Evaluation of carbon nanostructures as chiral selectors for direct enantiomeric separation of ephedrines by EKC

Moliner‐Martínez, Y.; Cárdenas, Soledad; Valcárcel, Miguel

doi:10.1002/elps.200600773

Cited by 66 publications

(62 citation statements)

References 27 publications

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“…This application of CNTs stems from their high adsorption capacities and surface areas (6). Single-walled and multiwalled CNTs were coated with surfactants and then used as the chiral selector phase in MEKC (7). Enantiomers of nonephedrine and ephedrine were separated with resolution ranging from 1.35 to 1.45.…”

Section: Technique Developments Separation Schemesmentioning

confidence: 99%

Capillary Electrophoresis in Bioanalysis

2008

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Science reports ∼4800 hits on capillary electrophoresis (CE) including 410 reviews. Because of the prominence of CE techniques in bioanalysis, we decided make them the focus of this review and selected 200 hundred papers representing advances in this field. The selected papers cover advances in CE theory, instrumentation, and methodologies that are specific to various analytes of biological origin or relevance. The group of analytes includes nucleic acids, proteins and peptides, carbohydrates, lipids, single cells, and bioparticles. In addition, we have included advances in the use of CE to define functional assays or to investigate biomolecular interactions. The use of microfabricated devices for CE analysis was not included because this is already covered in other review. Technique Developments Separation SchemesDetermining the velocity of the electroosmotic flow (EOF) and how it changes during an electrophoretic separation is still an important research topic. A simple method for EOF measurements using so-called thermal marks was reported (1). Here, a tungsten filament caused punctual heating at the capillary wall and caused a perturbation in the electrolyte concentration. A sequence of these "thermal marks" then migrated with the EOF until each mark reached and was detected by a conductivity detector. The feasibility of using thermal marks as internal EOF standards in different separation systems was thereby demonstrated.Isoelectric focusing separates amphoteric analytes such as proteins or peptides by the differences in their isoelectric points. Most of the reports on capillary isoelectric focusing (cIEF) describe an initial focusing phase after which the focused zones are mobilized and detected. A dynamic cIEF method for protein analysis was reported (2). This technique made it possible to control each protein's position and focused width by moving the pH gradient within the capillary through manipulation of the electric fields. An important advantage of this approach is the capability of collecting focused analytes from the central section, suggesting that there may be great potential for introducing selectively focused proteins to a second separation dimension such as LC or CE.Micellar electrokinetic capillary chromatography (MEKC) is typically incompatible with electrospray mass spectrometry (ESI-MS) because the nonvolatile surfactants in the micellar phase result in complicated adduct formation and loss of sensitivity during the electrospray process and because the presence of the organic solvent needed for electrospray may cause instability in the micellar phase. These drawbacks were overcome by using synthetic polymeric surfactants that can work as a pseudostationary phase and provide stable electrospray (3). The polymeric surfactant was made by polymerizing three amino acidderived (L-leucinol, L-isoleucinol, L-valinol) sulfated chiral surfactants. These polymeric

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Section: Technique Developments Separation Schemesmentioning

confidence: 99%

Capillary Electrophoresis in Bioanalysis

2008

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“…SC-MWCNTs in EKC demonstrated an inherent ability for the enantioseparation of the tested ephedrines after modification with SDS and sonication for 20 min [32]. The existence of chirality in the structures of SWCNTs and MWCNTs has been confirmed [32]. The use of sonication with a modification of MWCNTs played an important role to reveal the chirality in the structure of MWCNTs and hence, improved their inherent abilities for the enantioseparation in EKC.…”

Section: Mwcnts For Chiral Separation Of Pharmaceuticalsmentioning

confidence: 88%

“…The partial filling technique depends on adding a small amount of concentrated surfactant-carbon nanotubes to enhance the baseline resolution by the interaction between the side wall of CNTs and the racemic compounds [89]. SC-SWCNTs were not able to separate any enantiomer of the tested compounds when applied as a pseudo-stationary phase in EKC [32]. Chirality also exists in the structure of MWCNTs which mainly relies on the way that carbon nanotubes are arranged [32,90].…”

Section: Mwcnts For Chiral Separation Of Pharmaceuticalsmentioning

confidence: 99%

“…Several methods such as HPLC [91][92][93], GC [94], TLC [95] have been used to determine the quantity of ephedrine isomers but they suffered from poor accuracy, sensitivity and separation [93]. SC-MWCNTs in EKC demonstrated an inherent ability for the enantioseparation of the tested ephedrines after modification with SDS and sonication for 20 min [32]. The existence of chirality in the structures of SWCNTs and MWCNTs has been confirmed [32].…”

Section: Mwcnts For Chiral Separation Of Pharmaceuticalsmentioning

confidence: 99%

“…The use of nonfunctionalized CNTs for enantioseparations has been reported with nano-HPLC that utilises immobilization or encapsulation on polymer monolithic columns [46]. Functionalized CNTs with chiral selectors have been reported to enhance enantioseparations with HPLC [47], GC [37] and CE [32,48]. The use of unmodified and functionalized CNTs for achiral separations with HPLC [49] and CE [50] have also been reported.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

Hemasa

Naumovski

Maher

et al. 2017

Preprint

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Carbon nanotubes (CNTs) possess unique mechanical, physical, electrical and absorbability properties coupled with their nanometer dimensional scale that renders them extremely valuable for applications in many fields including nanotechnology and chromatographic separation. The aim of this review is to provide an updated overview about the applications of CNTs in chiral and achiral separations of pharmaceuticals, biologics and chemicals. Chiral SWCNTs and MWCNTs have been directly applied for the enantioseparation of pharmaceuticals and biologicals by using them as stationary or pseudostationary phases in chromatographic separation techniques such as high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and gas chromatography (GC). Achiral MWCNTs have been used for achiral separations as efficient sorbent objects in solid-phase extraction techniques of biochemicals and drugs. Achiral SWCNTs have been applied in achiral separation of biological samples. Achiral SWCNTs and MWCNTs have been also successfully used to separate achiral mixtures of pharmaceuticals and chemicals. Collectively, functionalized CNTs have been indirectly applied in separation science by enhancing the enantioseparation of different chiral selectors whereas, non-functionalized CNTs have shown efficient capabilities for chiral separations by using techniques such as encapsulation or immobilization in polymer monolithic columns.

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Micellar Electrokinetic Chromatography

Khaledi

2012

Encyclopedia of Drug Metabolism and Interactions

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Micellar electrokinetic chromatography (MEKC) has extended the scope of applications of capillary electrophoresis (CE) to separation of uncharged molecules. MEKC offers a combination of unique features of capillary zone electrophoresis (CZE) and reversed phase liquid chromatography (RPLC) such as high efficiency, rapid analysis, small sample size, and small solvent consumption. Another unique advantage of MEKC is the flexibility and versatility of incorporating chemical selectivity in the separation process through careful adjustment of the pseudo‐stationary phase composition. This chapter provides an overview of electrokinetic chromatography covering topics such as fundamental parameters influencing retention, selectivity, and resolution, an overview of different classes of pseudo‐stationary phases, detection, microfluidic platforms for MEKC separations, use of MEKC as part of two‐dimensional separation methods, and applications.

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Evaluation of carbon nanostructures as chiral selectors for direct enantiomeric separation of ephedrines by EKC

Cited by 66 publications

References 27 publications

Capillary Electrophoresis in Bioanalysis

Capillary Electrophoresis in Bioanalysis

Application of Carbon Nanotubes in Chiral and Achiral Separations of Pharmaceuticals, Biologics and Chemicals

Micellar Electrokinetic Chromatography

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