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Separation Techniques (separation + techniques)
Selected AbstractsElectric field-enhanced transport across phase boundaries and membranes and its potential use in sample pretreatment for bioanalysisELECTROPHORESIS, Issue 5 2010Pavel Kubá Abstract Separation techniques, such as electrodialysis, electroextraction, electro-membrane extraction and extraction across phase interfaces, are reviewed and discussed as methods for sample cleanup and preconcentration. This survey clearly shows that electromigration of ionic species across phase interfaces, especially across supported liquid membranes, may be very selective and is strongly dependent on the chemical composition of these interfaces. Thus, electric field-enhanced transport across chemically tailored liquid membranes may open new perspectives in preparative analytical chemistry. This review offers comprehensive survey of related literature and discussion of the topic, which may stimulate interest of experts and practitioners in bioanalysis. [source] Separation techniques for the analysis of artists' acrylic emulsion paintsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2004Dominique Scalarone Abstract Emulsion paints are complex chemical systems. The main problems in their characterization are related to the similarities in polymer composition and to the presence of many different types of additives. Thus high resolution separations, sensitivity, and response specificity are required to identify simultaneously the polymer matrix and the minor components. Especially surfactants and pigments are thought to affect significantly the properties of the paint layers during ageing and their identification is the first step in evaluating the behaviour of these products in working conditions. Representative samples of acrylic emulsion paints for artists have been investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and size exclusion chromatography-Fourier transform infrared spectroscopy (SEC-FTIR), and the results have been compared. All the analysed samples were bound in ethyl acrylate-methyl methacrylate, poly(EA-co-MMA), or n -butyl acrylate-methyl methacrylate, poly(nBA-co-MMA), copolymers. Two types of nonionic surfactants, ethoxylated fatty alcohols and alkylaryl polyethoxylates, commonly used as emulsifiers and dispersive agents have been identified, together with a number of organic pigments. [source] Liquid chromatography on chipELECTROPHORESIS, Issue 15 2010Karine Faure Abstract LC is one of the most powerful separation techniques as illustrated by its leading role in analytical sciences through both academic and industrial communities. Its implementation in microsystems appears to be crucial in the development of ,-Total Analysis System. If electrophoretic techniques have been widely used in miniaturized devices, LC has faced multiple challenges in the downsizing process. During the past 5 years, significant breakthroughs have been achieved in this research area, in both conception and use of LC on chip. This review emphasizes the development of novel stationary phases and their implementation in microchannels. Recent instrumental advances are also presented, highlighting the various driving forces (pressure, electrical field) that have been selected and their respective ranges of applications. [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] Achiral and chiral separations using MEKC, polyelectrolyte multilayer coatings, and mixed mode separation techniques with molecular micellesELECTROPHORESIS, Issue 6 2010Candace A. Luces Abstract Mixed mode (MM) separation using a combination of MEKC and polyelectrolyte multilayer (PEM) coatings is herein reported for the separation of achiral and chiral analytes. Many analytes are difficult to separate by MEKC and PEM coatings alone. Therefore, the implementation of a MM separation provides several advantages for overcoming the limitations of these well-established methods. In this study, it was observed that achiral separations using MEKC and PEM coatings individually resulted in partial resolution of eight very similar aryl ketones when the molecular micelle (sodium poly(N -undecanoyl- L -glycinate)) concentration was varied from 0.25 to 1.00%,w/v and the bilayer number varied from 2 to 4. However, when MM separation was introduced, baseline resolution was achieved for all eight analytes. In the case of chiral separations, temazepam, aminoglutethimide, benzoin, benzoin methyl ether, and coumachlor were separated using the three separation techniques. For chiral separations, the chiral molecular micelle, sodium poly(N -undecanoyl- L -leucylvalinate), was employed at concentrations of 0.25,1.50%,w/v for both MEKC and PEM coatings. Overall, the results revealed partial separation with MEKC and PEM coatings individually. However, MM separation enabled baseline separation of each chiral mixture. The separation of achiral and chiral compounds from different compound classes demonstrates the versatility of this MM approach. [source] Mercury speciation by CE: An updateELECTROPHORESIS, Issue 1 2009Petr Kubán Abstract This review provides an update on mercury speciation by CE. It includes a brief discussion on physicochemical properties, toxicity and transformation pathways of mercury species (i.e. methyl-, ethyl-, phenyl- and inorganic mercury) and outlines recent trends in Hg speciation by CE. CE is presented as a complementary technique to chromatographic separation techniques, especially in cases when speed, high efficiency and low sample volumes are required. The development of suitable sample preconcentration/isolation (sample stacking, ion exchange, liquid,liquid,liquid extraction, dual-cloud point extraction) to achieve low LODs for analysis of trace concentrations of mercury species in real samples is emphasized. Hyphenation of CE to element specific detectors (i.e. electrothermal atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry) is discussed as well as a potential of CE in interaction studies that may provide useful information on interaction of various Hg species with selected bio-macromolecules. [source] Cover Picture: Electrophoresis 18'2008ELECTROPHORESIS, Issue 18 2008Article first published online: 10 OCT 200 Issue number 18 is a Special Issue on "CE and CEC Innovations" consisting of 26 papers arranged into six sections. This Issue has one review article on the application of modern separation techniques in metabonomics, while the remaining articles pertain to microfluidics and miniaturization, novel trends in fundamentals and methodologies, various aspects of capillary coatings, open tubular CEC, MIP-CE, polar and nonpolar monoliths, MEEKC, MEKC and enantioseparations by CE and CEC. In addition Issue 18 has a "Fast Track" article on the CE-based assay of sirtuin enzymes. [source] Cover Picture: Electrophoresis 4/2008ELECTROPHORESIS, Issue 4 2008Article first published online: 22 FEB 200 This special issue on capillary electrochromatography (CEC) and electrokinetic capillary chromatography (EKC) provides the reader with the latest developments and improvements in these two closely related micro-column separation techniques. Issue 4 also offers one Fast Track article describing particularly important investigations in electrophoresis: Identification of unknown protein complex members by radiolocalization and analysis of low-abundance complexes resolved using native polyacrylamide gel electrophoresis Mahuya Bose, Brian P. Adams, Randy M. Whittal, Himangshu S. Bose [source] Dynamic analyte introduction and focusing in plastic microfluidic devices for proteomic analysisELECTROPHORESIS, Issue 1-2 2003Yan Li Abstract Isoelectric focusing (IEF) separations, in general, involve the use of the entire channel filled with a solution mixture containing protein/peptide analytes and carrier ampholytes for the creation of a pH gradient. Thus, the preparative capabilities of IEF are inherently greater than most microfluidics-based electrokinetic separation techniques. To further increase sample loading and therefore the concentrations of focused analytes, a dynamic approach, which is based on electrokinetic injection of proteins/peptides from solution reservoirs, is demonstrated in this study. The proteins/peptides continuously migrate into the plastic microchannel and encounter a pH gradient established by carrier ampholytes originally present in the channel for focusing and separation. Dynamic sample introduction and analyte focusing in plastic microfluidic devices can be directly controlled by various electrokinetic conditions, including the injection time and the applied electric field strength. Differences in the sample loading are contributed by electrokinetic injection bias and are affected by the individual analyte's electrophoretic mobility. Under the influence of 30 min electrokinetic injection at constant electric field strength of 500 V/cm, the sample loading is enhanced by approximately 10,100 fold in comparison with conventional IEF. [source] Applications of the Liquid Cyclone in Biological SeparationsENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 2 2004E. Ortega-Rivas Abstract Hydrocyclone technology has been suggested as a practical alternative in solid/liquid separations involving biological materials. This paper reviews applications of hydrocyclones in food processing, considering the non-Newtonian nature of most suspensions treated in the food industry. The hydrocyclone is easy to install and operate, and requires very limited space. It represents an unsophisticated piece of equipment, which runs in a continuous manner and it can be operated at lower costs than most solid/liquid separation techniques. Hydrocyclones have been used in the food industry for the refining of starch, to separate gossypol from cottonseed protein in cottonseed oil processing, and for some other applications, such as multi-stage mixer/separator extraction systems for soluble coffee. More recently, some other applications in biological systems, which will be discussed in this article, have also been tested. [source] Nanotube Surfactant Design: The Versatility of Water-Soluble Perylene BisimidesADVANCED MATERIALS, Issue 7 2010Claudia Backes Abstract The synthesis of perylene-based single-walled carbon nanotube (SWCNT) surfactants and the dispersion and exfoliation of SWCNTs in water by a variety of designed surfactants is investigated. The quality of the nanotube dispersions is evaluated by optical absorption and emission spectroscopy, zeta-potential measurements and statistical atomic force microscopy (AFM). Significantly the dispersion efficiency can be increased at higher pH, as water solubility of the surfactants is ensured by peripheral derivatization with carboxyl-functionalized first- and second-order Newkome dendrimers. Even at very low perylene concentrations of 0.1,g L,1 and a nanotube-to-surfactant ratio of 1:1, the nanotube supernatant after centrifugation contains up to 73% of the pristine material with exfoliation degrees (the number of fractions of individualized nanotubes NI/NT) of up to 76%. The adsorption of the perylene core to the nanotube scaffold is indicated by red-shifted perylene-absorption and SWCNT-emission features except for the smallest perylene amphiphile, where solubilization is presumably based on a micellar arrangement. The nanotube fluorescence is significantly altered and reduced in intensity compared to nanotubes dispersed in sodium dodecylbenzene sulfonate (SDBS) being strongly dependent on the structure of the perylene surfactant. We attribute this observation to the homogeneity of the surfactant coverage, e.g., the supramolecular arrangement onto the nanotube backbone. This study represents a step forward in understanding the structure,property relationship of nanotube surfactants. Furthermore high-quality nanotube dispersions with increased degrees of exfoliation are highly desirable, as the efficiency of nanotube separation techniques relies on highly individualized samples. [source] Efficient MILP formulations for the simultaneous optimal peptide tag design and downstream processing synthesisAICHE JOURNAL, Issue 9 2009João M. Natali Abstract Novel and efficient linear formulations are developed for the problem of simultaneously performing an optimal synthesis of chromatographic protein purification processes, and the concomitant selection of peptide purification tags, that result in a maximal process improvement. To this end, two formulations are developed for the solution of this problem: (1) a model that minimizes both the number of chromatographic steps in the final purification process flow sheet and the composition of the tag, by use of weighted objectives, while satisfying minimal purity requirements for the final product; and (2) a model that attempts to find the maximal attainable purity under constraints on the maximum number of separation techniques and tag size. Both models are linearized using a previously developed strategy for obtaining optimal piecewise linear approximations of nonlinear functions. Proposed are models to two case studies based on protein mixtures with different numbers of proteins. Results show that the models are capable of solving to optimality all the implemented cases with computational time requirements of under 1 s, on average. The results obtained are further compared with previous nonlinear and linear models attempting to solve the same problem, and, thus, show that the approach represents significant gains in robustness and efficiency. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Behaviour of polysorbate 20 during dialysis, concentration and filtration using membrane separation techniquesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2008Hanns-Christian Mahler Abstract During formulation development of a therapeutic protein, combinations of buffers, pH and excipients need to be tested. As the protein bulk solution used for formulation development usually contains a buffer component at a defined pH and potentially one or more excipients already, this bulk requires to be processed. In case low concentrations of non-ionic surfactants, for example polysorbate 20, are already present in the bulk, the surfactant needs to be removed in lab-scale for further development use. The scope of the work was to study the behaviour of low concentrations of polysorbate 20 during membrane separation processes. The first part focuses on evaluating the behaviour of polysorbate 20 during a dialysis process, whereas the second part analyses concentration changes of polysorbate during a membrane concentration process using a stirred cell. The third part analyses potential membrane absorption of polysorbate at sterilizing-grade filters. In conclusion, it was found that polysorbate could not be significantly reduced during a dialysis process and accumulated during a membrane concentration process in unreproducable manner. During sterile filtration, no significant influence on the concentration of polysorbate was measurable. In any case, it is recommendable to quantify the concentration of polysorbate during critical membrane process steps in pharmaceutical industry. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:764,774, 2008 [source] Capillary electrophoresis applied to proteomic analysisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2009Bryan R. Fonslow Abstract In the postgenomic era, proteomics has become a dominant field for identifying and quantifying the complex protein machinery of the cell. The expression levels, posttranslational modifications, and specific interactions of proteins control the biology of such processes as development, differentiation, and signal transduction. Studies of the proteins involved in these processes often lead to a better understanding of biology and of human disease. Powerful separation techniques and sensitive detection methods enable researchers to untangle these complicated networks of processes. CE coupled with either MS or LIF are two of the techniques that make this possible. This review will cover proven CE-based methods for proteomics on the cell and tissue level and their application in biological and clinical studies, relevant new developments in enabling technology such as microfluidic CE-MS demonstrated on model systems, and comment on the future of CE in proteomics. [source] Utilisation of separation methods in the analysis of chemical warfare agentsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2006Barbora Papou Abstract Chemical warfare agents and their degradation products represent a broad group of compounds with different chemical properties (polarity, volatility, thermostability, etc.). These chemicals often have to be detected and determined in complex matrices and therefore highly efficient separation techniques hyphenated to selective and sensitive detectors play an indispensable role. This review offers an overview of selected papers devoted to the title subject. It cannot be considered as a comprehensive literature compilation but should allow the reader to obtain an insight into the application of separation techniques in the important area of human protection and control of chemical weapons. [source] Characterization of Azerbaijani and Croatian brown naphthalaneJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2005Andja Alajbeg Abstract In spite of the fact that noncolored (nonaromatic) naphthalane containing high sterane content has been proved as bioactive and efficient in the treatment of psoriasis vulgaris, brown naphthalanes, which contain aromatics, are still in use. Thousands of patients, who have been passing through the therapy, deserve thorough and permanent study of brown naphthalanes. For that reason, two frequently used brown naphthalane preparations, one of the Azerbaijani (N1) and the other of the Croatian (N2) origin, were studied. The samples underwent the study by means of GC, OT LC, and normal-phase HPLC, as separation techniques. In addition, some bulk properties, elemental composition, and group composition by 1H NMR were determined. GC-MS served in compound types, especially in sterane detection. Both of the samples were found to be unresolved complex mixtures, relatively poor in n -alkanes. Isoalkanes, cycloalkanes, and aromatic compounds, in a great variety of isomers and homologs, made the majority of both of the samples. N1 was a dark, viscous, nontransparent fluid with a strong petroleum smell. Aromatics, which made 53% mass by OT LC and 54% mass by 1H NMR were found to be composed of mono-, di-, and tri+-aromatic compounds. Tri+-aromatic compounds were three to four times more abundant in N1 than in N2. Beside hydrocarbons, N1 comprised some organic compounds with polar functional groups. Also, some asphaltenes were found in it. N1 contained well-presented steranes, which are thought to be bioactive naphthalane ingredients. N2 was a pale brown liquid, with smell similar to gasoline. It contained somewhat lower percentage of aromatics (46% mass) and comparatively lower percentage of tri+ fused aromatics among which carcinogens might be expected. N2 was almost purely composed of hydrocarbons. It seemed to contain low content of steranes due to relatively low upper temperature of the distillation range applied in N2 preparation. [source] Power and limitations of electrophoretic separations in proteomics strategiesMASS SPECTROMETRY REVIEWS, Issue 5 2009Thierry Rabilloud Abstract Proteomics can be defined as the large-scale analysis of proteins. Due to the complexity of biological systems, it is required to concatenate various separation techniques prior to mass spectrometry. These techniques, dealing with proteins or peptides, can rely on chromatography or electrophoresis. In this review, the electrophoretic techniques are under scrutiny. Their principles are recalled, and their applications for peptide and protein separations are presented and critically discussed. In addition, the features that are specific to gel electrophoresis and that interplay with mass spectrometry (i.e., protein detection after electrophoresis, and the process leading from a gel piece to a solution of peptides) are also discussed. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 28:816,843, 2009 [source] Microfabricated devices: A new sample introduction approach to mass spectrometryMASS SPECTROMETRY REVIEWS, Issue 4 2006Iulia M. Lazar Abstract Instrument miniaturization is one way of addressing the issues of sensitivity, speed, throughput, and cost of analysis in DNA diagnostics, proteomics, and related biotechnology areas. Microfluidics is of special interest for handling very small sample amounts, with minimal concerns related to sample loss and cross-contamination, problems typical for standard fluidic manipulations. Furthermore, the small footprint of these microfabricated structures leads to instrument designs suitable for high-density, parallel sample processing, and high-throughput analyses. In addition to miniaturized systems designed with optical or electrochemical detection, microfluidic devices interfaced to mass spectrometry have also been demonstrated. Instruments for automated sample infusion analysis are now commercially available, and microdevices utilizing chromatographic or capillary electrophoresis separation techniques are under development. This review aims at documenting the technologies and applications of microfluidic mass spectrometry for the analysis of proteomic samples. © 2006 Wiley Periodicals, Inc., Mass Spec Rev 25:573,594, 2006 [source] Contribution of mass spectrometry to the study of the Maillard reaction in foodMASS SPECTROMETRY REVIEWS, Issue 4 2005Laurent B. Fay Abstract The Maillard reaction or non-enzymatic browning corresponds to a set of reactions occurring between amines and carbonyl compounds, especially reducing sugars. The Maillard reaction is known to occur in heated, dried, or stored foods and in vivo in mammalian organisms. In food, the Maillard reaction is responsible for changes in colour, flavor, and nutritive value but also for the formation of stabilizing and mutagenic compounds. Because of the complexity of the Maillard reaction, mass spectrometry, coupled or not to separation techniques, is a key tool in this research area and we will review in this article the contribution of mass spectrometry to the understanding of this reaction. Different steps of Maillard reaction will be described and the importance and the role played by mass spectrometry will be highlighted. In addition, different approaches to investigate the Maillard reaction from the formation of Amadori products (early Maillard reaction product) to the flavor and melanoidin production will also be covered. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:487,507, 2005 [source] The role of electron capture dissociation in biomolecular analysisMASS SPECTROMETRY REVIEWS, Issue 2 2005Helen J. Cooper Abstract The introduction of electron capture dissociation (ECD) to electrospray (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) constitutes a significant advance in the structural analysis of biomolecules. The fundamental features and benefits of ECD are discussed in this review. ECD is currently unique to FT-ICR MS and the fundamentals of that technique are outlined. The advantages and complementarity of ECD in relation to other tandem mass spectrometry (MS/MS) techniques, such as infrared multiphoton dissociation (IRMPD) and sustained off-resonance collision-induced dissociation (SORI-CID), are discussed. The instrumental considerations associated with implementation of ECD, including activated ion techniques and coupling to on-line separation techniques, are covered, as are the allied processes electronic excitation dissociation (EED), electron detachment dissociation (EDD), and hot electron capture (HECD). A major theme of this review is the role of ECD in proteomics, particularly for characterization of post-translational modifications (phosphorylation, glycosylation, carboxyglutamic acid, sulfation, acylation, and methionine oxidation) and the top-down approach to protein identification. The application of ECD to the analysis of polymers, peptide nucleic acids, and oligonucleotides is also discussed. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:201,222, 2005 [source] Detailed proteome analysis of growing cells of the planctomycete Rhodopirellula baltica SH1TPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 8 2008Cao Xuan Hieu Abstract Rhodopirellula baltica SH1T, which was isolated from the water column of the Kieler Bight, a bay in the southwestern Baltic Sea, is a marine aerobic, heterotrophic representative of the ubiquitous bacterial phylum Planctomycetes. We analyzed the R. baltica proteome by applying different preanalytical protein as well as peptide separation techniques (1-D and 2-DE, HPLC separation) prior to MS. That way, we could identify a total of 1115 nonredundant proteins from the intracellular proteome and from different cell wall protein fractions. With the contribution of 709 novel proteins resulting from this study, the current comprehensive R. baltica proteomic dataset consists of 1267 unique proteins (accounting for 17.3% of the total putative protein-coding ORFs), including 261 proteins with a predicted signal peptide. The identified proteins were functionally categorized using Clusters of Orthologous Groups (COGs), and their potential cellular locations were predicted by bioinformatic tools. A unique protein family that contains several YTV domains and is rich in cysteine and proline was found to be a component of the R. baltica proteinaceous cell wall. Based on this comprehensive proteome analysis a global schema of the major metabolic pathways of growing R. baltica cells was deduced. [source] Method for the elucidation of the elemental composition of low molecular mass chemicals using exact masses of product ions and neutral losses: application to environmental chemicals measured by liquid chromatography with hybrid quadrupole/time-of-flight mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2005Shigeru Suzuki A method for elucidating the elemental compositions of low molecular weight chemicals, based primarily on mass measurements made using liquid chromatography (LC) with time-of-flight mass spectrometry (TOFMS) and quadrupole/time-of-flight mass spectrometry (LC/QTOFMS), was developed and tested for 113 chemicals of environmental interest with molecular masses up to ,400,Da. As the algorithm incorporating the method is not affected by differences in the instrument used, or by the ionization method and other ionization conditions, the method is useful not only for LC/TOFMS, but also for all kinds of mass spectra measured with higher accuracy and precision (uncertainties of a few mDa) employing all ionization methods and on-line separation techniques. The method involves calculating candidate compositions for intact ionized molecules (ionized forms of the sample molecule that have lost or gained no more than a proton, i.e., [M+H]+ or [M,H],) as well as for fragment ions and corresponding neutral losses, and eliminating those atomic compositions for the molecules that are inconsistent with the corresponding candidate compositions of fragment ions and neutral losses. Candidate compositions were calculated for the measured masses of the intact ionized molecules and of the fragment ions and corresponding neutral losses, using mass uncertainties of 2 and 5,mDa, respectively. Compositions proposed for the ionized molecule that did not correspond to the sum of the compositions of a candidate fragment ion and its corresponding neutral loss were discarded. One, 2,5, 6,10, 11,20, and >20 candidate compositions were found for 65%, 39%, 1%, 1%, and 0%, respectively, for the 124 ionized molecules formed from the 113 chemicals tested (both positive and negative ions were obtained from 11 of the chemicals). However, no candidate composition was found for 2% of the test cases (i.e., 3 chemicals), for each of which the measured mass of one of the product ions was in error by 5,6.7,mDa. Copyright © 2005 John Wiley & Sons, Ltd. [source] A simple and robust conductive graphite coating for sheathless electrospray emitters used in capillary electrophoresis/mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2001Stefan Nilsson A graphite-polyimide mixture was used as a conductive coating for sheathless electrospray emitters. The coating procedure described is simple and inexpensive compared to previously described methods. An investigation of the stability of the conductive coating carried out by electrochemical methods revealed good performances during oxidative stress. In addition, no decrease in emitter performance was seen during continuous electrospray in the positive electrospray mode for two weeks. Fast capillary electrophoresis with attomole sensitivity demonstrated the excellent performance of the described sheathless interface when used in conjunction with an orthogonal time-of-flight mass spectrometer. The overall simplicity, stability and low cost of this type of sheathless emitter make the described approach highly suitable for any on-column coupling of low flow rate separation techniques to a mass spectrometer. Copyright © 2001 John Wiley & Sons, Ltd. [source] Design and synthesis of separation process based on a hybrid methodASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009Chunshan Li Abstract A new general hybrid methodology for separation process synthesis and design is proposed, which considers different separation technologies by integrating mathematical modeling,Analytical Hierarchy Process (AHP) with heuristic approaches and thermodynamic insights. The methodology can provide suitable guidance for the initial separation process design and energy saving. Firstly, a general separation synthesis system based on thermodynamic insights is developed to select suitable separation techniques before sequencing, which reduces the complexity and size of synthesis search space. Then, the pseudo-component concept is proposed and used to deal with the azeotrope contained in the mixture, which widens the scope of the application of the proposed methodology. The AHP method is used to make a separation sequence by pairwise comparison matrices. Lastly, the separation of the pseudo-component will be considered, and it performs energy integration and a detailed process design. Application of the proposed methodology is highlighted through two industrial examples: one is the separation synthesis of a light-end refinery mixture. The other is azeotrope system, the mixture of phenol, o -cresol, p -cresol, and m -cresol. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Separation and Mineralogical Analysis of Bayer Red MudASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5-6 2002T. Picaro This paper describes preliminary work to assess the potential for recovering valuable components from Queensland Alumina Limited (QAL) red mud by physical beneficiation. Upgrading of Weipa bauxites residue was trialed using a 50 mm hydrocyclone and a Mozley Multigravity Separator (MGS) to recover desilication product (DSP) and TiO2 fractions. The mineralogy of the original red muh and the various sub-fractions produced was studied by chemical assay, selective leaching, XRD and SEM techniques. DSP is present in QAL red mud in two forms: (i) as balls in the size range from 0.8 to 10 ,m that appear to be liberated; and (ii) as finely grained DSP intermixed with the other minerals. The hydrocycloning tests produced a DSP rich (39.5 wt%) fraction at 89% recovery from a feed containing 31.9 wt.% DSP. This represents an upgrade (enrichment) of 1.24 times. These results suggest that the greatest DSP enrichment will be achieved by targeting the 0.8 to 10 ,m DSP balls. The richest TiO2 fraction produced varied from 20 to 36 wt.% TiO2 from a feed value of 7 wt.% at a recovery of 7.5%. Mineralogical examination showed that most of the TiO2 in this fraction was as liberated particles in the size range 8 to 20 ,m. Most of the TiO2 particles in the other fractions were not fully liberated from mainly iron minerals. The present work indicates that it is possible to further upgrade DSP fractions by investigating finer particle separation techniques, e.g. smaller, 25 mm and 10 mm, hydrocyclones. [source] Isolation of chicken immunoglobulins (IgY) from egg yolk,BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 3 2003J. P. Dean Goldring Abstract Separating individual proteins from complex mixtures of molecules is the basis of many biochemical investigations. The method describes the separation of immunoglobulin Y (IgY) from chicken eggs using a series of physical and chemical separation techniques. The separation is rapid, and the success of each step is readily viewed on an SDS-polyacrylamide gel. IgY identity can be confirmed on a Western blot probed with enzyme-labeled anti-IgY antibodies. The method is a good illustration of protein separation when there is no enzyme activity to follow. [source] Carbon-based sorbents in chromatography.BIOMEDICAL CHROMATOGRAPHY, Issue 2 2009New achievements Abstract The newest results in the employment of carbon-based composites in various chromatographic techniques such as gas,liquid chromatography, high-performance liquid chromatography and electrically driven separation techniques for the separation, quantitative determination and identification of a wide variety of compounds in complicated matrices are compiled. The results are concisely described and critically evaluated. The future trends in the application of carbon-based compounds in the chromatographic separation methods are briefly discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Proteomics meets microbiology: technical advances in the global mapping of protein expression and functionCELLULAR MICROBIOLOGY, Issue 8 2005Carolyn I. Phillips Summary The availability of complete genome sequences for a large number of pathogenic organisms has opened the door for large-scale proteomic studies to dissect both protein expression/regulation and function. This review highlights key proteomic methods including two-dimensional gel electrophoresis, reference mapping, protein expression profiling and recent advances in gel-free separation techniques that have made a significant impact on the resolution of complex proteomes. In addition, we highlight recent developments in the field of chemical proteomics, a branch of proteomics aimed at functionally profiling a proteome. These techniques include the development of activity-based probes and activity-based protein profiling methods as well as the use of synthetic small molecule libraries to screen for pharmacological tools to perturb basic biological processes. This review will focus on the applications of these technologies to the field of microbiology. [source] Aerosole und ihre technische BedeutungCHEMIE-INGENIEUR-TECHNIK (CIT), Issue 12 2003S. Heidenreich Dr.-Ing. Abstract Aerosole , gezielt erzeugt oder unerwünscht gebildet , treten in vielen technischen Prozessen auf. So werden zum Beispiel Aerosole gezielt erzeugt, wenn Produkte, die aus feindispersen Feststoffen bestehen, in einem Gasphasenprozess (im weitesten Sinn) hergestellt werden. Partikelbildung und -wachstum im Aerosolzustand prägen dabei die Größe, Form und Struktur der Partikel und damit entscheidend die Produkteigenschaften. Aerosole können sich auch unerwünscht in Prozessen bilden. Dies führt zur Verunreinigung von Prozessgasen oder Produkten beziehungsweise zu erhöhten Beladungen von Abluftströmen. Kann die unerwünschte Aerosolbildung nicht vermieden werden, müssen wirkungsvolle Abscheideverfahren eingesetzt werden. Effiziente Abscheider sind auch zur Gewinnung von Produktpartikeln aus der Gasphase notwendig. Ob gezielt erzeugt oder unerwünscht gebildet, Aerosole müssen hochauflösend erfasst und charakterisiert werden. Dies erfordert eine entsprechend leistungsfähige Aerosolmesstechnik. Der Beitrag vermittelt einen Überblick über die technische Bedeutung von Aerosolen. Aerosols and Their Technical Significance Aerosols occur in many technical processes. For example, aerosols are formed to generate products of highly disperse solids in gas phase processes. Particle formation and growth in the aerosol state decisively determine the product properties by the size, shape, and structure of the particles. Undesired aerosol formation can also occur in technical processes. These undesired aerosols pollut process gases or products or increase the pollutant content of exhaust gases. If undesired aerosol formation cannot be avoided, efficient separation techniques have to be used. Efficient separators are also required to recover fine product particles from the gas phase. Moreover, aerosols, whether desired or undesired, have to be measured and characterized. This requires high performing measuring techniques. The paper outlines the technical significance of aerosols. [source] | ||||||||||||||||