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1.
J Chromatogr A ; 1689: 463771, 2023 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-36610188

RESUMO

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.


Assuntos
Líquidos Iônicos , Microextração em Fase Líquida , Parabenos/análise , Microextração em Fase Líquida/métodos , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Fenômenos Magnéticos , Bebidas/análise
2.
Anal Methods ; 14(46): 4775-4783, 2022 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-36374117

RESUMO

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.


Assuntos
Líquidos Iônicos , Microextração em Fase Líquida , Microextração em Fase Líquida/métodos , Parabenos/análise , Cloreto de Sódio , Fenômenos Magnéticos , Água
3.
J Sep Sci ; 45(23): 4224-4235, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36189856

RESUMO

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.


Assuntos
Fenóis , Estanho , Extração em Fase Sólida
4.
J Pharm Biomed Anal ; 219: 114903, 2022 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-35759827

RESUMO

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.


Assuntos
Líquidos Iônicos , Microextração em Fase Líquida , Antibacterianos/análise , Fluoroquinolonas/análise , Limite de Detecção , Microextração em Fase Líquida/métodos , Fenômenos Magnéticos , Solventes , Água
5.
J Chromatogr A ; 1673: 463101, 2022 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-35525193

RESUMO

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%.


Assuntos
Leite , Fenóis , Animais , Arachis , Carvão Vegetal , Cromatografia Líquida de Alta Pressão/métodos , Leite/química , Fenóis/análise , Extração em Fase Sólida/métodos , Solventes/análise , Água/análise
6.
J Chromatogr A ; 1662: 462728, 2022 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-34902719

RESUMO

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.


Assuntos
Microextração em Fase Líquida , Poluentes Químicos da Água , Animais , Bebidas , Solventes Eutéticos Profundos , Limite de Detecção , Leite/química , Fenóis , Solventes , Viscosidade , Água , Poluentes Químicos da Água/análise
7.
J Sep Sci ; 44(18): 3357-3365, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34270174

RESUMO

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.

8.
J Chromatogr A ; 1652: 462372, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34246058

RESUMO

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.


Assuntos
Antibacterianos , Técnicas de Química Analítica , Dissulfetos , Extração em Fase Sólida , Antibacterianos/isolamento & purificação , Técnicas de Química Analítica/instrumentação , Técnicas de Química Analítica/métodos , Limite de Detecção , Fenômenos Magnéticos
9.
Nat Commun ; 12(1): 813, 2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33547305

RESUMO

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.

10.
J Sep Sci ; 43(6): 1071-1079, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31883201

RESUMO

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.

11.
J Chromatogr A ; 1559: 141-148, 2018 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-28734605

RESUMO

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.


Assuntos
Flavonoides/análise , Imidazóis/química , Líquidos Iônicos/química , Amidas/química , Cromatografia Líquida de Alta Pressão , Flavonoides/isolamento & purificação , Flavonoides/urina , Humanos , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Sais/química , Dióxido de Silício/química , Glycine max/química , Glycine max/metabolismo
12.
J Chromatogr A ; 1420: 1-15, 2015 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-26463427

RESUMO

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.


Assuntos
Cromatografia Líquida/métodos , Líquidos Iônicos/química , Dióxido de Silício/química , Ânions , Interações Hidrofóbicas e Hidrofílicas
13.
Chem Commun (Camb) ; 51(56): 11321-4, 2015 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-26084868

RESUMO

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.


Assuntos
Aminoácidos/sangue , Aminoácidos/metabolismo , Compostos Azo/química , Corantes Fluorescentes/química , Nanopartículas/química , Dióxido de Silício/química , Catecolaminas/sangue , Dipeptídeos/sangue , Humanos , Tamanho da Partícula , Poliaminas/sangue , Porosidade , Propriedades de Superfície
14.
J Chromatogr A ; 1396: 62-71, 2015 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-25890438

RESUMO

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.


Assuntos
Cromatografia Líquida de Alta Pressão/instrumentação , Dióxido de Silício/química , Cromatografia de Fase Reversa/instrumentação , Química Click , Flavonoides/isolamento & purificação , Interações Hidrofóbicas e Hidrofílicas , Imidazóis/química , Líquidos Iônicos , Nucleosídeos/isolamento & purificação , Compostos de Sulfidrila/química , Água/química
15.
Anal Bioanal Chem ; 407(1): 331-41, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25410638

RESUMO

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.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Espectrometria de Massas/métodos , Panax/química , Extratos Vegetais/química , Saponinas/química , Triterpenos/química , Automação , Cromatografia Líquida de Alta Pressão/instrumentação , Extratos Vegetais/isolamento & purificação , Raízes de Plantas/química , Saponinas/isolamento & purificação , Triterpenos/isolamento & purificação
16.
J Chromatogr A ; 1375: 101-9, 2015 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-25512125

RESUMO

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.


Assuntos
Cromatografia Líquida/métodos , Imidazóis/química , Líquidos Iônicos/química , Compostos de Vinila/química , Hidrocarbonetos Halogenados/isolamento & purificação , Interações Hidrofóbicas e Hidrofílicas , Nucleosídeos/isolamento & purificação , Reprodutibilidade dos Testes , Dióxido de Silício/química
17.
J Chromatogr A ; 1360: 240-7, 2014 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-25129388

RESUMO

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.


Assuntos
Cromatografia por Troca Iônica/métodos , Glucanos/química , Interações Hidrofóbicas e Hidrofílicas , Líquidos Iônicos/química , Ânions/química , Cromatografia por Troca Iônica/instrumentação , Cromatografia Líquida/métodos , Química Click , Concentração de Íons de Hidrogênio , Nucleosídeos , Dióxido de Silício/química , Propriedades de Superfície
18.
J Chromatogr A ; 1330: 40-50, 2014 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-24484692

RESUMO

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.


Assuntos
Compostos Alílicos/química , Cromatografia Líquida/métodos , Imidazóis/química , Líquidos Iônicos/química , Soluções Tampão , Cátions , Química Click , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Nucleosídeos/análise , Dióxido de Silício , Compostos de Sulfidrila/química , Água
19.
J Chromatogr A ; 1321: 65-72, 2013 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-24238711

RESUMO

A novel on-line two dimensional liquid chromatography (2D LC) based on stop-flow mode coupled with electrospray ionization mass spectrometry (ESI-MS) method was established to separate lipids in human plasma. Hydrophilic interaction liquid chromatography (HILIC) in the first dimension and reversed-phase liquid chromatography (RP LC) in the second dimension were used to separate the lipids into six fractions based on their polar head groups and further into peaks based on aliphatic chains, respectively. A new stop-flow interface with a trap column and an extra make-up flow was designed to construct this system and trap the components eluted from the first dimension. Moreover, the same length of analytical columns and similar flow rates were used in the first and second dimensions. Therefore, the new stop-flow 2D LC system can avoid the sensitivity decrease caused by the dilution effect, which is the shortcoming of comprehensive 2D LC. Three hundred and seventy-two lipids were identified from plasma extract using this 2D LC coupled with ESI-MS in positive mode, and 88 more lipids were detected than one-dimensional RP LC analysis. Peak capacity of this stop-flow 2D LC was 415, which is similar to that of comprehensive 2D LC. The linearity, repeatability and sensitivity of this method were satisfactory, which demonstrated that this method was also suitable for quantitative analysis. All these results indicated that this on-line 2D LC method is powerful for qualitative and quantitative analysis of complex lipids.


Assuntos
Cromatografia Líquida/métodos , Lipídeos/sangue , Espectrometria de Massas por Ionização por Electrospray/métodos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Padrões de Referência , Reprodutibilidade dos Testes
20.
Anal Chem ; 85(23): 11585-92, 2013 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-24171488

RESUMO

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.


Assuntos
Ácidos Borônicos/síntese química , Magnetismo/métodos , Nanopartículas/química , Nucleosídeos/química , Polietilenoimina/síntese química , RNA/química , Humanos , RNA/metabolismo
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