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Determination of 5-nitroimidazole residues in milk by capillary electrochromatography with packed C18 silica beds. Talanta 2015; 144:542-50. [DOI: 10.1016/j.talanta.2015.06.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 06/11/2015] [Accepted: 06/19/2015] [Indexed: 11/18/2022]
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2
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Hernández-Mesa M, D'Orazio G, Rocco A, García-Campaña AM, Blanco CC, Fanali S. Capillary electrochromatography-mass spectrometry for the determination of 5-nitroimidazole antibiotics in urine samples. Electrophoresis 2015. [PMID: 26200811 DOI: 10.1002/elps.201500126] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The separation of eight antibiotics belonging to 5-nitroimidazole family was carried out by means of CEC coupled with MS. Preliminary experiments were carried out with ultraviolet detection in order to select the proper stationary and mobile phase. Among the different stationary phases studied (namely Lichrospher C18, 5 μm particle size; Cogent(TM) Bidentate C18, 4.2 μm; Pinnacle II™ Phenyl, 3 μm; Pinnacle II™ Cyano, 3 μm), Cogent™ Bidentate C18 (4.2 μm) gave the best performance. For CEC-MS coupling, a laboratory assembled liquid-junction-nano-spray interface was used. In order to achieve a good sensitivity, special attention was paid to both optimization of the sheath liquid composition as well as selection of the injection mode. Under optimized CEC-ESI-MS conditions, the separation was accomplished within 22 min by using a column packed with a mixture of Bidentate C18:Lichrospher Silica-60 (5 μm) 3:1 w/w, an inlet pressure of 11 bar, a voltage of 15 kV, and a mobile phase composed by 45:10:45 v/v/v ACN/MeOH/water containing ammonium acetate (5 mM pH 5). A combined hydrodynamic and electrokinetic injection of 8 bar, 15 kV, and 96 s was adopted. The method was validated in terms of repeatability and intermediate precision of retention times and peak areas, linearity, and LODs and LOQs. RSDs values were <2.9% for retention times and <16.1% for peak areas in both intraday and interday experiments. LOQ values were between 0.09 and 0.42 μg/mL for all compounds. Finally, the method was applied to the determination of three most employed 5-nitroimidazole antibiotics (metronidazole, secnidazole, and ternidazole) in spiked urine samples, subjected to a SPE procedure. Recovery values in the 67-103% range were obtained. Furthermore, for the selected antibiotics, CEC-MS(2) spectra were obtained providing the unambiguous confirmation of these drugs in urine samples.
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Affiliation(s)
- Maykel Hernández-Mesa
- Istituto di Metodologie Chimiche, Consiglio Nazionale delle Ricerche, Monterotondo, Italy.,Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Granada, Spain
| | - Giovanni D'Orazio
- Istituto di Metodologie Chimiche, Consiglio Nazionale delle Ricerche, Monterotondo, Italy
| | - Anna Rocco
- Istituto di Metodologie Chimiche, Consiglio Nazionale delle Ricerche, Monterotondo, Italy
| | - Ana M García-Campaña
- Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Granada, Spain
| | - Carmen Cruces Blanco
- Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Granada, Spain
| | - Salvatore Fanali
- Istituto di Metodologie Chimiche, Consiglio Nazionale delle Ricerche, Monterotondo, Italy
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3
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Wei GT, Hsu CF, Liu FK, Chou FM. The Development of Reversed-Phase Capillary Electrochromatography for the Separation of Steroids. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200500104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Poole CF, Poole SK. Foundations of retention in partition chromatography. J Chromatogr A 2009; 1216:1530-50. [PMID: 19013576 DOI: 10.1016/j.chroma.2008.10.092] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 10/22/2008] [Accepted: 10/28/2008] [Indexed: 10/21/2022]
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Riveros T, Hanrahan G, Muliadi S, Arceo J, Gomez FA. On-capillary derivatization using a hybrid artificial neural network-genetic algorithm approach. Analyst 2009; 134:2067-70. [DOI: 10.1039/b909143b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Liu H, Zhuang X, Turson M, Zhang M, Dong X. Enrofloxacin-imprinted monolithic columns synthesized using reversible addition-fragmentation chain transfer polymerization. J Sep Sci 2008; 31:1694-701. [DOI: 10.1002/jssc.200700602] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Montes RE, Gomez FA, Hanrahan G. Response surface examination of the relationship between experimental conditions and product distribution in electrophoretically mediated microanalysis. Electrophoresis 2008; 29:375-80. [PMID: 18081199 DOI: 10.1002/elps.200700196] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This work presents the first known use of response surface methodology (RSM) in electrophoretically mediated microanalysis. This concept is demonstrated by examining the optimization of reaction conditions for the conversion of nicotinamide adenine dinucleotide to nicotinamide adenine dinucleotide, reduced form by glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) in the conversion of glucose-6-phosphate to 6-phosphogluconate. Experimental factors including voltage, enzyme concentration, and mixing time of reaction at the applied voltage were selected at three levels and tested in a Box-Behnken response surface design. Upon migration in a capillary under CE conditions, plugs of substrate and enzyme are injected separately in buffer and allowed to react at variable conditions. Extent of reaction and product ratios were subsequently determined by CE. The model predicted results are shown to be in good agreement (7.1% discrepancy difference) with experimental data. The use of chemometric RSM provides a direct relationship between electrophoretic conditions and product distribution of microscale reactions using CE, thereby offering a new and versatile approach to optimizing enzymatic experimental conditions.
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Affiliation(s)
- Ruth E Montes
- Department of Chemistry, California Lutheran University, Thousand Oaks, CA, USA
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Abstract
This review is concerned with the phenomenological fluid dynamics in capillary and chip electrochromatography (EC) using high-surface-area random porous media as stationary phases. Specifically, the pore space morphology of packed beds and monoliths is analyzed with respect to the nonuniformity of local and macroscopic EOF, as well as the achievable separation efficiency. It is first pointed out that the pore-level velocity profile of EOF through packed beds and monoliths is generally nonuniform. This contrasts with the plug-like EOF profile in a single homogeneous channel and is caused by a nonuniform distribution of the local electrical field strength in porous media due to the continuously converging and diverging pores. Wall effects of geometrical and electrokinetic nature form another origin for EOF nonuniformities in packed beds which are caused by packing hard particles against a hard wall with different zeta potential. The influence of the resulting, systematic porosity fluctuations close to the confining wall over a distance of a few particle diameters becomes aggravated at low column-to-particle diameter ratio. Due to the hierarchical structure of the pore space in packed beds and silica-based monoliths which are characterized by discrete intraparticle (intraskeleton) mesoporous and interparticle (interskeleton) macroporous spatial domains, charge-selective transport prevails within the porous particles and the monolith skeleton under most general conditions. It forms the basis for electrical field-induced concentration polarization (CP). Simultaneously, a finite and -- depending on morphology -- often significant perfusive EOF is realized in these hierarchically structured materials. The data collected in this review show that the existence of CP and its relative intensity compared to perfusive EOF form fundamental ingredients which tune the fluid dynamics in EC employing monoliths and packed beds as stationary phases. This addresses the (electro)hydrodynamics, associated hydrodynamic dispersion, as well as the migration and retention of charged analytes.
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Affiliation(s)
- Ivo Nischang
- Institut für Verfahrenstechnik, Otto-von-Guericke-Universität, Magdeburg, Germany
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Zheng J, Rizvi SAA, Shamsi SA, Hou J. Photopolymerized Sol‐Gel Monolithic Column for Capillary Electrochromatography (CEC) and CEC Coupled to Atmospheric Pressure Photoionization Mass Spectrometry. J LIQ CHROMATOGR R T 2007. [DOI: 10.1080/10826070601034238] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Jie Zheng
- a Department of Chemistry , Center of Biotechnology and Drug Design, Georgia State University , Atlanta, Georgia, USA
| | - Syed A. A. Rizvi
- a Department of Chemistry , Center of Biotechnology and Drug Design, Georgia State University , Atlanta, Georgia, USA
| | - Shahab A. Shamsi
- a Department of Chemistry , Center of Biotechnology and Drug Design, Georgia State University , Atlanta, Georgia, USA
| | - Jingguo Hou
- b Department of Clinical Sciences and Administration , College of Pharmacy, University of Houston, Texas Medical Center , Houston, Texas, USA
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Natishan TK. Recent Progress in the Analysis of Pharmaceuticals by Capillary Electrophoresis. J LIQ CHROMATOGR R T 2007. [DOI: 10.1081/jlc-200053014] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Theresa K. Natishan
- a Merck & Co., Inc. , Merck Research Laboratories, Analytical Research , Rahway, New Jersey, USA
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11
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Horiuchi K, Dutta P, Ivory CF. Electroosmosis with step changes in zeta potential in microchannels. AIChE J 2007. [DOI: 10.1002/aic.11275] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Hlushkou D, Khirevich S, Apanasovich V, Seidel-Morgenstern A, Tallarek U. Pore-Scale Dispersion in Electrokinetic Flow through a Random Sphere Packing. Anal Chem 2006; 79:113-21. [PMID: 17194128 DOI: 10.1021/ac061168r] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The three-dimensional velocity field and corresponding hydrodynamic dispersion in electrokinetic flow through a random bulk packing of impermeable, nonconducting spheres are studied by quantitative numerical analysis. First, a fixed bed with interparticle porosity of 0.38 is generated using a parallel collective-rearrangement algorithm. Then, the interparticle velocity field is calculated using the lattice-Boltzmann (LB) method, and a random-walk particle-tracking method is finally employed to model advection-diffusion of an inert tracer in the LB velocity field. We demonstrate that the pore-scale velocity profile for electroosmotic flow (EOF) is nonuniform even under most ideal conditions, including a negligible thickness of the electrical double layer compared to the mean pore size, a uniform distribution of the electrokinetic potential at the solid-liquid interface, and the absence of applied pressure gradients. This EOF dynamics is caused by a nonuniform distribution of the local electrical field strength in the sphere packing and engenders significant hydrodynamic dispersion compared to pluglike EOF through a single straight channel. Both transient and asymptotic dispersion behaviors are analyzed for EOF in the context of packing microstructure and are compared to pressure-driven flow in dependence of the average velocity through the bed. A better hydrodynamic performance of EOF originates in a still much smaller amplitude of velocity fluctuations on a mesoscopic scale (covering several particle diameters), as well as on the microscopic scale of an individual pore.
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Affiliation(s)
- Dzmitry Hlushkou
- Institut für Verfahrenstechnik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany
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Kasicka V. Recent developments in capillary electrophoresis and capillary electrochromatography of peptides. Electrophoresis 2006; 27:142-75. [PMID: 16307429 DOI: 10.1002/elps.200500527] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The article gives a comprehensive review on the recent developments in the applications of high-performance capillary electromigration methods, zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography, to analysis, preparation, and physicochemical characterization of peptides. The article presents new approaches to the theoretical description and experimental verification of electromigration behavior of peptides, covers the methodological aspects of capillary electroseparations of peptides, such as rational selection of separation conditions, sample preparation, suppression of peptide adsorption, new developments in individual separation modes, and new designs of detection systems. Several types of applications of capillary electromigration methods to peptide analysis are presented: conventional qualitative and quantitative analysis, purity control, determination in biomatrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid and sequence analysis, and peptide mapping of proteins. Some examples of micropreparative peptide separations are given and capabilities of capillary electromigration techniques to provide important physicochemical characteristics of peptides are demonstrated.
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Affiliation(s)
- Václav Kasicka
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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Courtois J, Fischer G, Sellergren B, Irgum K. Molecularly imprinted polymers grafted to flow through poly(trimethylolpropane trimethacrylate) monoliths for capillary-based solid-phase extraction. J Chromatogr A 2006; 1109:92-9. [PMID: 16376897 DOI: 10.1016/j.chroma.2005.12.014] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2005] [Revised: 11/29/2005] [Accepted: 12/02/2005] [Indexed: 10/25/2022]
Abstract
Monolithic molecularly imprinted polymers (mMIPs) have been synthesized in a novel way using a trimethylolpropane trimethacrylate core material photo-polymerized in situ in a 100 microm I.D. UV-transparent capillary and further photo-grafted to create specific cavities in the grafted layer. This polymerization technique allows the imprints to be directly created on the surface of the material using a minimum amount of template. Three different anaesthetics of similar structures (bupivacaine, mepivacaine and S-ropivacaine) were used as model target molecules to synthesize sample enrichment media. Hence, various mMIPs have been prepared and evaluated on a micro-system against each analyte in order to test the retention properties and cross-selectivities of the materials. The retention factors were determined and compared with the non-imprinted reference column (mNIP), yielding high imprinting factors together with good selectivity factors between the three analytes. A study with a pure enantiomeric target was carried out to assess the degree of stereo-specific imprinting for injection of racemic mixtures. Finally, one column was imprinted with an equimolar mixture of all three anaesthetics to provide further comprehension of the retention mechanism and accredit the possibility of using the material as a sample enrichment entity. Scanning electron microscopy (SEM), nitrogen absorption/desorption (BET) and mercury intrusion porosimetry were used to characterize the monolith and the mMIPs properties. Nuclear magnetic resonance (NMR) has been used to assess the similarities between the mMIP and mNIP.
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Hsieh YL, Chen TH, Liu CP, Liu CY. Titanium dioxide nanoparticles-coated column for capillary electrochromatographic separation of oligopeptides. Electrophoresis 2005; 26:4089-97. [PMID: 16252330 DOI: 10.1002/elps.200500462] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A novel column made through the condensation reaction of TiO2 nanoparticles (TiO2 NPs) with silanol groups of the fused-silica capillary is described. EOF measurements under various buffer constitutions were used to monitor the completion of reactions. The results indicated that the EOF was dependent on the interactions between buffers and the bonded TiO2 NPs. With formate/Tris buffer, EOF reversal at pH below 5 and cathodic EOF at pH above 5 were indicated. The pI of the bonded TiO2 NPs was found at approximately ph 5. Only cathodic EOF was illustrated by substituting the mobile phase with either glutamate or phosphate buffer. It was elucidated that both glutamate and phosphate buffer yield a negative charge layer on the surface of TiO2 NPs attributable to the formation of a titanium complex. The CEC performance of the column was tested with angiotensin-type oligopeptides. Some parameters that would affect the retention behavior were investigated. The interactions between the bonded phases and the analytes were explicated by epitomized acid-base functional groups of the oligopepetides and the speciation of the surface oxide in different pH ranges. The average separation efficiencies of 3.1 x 10(4) plates/m is readily achieved with a column of 70 cm (50 cm) x 50 mum ID under an applied voltage of 15 kV, phosphate buffer (pH 6.0, 40 mM), and UV detection at 214 nm.
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Affiliation(s)
- Yi-Ling Hsieh
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
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Mangelings D, Discry J, Maftouh M, Massart DL, Vander Heyden Y. Strategy for the chiral separation of non-acidic pharmaceuticals using capillary electrochromatography. Electrophoresis 2005; 26:3930-41. [PMID: 16167306 DOI: 10.1002/elps.200500079] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In completion of an earlier defined generic chiral screening approach, a generic separation strategy for basic, bifunctional, and neutral compounds was proposed and evaluated. This strategy adds to a previously defined strategy for acidic compounds. The screening experiment of the actual strategy used a mobile phase of 5 mM phosphate buffer pH 11.5/ACN (30/70 v/v), a temperature of 25 degrees C, and a voltage of 15 kV. The selected chiral stationary phases were Chiralpak AD-RH, Chiralcel OD-RH, Chiralcel OJ-RH, and Chiralpak AS-RH, all based on polysaccharide selectors. It was seen that 31 out of 48 test compounds were partially or baseline-resolved under screening conditions. After execution of the optimization steps of the strategy, this number increased to 41, with a total of 21 baseline-separated compounds. Combined with the results obtained from the acidic test set examined in the earlier defined strategy, of all tested compounds 82.5% showed enantioselectivity and 49.2% could be baseline-separated.
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Affiliation(s)
- Debby Mangelings
- Department of Pharmaceutical and Biomedical Analysis, Pharmaceutical Institute, Vrije Universiteit Brussel-VUB, Brussels, Belgium
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Zhang L, Zhang J, Wang H, Zhang L, Zhang W, Zhang Y. Analysis of flavonoids in leaves of Adinandra nitida by capillary electrochromatography on monolithic columns with stepwise gradient elution. J Sep Sci 2005; 28:774-9. [PMID: 15938186 DOI: 10.1002/jssc.200400080] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Extracts of Adinandra nitida leaves, known as Shiyacha in China, were analyzed by monolithic columns of capillary electrochromatography (CEC). To obtain good resolution within a short time, stepwise gradient elution of CEC was employed, and the effects of experimental parameters, such as the buffer, the gradient conditions, and the mode of injection were studied systematically. Under optimized conditions, analysis could be accomplished in 25 min on a monolithic rod of macroporous poly(butyl methacrylate-co-ethylene dimethacrylate). With two identified flavonoids, epicatechin and apigenin, as markers, a quality control method for Shiyacha and its relevant products was established. The calibration curves exhibited good linear behavior over the concentration range of two orders of magnitude. On combination with an on-line concentration technique, the detection limit of flavonoids could be decreased to 25 ng for apigenin.
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Affiliation(s)
- Lingyi Zhang
- National Chromatographic Research & Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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