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  • Capillary electrophoresis  (140)
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  • 2020-2024
  • 1995-1999  (140)
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  • 101
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2432-2439 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Capillary electrochromatography ; Fluid flow ; Boundary element modeling ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: In recent years there has been considerable intrerest in fabricating electrophoretic separation systems on microchips. In this study the boundary element method is used to numerically model both the electrical charge density and the electrokinetically driven fluid flow velocity field in two-dimensional micro-channels containing an arbitrary configuration of circular flow obstacles. An estimate of both the average velocity and the resolution has been determined for various obstacle configurations, obstacle sizes, area fractions, surface line lengths per unit area and for different values of the thickness of the electrical double layer. Based on the results, an optimal microchannel design is suggested. In addition, the recently observed phenomenon of recirculated flow in an open region of an otherwise packed electrochromatography column has been confirmed with the numerical model.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 102
    ISSN: 0173-0835
    Schlagwort(e): Proteins ; Capillary electrophoresis ; Mass spectrometry ; On-line preconcentration ; Aqueous humor ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The significance of proteomic research is coupled with the recent exponential growth of these investigations. Currently, the most popular techniques used for these studies include the coupling of 1- and 2-dimensional electrophoresis with mass spectrometric analysis of the extracted and digested proteins. However, detection limits of gel staining methods have led to a search for complimentary techniques that afford the detection of lower concentrations of biologically relevant proteins. In the present studies, we have evaluated the applicability of on-line capillary electrophoresis  -  mass spectrometry (CE-MS) for this application. Specifically, we used membrane preconcentration-CE-MS (mPC-CE-MS) to analyze 13 samples of human aqueous humor (AH) from patients with various ocular pathologies (cataract, cataract plus glaucoma, and cataract plus pseudoexfoliation syndrome). This approach enabled rapid analysis of a relatively large volume (1) μL of each specimen, and a protein map for each was created. Measured average molecular weights (Mr) were used to tentatively identify proteins after search of the SWISS-PROT database using Tagldent from ExPaSy. Among those proteins tentatively identified are β-2 microglobulin (Mr 11731.2), apolipoprotein A1 (Mr 28078.6) and serum albumin (Mr 66400). Proteins with Mr of 4349 (unidentified), 11731.2 (β-2 microglobulin), 13400-14100 (immunoglobulin fragments), 28078.2 (apolipoprotein A1) and ∼68000 (serum albumin) were observed in the majority of specimens. Generally no significant differences were noted in the protein composition of aqueous humor samples from different pathologies. However, the absence of an Mr 13345 protein and its oxidized form (Mr 13361) in samples from patients with pseudoexfoliation syndrome was noted. Occasionally the α-and β-chains of hemoglobin, a contaminant in aqueous humor introduced during sampling, were also detected. We conclude from these studies that mPC-CE-MS is an attractive complimentary technique for proteome research, as this approach enables direct mapping and characterization of low concentrations of proteins that are present in complex physiologically derived fluids.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 103
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 3149-3153 
    ISSN: 0173-0835
    Schlagwort(e): Poly(ethylene oxide) solution ; kbp-sized dsDNA ; Capillary electrophoresis ; Electroosmotic flow ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: DNA fragments of 1 to 10 kbp in length were separated by capillary electrophoresis (CE), using poly(ethylene oxide) (PEO) solutions in the presence of electroosmotic flow. The technique requires filling the capillary with the polymer solution by means of electroosmotic flow (EOF). Separation times of 6-7 min in PEO solutions ranging from 0.3 to 8 × 106 Mr at 375 V/cm were sufficient to separate the 11 components of the dsDNA ladder (0.5 to 10 kbp) by size. The migration behavior of the double-stranded (ds)DNA fragments, interpreted by “Ferguson plot analysis”, in the system is indistinguishable from that previously reported for capillary zone electrophoresis (CZE) in a polyacrylamide solution without EOF. Potential advantages of conducting CZE using polymer solutions in the presence of EOF are: (i) Possibility of long migration times on short columns; (ii) possibility of introducing relatively viscous, high Mr polymer solutions into narrow capillaries; (iii) possibility of establishing polymer concentration gradients in capillaries; (iv) possibility of concentrating the starting zone by balancing electrophoretic migration and electroosmotic transport.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 104
    ISSN: 0173-0835
    Schlagwort(e): Electrophoresis ; Capillary electrophoresis ; Proteins ; Glycoproteins ; Recombinant ; Quality control ; Process monitoring ; Glycosylation ; Oligosaccharides ; Glycoforms ; Review ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: In many ways electrophoretic techniques appear ideal for quality monitoring of proteins and are thus well suited for the analysis of recombinant glycoproteins. The requirements of high throughput, comparative analysis and resolution of many variants are met by several electrophoretic techniques. A wide variety of such techniques are available to biotechnologists in the rapidly developing area of recombinant glycoproteins. It is the aim of this review to specifically cover recent work which has been applied to the analysis of DNA-derived glycoproteins, both from a process control standpoint and final product validation. All major areas of electrophoresis including sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing and techniques utilizing capillary electrophoresis are covered, with emphasis on analysis of glycoforms and oligosaccharide profiles of recombinant glycoproteins. As illustration, actual examples rather than standard glycoproteins are given to indicate the potential and limitations which may be encountered. It is anticipated that this review will prove a useful and practical guide to the latest developments by indicating the relevant merits of different methods.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 105
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Conductivity detection ; Indirect UV detection ; Inorganic anions ; Carboxylic acids ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The analysis of low-molecular-mass anionic compounds using capillary zone electrophoresis (CZE) with simultaneous direct conductivity and indirect UV detection is described. A number of carrier electrolyte compositions has been investigated with respect to the crucial parameters for their compatibility with both detection principles discussed in this paper (UV absorptivity and electrophoretic mobility of the buffer coion). Additionally, parameters including pH and buffer concentration affecting both peak symmetry and signal-to-noise ratio obtained for the analytes of interest had to be optimized. Best results could be achieved with a carrier electrolyte consisting of 4-aminobenzoic acid, bis(2-hydroxyethyl)imino-tris(hydroxymethyl)aminomethane (BIS-Tris) and a pH of 7.0 adjusted with LiOH. This running buffer was used for the analysis of low-molecular-mass anionic compounds in a sample of white wine.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 106
    ISSN: 0173-0835
    Schlagwort(e): Plasmid copy number ; DNA separation ; Capillary electrophoresis ; Liquid polymer ; Bacterial fermentation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Capillary electrophoresis (CE) is an effective instrumental alternative to conventional slab gel electrophoresis in the determination of plasmid copy number during recombinant protein formation processes. This analytical setup provides efficient separation of different species of linearized plasmid molecules and quantification by UV detection. Both fused silica and gel-filled capillaries are assessed with respect to peak resolution and reproducibility. The application of coated capillaries eliminates the electroosmatic flow to a large extent, resulting in excellent separation of DNA fragments. The application of UV detection enables the analysis of linearized plasmid DNA with a conventional laboratory CE device. All investigated plasmids show good peak resolution due to their significant differences in molecular size, which is essential for sufficient separation of individual DNA molecules.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 107
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Cyclodextrins ; Glycoproteins ; Oligosaccharides ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Oligomers of glucose and oligosaccharides released from glycoproteins were derivatized with 2-aminobenzamide. As this fluorophore imparts no charge to the oligosaccharides, several strategies were investigated to achieve capillary electrophoresis (CE) separation of both neutral and charged derivatized glycans. Micellar electrokinetic capillary chromatography (MEKC) with the addition of anionic surfactants was evaluated as a first approach: sodium dodecyl sulfate (SDS) produced the best separation of the oligoglucose fragments, where the migration was inversely related to their degree of polymerization. To demonstrate the applicability of this method for complex carbohydrate analysis, oligosaccharide mixtures derived from ribonuclease B (RNase B) and α-acid glycoprotein (α-AGP) were analyzed. A satisfactory separation for the high-mannose structures found in RNase B could be obtained, whereas charged oligosaccharides from α-AGP were poorly resolved. Cyclodextrin-modified CE was chosen as the second approach: the effect of the addition of sulfobutylether-β-cyclodextrin (SBE-β-CD) or sulfobutylether-γ-cyclodextrin (SBE-γ-CD) on the electrophoretic mobilities and resolution of neutral and charged oligosaccharides was then studied. Selectivity of sialylated structures could be further improved by using anionic cyclodextrins (CDs) instead of micelles. However, this latter approach failed to baseline-resolve the different high-mannose structures of RNase B. A successful separation of the complex mixture of oligosaccharides from α-AGP was obtained with the addition of 4% of SBE-γ-CD and triethylamine (TEA) in a phosphate buffer, pH 6.7.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 108
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2654-2664 
    ISSN: 0173-0835
    Schlagwort(e): Glycoprotein ; Glycopeptide ; Peptide ; Capillary electrophoresis ; Mass spectrometry ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: An evaluation of capillary zone electrophoresis-mass spectrometry (CZE-MS) as an analytical methodology for the separation and characterization of complex glycopeptides and nonglycopeptide structures has been performed. The evaluation employed endoproteinase V8 digested recombinant human erythropoietin (rHuEPO) that was further fractionated by reverse phase chromatography. The peptides were subjected to sequence analysis and evaluated by capillary electrophoresis, with or without mass detection, for peptide purity. The peptide mass determined from the sequence was then compared to the mass obtained from CZE-MS. Glycosylation sites and carbohydrate branch patterns were easily determined, site specific microheterogeneity (either O-acetylation of N-acetylneur-aminic acids or lactosamine extensions of the carbohydrate chain length) was assessed directly, glycosylation site occupancy was evaluated qualitatively, and nonglycopeptides were resolved and analyzed on-line with ease. Incomplete peptide digestion products were detected and identified by CZE-MS. Protein sequence coverage by CZE-MS was 98.2 percent complete from a single map. Offline evaluation of peptide purity by CZE greatly aided the interpretation of multiple sequence analysis and, in validating that, the CZE-MS was detecting all peptides present. All off-line CZE and on-line CZE-MS experiments employed a capillary that was dynamically coated with Polybrene in the presence of polyethylene glycol; separations were conducted in 0.67 M formic acid.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 109
    ISSN: 0173-0835
    Schlagwort(e): Cyclodextrin sulfate ; Glycosaminoglycan ; Polyacrylamide gel electrophoresis ; Capillary electrophoresis ; Electrospray ionization ; Mass spectrometry ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A β-cyclodextrin sulfate mixture has been fractionated using discontinuous gradient polyacrylamide gel electrophoresis. Semidry electrotransfer of the sample onto a positively charged nylon membrane and visualization of a portion of this membrane with Alcian blue stain showed multiple bands. The bands were cut from the remaining portion of the membrane and after washing with 8 M urea, the β-cyclodextrin sulfate fractions were eluted with 2 M sodium chloride and dialyzed. Analysis of each fraction using high resolution analytical gradient polyacrylamide gel electrophoresis as well as capillary electrophoresis, using indirect detection, showed some of the fractions to be pure while others were mixtures. Each β-cyclodextrin sulfate fraction was complexed with a basic synthetic peptide and analyzed by electrospray ionization mass spectrometry to define the mass of the components in each mixture and thereby to determine the purity of each sample.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 110
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2695-2752 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Method development ; Micellar electrokinetic capillary chromatography ; Validation ; Troubleshooting ; Review ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: This review is in support of the development of selective, reproducible and validated capillary electrophoretis (CE) methods. Focusing on pharmaceutical and biological applications, the successful use of CE is demonstrated by more than 800 references, mainly from 1994 until 1998. Approximately 80 recent reviews have been catalogued. These articles sum up the existing strategies for method development in CE, especially in the search for generally accepted concepts, but also looking for new, promising reagents and ideas. General strategies for method development were derived not only with regard to selectivity and efficiency, but also with regard to precision, short analysis time, limit of detection, sample pretreatment requirements and validation. Standard buffer recipes, surfactants used in micellar electrokinetic capillary chromatography (MEKC), chiral selectors, useful buffer additives, polymeric separation media, electrosmotic flow (EOF) modifiers, dynamic and permanent coatings, actions to deal with complex matrices and aspects of validation are collected in 20 tables. Detailed schemes for the development of MEKC methods and chiral separations, for optimizing separation efficiency, means of troubleshooting, and other important information for key decisions during method development are given in 19 diagrams. Method development for peptide and protein separations, possibilities to influence the EOF and how to stabilize it, as well as indirect detection are considered in special sections.
    Zusätzliches Material: 20 Tab.
    Materialart: Digitale Medien
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  • 111
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Enantioseparation ; Optimization strategy ; Cyclodextrins ; Chiral drugs ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: General strategies for the development of capillary electrophoretic methods for the enantiomeric separation of basic, acidic or neutral drugs were developed. For all kinds of compounds, the use of a buffer made of 100 mM phosphoric acid adjusted to pH 3 with triethanolamine and containing anionic and/or uncharged cyclodextrin (CD) derivatives as chiral selectors was recommended. Two different optimization schemes depending on the acidic or basic character of the analytes, were elaborated. For most basic compounds present in cationic form at pH 3, enantiomeric separation could be achieved in the normal polarity mode. Different β-cyclodextrin derivatives were first tested at a given concentration. Five derivatives were found to be particularly useful for enantioseparations in capillary electrophoresis (CE): the anionic carboxymethyl-β-CD (CMCD) and sulfobutyl-β-CD (SBCD) and the neutral dimethyl-β-CD (DMCD), trimethyl-β-CD (TMCD) and hydroxypropyl-β-CD (HPCD). After selection of the most suitable CD, its concentration was optimized with respect to chiral resolution. If necessary, a further improvement in resolution could often be obtained for the enantiomers of cationic solutes by increasing the buffer pH from 3 to 5 using CMCD as chiral additive. Another possible alternative for enhancement in chiral resolution was the addition of methanol or cyclohexanol to the buffer. For acidic drugs, essentially present in uncharged form at pH 3, and for neutral solutes, anionic CD derivatives such as SBCD or CMCD were first tested at a given concentration in the reversed polarity mode. Dual systems, based on the simultaneous addition of a charged CD (SBCD or CMCD) and a neutral CD (TMCD or DMCD), could then be investigated for resolution improvement. After optimization of the CD concentrations, the use of dual systems with CMCD at pH 5 could also be tested if necessary, especially for very weak acidic and neutral drugs. By applying these optimization strategies, 48 of the 50 drugs examined as model compounds could be fully enantioseparated by CE in short analysis times (usually less than 10 min).
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 112
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Dialysis ; Sample pretreatment ; Serum ; Sulfonamides ; Urine ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A fully automated dialysis solid-phase extraction (SPE) sample preparation procedure is coupled on-line to capillary electrophoresis (CE) for the first time. The system is used to determine sulfonamides in serum and urine. The dialysis unit serves to remove proteins and particulate matter. Reconcentration of the analytes is performed with a small SPE column while (in)organic salts and other interferences are removed simultaneously. Finally, the analytes are desorbed and injected, via a homemade interface, into the CE system. Limits of detection (LOD) of 0.05-0.1 and 0.05-0.3 μg/mL are obtained in urine and serum, respectively. The within-day and between-day precisions are in the range of 2-6% and 3-8%, respectively, for a concentration of five times the LOD. The dialysis SPE-CE system was used over a period of six months for the analysis of over 500 serum and urine samples without problems such as clogging of the CE capillary or SPE column.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 113
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Amphetamines ; Fluorescein isothiocyanate derivatization ; Chip-based instrumentation ; Fused-silica capillary instrumentation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Amines can easily be derivatized with fluorescein isothiocyanate isomer I (FITC) and analyzed by capillary electrophoresis (CE) using alkaline buffers with or without dodecyl sulfate micelles. This paper reports the CE analysis of FITC-derivatized amphetamine, methamphetamine, 3,4-methylenedioxymethamphet-amine and β-phenylethylamine in human urine using chip-based and fused-silica capillary instrumentation with laser-induced fluorescence detection. Data obtained via direct labeling of fortified urine are compared to those generated after FITC labeling of urinary extracts that were prepared by solid-phase extraction using a copolymer phase. For a urine volume of 5 mL with a “spiked amine”: FITC ratio of 1:250, the latter approach was found to provide a sensitivity that is relevant for toxicological drug screening and confirmation (about 200 ng/mL urine). With direct labeling of 10 μL urine that was alkalinized and diluted for derivatization, the limit of identification was determined to be about 10 μg/mL, a value that is too high for practical purposes. Compared to fused-silica capillaries, electrophoresis in microstructures is shown to provide faster separations and higher efficiencies without loss of accuracy and precision.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 114
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Nicotine ; Quantitation ; Alkaloid profiling ; ATF-regulated products ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Tobacco products regulated by the Bureau of Alcohol, Tobacco and Firearms (ATF), are classified at different excise tax rates according to the Code of Federal Regulations. These include the smoking (cigars, cigarettes, pipe tobacco and roll-your-own) and smokeless (chewing tobacco and snuff) tobacco products. The active principal components in all tobacco products belong to a class of compounds known as alkaloids. Nicotine is the major tobacco alkaloid, comprising about 98% of the total alkaloids. It is also the primary determinant of what constitutes a tobacco product from a regulatory standpoint. Nornicotine, anabasine and anatabine constitute the minor tobacco alkaloids of importance and interest to ATF. We have previously shown capillary electrophoresis (CE) to be a powerful analytical tool for monitoring nicotine in ATF-regulated products. Here we have extended those CE studies to (i) quantitate nicotine in ATF-regulated tobacco products and (ii) to characterize these different tobacco products according to their alkaloid profiles. Results from these studies will be presented.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 115
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 3-5 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Inorganic ions ; Trace explosive ; Explosives residue ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Capillary electrophoresis was developed for the analysis of low explosive residue, because a significant amount of inorganic anions and cations remain after deflagration. Certain high explosives, such as emulsion explosives, produce a vast quantity of inorganic ions after a blast and can readily be analyzed using capillary electrophoresis. Often, trace amounts of explosive residues may be present on physical evidence submitted in criminal cases. Trace amounts of inorganic ions such as nitrate, chlorate, and ammonium may be detected using capillary electrophoresis owing to the low detection limit of these species. The utility of capillary electrophoresis in the analysis of explosive residues is in its ability to simultaneously analyze trace explosives and ionic products present on physical evidence.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 116
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 27-30 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Indole alkaloids ; Psilocybe semilanceata ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: While the hallucinogenic mushrooms Psilocybe semilanceata have previously been analyzed for the indole alkaloids psilocybin and baeocystin by capillary zone electrophoresis (CZE) at pH 11.5, the present work focused on the development of an alternative and complementary capillary electrophoretic method for their identification. Owing to their structural similarity and zwitterionic nature, the compounds were difficult to resolve based on different interactions with cationic or anionic micelles. However, while the attempts with micellar electrokinetic chromatography (MEKC) were unsuccessful, rapid derivatization with propyl chloroformate and reanalysis by CZE at pH 11.5 was effective to support identification of the two indole alkaloids. Psilocin was difficult to analyze by CZE at pH 11.5 owing to comigration with the electroosmotic flow. For this compound, the pH of the running buffer was reduced to 7.2 to effectively enhance the electrophoretic mobility.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 117
    ISSN: 0173-0835
    Schlagwort(e): DNA fingerprinting ; Capillary electrophoresis ; Polymerase chain reaction ; Entobacterial repetitive intergenic consensus motifs ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The molecular technique, enterobacterial repetitive intergenic consensus (ERIC)-polymerase chain reaction (PCR) produces genomic DNA fingerprint that discriminate bacterial species and strains. This technique was applied to the characterization of Listeria monocytogenes, an important food-borne pathogen implicated in numerous cases of listeriosis. The ERIC-PCR resulted in distinct DNA fingerprinting patterns of all L. monocytogene serotypes and Listeria species. Analysis of the genomic DNA fingerprints was accomplished using capillary electrophoresis (CE), an alternative technique to the conventional agarose gel method. The optimization of CE conditions (electrokinetic injection, applied voltage) resulted in the resolution of amplified DNA fragments up to 1000 bp. Comparisons of electropherograms provided genomic fingerprint templates which could be further used for supplementary information. The ERIC-PCR method coupled to CE provides a rapid technique in differentiating bacterial spp., and may contribute relevant information in food-borne outbreak studies.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 118
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; DNA ; Mitochondrial DNA ; Forensic DNA typing ; Polymerase chain reaction analysis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The polymorphic control region of mitochondrial DNA (mtDNA) is becoming more commonly used in forensic applications to differentiate among individuals in a population. Two hypervariable regions (HV1 and HV2) are often sequenced following amplification of the mtDNA via the polymerase chain reaction (PCR). More rapid screening assays would reduce both the effort and the expenses of comparing two samples. A methodology has been developed that first uses restriction endonuclease digestion of the PCR-amplified mtDNA using RsaI and Mn/I and then capillary electrophoresis (CE) to separate and size the PCR-RFLP fragments. This rapid procedure offers an alternative method for screening of polymorphisms in amplified mtDNA samples. In addition, the presence of a T→C transition at position 16189, which gives rise to the so-called “C-stretch” in HV1, may be predicted from the presence of nonspecific PCR products in the CE results.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 119
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Laser-induced fluorescence ; Microsatellite repeat ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The optimum separation conditions of polymerase chain reaction (PCR) products have been found for high-speed capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection. DNA fragments obtained after PCR amplification of the region covering the (CA)18 microsatellite repeat in nitron 5 of the gene for FcERIβ, a high affinity glycoprotein receptor for IgE, located on chromosome 11 (11q13), were analyzed with the aim of investigating the repeat polymorphism. The results of polyacrylamide slab gel electrophoresis (PAGE), agarose gel electrophoresis, CE with absorbance detector and CE with LIF are compared. The CE with LIF proved to shorten analysis time by a factor of 100 when compared to slab gel electrophoresis. CE-LIF utilizes a short capillary with an effective length of 6.3 cm and electric field strength from 100 to 550 V/cm. The respective PCR products of sizes from 116 to 210 base pairs (bp) were analyzed in 3 min.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 120
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 270-275 
    ISSN: 0173-0835
    Schlagwort(e): Selenium ; Speciation ; Capillary electrophoresis ; Inductively coupled plasma mass spectrometry ; Hyphenation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The high resolution potential of capillary electrophoresis (CE) makes CE techniques valuable for separations of selenium species. Further, inductively coupled plasma-mass spectrometry (ICP-MS) affords element-specific multi-element detection, providing extremely low detection limits. The combination of CE with ICP-MS promises to become a powerful tool for metal speciation. Therefore, an on-line hyphenation of CE with ICP-MS, which was developed earlier (Michalke, B., Schramel, P., Fresenius' J. Anal. Chem. 1997, 257, 594-599), was modified and applied to selenium speciation. For this reason, capillary zone electrophoresis (CZE) methods were developed, providing the possibility to analyze six Se species of interest in one run: Se (IV), Se (VI), selenium carrying glutathione (GSSeSG), selenomethionine (SeM), selenocystine (SeC), and selenocystamine (SeCM). The final CE method used an alkaline background electrolyte (Na2CO3/NaOH) with separation differentiated from the detection step during hyphenation. This resulted in short separation times (10 min) and a subsequent detection step of 100s. The Se species were sufficiently separated from each other and appeared at 7s (SeCM), 16s (Se (VI)), 22s (SeC), 27s (Se (IV)), 35s (SeM) and 56s (GSSeSG) during the detection step. Detection limits were calculated as 10 or 20 μg Se/L for inorganic Se species and 35-50 μg Se/L for organic Se species.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 121
    ISSN: 0173-0835
    Schlagwort(e): Isoelectric buffers ; Capillary electrophoresis ; Gliadins ; Wheat ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A modified method is reported for screening of wheat cultivars: capillary zone electrophoresis of gliadins in isoelectric buffers. Previously published procedures recommended a 100 mM phosphate buffer, supplemented with 0.05% hydroxypropylmethylcellulose and 20% acetonitrile, in uncoated capillaries. Due to the very high conductivity of such a buffer (4.7 mmhos at 25°C) high speed separations (10 - 12 min analysis time at 800 V/cm) could only be elicited in 20 μm internal diameter (ID) capillaries, at the expense of sensitivity. In the present report, we optimized the background electrolyte as follows: 40 mM aspartic acid (pH = pI = 2.77) in the presence of 7 M urea and 0.5% short-chain hydroxyethylcellulose (Mn 27000 Da; apparent pH 3.9 in 7 M urea). As an alternative recipe, the same isoelectric buffer can be supplemented with a mixed organic solvent composed of 4 M urea and 20% acetonitrile (apparent pH 3.66). Due to the much lower conductivity (0.7 mmhos), separations can be carried out at 1000 V/cm in only 10 min, but in larger bore capillaries (50 μm ID), ensuring a five-times higher sensitivity. The gliadin patterns thus obtained are species-specific and allow easy identification of all cultivars tested of both durum and bread wheat. No adsorption of proteins to the silica wall seems to occur and high reproducibility in peak areas and transit times is obtained.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 122
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 420-426 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Enzyme-catalyzed microreactors ; Quantitation ; In-capillary microreactions ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: This work evaluates the concept of a double enzyme-catalyzed microreactor using capillary electrophoresis (CE). Migrating in a capillary under electrophoresis conditions, plugs of substrate and two enzymes are injected separately in buffer and allowed to react. Extent of reaction and product ratios were subsequently determined by CE. This concept is demonstrated using two model systems: the conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and adenosine monophosphate (AMP) by hexokinase (HK, EC 2.7.1.1) and apyrase (APY, EC 3.6.1.5), respectively, in the conversion of glucose to glucose-6-phosphate and inorganic phosphate, respectively, and the conversion of nicotinamide adenine dinucleotide, reduced form (NADH), to nicotinamide adenine dinucleotide (NAD) and back to NADH by lactate dehydrogenase (LDH, EC 1.1.1.27) and glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49), respectively, in the conversion of pyruvate to lactate and glucose-6-phosphate (glc-6-P) to 6-phosphogluconate, respectively. These procedures illustrate the use of the capillary as a double microreactor and the ease of quantitation of reaction products under conditions of electrophoresis.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 123
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Staphylococcus aureus bacteriophage ; DNA cycle sequencing ; Linear polyacrylamide ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The nucleotide sequence of a part of a 4.9 kbp common restriction fragment isolated from Staphylococcus aureus bacteriophage (bacterial virus) 3A has been determined by capillary electrophoresis (CE). The fast separation of sequencing fragments in linear polyacrylamide solution at a temperature of 55°C allowed the reading of more than 650 bases of sequence in 60 min. The single strand (ss)DNA fragments were prepared by cycle sequencing with fluo-rescently labeled dideoxy-terminators on the cloned bacteriophage DNA template. With respect to analysis speed, sequence read-length, low sample consumption and automation, CE offers a simple, labor-saving and inexpensive procedure for DNA sequencing. Operating the CE columns at elevated temperature proved to be a rapid procedure capable of extending sequence read-length. The resulting sequence of the common restriction fragment can be used for the preparation of specific primers and oligonucleotide hybridization probes for identification of Staphylococcus aureus bacteriophages and/or prophages belonging to the bacteriophage species 3A.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 124
    ISSN: 0173-0835
    Schlagwort(e): Belgian population ; Short tandem repeat ; Polymerase chain reaction ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Allele frequencies of four short tandem repeat loci (HumCD4, HumTH01, HumD21S11 and HumSE33) were investigated in a sample of 395 unrelated Belgian individuals using multiplex polymerase chain reaction and capillary electrophoresis. Automated laser fluorescence was used to detect four fluorescent dyes, enabling the use of an internal standard within each lane. With this method rapid typing with high resolution was obtained and the different alleles were grouped on a statistical base. All loci meet Hardy-Weinberg expectations. The allelic frequency data, together with the constructed allelic ladder, can be used in paternity testing and personal identification in the medical and forensic sciences.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
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  • 125
    ISSN: 0173-0835
    Schlagwort(e): Double-stranded DNA ; Isoelectric buffers ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: When separating ds-DNA in isoelectric His buffer (pH=pI=7.6), in the 50-250 mM concentration range, some unique phenomena were observed: improved resolution for smaller DNA fragments, up to ca. 150 bp, and a rapid deterioration of resolution above this critical length (which corresponds to the persistence length). Such phenomenon depended also on voltage and concentration of sieving liquid polymer. Direct binding of His to the DNA helix was hypothesized, with resultant stiffening and an increment of diameter of the DNA fragments, thus inducing an early onset of reptation at the applied voltage in the 100-300 V/cm range. In order to prove this hypothesis, “competing ions” (notably NaCl and KBr) were added to the His background electrolyte: a partial reversal of the His effect was already apparent at low concentrations of such ions (10 mM) and was complete at higher concentrations (30 and 50 mM). By molecular modeling, it was found that His could be docking on the negatively charged oxygen (bound to the phosphate) by offering both charged (primary and tertiary amino) groups to simultaneous binding, thus forming a salt and neutralizing the negative charge borne by the oxygen. The following characteristic bond distances were found: 0.34 nm between the N (imidazolic) and O; 0.32 nm between the primary N and O; 0.36 nm between the two nitrogens engaged in salt formation with the oxygen. In addition, for complexation to occur, the distance between the noncharged nitrogen in the imidazole ring and the nearest phosphate oxygen (engaged in the phosphodiester bridge) should be 0.44 nm. Under these conditions, the two rings present (a six-membered, ideal one, salt-linked with the oxygen and rather highly elongated, and the imidazole) will not be precisely coplanar, since the primary and tertiary nitrogens will be one slightly above and one slightly below the plane of the drawing. Upon extensive binding, occupying every available phosphate site, π-π interactions could occur among the stacks of bound His residues, thus further stabilizing the complex.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 126
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1752-1770 
    ISSN: 0173-0835
    Schlagwort(e): Urinary proteins ; Isoelectric focusing ; Sodium dodecyl sulfate-polyacrylamide gel electrophoresis ; Two-dimensional polyacrylamide gel electrophoresis ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The application of isoelectric focusing (IEF), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional electrophoresis (2-DE) and capillary electrophoresis (CE) for high resolution electrophoretic analysis of human urinary proteins is reviewed. In each case, the information is tabulated chronologically with details of sample preparation, electrophoretic system, detection method and clinical application. The text includes an historical perspective of the use of each method for urinalysis and a detailed review of the application of the methods to the investigation of renal disease, renal transplantation, Bence Jones proteinuria (BJP), diabetes mellitus, cadmium toxicity, nephrolithiasis and cancers of the urogenital tract.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 127
    ISSN: 0173-0835
    Schlagwort(e): Electrospray ionization ; Mass spectrometry ; Capillary electrophoresis ; Two-dimensional gel electrophoresis ; Proteome ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Analytical and preparative electrophoresis separation techniques have been essential tools in protein biochemistry and the biological sciences in general. The combination of high resolution electrophoresis techniques with high performance analytical procedures has dramatically enhanced analytical protein biochemistry. In this report we describe the combination of electrophoretic separation techniques with electrospray ionization (ESI) tandem mass spectrometry (MS/MS). A series of different techniques, consisting of automated high performance liquid chromatography (HPLC)-MS/MS, capillary-HPLC-MS/MS, and solid phase extraction (SPE)-capillary zone electrophoresis (CZE)-MS/MS, are described in the context of the identification of high pmol to the low fmol amounts of proteins. Application of these powerful new tools for the analysis of proteins on a large proteome-wide scale is presented. Furthermore, the combination of orthogonal separation techniques, such as immobilized metal affinity chromatography (IMAC) with SPE-CZE-MS/MS, and IMAC followed by HPLC, and by SPE-CZE-MS/MS, are presented for the detailed investigation of post-translational modifications of specific proteins.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 128
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2140-2144 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Arsenic compounds ; Indirect fluorescence detection ; Fluorescein ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A capillary electrophoresis (CE)-indirect fluorescence detection method for arsenic compounds is described. The five arsenic species, viz., arsenite (As(III)), arsenate (As(V)), monomethylarsonate (MMA), dimethylarsinate (DMA) and phenylarsonate (PhA), were efficiently separated by CE in 8 min with an 1.5 mM fluorescein solution at pH 9.8. Fluorescein also functioned as a background fluorophore for the indirect detection of these nonfluorescent arsenic species. Linearity (r〉0.996) of more than two orders of magnitude was generally obtained. The relative standard deviation (RSD) values were in the ranges 0.4-0.7% and 2.2-8.2% for migration times and peak areas, respectively. The concentration limits of detection (CLODs) for the arsenic compounds studied were between 0.04 and 0.16 μ/mL (as arsenic). The detection sensitivity was generally dependent upon the transfer ratio (TR, defined as the number of moles of fluorescein ions displaced by one mole of analyte ions) of each arsenic species. The applicability of the method for the analysis of ground water was examined.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 129
    ISSN: 0173-0835
    Schlagwort(e): On-line preconcentration ; Capillary electrophoresis ; Transient isotachophoresis ; Polybrene ; Microspray mass spectrometry ; Peptide sequencing ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Sequence analysis of antigenic major histocompatibility complex (MHC) class I peptides requires minimizing sample loss and enhancing mass spectrometric sensitivity. In order to facilitate such analyses, we have coupled on-line membrane preconcentration-capillary electrophoresis (mPC-CE) with microspray mass spectrometry (mPC-CE-μMS) and tandem mass spectrometry (mPC-CE-μMS/MS). Specifically, cell lysate from ∼ 109 EG-7 mouse tumor cells was immunoprecipitated and the released MHC class I peptides were subjected to reverse-phase HPLC. An HPLC fraction containing antigenic peptide(s) shown to induce T-cell stimulation was subjected to mPC-CE-μMS. Approximately 10 μL (from 100 μL) of the fraction was pressure-injected and concentrated on a styrenedivinylbenzene (SDB) impregnated membrane. The peptides were eluted from the membrane with ∼100 nL of 80% methanol, sandwiched between a leading stcking buffer (LSB, also serving as CE separation medium) of ∼110 nL of 0.1% acetic acid in 10% methanol, and a trailing stacking buffer (TSB) of ∼ 110 nL of 0.1% NH4OH. On application of the CE voltage the peptides are subjected to moving boundary transient isotachophoresis and focused. The peptides were separated in a Polybrene-coated capillary with application of -20 kV in reverse polarity mode and subsequently sprayed via an emitter coupled to the CE capillary by a liquid junction containing a platinum wire. An ion at m/z 482.3 was detected and subjected to mPC-CE-μMS/MS and determined to be SIINFEKL, a peptide (OVA) known to be antigenic in the mouse model system. Sensitivity enhancement over conventional mPC-CE-MS and MS/MS was ∼100-fold.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 130
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2233-2238 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Fluorescence ; UV detection ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A new method for investigation of axial-beam absorption detection for improved detection limits in microcolumn separations is reported. The method is based on fluorescence imaging of light absorption along a separation capillary. The probing UV light is introduced at one end of the capillary and shows an exponential fall-off along the capillary. As the UV light propagates through the sample peaks, an additional loss in intensity will be observed. In order to view the absorption profile along the capillary, a background fluorophore is added to the buffer. A charge-coupled device (CCD) detector and imaging optics are placed beside the capillary to view the capillary in a direction perpendicular to the capillary. Signal integration is employed for consecutive exposures as well as for neighboring detector pixels in order to increase the signal-to-noise ratio. Measurements for stilbene 3 with sulforhodamine B as a background fluorophore are presented. The characteristics of the detection method and potential improvements are discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 131
    ISSN: 0173-0835
    Schlagwort(e): Protein identification ; Mass spectrometry ; Tandem mass spectrometry ; Capillary electrophoresis ; Solid phase extraction ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: We have previously described the use of a solid phase extraction (SPE) - capillary zone electrophoresis (CZE) - tandem mass spectrometry (MS/MS) system for protein analysis at the low femtomole to subfemtomole level. Here we describe the systematic optimization of a number of parameters which facilitate the use of the SPE-CZE-MS/MS system and further enhance its performance. Specifically, we describe a robust SPE cartridge design which can be assembled without the use of glue, the evaluation of procedures to chemically modify the inner wall of the fused-silica capillaries used in the system to improve separation and reproducibility, and the comparison of different reverse-phase (RP) resins used for the SPE cartridge. We also explored the effects of transient isotachophoresis with respect to system performance and compatibility with different fused-silica surface coatings, the RP resins used, and MS/MS. The enhanced performance of the optimized system is demonstrated by the analysis of calibrated tryptic digests of bovine serum albumin (BSA).
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 132
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2440-2444 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Sample stacking ; Microsequence analysis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Capillary zone electrophoresis (CZE) in the presence of ethanolamine was used in a micropreparative mode. Sample volumes up to 1 μL could be loaded onto a 100 μm diameter capillary without loss in resolution. Coupled to narrow-bore reversed-phase high-performance liquid chromatography, ethanolamine-CZE allowed the collection of sufficient amounts of pure peptidic material to perform amino acid sequence analysis.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 133
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2625-2629 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Glucose determination ; Subcutaneous fluid ; Noninvasive sampling ; Laser-induced fluorescence ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection has been used for the determination of glucose in samples collected by noninvasive means. The method uses an enzymatic reaction scheme that provides for the determination of small quantities of glucose with detection limits of 80 nM. This approach is used to evaluate passive transdermal diffusion as a noninvasive means to sample glucose in vivo. A simple sampling cell design is presented. Sample collection was performed on volunteer human subjects. Our experiments show that fluctuations in blood glucose concentration are reflected in the samples obtained by passive transdermal diffusion after glucose intake. The results indicate that glucose from the subcutaneous fluid can be accessed by passive diffusion.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 134
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2650-2653 
    ISSN: 0173-0835
    Schlagwort(e): Capillary affinity chromatography ; Affinity chromatography ; Capillary electrophoresis ; Heparin ; Protein ; Interaction ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A new approach for separation, capillary affinity chromatography, is introduced for studying the interaction of heparin with antithrombin III and secretory leukocyte proteinase inhibitor. Heparin is covalently immobilized on the surface of an etched capillary through a silane spacer. The proteins are injected into the heparinized capillary, bound to the heparin, washed with buffer, eluted with sodium chloride in the same buffer using a pressure injection mode and eluting protein detected by absorbance. The resulting affinity separation is similar to that obtained from traditional affinity chromatography. The quantity of loaded protein in capillary affinity chromatography is at the nanogram level, offering an improvement over the milligram levels required for standard affinity chromatographic methods.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 135
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2639-2644 
    ISSN: 0173-0835
    Schlagwort(e): Erythropoietin ; Fetuin ; Kallikrein ; Ribonuclease B ; 8-Amino-1,3,6-trisulfonic acid ; Sialidase ; Capillary electrophoresis ; Laser-induced fluoresence detection ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A method for analysis of N-linked oligosaccharides derived from glycoproteins including sialic acid-containing species is presented. It is based on the combination of specific chemical and enzymatic conversions coupled with capillary electrophoretic (CE) separation and laser-induced fluorescence (LIF) detection. Glycoproteins were heat-denatured in the presence of a reducing agent and the N-linked oligosaccharides were released by peptide N-glycosidase (PNGase F; EC3.5.1.52)-catalyzed hydrolysis. The released N-linked oligosaccharides were derivatized with 8-aminopyrene-1,3,6-trisulfonate (APTS) under mild reductive amination conditions in which desialylation and loss of fucose residues are minimized. A model N-linked oligosaccharide, desialylated, galactosylated biantennary, core-substituted with fucose (A2F) was tested for APTS-based derivatization chemistry with excellent recovery of the adduct without losing fucose and neuraminic acid residues. The profiles of heavily sialylated N-linked oligosaccharides derived from fetuin, recombinant human erythropoietin and kallikrein are reported and the data show that the present method produces a high resoluton of the N-linked oligosaccharide profile for fingerprinting glycans derived from glycoproteins.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 136
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2691-2694 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Drugs ; Pharmaceuticals ; Clinical analysis ; Forensic analysis ; Pharmaceutical analysis ; Review ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Capillary electrophoresis has become one of the advanced analytical methods for drugs in pharmaceutical, therapeutic, diagnostic and forensic applications. This review discusses key issues and provides key references to the topic of drug analysis using capillary electrophoresis. It gives readers a brief summery for the current status of the technology and serves as an editorial for the paper symposium “Capillary electrophoresis in drug analysis” (Electrophoresis 1998, 19, 2691-3054).
    Materialart: Digitale Medien
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  • 137
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2798-2833 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Chiral separations ; Chiral selectors ; Applications ; Review ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: This review presents the different chiral selectors used in capillary electrophoresis (CE) for the separation of enantiomers. The use of charged cyclodextrins, crown ethers, polysaccharides, proteins, natural and synthetic micelles, macrocyclic antibiotics and ergot alkaloids is discussed in detail. Neutral native and derivatized cyclodextrins are not treated because several review articles have already been published on this topic. Recent developments like the application of two chiral selectors in the same background electrolyte are highlighted.
    Zusätzliches Material: 29 Ill.
    Materialart: Digitale Medien
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  • 138
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Fluorescence detection ; Fluorescence polarization immunoassay ; Methamphetamine ; Urine ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: An accurate and simple immunoassay using capillary electrophoresis (CE) with laser-induced fluorescence (LIF) was performed for the detection of methamphetamine (MA) in urine. The CE-LIF was conducted with an untreated fused-silica column using antiserum and a tracer of fluorescein isothiocyanate (FITC)-labeled MA. This CE-LIF system was compared with fluorescence polarization immunoassay (FPIA) in a TDx analyzer in the photo-check mode using the same FITC-labeled tracer and the same antiserum. Various antibodies, not only those prepared by our own immunogens but also those from commercial sources, were screened and characterized in both assay systems with regard to sensitivity, precision, and cross-reactivity. Both systems satisfied analytical precision and gave similar cross-reactivity patterns. However, the CE-LIF-based immunoassay was approximately one order superior to FPIA in sensitivity, requiring less volume of sample, antiserum, and tracer for the assay. Considering that the FPIA system is well known to be a useful tool for screening antibodies and detecting drugs, the CE-LIF-based immunoassay system, which is seemingly more advantageous than the FPIA system, appears to have great power for the characterization of antibodies and for the detection of MA in urine.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 139
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2777-2790 
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Drug ; Laser-induced fluorescence ; Review ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: This review briefly presents the different laser-induced fluorescence detectors, outlines the different dyes used to derivatize molecules which are used with capillary electrophoresis/laser-induced fluorescence (CE-LIF), and provides an overview and current status of CE-LIF in drug analysis.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
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  • 140
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Lithium ; Poecilia ; Teleost ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Capillary ion analysis (CIA) is a form of capillary electrophoresis that uses the differential electrophoretic mobility of ions to perform a separation of an ionic mixture. Application of this technique for detection of lithium concentrations in plasma and tissues of Poecilia was the purpose of this investigation. CIA was performed using a 75 μm ID × 60 cm length fused-silica capillary and a run electrolyte of 67.7 mg hydroxyisobutyric acid (HIBA), 52.8 mg 18-crown-6-ether and 64 μL UV-CAT-1 reagent (4-methylbenzylamine) in a volume of 100 mL water (18 MΩ) with a voltage of 20 kV using ultraviolet absorption detection at 214 nm. Migration times were: potassium, 2.98 min; calcium, 3.48 min; sodium, 3.60 min; barium (internal standard), 4.15 min and lithium, 4.26 min. Lithium and barium migration times were stable and reproducible. Correlation coefficients (r) between peak area ratios of lithium/barium for concentrations ranging from 0.1 to 2.0 mM were from 0.976 to 0.996. Coefficients of variation (CV) for lithium concentrations ranged from 4.07 to 15.71% between days and 4.38 to 7.76% within-day. Application of this methodology for determination of lithium concentrations in the plasma, brains and livers of fish dosed with lithium for 23 days are presented. CIA is applicable to analysis of lithium concentrations in biological fluids and tissues of fish.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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