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High-resolution Separation (high-resolution + separation)
Selected AbstractsData processing in metabolic fingerprinting by CE-UV: Application to urine samples from autistic childrenELECTROPHORESIS, Issue 6 2007Ana C. Soria Abstract Metabolic fingerprinting of biofluids such as urine can be used to detect and analyse differences between individuals. However, before pattern recognition methods can be utilised for classification, preprocessing techniques for the denoising, baseline removal, normalisation and alignment of electropherograms must be applied. Here a MEKC method using diode array detection has been used for high-resolution separation of both charged and neutral metabolites. Novel and generic algorithms have been developed for use prior to multivariate data analysis. Alignment is achieved by combining the use of reference peaks with a method that uses information from multiple wavelengths to align electropherograms to a reference signal. This metabolic fingerprinting approach by MEKC has been applied for the first time to urine samples from autistic and control children in a nontargeted and unbiased search for markers for autism. Although no biomarkers for autism could be determined using MEKC data here, the general approach presented could also be applied to the processing of other data collected by CE with UV,Vis detection. [source] Monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for simultaneous separation of low- and high-molecular-weight compoundsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2009Andreas Greiderer Abstract Monolithic poly(1,2-bis(p -vinylphenyl)ethane (BVPE)) capillary columns were prepared by thermally initiated free radical polymerisation of 1,2-bis(p -vinylphenyl)ethane in the presence of inert diluents (porogens) and ,,,,-azoisobutyronitrile (AIBN) as initiator. Polymerisations were accomplished in 200 ,m ID fused silica capillaries at 65°C and for 60 min. Mercury intrusion porosimetry measurements of the polymeric RP support showed a broad bimodal pore-size-distribution of mesopores and small macropores in the range of 5,400 nm and flow-channels in the ,m range. N2 -adsorption (BET) analysis resulted in a tremendous enhancement of surface area (101 m2/g) of BVPE stationary phases compared to typical organic monoliths (,20 m2/g), indicating the presence of a considerable amount of mesopores. Consequently, the adequate proportion of both meso- and (small) macropores allowed the rapid and high-resolution separation of low-molecular-weight compounds as well as biomolecules on the same monolithic support. At the same time, the high fraction of flow-channels provided enhanced column permeability. The chromatographic performance of poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for the separation of biomolecules (proteins, oligonucleotides) and small molecules (alkyl benzenes, phenols, phenons) are demonstrated in this article. Additionally, pressure drop versus flow rate measurements of novel poly(1,2-bis(p -vinylphenyl)ethane) capillary columns confirmed high mechanical robustness, low swelling in organic solvents and high permeability. Due to the simplicity of monolith fabrication, comprehensive studies of the retention and separation behaviour of monolithic BVPE columns resulted in high run-to-run and batch-to-batch reproducibilities. All these attributes prove the excellent applicability of monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for ,-HPLC towards a huge range of analytes of different chemistries and molecular sizes. [source] Copper-coated microsprayer interface for on-line sheathless capillary electrophoresis electrospray mass spectrometry of carbohydratesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 3 2006Alina D. Zamfir Abstract A sturdy home-built sheathless CE/ESI-QTOF-MS system was developed and optimized for carbohydrate analysis. The interface and employed methodology provided a simple analytical solution to laborious CE/MS interfacing methods and to problems in characterization of complex carbohydrate mixtures that require high-resolution separation of the components. The CE/ESI interface, feasible in any MS laboratory, consists of a one-piece CE column having the CE terminus in-laboratory shaped as a microsprayer and coated with copper. The CE microsprayer was inserted into an in-house made stainless steel clenching device and the whole assembly was mounted onto a quadrupole TOF mass spectrometer. The analytical potential of the interface in terms of suitability, microsprayer performance, copper coat durability, ionization efficiency, spray stability, and sensitivity was tested first on a simple mixture of standard saccharides, which were separated, resolved, and detected with high separation efficiency. The approach was next assessed for the screening of a biological sample, a complex mixture of O -glycosylated sialylated amino acids from urine of a patient suffering from Schindler disease. Preliminary data allow this method to be considered as one of general applicability in structural glycobiology and glycomics and easy to be implemented for proteomic surveys as well. [source] The capillary electrophoresis separation of benzodiazepine drug using dextran sulfate and SDS as running bufferBIOMEDICAL CHROMATOGRAPHY, Issue 3 2004Yoshio Suzuki Abstract Capillary electrophoresis has been applied the analyses of many clinical drugs due to its rapid, high-resolution separation. In this study, electrokinetic chromatography involving the combination of SDS and dextran sulfate, which are synthetic polymers, was examined in order to obtain high resolution. Use of 2% dextran sulfate (10,000 molecular weight), 20 mm SDS running buffer containing boric acid solution (pH 9.2) and a silica capillary (inner diameter of 75 µm, effective length of 50 cm, 57 cm overall length) afforded separation of 10 kinds of benzodiazepines. The detection limit was 0.2 µg/mL; additionally, reproducibilities were de,ned as the peak height and migration time. The average peak height was 5.92% (2.46,17.61), whereas the average migration time was 0.44% (0.18,0.76; n = 5). This separations system can be applied to the analysis and measurement of other pharmaceuticals as well. Copyright © 2004 John Wiley & Sons, Ltd. [source] Capillary electrophoresis for the analysis of glycosaminoglycans and glycosaminoglycan-derived oligosaccharidesBIOMEDICAL CHROMATOGRAPHY, Issue 2 2002Wenjun Mao Glycosaminoglycans are a family of polydisperse, highly sulfated complex mixtures of linear polysaccharides that are involved in many life processes. Defining the structure of glycosaminoglycans is an important factor in elucidating their structure,activity relationship. Capillary electrophoresis has emerged as a highly promising technique consuming an extremely small amount of sample and capable of rapid, high-resolution separation, characterization and quantitation of analytes. Numerous capillary electrophoresis methods for analysis of intact glycosaminoglycans and glycosaminoglycan-derived oligosaccharides have been developed. These methods allow for both qualitative and quantitative analysis with a high level of sensitivity. This review is concerned with separation methods of capillary electrophoresis, detection methods and applications to several aspects of research into glycosaminoglycans and glycosaminoglycan-derived oligosaccharides. The importance of capillary electrophoresis in biological and pharmaceutical samples in glycobiology and carbohydrate biochemistry and its possible applications in disease diagnosis and monitoring chemical synthesis are described. Copyright © 2002 John Wiley & Sons, Ltd. [source] Enantioselective analysis of ketamine and its metabolites in equine plasma and urine by CE with multiple isomer sulfated ,-CDELECTROPHORESIS, Issue 15 2007Regula Theurillat Abstract CE with multiple isomer sulfated ,-CD as the chiral selector was assessed for the simultaneous analysis of the enantiomers of ketamine and metabolites in extracts of equine plasma and urine. Different lots of the commercial chiral selector provided significant changes in enantiomeric ketamine separability, a fact that can be related to the manufacturing variability. A mixture of two lots was found to provide high-resolution separations and interference-free detection of the enantiomers of ketamine, norketamine, dehydronorketamine, and an incompletely identified hydroxylated metabolite of norketamine in liquid/liquid extracts of the two body fluids. Ketamine, norketamine, and dehydronorketamine could be unambiguously identified via HPLC fractionation of urinary extracts and using LC-MS and LC-MS/MS with 1,mmu mass discrimination. The CE assay was used to characterize the stereoselectivity of the compounds' enantiomers in the samples of five ponies anesthetized with isoflurane in oxygen and treated with intravenous continuous infusion of racemic ketamine. The concentrations of the ketamine enantiomers in plasma are equal, whereas the urinary amount of R -ketamine is larger than that of S -ketamine. Plasma and urine contain higher S - than R -norketamine levels and the mean S -/R -enantiomer ratios of dehydronorketamine in plasma and urine are lower than unity and similar. [source] Studies on azaspiracid biotoxins.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2002In this study, the performance of monolithic columns was evaluated for ultrafast liquid chromatography/mass spectrometry (LC/MS) analyses and for high-resolution separations of several azaspiracid biotoxin analogs. Because of their high permeability, monolithic columns offer a number of advantages over conventional packed columns; viz., very low backpressures and relatively flat van Deemter curves at high flow rates. That is, very high flow rates can be used for ultrafast analyses or, by using longer than normal columns, high-resolution separations are possible. In a series of experiments, we varied the mobile phase flow rates between 1 and 8,mL/min, and studied their impact on chromatographic parameters such as retention time, resolution, number of plates and pressure. The chromatographic run times could be reduced to ca. 30,s without a significant change in the separation efficiency. A signal intensity comparison revealed interesting differences between atmospheric-pressure chemical ionization (APCI) and electrospray ionization (ESI) in their flow-rate dependency. An explanation with respect to the behavior as of a mass-flow or a concentration-dependent device is given in the paper. Additionally, the column length was varied between 10 and 70,cm. As a result, the number of theoretical plates increased substantially. In the example shown in the report, an increase from 13,000 plates for a 10-cm column to 80,000 for a 70-cm column is demonstrated. In addition, the potential of the monolithic columns for high-resolution LC/MS separations is shown for a complex biotoxin mixture, which was separated on a 40-cm-long column. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||