Home About us Contact
|
Home About us Contact | ||
|
|
||
Separation Systems (separation + system)
Selected AbstractsAn Aptamer-Based Bound/Free Separation System for Protein DetectionELECTROANALYSIS, Issue 11 2009Mieko Fukasawa Abstract Aptamer hybridizes with its complementary strand. However, the complementary strand has difficulties to hybridize with the aptamer bound to a target because the aptamer forms higher-order structures. Exploiting this property, we developed simple bound/free separation systems for thrombin and IgE detection. The complementary strand was immobilized onto beads and the aptamer was labeled with pyrroquinoline quinone glucose dehydrogenase (PQQGDH). In the absence of a target, the aptamer is trapped by beads, whereas in the presence of a target, the aptamer bound to the target is not trapped. Thus the aptamer-target complexes can be recovered easily and detected by PQQGDH activity. This system allow the detection of 270,pM thrombin and 1,nM IgE. [source] Cationic and anionic lipid-based nanoparticles in CEC for protein separationELECTROPHORESIS, Issue 11 2010Christian Nilsson Abstract The development of new separation techniques is an important task in protein science. Herein, we describe how anionic and cationic lipid-based liquid crystalline nanoparticles can be used for protein separation. The potential of the suggested separation methods is demonstrated on green fluorescent protein (GFP) samples for future use on more complex samples. Three different CEC-LIF approaches for protein separation are described. (i) GFP and GFP N212Y, which are equally charged, were separated with high resolution by using anionic nanoparticles suspended in the electrolyte and adsorbed to the capillary wall. (ii) High efficiency (800,000 plates/m) and peak capacity were demonstrated separating GFP samples from Escherichia coli with cationic nanoparticles suspended in the electrolyte and adsorbed to the capillary wall. (iii) Three single amino-acid-substituted GFP variants were separated with high resolution using an approach based on a physical attached double-layer coating of cationic and anionic nanoparticles combined with anionic lipid nanoparticles suspended in the electrolyte. The soft and porous lipid-based nanoparticles were synthesized by a one-step procedure based on the self-assembly of lipids, and were biocompatible with a large surface-to-volume ratio. The methodology is still under development and the optimization of the nanoparticle chemistry and separation conditions can further improve the separation system. In contrast to conventional LC, a new interaction phase is introduced for every analysis, which minimizes carry-over and time-consuming column regeneration. [source] Enantioselective analysis of pheniramine in urine by charged CD-mediated CZE provided with a fiber-based DAD and an on-line sample pretreatment by capillary ITPELECTROPHORESIS, Issue 15 2007Jozef Marák Abstract Application potentialities of CZE on-line coupled with capillary ITP and DAD to the identification and determination of trace concentration levels (,g/L) of pheniramine (PHM) enantiomers and their metabolites present in complex ionic matrices of biological origin (urine) are shown. An enhanced (enantio)selectivity of the CZE separation system obtained by the addition of carboxyethyl-,-CD (CE-,-CD) to the carrier electrolyte provided CZE conditions for a reliable identification of similar/identical DAD spectra of structurally related compounds (PHM enantiomers and their metabolites) in clinical urine samples differing in qualitative and quantitative composition of sample matrix constituents. A high sample loadability (a 30,,L sample injection volume), partial sample clean-up (removing macroconstituents from the sample), and preconcentration of the analytes in ITP stage resulted in the decrease of concentration LOD for PHM enantiomers in urine to 5.2 and 6.8,,g/L (2.2×10,8 and 2.8×10,8,mol/L), without using any sample pretreatment technique. The background correction and smoothing procedure applied to the raw DAD spectra provided analytically relevant DAD spectra of PHM enantiomers and their metabolites also when they were present in urine sample (30,,L injection volumes of ten-times diluted urine sample) at a 9×10,8,mol/L concentration. DAD spectra of PHM enantiomers present in urine samples matched their reference spectra with reasonable certainties. DAD spectra of PHM metabolites were compared with the reference spectra of PHM enantiomers and a good match was found which indicates the similarities in the structures of enantiomers and their metabolites detected in the urine samples. This fact allows performing the quantitative analyses of PHM metabolites in the urine samples by applying the calibration parameters of PHM enantiomers also for PHM metabolites and the results show the possibilities of using the ITP,CZE,DAD combination for the direct analysis of PHM enantiomers and/or their metabolites in urine without any sample pretreatment. ITP,CZE,DAD method with oppositely charged selector is suggested to use in clinical research as it provides favorable performance parameters including sensitivity, linearity, precision, recovery, and robustness with minimal demands on sample preparation. [source] A self-contained polymeric 2-DE chip system for rapid and easy analysisELECTROPHORESIS, Issue 18 2006Keisuke Usui Abstract We developed a polymeric 2-DE chip system. The chip consisted of an IEF region, an SDS-PAGE region, a valveless connection port, and a sample introduction port. A "junction structure" as a valveless connection port, which allowed separating and connecting the first- and second-dimensional gels, was fabricated between their regions. A "solution inlet" as a sample introduction port was fabricated to perform the liquid and sample introductions without solution leakage. Simultaneous sample monitoring was performed using the on-chip detection system. The performances of the system were demonstrated using commercially available proteins as a standard specimen and tissue-extracted proteins as the real samples. All procedures were employed without any movement of relocation part. This new 2-D separation system realized improved labor-intensive operations and a reduced experimental time. [source] Profiling of polar metabolites in biological extracts using diamond hydride-based aqueous normal phase chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2009Damien L. Callahan Abstract Highly polar metabolites, such as sugars and most amino acids are not retained by conventional RP LC columns. Without sufficient retention low concentration compounds are not detected due ion suppression and structural isomers are not resolved. In contrast, hydrophilic interaction chromatography (HILIC) and aqueous normal phase chromatography (ANP) retain compounds based on their hydrophilicity and therefore provides a means of separating highly polar compounds. Here, an ANP method based on the diamond hydride stationary phase is presented for profiling biological small molecules by LC. A rapid separation system based upon a fast gradient that delivers reproducible chromatography is presented. Approximately 1000 compounds were reproducibly detected in human urine samples and clear differences between these samples were identified. This chromatography was also applied to xylem fluid from soyabean (Glycine max) plants to which 400 compounds were detected. This method greatly increases the metabolite coverage over RP-only metabolite profiling in biological samples. We show that both forms of chromatography are necessary for untargeted comprehensive metabolite profiling and that the diamond hydride stationary phase provides a good option for polar metabolite analysis. [source] Separation and quantification of 9-(alkylthio)acridines by capillary micellar electrokinetic chromatography and capillary liquid chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2007Jana Nejmanová Abstract Various thioacridine derivatives are potential chemotherapeutics against various diseases which are intensively synthesized, characterized, and investigated by many research groups. Efficient, fast, and reliable separation and quantification methods for their analysis are still to be developed. MEKC and capillary LC (CLC) were applied for the separation and quantification of five highly hydrophobic, weakly basic, and structurally similar 9-(alkylthio)acridines. Since the common anionic and cationic surfactants failed to separate the strongly hydrophobic thioacridines by MEKC, sodium cholate was used in an alkaline BGE and successfully employed for their fast separation. In CLC, the weakly basic nature of the thioacridines necessitated use of LiChrosorb RP-select B sorbent as the stationary phase, which combined with a very simple mobile phase methanol/water yielded an efficient chromatographic separation system. Both, the MEKC and CLC optimized separation methods were then applied to quantify the thioacridines within a concentration range of 1.0×10,5,1.0×10,3 mol/L and the obtained experimental results were critically compared. In practical terms, the MEKC analytical method can quantify the analytes much faster but with a lower reliability while the CLC method performs slower analysis with a higher repeatability of the experimental results. [source] Determination of oxalate in beer by zone electrophoresis on a chip with conductivity detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2003Marián Masár Abstract The use of a poly(methylmethacrylate) capillary electrophoresis chip, provided with a high sample load capacity separation system (a 8500 nL separation channel combined with a 500 nL sample injection channel) and a pair of on-chip conductivity detectors, for zone electrophoresis (ZE) determination of oxalate in beer was studied. Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the chip were suppressed and electrophoresis was a dominant transport process in the separations performed on the chip. A low pH of the carrier electrolyte (3.8), implemented by aspartic acid and bis-tris propane, provided an adequate selectivity in the separation of oxalate from anionic beer constituents and, at the same time, also a sufficient sensitivity in its conductivity detection. Under our working conditions, this anion could be detected at a 0.5 ,mol/L concentration also in samples containing chloride (a major anionic constituent of beer) at a 1800 higher concentration. Such a favorable analyte/matrix concentration ratio made possible accurate and reproducible [typically, 2,5% relative standard deviation (RSD) values of the peak areas of the analyte in dependence on its concentration in the sample] determination of oxalate in 500 nL volumes of 20,50-fold diluted beer samples. Short analysis times (about 200 s), minimum sample preparation, and reproducible migration times of this analyte (0.5,1.0% RSD values) were characteristic for ZE on the chip. [source] Establishment of a PF2D-MS/MS platform for rapid profiling and semiquantitative analysis of membrane protein biomarkersPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 11 2008Hyoung-Joo Lee Abstract Current proteome profiling techniques have identified relatively few mammalian membrane proteins despite their numerous important functions. To establish a standard throughput-potential profiling platform for membrane proteins, Triton X-100-solubilized rat liver microsomal proteins were separated on a 2-D separation system (2-D liquid phase fractionation (PF2D)) in two different pH ranges (4.0,8.5 and 7.0,10.5). This system produced 182 proteins with more than two transmembrane domain (TMD), including 16,TMDs with high confidence. Comparative 2-D liquid maps with high resolution and reproducibility have been constructed for liver microsome from the phenobarbital (PB) treated rats. PF2D was also found to be useful for the semiquantification of some representative cytochrome P450 family proteins (e.g., cytochrome P450 2B2) that were induced by PB treatment compared with untreated controls. Thus, the combination of both high-detection capacity and rapid preliminary semiquantification in a PF2D platform could become a standard system for the routine analysis of membrane proteins. [source] Unstable Operation in an Acetaldehyde Purification TowerCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2004F. Abdolahi Abstract There are many reasons, such as an inappropriate control system, improper hydraulic design, and operational faults, which can make a tower unstable. In this case, with the aid of simulation and checks on the control system, it has been confirmed using the foaming test that instability is due to foaming in the system. The method described in this article can be used for any separation system with instability problems. [source] Capillary Electrophoresis for the Simultaneous Determination of Metals by Using Ethylenediamine Tetraacetic Acid as Complexing Agent and Vancomycin as Complex SelectorCHINESE JOURNAL OF CHEMISTRY, Issue 12 2006Jirasak Threeprom Abstract A new separation system of capillary electrophoresis for the simultaneous determination of metals by using ethylenediamine tetraacetic acid (EDTA) as complexing agent and employing vancomycin as complex selector was described. The Z-shape cell capillary electrophoresis was used to enhance the sensitivity for the determination of the complexes of Cu(II), Ni(II), Co(II) and Fe(III) with EDTA. The partial filling method (co-current mode) was used in order to increase the selectivity of the electrophoretic method, meanwhile vancomycin was not present at the detector path during the detection of metal-EDTA complexes. The vancomycin concentration, phosphate concentration and pH of the buffer strongly influenced mobility, resolution and selectivity of the studied analytes. Under the optimal condition, the relative standard deviations (n=5) of the migration time and the peak area were less than 3.14% and 7.35%, respectively. Application of the Z-shape cell capillary electrophoresis method with UV detection and vancomycin loading led to the reliable determination of these metal ions in tap water and the recoveries were97%,101%. The detection limits based on a signal to noise ratio of 3:1 were found in the range of 2,10 µg·L,1. [source] Inhibitory effects of N -acetylcysteine on the functional responses of human eosinophils in vitroCLINICAL & EXPERIMENTAL ALLERGY, Issue 5 2007M. Martinez-Losa Summary Background Oxidative stress appears to be relevant in the pathogenesis of inflammation in allergic diseases like bronchial asthma. Eosinophils are oxidant-sensitive cells considered as key effectors in allergic inflammation. Objective The aim of this work was to study the effects of the clinically used antioxidant N -acetyl- l -cysteine (NAC) on the functional responses of human-isolated eosinophils. Methods Human eosinophils were purified from the blood of healthy donors by a magnetic bead separation system. The effects of NAC were investigated on the generation of reactive oxygen species (chemiluminescence and flow cytometry), Ca2+ signal (fluorimetry), intracellular glutathione (GSH; flow cytometry), p47phox,p67phox translocation (Western blot) and eosinophil cationic protein (ECP) release (radioimmunoassay). Results NAC (0.1,1 mm) inhibited the extracellular generation of oxygen species induced by N -formyl- l -methionyl- l -leucyl- l -phenylalanine (fMLP) and eotaxin (in the presence of IL-5) with ,logIC50 values of 3.61±0.03 and 3.36±0.09, respectively. Also, the intracellular generation of hydrogen peroxide was virtually abolished by NAC (0.5,1 mm). NAC (1 mm) did not alter the fMLP-induced Ca2+ signal but augmented the eosinophil content of reduced GSH and inhibited p47phox,p67phox translocation. NAC inhibited the release of ECP (,90% inhibition at 1 mm) from fMLP-activated eosinophils. Conclusion Inhibition by NAC of human eosinophil functions in vitro is potentially useful in the treatment of allergic inflammation. [source] An Aptamer-Based Bound/Free Separation System for Protein DetectionELECTROANALYSIS, Issue 11 2009Mieko Fukasawa Abstract Aptamer hybridizes with its complementary strand. However, the complementary strand has difficulties to hybridize with the aptamer bound to a target because the aptamer forms higher-order structures. Exploiting this property, we developed simple bound/free separation systems for thrombin and IgE detection. The complementary strand was immobilized onto beads and the aptamer was labeled with pyrroquinoline quinone glucose dehydrogenase (PQQGDH). In the absence of a target, the aptamer is trapped by beads, whereas in the presence of a target, the aptamer bound to the target is not trapped. Thus the aptamer-target complexes can be recovered easily and detected by PQQGDH activity. This system allow the detection of 270,pM thrombin and 1,nM IgE. [source] Capillary and microchip electrophoresis in microdialysis: Recent applicationsELECTROPHORESIS, Issue 1 2010Elizabeth Guihen Abstract The theme of this review is to highlight the importance of microscale electrophoretic-based separation systems in microdialysis (,D). The ability of CE and MCE to yield very rapid and highly efficient separations using just nanolitre volumes of microdialysate samples will also be discussed. Recent advances in this area will be highlighted, by illustration of some exciting new applications while the need for further innovation will be covered. The first section briefly introduces the concept of ,D sampling coupled with electrophoresis-based separation and the inherent advantages of this approach. The following section highlights some specific applications of CE separations in the detection of important biomarkers such as low-molecular-weight neurotransmitters, amino acids, and other molecules that are frequently encountered in ,D. Various detection modes in CE are outlined and some of the advantages and drawbacks thereof are discussed. The last section introduces the concepts of micro-total analysis systems and the coupling of MCE and ,D. Some of the latest innovations will be illustrated. The concluding section reflects on the future of this important chemical alliance between ,D and CE/MCE. [source] Comparison of low temperature mixed refrigerant cycles for separation systemsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2009M. Mafi Abstract Numerous mixed refrigerant cycles (MRCs) were developed in the past several decades in different applications. In this paper, two sets of low temperature MRCs are developed and simulated for a typical olefin plant utilizing a mixture of methane, ethane, propane and nitrogen as cycle working fluid to replace the pure ethylene refrigeration cycle that is used in conjunction with propylene refrigeration cycle in conventional plants. The key parameters of the cycles including mixture compositions and operating pressure levels are optimized to meet the objective of minimum shaftwork in compressor. The results show that different cycle configuration has different optimal mixture composition and low and high operating pressures. The results of exergy analysis reveal that the main location of the exergy loss in the cycles is the heat exchanger system. Also, the Carnot factor versus heat flow diagram is provided to identify the distribution of inefficiencies in the heat exchangers for each cycle. The simulation results show that MRCs can improve the thermodynamic performance of refrigeration system using the optimal working fluid mixture composition, optimal high and low operating pressures and optimal arrangement of the cycle components. Copyright © 2008 John Wiley & Sons, Ltd. [source] Liquid membrane technology: fundamentals and review of its applicationsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2010M. F. San Román Abstract OVERVIEW: During the past two decades, liquid membrane technology has grown into an accepted unit operation for a wide variety of separations. The increase in the use of this technology owing to strict environmental regulations and legislation together with the wider acceptance of this technology in preference to conventional separation processes has led to a spectacular advance in membrane development, module configurations, applications, etc. IMPACT: Liquid membrane technology makes it possible to attain high selectivity as well as efficient use of energy and material relative to many other separation systems. However, in spite of the known advantages of liquid membranes, there are very few examples of industrial applications because of the problems associated with the stability of the liquid membrane. APPLICATIONS: Liquid membrane technology has found applications in the fields of chemical and pharmaceutical technology, biotechnology, food processing and environmental engineering. On the other hand, its use in other fields, such as in the case of hydrogen separation, the recovery of aroma compounds from fruits, the application of ionic liquids in the membrane formulation, etc., is increasing rapidly. Copyright © 2009 Society of Chemical Industry [source] Attainable reaction and separation processes from a superstructure-based methodAICHE JOURNAL, Issue 6 2003Patrick Linke Generic technology for the synthesis and optimization of integrated reaction and separation systems uses rich superstructure formulations comprising two types of generic synthesis units with flexible representation modes. A reactor/mass exchanger unit enables a detailed representation of the reaction and mass exchange phenomena. A conceptual representation of separation systems is facilitated through separation task units. All possible process designs featuring reaction, reactive separation, and separation are embedded in the superstructure formulations as combinations of generic units and their features. The design options are explored using stochastic optimization techniques suitable for this class of problems. The flexible representation framework enables technology applications to general process design, as well as design subproblems including reactor and reactive separator design. Four case studies demonstrate the ability of the methodology to address a wide variety of process systems and to deliver design novelty. [source] Comparison of HPLC enantioseparation of substituted binaphthyls on CD-, polysaccharide- and synthetic polymer-based chiral stationary phasesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2010Lucie Loukotková Abstract Retention and enantioseparation behavior of ten 2,2,-disubstituted or 2,3,2,-trisubstituted 1,1,-binaphthyls and 8,3,-disubstituted 1,2,-binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on ,-CD, polysaccharides (tris(3,5-dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans -1,2-diamino-cyclohexane, trans -1,2-diphenylethylenediamine and trans -9,10-dihydro-9,10-ethanoanthracene-(11S,12S)-11,12-dicarboxylic acid CSPs). Normal-, reversed-phase and polar-organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non-identical groups and a chiral axis in the 1,2, position had the greatest impact on the enantiomeric discrimination. The 8,3,-disubstituted 1,2,-binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose-based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system. [source] Immobilized trypsin systems coupled on-line to separation methods: Recent developments and analytical applicationsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2005Gabriella Massolini Abstract The ability to rapidly and efficiently digest and identify an unknown protein is of great utility for proteome studies. Identification of proteins via peptide mapping is generally accomplished through proteolytic digestion with enzymes such as trypsin. Limitations of this approach consist in manual sample manipulation steps and extended reaction times for proteolytic digestion. The use of immobilized trypsin for cleavage of proteins is advantageous in comparison with application of its soluble form. Enzymes can be immobilized on different supports and used in flow systems such as immobilized enzyme reactors (IMERs). This review reports applications of immobilized trypsin reactors in which the IMER has been integrated into separation systems such as reversed-phase liquid chromatography or capillary electrophoresis, prior to MS analysis. Immobilization procedures including supports, mode of integration into separation systems, and methods are described. [source] Speciation of oxidation states of elements by capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2003Marek Trojanowicz Abstract Progress made in the last five years in the application of capillary electrophoresis methods to chemical speciation of elements is reported on the basis of over 100 literature references. The main trends observed include development of new on- and off-capillary derivatization methods, application of new detection methods, and especially coupling of CE separation systems to powerful atomic spectroscopy and mass spectrometry instruments with various ionization techniques, providing either a sensitive element-specific detection method or a third dimension for high performance separation. Besides numerous CZE and MEKC capillary electrophoresis methods only very few examples of CE speciation with capillary electrochromatography can be found. Concerning the chemical forms of elements determined, the new procedures developed are mostly focused on redox speciation of various oxidation states of elements, metal-bound high molecular compounds, and organometallic species. [source] Investigation of the separability of thaumatin by capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2003Milena Vespalcová Abstract The electrophoretic behaviour of the highly basic protein thaumatin was explored in strongly acid (pH 2) and mildly acid (pH 4.5) separation systems using both bare and coated fused silica capillaries. The separation selectivity for thaumatin I, thaumatin II, and for other sample constituents was insufficient for their baseline separation at pH 2 in an uncoated capillary because the separation efficiency was markedly lower than is common in the electrophoretic separations of proteins. A separation selectivity higher by up to one order of magnitude has been reached at pH 4.5. A pronounced asymmetry of zones, which impaired resolution at this pH, was effectively suppressed by coating of the capillary wall with a polymer. In fact, adsorption on the capillary coating always plays a contributory role whenever a good separation of thaumatin constituents is attained. This indicates that electrochromatographic separation systems based on capillaries coated with the layer of either cationic or hydrophilic uncharged polymer hold promise for the development of methods for thaumatin analysis. [source] Single run measurements of drug-protein binding by high-performance frontal analysis capillary electrophoresis and mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2005Hong Wan A novel drug-protein binding measurement method based on high-performance frontal analysis and capillary electrophoresis (HPFA/CE) is presented. A single run measurement approach is proposed to circumvent utilization of a calibration curve that is often performed with HPFA. A sensitive mass spectrometer is applied as a detector enabling the measurement of in vitro protein binding at lower drug concentrations. Unbound free fraction and binding constants can be determined by a single run measurement by consecutive injections of an internal drug standard, a buffer plug and a drug-protein mixture. Effects of injection volumes on peak height and plateau profile were investigated in two different separation systems, non-volatile buffer and volatile buffer, with UV and mass spectrometry detection, respectively. A simplified one-to-one binding model is employed to evaluate the proposed method by using both single and multiple drug concentrations to measure the unbound free fraction and calculate the binding constants of some selected compounds. The method is suitable for rapid and direct screening of the binding of a drug to a specific protein or drug-plasma protein binding. Copyright © 2005 John Wiley & Sons, Ltd. [source] A New Numerical Approach for a Detailed Multicomponent Gas Separation Membrane Model and AspenPlus SimulationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2005M. H. Murad Chowdhury Abstract A new numerical solution approach for a widely accepted model developed earlier by Pan [1] for multicomponent gas separation by high-flux asymmetric membranes is presented. The advantage of the new technique is that it can easily be incorporated into commercial process simulators such as AspenPlusTM [2] as a user-model for an overall membrane process study and for the design and simulation of hybrid processes (i.e., membrane plus chemical absorption or membrane plus physical absorption). The proposed technique does not require initial estimates of the pressure, flow and concentration profiles inside the fiber as does in Pan's original approach, thus allowing faster execution of the model equations. The numerical solution was formulated as an initial value problem (IVP). Either Adams-Moulton's or Gear's backward differentiation formulas (BDF) method was used for solving the non-linear differential equations, and a modified Powell hybrid algorithm with a finite-difference approximation of the Jacobian was used to solve the non-linear algebraic equations. The model predictions were validated with experimental data reported in the literature for different types of membrane gas separation systems with or without purge streams. The robustness of the new numerical technique was also tested by simulating the stiff type of problems such as air dehydration. This demonstrates the potential of the new solution technique to handle different membrane systems conveniently. As an illustration, a multi-stage membrane plant with recycle and purge streams has been designed and simulated for CO2 capture from a 500,MW power plant flue gas as a first step to build hybrid processes and also to make an economic comparison among different existing separation technologies available for CO2 separation from flue gas. [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] | ||||||||||