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1.
J Sep Sci ; 45(23): 4224-4235, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36189856

RESUMEN

In this study, three-dimensional flower-like tin disulfide materials were prepared, and a highly efficient dispersive solid-phase extraction method was developed using the obtained three-dimensional tin disulfide adsorbents for the preconcentration and determination of six endocrine-disrupting phenols in combination with high-performance liquid chromatography-ultraviolet detection. Several important experimental parameters influencing extraction efficiency were investigated, including the amount of adsorbent, ultrasound time, sample solution pH, sample volume, type of elution solvent, desorption time, and the number of desorption times. Under the optimized experimental conditions, the developed method showed good linearity with the determination coefficients of 0.993-0.998 in the linear range of 0.5-400 ng/ml and low limits of detection in the range of 0.15-1.0 ng/ml, as well as satisfactory intra-day and inter-day precisions with relative standard deviations of 0.1-9.8%. Finally, the proposed method was successfully applied for the enrichment and determination of trace endocrine-disrupting phenols in milk, tea beverage, and plastic bottled water samples, and acceptable recoveries were obtained from 70.1% to 119.1% under four different spiked concentration levels. The results showed that the three-dimensional tin disulfide materials had great potential for the extraction of endocrine-disrupting phenols contaminants in environmental and food samples.


Asunto(s)
Fenoles , Estaño , Extracción en Fase Sólida
2.
J Sep Sci ; 44(18): 3357-3365, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34270174

RESUMEN

Guanidinium-based ionic liquids possess lower toxicity and greater designability than commonly used species and have presented good performances in liquid-phase extraction and stationary phase for capillary gas chromatography. In the present work, a novel type of surface-confined guanidinium ionic liquid stationary phase was developed by bonding a hexaalkylguanidinium ionic liquid N,N,N',N'-tetramethyl-N",N"-diallylguanidinium bromide onto the surface of 3-mercaptopropyl modified silica. The obtained surface-confined guanidinium ionic liquid silica materials were characterized by elemental analysis, infrared spectroscopy and thermogravimetric analysis, and then packed as a high-performance liquid chromatography column for the evaluation of chromatographic retention behavior. Typical polar compounds were used to evaluate the separation performances, and the changes of retention with water content in mobile phase further suggested the hydrophilic interaction liquid chromatography retention mechanism. Moreover, the effect of different chromatographic factors (salt concentration, mobile phase pH, and column temperature) on retention was investigated with a series of compounds as test solutes to gain insights into the retention mechanism. The results indicated that the surface-confined guanidinium ionic liquid stationary phase exhibited a hydrophilic interaction liquid chromatography/anion-exchange mixed-mode retention behavior and possessed promising potential in separating a wide range of compounds as an alternative stationary phase for high-performance liquid chromatography.

3.
J Sep Sci ; 43(6): 1071-1079, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31883201

RESUMEN

Surface-bonded zwitterionic stationary phases have shown highlighted performances in separation of polar and hydrophilic compounds under hydrophilic interaction chromatography mode. So, it would be helpful to evaluate the characteristics of zwitterionic stationary phases with different arranged charged groups. The present work involved the preparation and comparison of three zwitterionic stationary phases. An imidazolium ionic liquid was designed and synthesized, and the cationic and anionic moieties respectively possessed positively charged imidazolium ring and negatively charged sulfonic groups. Then, the prepared ionic liquid, phosphorylcholine and an imidazolium-based zwitterionic selector were bonded on the surface of silica to obtain three zwitterionic stationary phases. The selectivity properties were characterized and compared through the relative retention of selected solute pairs, and different kinds of hydrophilic solutes mixtures were used to evaluate the chromatographic performances. Moreover, the zwitterionic stationary phases were further characterized by the modified linear solvation energy relationship model to probe the multiple interactions. All the results indicated that the types and arrangement of charged groups in zwitterionic stationary phases mainly affect the retention and separation of ionic or ionizable compounds, and for interaction characteristics the contribution from n and π electrons and electrostatic interactions displayed certain differences.

4.
Anal Bioanal Chem ; 407(1): 331-41, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25410638

RESUMEN

A method based on stop-flow two-dimensional liquid chromatography coupled with electrospray ionization mass spectrometry (2D LC-ESI MS) was established and applied to analyze triterpenoid saponins from the main root of ginseng. Due to the special structure of triterpenoid saponins (they contain polar sugar side chains and nonpolar aglycones), hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RPLC) were used for the two dimensions, respectively. A trap column was used to connect the two dimensions. The dilution effect, which is one of the main shortcomings of traditional comprehensive 2D LC methods, was largely avoided. The peak capacity of this system was 747 and the orthogonality was 56.6 %. Compared with one-dimensional HILIC or RP LC MS analysis, 257 and 185 % more mass spectral peaks (ions with intensities that were higher than 1,000) were obtained from the ginseng main root extracts, and 94 triterpenoid saponins were identified based on MS(n) information and summarized aglycone structures. Given its good linearity and repeatability, the established method was successfully applied to classify ginsengs of different ages (i.e., years of growth), and 19 triterpenoid saponins were found through statistical analysis to vary in concentration depending on the age of the ginseng.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Espectrometría de Masas/métodos , Panax/química , Extractos Vegetales/química , Saponinas/química , Triterpenos/química , Automatización , Cromatografía Líquida de Alta Presión/instrumentación , Extractos Vegetales/aislamiento & purificación , Raíces de Plantas/química , Saponinas/aislamiento & purificación , Triterpenos/aislamiento & purificación
5.
Anal Chem ; 85(23): 11585-92, 2013 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-24171488

RESUMEN

Ribosylated metabolites, especially modified nucleosides, have been extensively evaluated as cancer-related biomarkers. Boronate adsorbents are considered to be promising materials for extracting them from complex matrices. However, the enrichment of ribosylated metabolites in low abundance is still a challenge due to the limited capacity and selectivity of the existing boronate adsorbents. In this study, a novel type of magnetic nanoparticles named Fe3O4@SiO2@PEI-FPBA was synthesized by grafting polyethyleneimine (PEI) onto the surface of Fe3O4@SiO2 before modification by boronate groups. The high density of the amino groups on the PEI chains supplied a large number of binding sites for boronate groups. Thus, the adsorption capacity (1.34 ± 0.024 mg/g) of the nanoparticles, which is 6- to 7-fold higher than that of analogous materials, was greatly improved. The unreacted secondary amines and tertiary amines of the PEI enhanced the aqueous solubility of the nanoparticles, which could efficiently reduce nonspecific adsorption. The nanoparticles were able to capture 1,2 cis-diol nucleosides from 1000-fold interferences. Moreover, the flexible chains of PEI were favorable for effective enrichment and quick equilibration (<2 min). Finally, 60 ribose conjugates were enriched from human urine using the nanoparticles. Among them, 43 were identified to be nucleosides and other ribosylated metabolites. Nine low abundance modified nucleosides were detected for the first time. In conclusion, Fe3O4@SiO2@PEI-FPBA is an attractive candidate material for the highly selective enrichment of 1,2-cis-diol compounds.


Asunto(s)
Ácidos Borónicos/síntesis química , Magnetismo/métodos , Nanopartículas/química , Nucleósidos/química , Polietileneimina/síntesis química , ARN/química , Humanos , ARN/metabolismo
6.
J Chromatogr A ; 1689: 463771, 2023 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-36610188

RESUMEN

In this paper, several new multi-magnetic center magnetic ionic liquids (MMILs) were prepared with paramagnetic component simultaneously contained in both the cation and anion and used as extractants to establish a dispersive liquid-liquid microextraction (DLLME) approach followed by in-situ MMIL decomposition based back-extraction for the enrichment and determination of four parabens in beverages. The appropriate MMIL was selected by investigating the extraction performances of the obtained MMILs combined with high performance liquid chromatography-ultraviolet detection (HPLC-UV), and some other experimental factors were explored. Under the optimized DLLME conditions, the four parabens exhibited coefficients of determination (R2) above 0.9987 in the linear range of 0.1-500 ng·mL-1 for ethylparaben, propylparaben and butylparaben and 0.2-500 ng·mL-1 for methylparaben. The limits of detection (LODs) and limits of quantification (LOQs) were respectively within 0.03-0.06 ng·mL-1 and 0.1-0.2 ng·mL-1, and the relative standard deviations (RSDs) for intra-day and inter-day precision were below 10.8%. Moreover, the application of the developed MMIL-based DLLME method in beverage samples exhibited recoveries within 81.3%-112.1% with RSDs of 0.3%-13.1% at three different spiked levels.


Asunto(s)
Líquidos Iónicos , Microextracción en Fase Líquida , Parabenos/análisis , Microextracción en Fase Líquida/métodos , Cromatografía Líquida de Alta Presión/métodos , Límite de Detección , Fenómenos Magnéticos , Bebidas/análisis
7.
J Chromatogr A ; 1662: 462728, 2022 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-34902719

RESUMEN

In the present work, several new hydrophobic deep eutectic solvents (HDESs) were prepared with quaternary ammonium salts as hydrogen bond acceptors (HBAs) and salicylate esters as hydrogen bond donors (HBDs). Then, the obtained HDESs were used as extraction solvents to establish an ultrasound-assisted dispersive liquid-liquid microextraction method combined with high-performance liquid chromatography-ultraviolet detection technique for the determination of four endocrine-disrupting phenols (EDPs) compounds. One of the obtained HDESs composed of tetrabutylammonium chloride (N4444Cl) and methyl salicylate possessed a viscosity of 89.28 mPa•s lower than most reported ionic HDESs (>200 mPa•s), and the low viscous HDES was selected as the optimal extraction solvent. Several key parameters affecting the extraction efficiency were investigated, including the type and volume of HDES, ultrasound time, sample solution pH and salt addition. Under the optimized experimental conditions, the proposed method had good coefficients of determination (R2 > 0.9976) in the linear range of 0.5-400 µg•L-1, the limits of quantification and limits of detection respectively were 0.5-2.5 µg•L-1 and 0.25-1 µg•L-1, and the recoveries were in the range of 81.79-109.82%. Finally, the method was used for the preconcentration and determination of EDPs in different samples, including bottled water, tea beverage and milk.


Asunto(s)
Microextracción en Fase Líquida , Contaminantes Químicos del Agua , Animales , Bebidas , Disolventes Eutécticos Profundos , Límite de Detección , Leche/química , Fenoles , Solventes , Viscosidad , Agua , Contaminantes Químicos del Agua/análisis
8.
J Pharm Biomed Anal ; 219: 114903, 2022 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-35759827

RESUMEN

In the present work, a magnetic ionic liquid (MIL) ([Co(DMBG)2][Co(hfaca)3]) was designed and synthesized with both the cation and anion respectively containing a paramagnetic component. With the prepared MIL as the extraction solvent, a vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) method was developed and combined with back-extraction for the enrichment of five fluoroquinolone antibiotics (FQs). The MIL can be easily collected and separated from the aqueous phase under an external magnetic field due to the strong magnetic susceptibility and red color. Some experimental factors affecting the extraction efficiency were investigated, and the optimum extraction efficiency was obtained in a basic solution (pH=9) for the extraction process and with 2% (v/v) formic acid as the back-extraction solvent. Under the optimized extraction and back-extraction conditions, the proposed method was validated and exhibited good linearity with coefficients of determination (R2) above 0.9956 in the range of 2.5-800 ng·mL-1 and 5.0-800 ng·mL-1, low limits of detection (LODs) within 0.75-1.5 ng·mL-1 and satisfactory intra-day and inter-day precisions with relative standard deviations (RSDs) respectively less than 10.6% and 8.6%. Finally, the method was applied for the determination of five FQs in four samples of tap water, milk, honey and chicken, and good precision with RSDs of 0.5-9.5% and acceptable recoveries (73.8-114.3%) were obtained.


Asunto(s)
Líquidos Iónicos , Microextracción en Fase Líquida , Antibacterianos/análisis , Fluoroquinolonas/análisis , Límite de Detección , Microextracción en Fase Líquida/métodos , Fenómenos Magnéticos , Solventes , Agua
9.
Anal Methods ; 14(46): 4775-4783, 2022 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-36374117

RESUMEN

In this study, a new magnetic ionic liquid (MIL) was designed and prepared, containing a magnetic cation from the ligand N,N-dimethyl biguanide (DMBG) complexing with magnetic center Co2+ and a bis-trifluoromethanesulfonimide (NTf2-) anion. Using the MIL as the extraction solvent, a salting-out assisted dispersive liquid-liquid microextraction (SA-DLLME) combined with high performance liquid chromatography-ultraviolet detection (HPLC-UV) was established for the enrichment and detection of four parabens in environmental water samples. The one-factor-at-a-time experiment was employed to optimize the conditions affecting the extraction efficiency. Under the optimized extraction conditions, the limits of quantification (LOQs) of the four target analytes ranged from 2.0 ng mL-1 to 2.8 ng mL-1, and the coefficients of determination (R2) were above 0.9996 in the linear range of 2.8-400 ng mL-1. On the other hand, the method displayed good repeatability and accuracy with intra-day and inter-day relative standard deviations (RSDs) of 2.1-13.0% and recoveries of 82.0-114.6%. The established method was applied to real samples with recoveries within 81.6-125.4%, and the results demonstrated that the method was practical.


Asunto(s)
Líquidos Iónicos , Microextracción en Fase Líquida , Microextracción en Fase Líquida/métodos , Parabenos/análisis , Cloruro de Sodio , Fenómenos Magnéticos , Agua
10.
J Chromatogr A ; 1673: 463101, 2022 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-35525193

RESUMEN

In the present work, a type of biochar materials derived from carbonizing peanut shells were obtained and employed as the adsorbents of pipette-tip solid-phase extraction (PT-SPE) for the enrichment and determination of six endocrine-disrupting phenols (EDPs) in combination with high-performance liquid chromatography equipped with ultraviolet detector (HPLC-UV). Abundant aliphatic and aromatic carbon structures and functional groups from polar heteroatoms (N, O, S) were distributed in the low-cost and eco-friendly peanut shells-derived biochar materials and were favorable for the enrichment of target EDPs. Moreover, the theoretical calculation based on density functional theory (DFT) proved that the effective enrichment of EDPs in aqueous samples benefited from the effective adsorption on the peanut shells-derived biochar materials. The experimental factors influencing the extraction efficiency were investigated, including adsorbent amount, aspirating/dispensing cycles, the type of elution solvent and elution times, salt addition, sample solution pH and type and volume of washing solvent. Under the optimal conditions, the proposed PT-SPE method exhibited good linear relationship (R2 > 0.993) in the range of 0.5-400 µg/L and low limits of detections (LODs) from 0.25 to 2.5 µg/L, as well as good precision and accuracy with relative standard deviations (RSDs) of 0.3%-13.2% and recoveries of 83.5%-117.1%. Finally, the biochars-based miniaturized pretreatment method was employed for the determination of six EDPs in bottled water, milk, tea beverage and disposal plastic bag soaked solution with recoveries from 77.5% to 116.5%.


Asunto(s)
Leche , Fenoles , Animales , Arachis , Carbón Orgánico , Cromatografía Líquida de Alta Presión/métodos , Leche/química , Fenoles/análisis , Extracción en Fase Sólida/métodos , Solventes/análisis , Agua/análisis
11.
J Chromatogr A ; 1652: 462372, 2021 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-34246058

RESUMEN

In the present work, three-dimensional (3D) and flower-like SnS2 materials were coated on the surface of Fe3O4@nSiO2 through an in-situ growth method. The 3D architecture could avoid the accumulation and reaggregation with better stability and was beneficial for the exposure of more active sites. The prepared magnetic SnS2 composites were used for the enrichment of sulfonamide antibiotics (SAs), and various experimental parameters affecting the extraction efficiency were investigated. The results showed the equilibrium of extraction and desorption towards target SAs could be reached within 3 min by using the Fe3O4@nSiO2-SnS2 composites. Under optimized conditions, the proposed approach possessed good linearity in the range of 0.1-200 ng·mL-1 with correlation coefficients r2 above 0.9964 and low limits of detection (LODs) from 0.025 to 0.250 ng·mL-1 for the five target SAs. Moreover, good repeatability was obtained with the intra-day and inter-day precision in terms of relative standard deviations (RSDs) within 1.1%-10.8% and 7.4%-13.1%, and the recoveries under three spiked concentrations were between 81.8% and 119.7% with adequate accuracy. Different samples including tap water, milk and honey were collected for magnetic solid-phase extraction and determination of target SAs by using the obtained Fe3O4@nSiO2-SnS2 composites to demonstrate the utility. All the results indicated that the proposed method had great potential for effective preconcentration and determination of SAs in complex samples.


Asunto(s)
Antibacterianos , Técnicas de Química Analítica , Disulfuros , Extracción en Fase Sólida , Antibacterianos/aislamiento & purificación , Técnicas de Química Analítica/instrumentación , Técnicas de Química Analítica/métodos , Límite de Detección , Fenómenos Magnéticos
12.
Nat Commun ; 12(1): 813, 2021 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-33547305

RESUMEN

Metal-organic layers with ordered structure and molecular tunability are of great potential as heterogeneous catalysts due to their readily accessible active sites. Herein, we demonstrate a facile template strategy to prepare metal-organic layers with a uniform thickness of three metal coordination layers (ca. 1.5 nm) with graphene oxide as both template and electron mediator. The resulting hybrid catalyst exhibits an excellent performance for CO2 photoreduction with a total CO yield of 3133 mmol g-1MOL (CO selectivity of 95%), ca. 34 times higher than that of bulky Co-based metal-organic framework. Systematic studies reveal that well-exposed active sites in metal-organic layers, and facile electron transfer between heterogeneous and homogeneous components mediated by graphene oxide, greatly contribute to its high activity. This work highlights a facile way for constructing ultrathin metal-organic layers and demonstrates charge transfer pathway between conductive template and catalyst for boosting photocatalysis.

13.
J Chromatogr A ; 1559: 141-148, 2018 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-28734605

RESUMEN

The amide group modified silica materials are popular stationary phases for hydrophilic interaction liquid chromatography (HILIC). Meanwhile, surface-confined imidazolium ionic liquids (ILs) have been proved to be useful HILIC stationary phases and possess many unique properties. In this study, the synthesis of an amide-functionalized imidazolium IL was conducted which was then bonded onto silica surface to obtain a novel imidazolium-embedded amide stationary phase for HILIC. The combination of the amide group and imidazolium IL moiety might bring some advantages in selectivity or retention and therefore extended its applications. After characterizing the prepared IL and the resulting modified silica materials, the chromatographic performance and separation selectivity of the packed column were evaluated and compared with a commercial amide column. Then, the retention behavior was investigated through observing the retention factors at different chromatographic conditions using a wide range of compounds. Exceptionally, the prepared amide IL column exhibited superior separation performance towards complex samples such as flavonoids mixture, soybean flavonoids and human urine. All the results indicated that the novel amide IL column possessed an anion-exchange/HILIC mixed-mode retention mechanism and could be useful in the sample analysis as a promising candidate for HILIC stationary phase.


Asunto(s)
Flavonoides/análisis , Imidazoles/química , Líquidos Iónicos/química , Amidas/química , Cromatografía Líquida de Alta Presión , Flavonoides/aislamiento & purificación , Flavonoides/orina , Humanos , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Sales (Química)/química , Dióxido de Silicio/química , Glycine max/química , Glycine max/metabolismo
14.
J Chromatogr A ; 1420: 1-15, 2015 Nov 13.
Artículo en Inglés | MEDLINE | ID: mdl-26463427

RESUMEN

Based on their particular physicochemical characteristics, ionic liquids have been widely applied in many fields of analytical chemistry. Many types of ionic liquids were immobilized on a support like silica or monolith as stationary phases for liquid chromatography. Moreover, different approaches were developed to bond covalently ionic liquids onto the supporting materials. The obtained ionic liquid stationary phases show multi-mode mechanism including hydrophobic, hydrophilic, hydrogen bond, anion exchange, π-π, and dipole-dipole interactions. Therefore, they could be used in different chromatographic modes including ion-exchange, RPLC, NPLC and HILIC to separate various classes of compounds. This review mainly summarizes the immobilized patterns and types of ionic liquid stationary phases, their retention mechanisms and applications in the recent five years.


Asunto(s)
Cromatografía Liquida/métodos , Líquidos Iónicos/química , Dióxido de Silicio/química , Aniones , Interacciones Hidrofóbicas e Hidrofílicas
15.
J Chromatogr A ; 1375: 101-9, 2015 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-25512125

RESUMEN

To develop a novel hybrid monolithic column based on pentafluorobenzyl imidazolium bromide ionic liquid, a new ionic liquid monomer was synthesized from 1-vinylimidazole and pentafluorobenzyl bromide. By employing a facile one-step copolymerization of polyhedral-oligomeric-silsesquioxane-type (POSS) cross-linking agent and the home-made ionic liquid monomer, the hybrid monolithic columns were in situ fabricated in fused-silica capillary. The morphology of monolithic column was characterized by scanning electron microscope (SEM) and the chemical composition was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and elemental analysis. Excellent mechanical stability and slight swelling propensity were exhibited which was ascribed to the rigid hybrid monolithic skeleton. Reproducibility results of run-to-run, column-to-column, batch-to-batch and day-to-day were investigated and the RSDs were less than 0.46%, 1.84%, 3.96% and 3.17%, respectively. The mixed-mode retention mechanism with hydrophobic interaction, π-π stacking, ion-exchange, electrostatic interaction and dipole-dipole interaction was explored systematically using analytes with different structure types. Satisfied separation capability and column efficiency were achieved for the analysis of small molecular compounds such as alkylbenzenes, polycyclic aromatic hydrocarbons, nucleosides and halogenated compounds.


Asunto(s)
Cromatografía Liquida/métodos , Imidazoles/química , Líquidos Iónicos/química , Compuestos de Vinilo/química , Hidrocarburos Halogenados/aislamiento & purificación , Interacciones Hidrofóbicas e Hidrofílicas , Nucleósidos/aislamiento & purificación , Reproducibilidad de los Resultados , Dióxido de Silicio/química
16.
J Chromatogr A ; 1396: 62-71, 2015 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-25890438

RESUMEN

Two tricationic ionic liquids were prepared and then bonded onto the surface of supporting silica materials through "thiol-ene" click chemistry as new stationary phases for high-performance liquid chromatography. The obtained columns of tricationic ionic liquids were evaluated respectively in the reversed-phase liquid chromatography (RPLC) mode and hydrophilic interaction liquid chromatography (HILIC) mode, and possess ideal column efficiency of 80,000 plates/m in the RPLC mode with naphthalene as the test solute. The tricationic ionic liquid stationary phases exhibit good hydrophobic and shape selectivity to hydrophobic compounds, and RPLC retention behavior with multiple interactions. In the HILIC mode, the retention and selectivity were evaluated through the efficient separation of nucleosides and bases as well as flavonoids, and the typical HILIC retention behavior was demonstrated by investigating retention changes of hydrophilic solutes with water volume fraction in mobile phase. The results show that the tricationic ionic liquid columns possess great prospect for applications in analysis of hydrophobic and hydrophilic samples.


Asunto(s)
Cromatografía Líquida de Alta Presión/instrumentación , Dióxido de Silicio/química , Cromatografía de Fase Inversa/instrumentación , Química Clic , Flavonoides/aislamiento & purificación , Interacciones Hidrofóbicas e Hidrofílicas , Imidazoles/química , Líquidos Iónicos , Nucleósidos/aislamiento & purificación , Compuestos de Sulfhidrilo/química , Agua/química
17.
Chem Commun (Camb) ; 51(56): 11321-4, 2015 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-26084868

RESUMEN

A novel type of mesoporous SiO2@H4/D4 tagged azobenzene-COOH chemoselective nanoprobe was developed for comprehensive mapping of amino metabolites in complex biological samples with high specificity and sensitivity.


Asunto(s)
Aminoácidos/sangre , Aminoácidos/metabolismo , Compuestos Azo/química , Colorantes Fluorescentes/química , Nanopartículas/química , Dióxido de Silicio/química , Catecolaminas/sangre , Dipéptidos/sangre , Humanos , Tamaño de la Partícula , Poliaminas/sangre , Porosidad , Propiedades de Superficie
18.
J Chromatogr A ; 1330: 40-50, 2014 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-24484692

RESUMEN

In the present study, several geminal dicationic ionic liquids based on 1,4-bis(3-allylimidazolium)butane and 1,8-bis(3-allylimidazolium)octane in combination with different anions bromide and bis(trifluoromethanesulphonyl)imide were prepared and then bonded to the surface of 3-mercaptopropyl modified silica materials through the "thiol-ene" click chemistry as stationary phases for hydrophilic interaction chromatography (HILIC). Compared with their monocationic analogues, the dicationic ionic liquids stationary phases presented effective retention and good selectivity for typical hydrophilic compounds under HILIC mode with the column efficiency as high as 130,000 plates/m. Moreover, the influence of different alkyl chain spacer between dications and combined anions on the retention behavior and selectivity of the dicationic ionic liquids stationary phases under HILIC mode was displayed. The results indicated that the longer linkage chain would decrease the hydrophilicity and retention on the dicationic ionic liquid stationary phase, and while differently combined anions had no difference due to the exchangeability under the common HILIC mobile phase with buffer salt. Finally, the retention mechanism was investigated by evaluating the effect of chromatographic factors on retention, including the water content in the mobile phase, the mobile phase pH and buffer salt concentration. The results showed that the dicationic ionic liquids stationary phases presented a mixed-mode retention behavior with HILIC mechanism and anion exchange.


Asunto(s)
Compuestos Alílicos/química , Cromatografía Liquida/métodos , Imidazoles/química , Líquidos Iónicos/química , Tampones (Química) , Cationes , Química Clic , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Nucleósidos/análisis , Dióxido de Silicio , Compuestos de Sulfhidrilo/química , Agua
19.
J Chromatogr A ; 1360: 240-7, 2014 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-25129388

RESUMEN

Glucaminium-based ionic liquids are a new class of recently developed ionic liquids and prepared by functionalizing the amine group of N-methyl-d-glucamine, which renders them good hydrophilicity due to the presence of the glucose structure and charged quaternary ammonium group. In the present study, a glucaminium-based ionic liquid N,N-diallyl-N-methyl-d-glucaminium bromide was synthesized and subsequently bonded to the surface of 3-mercaptopropyl modified silica materials through "thiol-ene" click chemistry. The obtained stationary phase was characterized by elemental analysis and infrared spectroscopy, and then packed as a HPLC column. A mixture of five nucleosides was used to characterize the separation performance of the obtained column under HILIC mode and the column efficiency was determined with cytidine as the test solute, reaching 80,000plates/m. Then, the retention behavior was evaluated by investigating the effect of various chromatographic factors on retention of different types of solutes, and the results revealed that the developed surface-confined glucaminium-based ionic liquid stationary phase exhibited a hydrophilic interaction/anion-exchange mixed-mode retention mechanism. Finally, two mixtures of nucleotides and flavonoids were separated on the glucaminium-based ionic liquid column, respectively under hydrophilic interaction and hydrophilic interaction/anion-exchange mixed-mode chromatography. In conclusion, the multimodal retention capabilities of the glucaminium-based ionic liquid column could offer a wider range of retention behavior and flexible selectivity toward polar and hydrophilic compounds.


Asunto(s)
Cromatografía por Intercambio Iónico/métodos , Glucanos/química , Interacciones Hidrofóbicas e Hidrofílicas , Líquidos Iónicos/química , Aniones/química , Cromatografía por Intercambio Iónico/instrumentación , Cromatografía Liquida/métodos , Química Clic , Concentración de Iones de Hidrógeno , Nucleósidos , Dióxido de Silicio/química , Propiedades de Superficie
20.
J Chromatogr A ; 1276: 112-9, 2013 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-23313301

RESUMEN

Room temperature ionic liquids (RTILs) as stationary phases for gas chromatography (GC) have made great achievements in both research and applications over the last decades. Until now, all of the RTIL stationary phases reported have involved imidazolium, ammonium, pyrrolidinium, and phosphonium-based RTILs, and however, no publications are available using guanidinium-based ionic liquids (GBILs) as GC stationary phases except two preliminary reports from our group. In the present work, three hexaalkyl GBILs stationary phases, namely N, N,N',N'-tetramethyl-N″, N″-dioctylguanidinum hexafluophosphate (DOTMG-PF(6)), N,N,N',N'-tetramethyl-N″, N″-dioctylguanidinium bis (trifluoromethylsulfonyl) imide (DOTMG-NTf(2)), and N,N,N',N'-tetraoctyl-N″, N″-dimethylguanidinium bis (trifluoromethylsulfonyl) imide (TODMG-NTf(2)), were synthesized and used as stationary phases for GC separation after they were statically coated onto the inner walls of fused-silica capillary columns. The evaluation of DOTMG-PF(6) and TODMG-NTf(2) as GC stationary phases is reported here for the first time, whereas additional results on the DOTMG-NTf(2) stationary phase are added here on the basis of our previous report. In this work, McReynolds constants and Abraham solvation system constants are used to evaluate the average polarity and the solvation properties of the GBILs stationary phases for GC separation, respectively. The results show that the GBILs stationary phases exhibit medium polarity with an average polarity of 293-390, and that the major molecular interactions of the GBILs with analytes are dipole/polarizable interactions, H-bond basicity and dispersion forces, etc. After this, the separation performance and thermal stability of the GBILs stationary phases were evaluated, showing that these stationary phases achieve excellent separation for analytes of great variety covering hydrocarbons, alcohols, esters, aldehydes, ketones, amines, amides and aromatics, and exhibit different retention behaviors from the most widely used GC stationary phases such as polyethylene glycol (PEG-20M) and 5% phenyl-95% dimethylpolysiloxane (SE-54) in terms of resolution and elution order, and good thermal stability (at least up to 250°C). The present work demonstrates that the GBILs stationary phases possess excellent separation performance and thermal stability, and may be applicable as a new type of GC stationary phases for separation of complex samples.


Asunto(s)
Cromatografía de Gases/métodos , Guanidina/química , Líquidos Iónicos , Cromatografía de Gases/instrumentación , Temperatura
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