionalized PDA coated OT-CEC columns in organic solvents via a novel one-step in situ solvothermal-assisted coating strategy. Through this developed solvothermal-assisted approach, the growth rate of ODA/PDA coating was significantly speeded up and their hybrid coating process on the capillary inner surface could be rapidly completed in 60 min. The successful preparation of the solvothermal-assisted ODA/PDA hybrid coating were systematically characterized and confirmed by several methods. The influence of the preparation parameters on the formation of hybrid coating and the separation ability of the ODA/PDA modified columns were systematically explored. Consequently, the high-efficiency baseline separation of four kinds of neutral, acidic and basic analytes were achieved based on the ODA/PDA modified columns. The repeatability of the solvothermal-assisted ODA/PDA coated column was also studied, and the relative standard deviations for intra-day, inter-day and column-to-column were all less than 5%. Additionally, the solvothermal-assisted ODA/PDA modified column exhibited good stability and long lifetime.


Assuntos
Aminas/química , Eletrocromatografia Capilar/métodos , Indóis/química , Polímeros/química , Solventes/química , Temperatura , Acetonitrilos/química , Tampões (Química) , Eletro-Osmose , Halogenação , Concentração de Íons de Hidrogênio , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo
4.
J Chromatogr A ; 1625: 461269, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709321

RESUMO

Fluorous affinity means remarkably specific interaction between highly organic fluorides. This work aims to explore the potential of fluoro-functionalized stationary phase for the separation of organic fluorides by means of fluorous-fluorous interaction. Here, by using the Michael addition strategy between 1H,1H,2H,2H-perfluorodecanethiol (PFDT) and polydopamine (PD), a novel fluoro-functionalized stationary phase was synthesized for open-tubular capillary electrochromatography (OT-CEC). The PFDT@PD was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray Photoelectron Spectrometer (XPS). The PFDT@PD@capillary exhibited outstanding separation performance towards neutral compounds (such as alkylbenzenes and chlorobenzenes) and organic fluorides (such as fluorobenzenes and perfluoroalkyl methacrylates etc.) with high resolution and high separation efficiency by hydrophobic interaction and fluorous-fluorous interaction. In addition, the column shows good stability and reproducibility. The relative standard deviations (RSDs) of the retention time for intra-day (n = 5) and inter-day (n = 3) runs and between columns (n = 3) are less than 0.39%, 1.22% and 3.87%, respectively. This novel type of fluoro-functionalized stationary phase represents a great application potential in organic fluorides separation field.


Assuntos
Eletrocromatografia Capilar/métodos , Fluoretos/isolamento & purificação , Flúor/química , Compostos Orgânicos/isolamento & purificação , Eletro-Osmose , Indóis/química , Parabenos/análise , Parabenos/química , Polímeros/química , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier
5.
J Chromatogr A ; 1625: 461284, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709334

RESUMO

In this work, a class of novel and eco-friendly open-tubular (OT) chiral column was presented for the first time by one step preparation with zeolite imidazolate framework-8 (ZIF-8) and bovine serum album (BSA) based on electrostatic adsorption and adsorption affinity. This stationary phase materials combined the features of large surface areas and adsorption affinity of ZIF-8, and also the multiple chiral binding sites of BSA, which contributes to the π-interaction and hydrophobic interaction with the analytes. The separation performance of BSA@ZIF-8-OT chiral columns was evaluated with a miniaturized capillary electrochromatography and amperometric detection (mini-CEC-AD) system; in particular, nine groups of model molecules, including homologues, structural isomers, and chiral compounds, were baseline separated under the certain optimum conditions. The RSDs of run-to-run, day-to-day, column-to-column, and batch-to-batch reproducibility were less than 13.8 %. Furthermore, the prepared OT columns were successfully applied to fast analysis of ephedrine isomers in Chinese herb ephedra, and the LODs achieved 1.5-2.0 ng mL-1 (S/N=3) by an electrophoretic stacking technique of moving chemical reaction boundary. This mini-CEC-AD system with BSA@ZIF-8-OT chiral columns provides a promising potential in pharmaceutical analysis due to its fast, sensitive, enantioselective, and low-cost characteristics.


Assuntos
Eletrocromatografia Capilar/métodos , Imidazóis/química , Soroalbumina Bovina/química , Zeolitas/química , Adsorção , Animais , Bovinos , Concentração de Íons de Hidrogênio , Limite de Detecção , Reprodutibilidade dos Testes , Estereoisomerismo
6.
J Chromatogr A ; 1623: 461213, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505297

RESUMO

In the present study separation of enantiomers of some chiral neutral, basic and weakly acidic analytes was investigated on the chiral stationary phase (CSP) made by covalent immobilization of amylose tris(3-chloro-5-methylphenylcarbamate) onto aminopropylsilanized (APS) silica in nano-liquid chromatography (nano-LC) in aqueous methanol or acetonitrile mixtures. It has been shown that similar to high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) this chiral selector is useful for separation of enantiomers of neutral, basic and acidic analytes also in nano-LC. In comparison to our previous research, in which the chiral selector (CS) was bonded on native silica, in this study, the CS was immobilized on APS silica in order to improve chromatographic performance towards basic analytes. In fact, some improvement was observed and surprisingly not only for basic but also for neutral and acidic analytes. Again, quite unexpectedly almost no electroosmotic flow (EOF) was observed in capillaries packed with ca. 20% (w/w) amylose tris(3-chloro-5-methylphenylcarbamate) immobilized onto APS silica although the same APS silica before attachment of chiral selector exhibited significant EOF. In order to generate EOF in the capillaries with the CSP and enable capillary electrochromatographic (CEC) experiment on it, the short segment of the capillary column was packed with APS silica without chiral selector. The EOF in such capillary enabled CEC experiment and some preliminary results are reported here.


Assuntos
Amilose/análogos & derivados , Eletrocromatografia Capilar/métodos , Cromatografia Líquida/métodos , Fenilcarbamatos/química , Dióxido de Silício/química , Ácidos/química , Amilose/química , Flavanonas/análise , Estereoisomerismo
7.
J Chromatogr A ; 1623: 461175, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505279

RESUMO

An ionic liquid hybrid zwitterionic polymer capillary microextraction (CME) column was prepared for the biomimetic enrichment of glycopeptides by one-step copolymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) and 1-butyl-3-vinylimidazolium bromide, in the presence of crosslinker trimethylolpropane trimethacrylate (TMA). The resultant monolith was characterized by scanning electron microscopy (SEM), fourier transform infrared (FT-IR) spectroscopy and pore size distribution measurement. Due to the incorporation of zwitterionic MPC owning a unique biomimic structure (i.e. hydrophilic cation/anion and hydrophobic long-alkyl chain), the monolithic column has large pore size and good biocompatibility, exhibiting high extraction efficiency, permeability and fast mass transfer to targets. Besides, the use of ionic liquids (ILs) as co-monomer in the polymerization endows the monolith with enhanced mechanical stability, uniformity and multiple interactions. The prepared column was successfully applied in CME coupled to capillary electrochromatography (CEC) for the efficient enrichment and separation of glycopeptide antibiotics in foodstuff. The method demonstrated a wide linear range (50.0-18000.0 µg L-1), low detection limits (5.0-10.0 µg L-1, S/N = 3) and satisfied recoveries (76.0-109.7%). This work shows the advantage of fine-tuning biomimetic monoliths in application-specific CME-CEC.


Assuntos
Antibacterianos/análise , Eletrocromatografia Capilar/métodos , Glicopeptídeos/análise , Líquidos Iônicos/química , Antibacterianos/isolamento & purificação , Materiais Biomiméticos , Fracionamento Químico , Análise de Alimentos/métodos , Glicopeptídeos/isolamento & purificação , Interações Hidrofóbicas e Hidrofílicas , Imidazóis/química , Metacrilatos/química , Microscopia Eletrônica de Varredura , Fosforilcolina/análogos & derivados , Fosforilcolina/química , Polimerização , Polímeros/química , Espectroscopia de Infravermelho com Transformada de Fourier , Compostos de Vinila/química
8.
Mikrochim Acta ; 187(3): 170, 2020 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-32060642

RESUMO

A new bilayer chiral stationary phase for use in open tubular capillary electrochromatography (OT-CEC) system is described. Gold nanoparticles were modified with L-cysteine, with a tetramethylammonium lactobionate ionic liquid that acts as the chiral selector. The gold nanoparticle-coated column provides good enantioseparation and favorable reproducibility. Compared with an uncoated separation system, the column developed displays improved separation of the racemic ß-blockers propranolol, esmolol, bisoprolol and sotalol (resolutions of enotiomers are 6.29, 6.11, 6.12 and 6.02, respectively). The materials and coatings were characterized by scanning electron microscopy and transmission electron microscopy. The main driving forces (CEC and electro-osmotic flow) were studied to evaluate the variation of the immobilized columns. The effects of buffer pH value, concentration of chiral selector, type of organic modifier and applied voltage were optimized. Satisfactory relative standard deviations were achieved in run-to-run, day-to-day and column-to-column experiments. Graphical abstractSchematic preparation of a capillary column with bilayer chiral selectors coated gold nanoparticles. This novel OT-CEC system was applied for separation of four basic racemic ß-blockers.


Assuntos
Antagonistas Adrenérgicos beta/química , Eletrocromatografia Capilar/métodos , Ouro/química , Líquidos Iônicos/química , Nanopartículas Metálicas/química , Compostos de Amônio Quaternário/química , Estereoisomerismo
9.
Mikrochim Acta ; 187(3): 178, 2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-32076848

RESUMO

Poly(glycidyl methacrylate)-co-(ethylene dimethacrylate) [poly(GMA-co-EDMA)] monoliths were prepared, and used as a support to attach gold nanoparticles (AuNP) via Au-S bond. Pepsin, acting as a chiral selector, was linked to the surface of the carboxyl-modified AuNP through a hydrochloride/N-hydroxysuccinimide coupling reaction. The material was characterized by scanning electron microscopy, energy dispersive X-ray spectrometry, transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and N2 adsorption-desorption isotherm. The pepsin@AuNP@poly(GMA-co-EDMA) monolith showed preferable enantioselectivity for hydroxychloroquine (HCQ), chloroquine (CHQ), hydroxyzine (HXY), labetalol (LAB), nefopam (NEF), clenbuterol (CLE), amlodipine (AML) and chlorpheniramine (CHL) in capillary electrochromatography (CEC). These racemic drugs were monitored at the maximum absorption wavelength (220 nm for HXQ, CHQ, HXY, LAB, NEF; 240 nm for AML; 215 nm for CLE, CHL). In comparison with the pepsin@poly(GMA-co-EDMA) monolith loaded with 5 nm AuNP, the pepsin@poly(GMA-co-EDMA) monolith loaded with 13 nm AuNP shows significantly enhanced enantiomeric resolution (HCQ: 0.62 → 3.45; CHQ: 0.60 → 2.11; HXY: 0.49 → 2.30; LAB: 1.03 → 2.45, 1.45 → 3.46, 0 → 0.67; NEF: 0.53 → 1.29; CLE: 0.42 → 0.56; AML: 0 → 0.83; CHL: 0.24 → 0.55). Pepsin concentration, buffer pH value, buffer concentration and applied voltage were investigated in detail with (±) HCQ and (±) HXY as model analytes. The reproducibility of intra-day, inter-day and column-to-column were explored, and found to be satisfactory. Graphical abstractSchematic presentation of the preparation of gold nanoparticles (AuNP) modified.


Assuntos
Eletrocromatografia Capilar/métodos , Ouro/química , Nanopartículas Metálicas/química , Humanos , Estereoisomerismo
10.
J Chromatogr A ; 1610: 460559, 2020 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-31564563

RESUMO

Mussel-inspired polydopamine (PDA) based materials are attractive as stationary phase for open-tubular capillary electrochromatography (OT-CEC) due to their many fascinating properties. However, all of the existing strategies for fabricating PDA based OT-CEC columns are limited in aqueous solutions. Consequently, it is a challenge work to directly immobilize the hydrophobic functional materials onto the inner wall of PDA modified capillary. Herein, by using the organic amine-inducing co-deposition strategy, a novel preparative method was developed for in situ one-pot synthesis of PDA/octadecylamine (ODA) co-deposited coating inside capillary as OT-CEC stationary phase. The formation and morphology of the PDA/ODA co-deposited coating were characterized by field emission scanning electron microscopy, atomic force microscope, attenuated total reflectance Fourier transform infrared spectroscopy and contact angle measurements. The separation performance of the fabricated PDA/ODA modified columns was validated by the separation of alkylbenzenes and steroids, which could achieve baseline separation with high separation efficiency. Their separation was found to follow the reversed phase chromatographic retention mechanism. The co-deposited column showed good stability and long lifetime. The repeatability of the PDA/ODA co-deposited column was also evaluated, with the relative standard deviations for intra-day and inter-day runs less than 5% and column-to-column runs less than 6%.


Assuntos
Aminas/química , Eletrocromatografia Capilar/métodos , Indóis/química , Polímeros/química , Acetonitrilos/química , Tampões (Química) , Cromatografia de Fase Reversa , Concentração de Íons de Hidrogênio , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier , Esteroides/análise
11.
J Chromatogr A ; 1606: 460425, 2019 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-31471135

RESUMO

In the present study separation of enantiomers of some chiral neutral and weakly acidic analytes was investigated on the chiral stationary phase (CSP) made by covalent immobilization of amylose tris(3-chloro-5-methylphenylcarbamate) onto silica in nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) in acetonitrile and aqueous acetonitrile. Few comparisons were made also between the enantioseparations in nano-LC and high-performance liquid chromatography (HPLC) with the chiral column of 4.6 × 250 mm dimension. Slightly better separation of enantiomers was observed in HPLC mode compared to nano-LC mode. It was shown that in the capillary columns packed with the CSP containing about 20% (w/w) of a covalently immobilized neutral chiral selector, amylose tris(3-chloro-5-methylphenylcarbamate), sufficient electroosmotic flow has been generated and enantioseparations with reasonable analysis time were performed also in CEC mode. It was shown once again that CEC offers a clear advantage over nano-LC from the viewpoint of plate numbers and peak resolution.


Assuntos
Amilose/análogos & derivados , Amilose/química , Eletrocromatografia Capilar/métodos , Cromatografia Líquida/métodos , Nanopartículas/química , Fenilcarbamatos/química , Dióxido de Silício/química , Cromatografia Líquida de Alta Pressão/métodos , Estereoisomerismo
12.
Electrophoresis ; 40(18-19): 2469-2477, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31268177

RESUMO

Via the ring-opening reaction of epoxy groups with epinephrine, a novel epinephrine functionalized polymethacrylate monolith with fumed silica nanoparticles has been fabricated for pressurized capillary electrochromatography. The preparation of epinephrine-modified monoliths has been optimized. In addition, morphology, electroosmotic flow, separation mechanism and column performance have been studied. The internal structure of the monolithic stationary phase was more uniform and the column efficiency increased after the incorporation of nanoparticles. With this column, satisfactory separation capability of aromatic compounds and alkaloids has been achieved and the column efficiency for naphthalene reached 138 696 plates/m. As for the real sample, 3 alkaloids were separated in Huanglian Shangqing capsules, a Chinese traditional medicine.


Assuntos
Eletrocromatografia Capilar/métodos , Epinefrina/química , Metacrilatos/química , Nanopartículas/química , Dióxido de Silício/química , Alcaloides de Berberina/análise , Alcaloides de Berberina/isolamento & purificação , Medicamentos de Ervas Chinesas
13.
J Chromatogr A ; 1603: 269-277, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31279475

RESUMO

In this study, a hydroxypropyl-ß-cyclodextrin (HP-ß-CD) functionalized monolithic capillary column was prepared by one-pot sequential reaction for the first time. The preparation of the HP-ß-CD functionalized monolithic column involves two sequential reactions in one pot: (1) the ring opening reaction between HP-ß-CD and glycidyl methacrylate (GMA) catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU); (2) the copolymerization of GMA-HP-ß-CD, ethylene dimethacrylate (EDMA) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS). A series of monolithic columns were successfully prepared by varying the temperature of the ring opening reaction or several copolymerization parameters (the type and composition of porogenic solvents, ratio of GMA-HP-ß-CD to EDMA and polymerization temperature). Then, the morphologies and structures of the resulting monolithic stationary phases were characterized by optical microscopy, scanning electron microscopy (SEM) and nitrogen adsorption analysis. Raman spectroscopy clearly indicated the successful bonding of HP-ß-CD onto the monolith. When the prepared chiral stationary phase (CSP) was applied for the separation of a set of racemic compounds by capillary electrochromatography (CEC), including racemic anticholinergic drugs, ß-adrenergic drugs, meptazinol and its intermediates, satisfactory separation selectivities were obtained. Additionally, the column also showed excellent separation abilities towards four flavanone glycosides epimers. Furthermore, the prepared monolithic columns exhibited satisfactory stability and reproducibilities of retention time, resolution and column efficiency. These results demonstrated the potential and usefulness of the developed one-pot sequential strategy in the preparation of other derivatized CD functionalized monolithic columns.


Assuntos
2-Hidroxipropil-beta-Ciclodextrina/química , Eletrocromatografia Capilar/métodos , Adsorção , Compostos de Epóxi/química , Metacrilatos/química , Nitrogênio/química , Permeabilidade , Polimerização , Polímeros/química , Espectroscopia de Prótons por Ressonância Magnética , Reprodutibilidade dos Testes , Análise Espectral Raman , Estereoisomerismo , Temperatura
14.
J Chromatogr Sci ; 57(8): 758-765, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31318022

RESUMO

The ability to detect catecholamines (CAs) and their metabolites is vital to understand the mechanism behind the neuronal diseases. Neurochemistry aims to provide an improved pharmacological, molecular and physiological understanding of complex brain chemistries by analytical techniques. Capillary electrophoresis (CE) is one such analytical technique that enables the study of various chemical species ranging from amino acids and peptides to natural products and drugs. CE can easily adapt the changes in research focus and in recent years remains an applicable technique for investigating neuroscience and single cell neurobiology. The prepared phenylalanine-based hydrophobic monolithic column, Polymethacryloyl-L-phenylalanine [PMAPA], was used as a stationary phase in capillary electrochromatography to separate CAs that are similar in size and shape to each other including dopamine (DA) and norepinephrine (NE) via hydrophobic interactions. Separation carried out in a short period of 17 min was performed with the electrophoretic mobility of 5.54 × 10-6 m2 V-1 s-1 and 7.60 × 10-6 m2 V-1 s-1 for DA and NE, respectively, at pH 7.0, 65% acetonitrile ratio with 100 mbar applied pressure by the developed hydrophobic monolithic column without needing any extra process such as imprinting or spacer arms to immobilize ligands used in separation.


Assuntos
Eletrocromatografia Capilar/métodos , Catecolaminas/isolamento & purificação , Metacrilatos/química , Fenilalanina/química , Eletrocromatografia Capilar/instrumentação , Catecolaminas/química , Dopamina/química , Dopamina/isolamento & purificação , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Norepinefrina/química , Norepinefrina/isolamento & purificação
15.
Mikrochim Acta ; 186(7): 462, 2019 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-31227901

RESUMO

This work shows that the metal organic framework (MOF) HKUST-1 of type Cu3(BTC)2 (also referred to as MOF-199; a face-centered-cubic MOF containing nanochannels) is a most viable coating for use in enantioseparation in capillary electrochromatography (CEC). A HKUST-1 modified capillary was prepared and characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, elemental analysis and thermogravimetric analysis. CEC-based enantioseparation of the basic drugs propranolol (PRO), esmolol (ESM), metoprolol (MET), amlodipine (AML) and sotalol (SOT) was performed by using carboxymethyl-ß-cyclodextrin as the chiral selector. Compared with a fused-silica capillary, the resolutions are improved (ESM: 1.79; MET: 1.80; PRO: 4.35; SOT: 1.91; AML: 2.65). The concentration of chiral selector, buffer pH value, applied voltage and buffer concentration were optimized, and the reproducibilities of the migration times and Rs values were evaluated. Graphical abstract Schematic presentation of the preparation of a HKUST-1@capillary for enantioseparation of racemic drugs. Cu(NO3)2 and 1,3,5-benzenetricarboxylic acid (BTC) were utilized to prepare the HKUST-1@capillary. Then the capillary was applied to construct capillary electrochromatography system with carboxymethyl-ß-cyclodextrin (CM-ß-CD) for separation of basic racemic drugs.


Assuntos
Anlodipino/isolamento & purificação , Estruturas Metalorgânicas/química , Metoprolol/isolamento & purificação , Propanolaminas/isolamento & purificação , Propranolol/isolamento & purificação , Sotalol/isolamento & purificação , Anlodipino/química , Eletrocromatografia Capilar/instrumentação , Eletrocromatografia Capilar/métodos , Metoprolol/química , Propanolaminas/química , Propranolol/química , Sotalol/química , Estereoisomerismo , beta-Ciclodextrinas/química
16.
J Chromatogr A ; 1602: 481-488, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31230876

RESUMO

A covalent organic framework, Schiff base network-1 (SNW-1), was synthesized and incorporated into cellulase based poly(glycidyl methacrylate-co-ethylene dimethacrylate) (cellulase@poly(GMA-EDMA-SNW-1)) monolith to afford a novel chiral stationary phase for capillary electrochromatography (CEC). SNW-1 is attractive as a stationary phase for CEC because it not only features high surface areas but also provides conjugate structures and abundant amine groups to give π-π electrostatic stacking and hydrogen bonding property. Incorporation of SNW-1 into monolithic column could improve the column efficiency and increase the interactions between the tested racemates and the stationary phase thus significantly improved their CEC separation. The obtained monoliths were characterized by scanning electron microscopy, elemental analysis and nitrogen adsorption. Moreover, effects of SNW-1 concentration, immobilization pH of cellulase and CEC conditions were also investigated. Under the optimized conditions, the cellulase@poly(GMA-EDMA-SNW-1) monolith exhibited excellent enantioseparation performance for eight pairs of different classes of chiral drugs including ß-blockers, antihistamines and anticoagulants. Satisfactory repeatability was achieved with relative standard deviations for intra-day, inter-day and column-to-column runs less than 4.5%, and batch-to-batch runs less than 6.8%. The experiment results reveal that the combination of the versatile features of monoliths and unique properties of SNW-1 could be a promising strategy for chiral separation.


Assuntos
Eletrocromatografia Capilar/métodos , Estruturas Metalorgânicas/química , Polímeros/química , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Metilmetacrilatos/química , Nanopartículas/química , Nanopartículas/ultraestrutura , Reprodutibilidade dos Testes , Estereoisomerismo
17.
J Chromatogr A ; 1602: 474-480, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31202495

RESUMO

Evodiae Fructus is used as a traditional Chinese medicine for the treatment of several kinds of diseases with its bioactive constituents. In this study, a capillary electrochromatography-mass spectrometry (CEC-MS) method was developed to determine three bioactive compounds including evodiamine, rutaecarpine and limonin in Evodiae Fructus fruit. Home-developed monolithic columns with methyl-vinylimidazole functionalized organic polymer monolilth as stationary phases were used in CEC-MS with excellent separation selectivity and high efficiency. The CEC-MS methods provided 4-16 folds improvement of LODs when compared with CEC-UV method. The conditions, which could affect separation efficiency and detection sensitivity, were optimized. Under optimum conditions, baseline separation with high detection sensitivity was obtained. The method showed good linearity (R2 >0.99) of 0.8-160 µg mL-1 with low limits of detection of 0.15-0.31 µg mL-1. Relative standard deviations of migration time and relative peak areas were <13.89%. Recoveries of evodiamine, rutaecarpine and limonin in Evodiae Fructus fruit were tested and calculated, which ranged from 102% to 113%. Finally, the three bioactive compounds in Evodiae Fructus herb samples from different regions were analyzed and studied. It has been demonstrated that the developed method has great potential for quality control of Evodiae Fructus herb.


Assuntos
Eletrocromatografia Capilar/métodos , Evodia/química , Imidazóis/química , Espectrometria de Massas/métodos , Polímeros/química , Acetonitrilos/química , Amônia/química , Calibragem , Medicamentos de Ervas Chinesas/química , Eletrólitos/química , Frutas/química , Concentração de Íons de Hidrogênio , Alcaloides Indólicos/química , Limite de Detecção , Limoninas/química , Quinazolinas/química , Padrões de Referência , Reprodutibilidade dos Testes
18.
Artigo em Inglês | MEDLINE | ID: mdl-31176269

RESUMO

Plant polyphenols can form functional coatings on various materials through self-polymerization. In this paper, a series of modified capillary columns, which possess diversity of charge characteristics for modulating electroosmotic flow (EOF), were prepared by one-step co-deposition of gallic acid (GA), a plant-derived polyphenol monomer, and branched polyethyleneimine (PEI). The physicochemical properties of the prepared columns were characterized by Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy and scanning electron microscopy (SEM). The magnitude and direction of EOF of GA/PEI co-deposited columns were modulated by changing a series of coating parameters, such as post-incubation of FeCl3, co-deposition time, and deposited amounts of GA and PEI with different relative molecular mass (PEI-600, PEI-1800, PEI-10000, and PEI-70000). Furthermore, the separation efficiencies of the prepared GA/PEI co-deposited columns were evaluated by separations of small molecules, including organic acids, polar nucleotides, phenols, nucleic acid bases and nucleosides. Results indicated that modulating of EOF plays an important role in enhancing the separation performance and reversing the elution order of the analytes. Finally, the developed method was successfully applied to quantitative analysis of acidic compounds in four real samples. The recoveries were in the range of 73.5%-85.8% for citric acid, benzoic acid, sorbic acid, salicylic acid and ascorbic acid in beverage and fruit samples, 101.6%-104.9% for cinnamic acid, vanillic acid, and ferulic acid in Angelica sinensis sample, while 84.6%-97.8% for guanosine-5'-monophosphate, uridine-5'-monophosphate, cytosine-5'- monophosphate and adenosine-5'-monophosphate in Cordyceps samples. These results indicated that the co-deposition of plant polyphenol-inspired GA/PEI coatings can provide new opportunities for EOF modulation of capillary electrophoresis.


Assuntos
Eletrocromatografia Capilar/métodos , Eletro-Osmose/métodos , Ácido Gálico/química , Polietilenoimina/química , Eletrocromatografia Capilar/instrumentação , Eletro-Osmose/instrumentação , Peso Molecular , Ácidos Nucleicos/isolamento & purificação , Nucleosídeos/isolamento & purificação , Nucleotídeos/isolamento & purificação , Compostos Orgânicos/isolamento & purificação , Polimerização
19.
Methods Mol Biol ; 1985: 445-452, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31069751

RESUMO

Capillary electrochromatography is employed for the enantioseparation of α-amino acids and their derivatives. The synthesis and application of a covalently bonded chiral stationary phase containing (-)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as chiral selector is described. Enantioseparations are performed using methanol/Tris-citric acid (20 mM, pH 3.0-4.5) (20:80, v/v) as mobile phase.


Assuntos
Eletrocromatografia Capilar/métodos , Éteres de Coroa/química , Aminoácidos/química , Éteres de Coroa/síntese química , Concentração de Íons de Hidrogênio , Dióxido de Silício/química , Estereoisomerismo
20.
Anal Chim Acta ; 1067: 147-154, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31047146

RESUMO

Surfactant bilayers or admicelles at the solid surface-liquid interface inside 50-200 µm inner diameter (i.d.) open-tube fused-silica capillaries were developed as 'soft' stationary pseudophases for the liquid chromatographic (LC) separations of neutral and charged analytes. Admicelles were formed in-situ from buffered aqueous mobile phases with cetytrimethylammonium bromide at concentrations between the critical surface aggregation concentration and critical micelle concentration, which were determined by electroosmotic flow measurements using capillary electrophoresis. There were no micelles in the mobile phase solution. Also, there was no solid phase that is classically required in LC. Pressure and voltage driven modes or open-tubular admicellar liquid chromatography (OT-AMLC) and electrochromatography, respectively were proposed based on the separation of neutral analytes. The parameters (i.e., pH, concentration of surfactant, salt, and methanol in the mobile phase and capillary i.d.) that affected the surprising chromatographic effect of admicelles at the interface were investigated. The analytical performance of OT-AMLC for small molecules were found acceptable. Applications to environmental water and biological (HepG cell line metabolism media) samples analysis with appropriate sample preparation procedures were also conducted. The use of pseudophases at the solid surface-liquid interface could be a viable solution to problems associated with the use of solid stationary or support materials in nano- and micro-liquid chromatography and electrochromatography.


Assuntos
Eletrocromatografia Capilar/métodos , Micelas , Eletrocromatografia Capilar/instrumentação , Cetrimônio/química , Cromatografia Líquida , Meios de Cultura/química , Células Hep G2 , Humanos , Dióxido de Silício/química , Poluentes Químicos da Água/química
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