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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International journal of legal medicine 109 (1996), S. 53-57 
    ISSN: 1437-1596
    Keywords: Ecstasy ; Amphetamine ; Methamphetamine MDA ; MDMA ; MDE ; Capillary electrophoresis ; Capillary zone electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Notes: Abstract Capillary electrophoresis (CE) and it's applications in forensic toxicology are demonstrated by the investigation of amphetamine derivatives in “Ecstasy” tablets. The method is based on capillary zone electrophoresis (CZE) with a phosphate running buffer (pH 2.2). The drugs were dissolved in 0.01 N hydrochloric acid, diluted with distilled water and phenylephrine was added to the samples as an internal standard. A separation of the charged substances is obtained by the different velocities in the electric field. The qualitative determination can be made by the migration times or more accurately by the relative migration times. Other possibilities for identification are the UV-spectra using a diode array detector or the on-column standard addition procedure. By this procedure the sample solution is initially injected followed by the standard solution. Both are concentrated in the column before separation begins. CE shows clear advantages in comparison to high-performance liquid (HPLC) or gas chromatography (GC). The quantitative analysis was carried out using the internal standard phenylephrine. The values obtained for 56 “Ecstasy” tablets and powder containing amphetamine or its derivatives were compared in this study after analysis with CE and HPLC. The results were in very good agreement. Because of it's speed, the high resolving power and the possibility of identification with the on-column standard addition, CE is a powerful alternative to HPLC or GC for the investigation of “Ecstasy” tablets.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Diastereomeric isomers ; β-Cyclodextrin in the running buffer ; 1,3-Disubstituted tetrahydro-β-carboline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capillary zone electrophoresis with β-cyclodextrin as electrolyte additive has been investigated for the separation of the diastereomers of a 1,3-disubstituted tetrahydro-β-carboline. The effects of pH, buffer concentration, β-cyclodextrin concentration and applied voltage on resolution were investigated. This study shows that optimizing the assay conditions leads to maximum chiral separation or resolution. The method enables further research on the quantitative analysis of these compounds.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary electrophoresis ; Phenolic compounds ; Water samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A comparative study of high-performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE) for determination of eleven EPA priority phenols in water samples is discussed. The repeatability, linearity and detection limits of both methods are compared. A solid-phase extraction method using a highly cross-linked styrene-divinylbenzene copolymer sorbent is used for the off-line preconcentration process in order to determine these compounds in water at low levels. Both methods are used to determine phenolic compounds in Ebro river and industrial waste water. Identification was achieved by comparison of the UV spectra corresponding to the different peaks, acquired with a diode-array detector, with those in a spectral library.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Adamantane derivatives ; 3-Cyclodextrin ; Indirect detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Binding constants between adamantane carboxylic acids and β-cyclodextrin derivatives were determined by capillary electrophoresis (CE) using indirect detection. In this procedure, a mixture of adamantane derivative and non-interacting anionic standards, is injected and analysis of the electrophoretic mobility, relative to the noninteracting anionic standards, as a function of the concentration of cyclodextrin, yields values for their binding constants to the adamantane derivative. The usefulness of the method for quantification of binding constants is demonstrated.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Micellar electrokinetic capillary chromatography ; Sensitized lanthanide ion luminescence ; Orotic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive and selective laser-induced luminescence detection scheme for orotic acid in urine, separated by micellar electrokinetic capillary chromatography (MEKC) has been developed. The 325 nm line from a helium cadmium laser is used to excite orotic acid, which transfers its energy to terbium. Resultant luminescence of terbium is linear with orotic acid concentration over more than 2.5 orders of magnitude. This novel and practical system enables the detection of 50 nm orotic acid in urine in less than 1.5 minutes while using only nanoliters of sample. The significant decrease in analysis time over traditional methods (spectrophotometric and chromatographic) comes from the high efficiency of MEKC. A dramatic improvement in sensitivity and selectivity over UV detection in capillary electrophoresis is achieved through the use of laser-induced lanthanide ion energy transfer luminescence detection. Finally, no sample pretreatment is needed and the method is free from any known interferences in urine.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 42 (1996), S. 323-328 
    ISSN: 1612-1112
    Keywords: Supercritical fluid extraction ; Capillary electrophoresis ; Carbamates residues ; Tobacco samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Determination of carbamate residues in tobacco samples was carried out by solid-liquid extraction (SLE) and supercritical-fluid extraction (SFE) methods, both developed for this purpose. The clean-up step was carried out on SPE-Florisil cartridges and the extracts analysed by capillary zone electrophoresis (CZE) with UV detection. The results were compared and SFE using CO2-acetone showed the best results in terms of recovery and generally higher extraction power. SFE in conjunction with CZE proved suitable for carbamate residue analysis in real tobacco samples.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1612-1112
    Keywords: Review ; Capillary electrophoresis ; Pharmaceutical raw materials ; Excipients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of capillary electrophoresis for the separation and quantitation of a range of pharmaceutical raw materials and excipients is reviewed. Capillary electrophoresis is shown to be a useful and versatile technique for a large number of applications. Features of the various methods include simplicity, detection of poor chromatophore species by extensive use of indirect UV detection or direct absorbance at low wavelengths, minimal operating costs and generation of high quality retrievable raw data. Specific novel examples described include separations of lactose, flavouring agents, inorganic salts, lecithin constituents, a range of organic acids, benzylalkonium chloride components, sodium lauryl sulphate, and the quality of input water. It is concluded that the versatility of CE will ensure that it is increasingly used in the analysis of pharmaceutical raw materials and excipients.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 43 (1996), S. 200-204 
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Capillary joining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Aspects of cracking and joining capillaries have been investigated. Capillary coupling was achieved using various methods. The most successful used hydrofluoric acid-etched capillaries to form male and female ends which were then joined together. This type of joint was used to connect sections of capillary of similar and different internal diameters with minimal loss in resolution, peak width and number of theoretical plates. (Uridine and hypoxanthine was used as a test mixture). For hypoxanthine on a 50 μm/50 μm etched joined capillary 10 cm from the detector window the number of theoretical plates was 96.6% of that for hypoxanthine on an unbroken capillary. Following the relative success of capillary joining, a coupled capillary flowcell (50 μm/200 μm) was produced and evaluated.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Non-aqueous electrolytes ; Chiral separation of dansyl amino acids ; N-methylformamide ; Formamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chiral separation of 12 dansyl amino acids has been achieved by capillary electrophoresis using β-cyclodextrin dissolved inN-methylformamide or formamide. The viscosity and the dielectric constants of these two solvents are very different, giving them disimilar electrophoretic properties. Intense electroosmotic flow, high electrophoretic mobilities and high efficiency were achieved inN-methylformamide, but high chiral selector concentration was needed for sufficient resolution. In contrast, the separation of dansyl amino acids in formamide was characterized by longer analysis time and lower efficiency, but the resolution and selectivity of the separation were better and baseline separation could be achieved at lower β-cyclodextrin concentrations.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 43 (1996), S. 247-253 
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Enantiomers ; Chiral resolution ; Cyclodextrin derivatives ; Drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary β-cyclodextrin derivatives, namely 6A methylamino-β-CD and hepta-methylamino-β-CD have been used as chiral selectors for the enantiomeric separation of a number of acidic and basic compounds by capillary electrophoresis employing either coated or uncoated capillaries. The effects of the CD type and concentration and the pH of the background electrolyte on the mobility and chiral resolution of the analytes have been studied. The use of monomethylamino-β-CD in a coated capillary allowed the enantiomeric resolution of phenyl lactic acid, warfarin and acenocoumarol but was not successful for tiaprofen and its 3-isomer. The heptamethylamino derivative, under the same experimental conditions, was a better chiral selector than the monosubstuted CD toward the arylpropionic acids and phenyl lactic acid while the anticoagulant drugs showed poor or no chiral resolution. Inversion of migration order was obtained for phenyl lactic acid, warfarin and acenocoumarol enantiomers. The enantiomers of basic compounds of pharmaceutical interest, namely propranolol, terbutaline, ketamine, chlorpheriramine and isoproterenol were only resolved using monomethylamino-β-CD dissolved in a phosphate buffer containing tetramethylammonium ions.
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Short-end injections
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Minimum capillary lengths on commercial instruments are fixed and cannot be decreased further. To effectively reduce the capillary length used for separation the sample can be injected from the end of the capillary nearest the detector. This procedure is known as a ‘short-end’ injection and can reduces analysis times by at least two-thirds compared to conventional injections. The time reduction benefits are shown in rapid separations of basic drugs, drug-related impurities and chiral compounds. Short-end injections, in combination with both increased electrolyte strength and reduced voltage are an effective approach to reducing the detrimental impact of high sample solution ionic strength. They can also lead to improved resolution by increasing stacking effects and reducing peak tailing. Peak area and migration time precision obtained are shown to be equivalent to those obtained for conventional injection procedures. It is concluded that short-end injections should be considered for routine operation as they are a useful means of reducing analysis time, increasing sensitivity, decreasing buffer depletion effects. They also allow use of higher electrolyte strengths which can improve resolution and reduce peak tailing, and can overcome significant problems which occur when analysing samples containing high salt contents.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Micellar electrokinetic chromatography ; Retention factors ; Band broadening ; Stepwise modifier gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gradient elution in micellar electrokinetic chromatography has been proposed as a technique for extending the elution range and adjusting retention factors for optimum values. It is shown that this approach in practice has not only to be evaluated for adjustment of retention factors but also for the reduced efficiency of the chromatographic system arising from alterations in the separation buffer during the run. Stepwise gradient elution, feasible with commercial instrumentation, results in marked peak broadening attributable to effects of the border zone passing the solute zone.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Enantiomer separation ; α-Cyclodextrin ; Chiral drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Enantiomer separation by capillary zone electrophoresis was studied for a set of 59 chiral drugs. With α-cyclodextrin as chiral solvating agent, six enantiomeric pairs could be resolved. Baseline separation was achieved for clidinium bromide, oxomemazine and tetryzoline, whereas ketamine, orphenadrine, tropicamide and others require further optimization. Aliphatic and monocyclic compounds prevail among compounds recognized by α-cyclodextrin. Statistical analysis reveals that a medium degree of migration retardation offers the best chance for successful separation.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Column liquid chromatography ; Cefotaxime impurities ; Cross validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A micellar electrokinetic chromatography method is presented which permits separation of cefotaxime and its major related impurities. Separation was carried out at 15 kV, using 30 mM sodium dihydrogen phosphate adjusted to pH 7.2 with 5 M NaOH and which contained 165 mM sodium dodecylsulfate as electrolyte. Results obtained by capillary electrophoresis were in good agreement with those of high-performance liquid chromatography with respect to the level of the major known impurities, total impurity content and cefotaxime purity.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 42 (1996), S. 263-268 
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Local anaesthetics ; Enantiomer separation ; Triethanolamine ; Dimethyl-β-cyclodextrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chiral capillary electrophoresis system for the highresolution separation of the enantiomers of the local anaesthetics mepivacaine, ropivacaine, bupivacaine and prilocaine is described. Triethanolamine was added to the background electrolyte to obtain a negative electroosmotic flow and hence higher resolutions. The interactions of the local anaesthetics and their chemical analogues with the chiral selector, dimethyl-β-cyclodextrin, were studied. From a model describing chiral capillary electrophoresis, the association equilibrium constants were determined by curve-fitting. The separation of mepivacaine, ropivacaine and bupivacaine was due to the different mobilities of the free analytes in solution, whereas the separation of a pair of enantiomers of a single analyte was due to differences between the association equilibrium constantsK 1 andK 2. Branching of the alkyl chain, which was situated close to the cavity in the inclusion complex, had strong effects on the chiral separation of the enantiomers.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Molecularly imprinted polymer ; Enantioseparation ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary electrophoresis method for the enantioseparation of D,L-aromatic amino acids using molecularly imprinted polymer as chiral selector has been developed. Methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate (EDMA) as crosslinking monomer. The molecularly imprinted polymer was packed in capillaries by incorporating with acrylamide gel. The composition of the polymerization mixtures affects the separation factor to some extent. The molar ratio of cross-linker to functional monomer to print molecule was 20∶4∶1, which gives the best separation for aromatic amino acid enantiomers by using L-phenylalanine anilide (L-pheAN) as print molecule. Under the same conditions, however, separation of D,L-phenylalanine using L-phenylalanine as print molecule is poorer than that using L-pheAN. Polymer particles (≤5 μm) were supported by 6% acrylamide and 5% bisacrylamide gel in the capillary. The effects of organic solvents, electrophoretic buffer and pH on separation were also investigated.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Organic acids ; Urine ; Neonates ; Lactate and Pyruvate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The determination of the organic acids oxalic, malonic, maleic, succinic, pyruvic, lactic, 3-hydroxybutyric and hippuric was investigated using capillary zone electrophoresis. They were separated in a fused-silica capillary (70 cm×75 μm id) which was filled with 50 mM sodium tetraborate (pH 10) containing a cationic surfactant as the electroosmotic flow modifier and Ca2+ in the buffer to aid separation of closely migrating peaks and improve peak shape. The developed method was successfully applied to the determination of organic acids in urine. The effect of passing samples through a C-18 solid phase extraction cartridge was investigated briefly, to try to simplify the sample prior to injection. Finally the developed screening procedure was used to study a set of urine samples some of which were obtained from children with metabolic errors resulting in the excretion of an abnormal organic acid profile. Discrimination between normal and abnormal samples was achieved. The results were in good agreement with information obtained by a GC-MS study of the same urine samples.
    Type of Medium: Electronic Resource
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  • 18
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Aminoglycosidic antibiotics ; DEAE-dextran ; Drugs ; Enantiomer separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Diethylaminoethyl (DEAE) dextran hydrochloride and three kinds of aminoglycosidic antibiotics; fradiomycin sulfate, kanamycin sulfate and streptomycin sulfate, were employed as chiral selectors in capillary electrophoresis, enantiomer separation. These selectors are cationic or basic because of amino functionality and therefore used for enantiomer separation of acidic compounds. To avoid adsorption of the basic or cationic selectors on the capillary inner surface, a coated capillary was employed. Among those tested, enantiomers of binaphthyl compounds and synthetic intermediates of diltiazem analogues were separated. Methanol addition was effective for the improvement of peak shape and resolution.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 99-104 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Micellear electrokinetic chromatography ; Organic modifiers ; Naphthalene sulfonates ; Surface water ; Thermostatting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The production and use of naphthalene sulfonates can easily cause pollution of surface and other types of waters. In the present study, capillary electrophoresis in combination with UV absorption detection was used to separate 21 amino- and hydroxy-substituted naphthalene sulfonates which included multiple isomeric compounds. The influence of various parameters such as pH (which turned out to be extremely important), temperature of the surrounding air flow, and the use of buffer additives (micelles, cyclodextrins, organic modifiers) was studied. Complete separation of all analytes including the isomers, was achieved in two runs with a 50 mM boric acid/borate buffer, containing either 100 mM sodium dodecylsulfonate or 15% acetonitrile. The limits of detection obtained for the individual compounds typically were 20μgI-1. River water samples spiked at this concentration level could be analysed using a simple three-step sample clean-up procedure.
    Additional Material: 6 Ill.
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  • 20
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Enantiomeric separations ; Acidic compounds ; Neutral β-cyclodextrins ; Sulfobutyl ether β-cyclodextrin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution could be achieved for the enantiomers of acidic drugs, namely, sulindac, fenoprofen, ketoprofen, warfarin, and hexobarbital, in a buffer of pH 3 by the simultaneous addition of uncharged and charged β-cyclodextrin derivatives. The interaction of the analytes with the anionic sulfobutyl ether β-cyclodextrin provides the analytes with an adequate electrophoretic mobility whereas the interaction with various neutral β-cyclodextrins generates high enantioselectivity. Five neutral cyclodextrins, the native β-cyclodextrin, as well as methyl-, dimethyl-, trimethyl- and hydroxypropyl-β-cyclodextrin, were tested to enhance the enantioselectivity of the electrophoretic system. High resolution values and the shortest analysis times for the five drugs tested were achieved in a buffer made of 100 mM phosphoric acid adjusted to pH 3 with triethanolamine and containing dimethyl- or trimethyl-β-cyclodextrin in addition to sulfobutyl ether β-cyclodextrin.
    Additional Material: 5 Ill.
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  • 21
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Mass spectrometry ; Electrospray ionization ; Fourier transform ion cyclotron ; Resonance ; Biomolecule analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe the current state of the on-line combination of capillary electrophoresis (CE) electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS), and discuss aspects of the FTICR technique relevant to its use as a detection scheme for on-line separations. Aspects including sensitivity, mass resolution, duty cycle, and tandem mass spectrometric capabilities are discussed in the context of online separations with examples from the authors' laboratory.
    Additional Material: 6 Ill.
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  • 22
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis-mass spectrometry ; Membrane preconcentration ; Capillary electrophoresis ; Sulfonated membrane ; Polar drug metabolites ; Toxic oil syndrome ; Eosinophilia-myalgia syndrome ; 3-Phenylamino-1,2-propanediol ; 3-Phenylamino-L-alanine ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 23
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 613-616 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Electrochemical detection ; End column detection ; Nickel electrode ; Carbohydrates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbohydrates were separated by capillary electrophoresis (CE) and detected electrochemically using a nickel microelectrode which was operated at a constant applied potential (∼0.6 V vs. Ag/AgCI). A simple capillary electrode holder design facilitated alignment between the separation capillary and the working microelectrode without the use of micro-positioning equipment. The separations were performed under alkaline conditions (pH 〉 11), matching the high pH requirements for amperometric detection at the nickel electrode. The analytical procedure developed showed detection limits for the carbohydrates studied in the micromolar range, showing a linear response in the range tested (micromolar to millimolar). The procedure was used to identify sugars in two real samples (i.e., urine and in a common beverage). The potential use of the system for the determination of amino acids was also demonstrated.
    Additional Material: 5 Ill.
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  • 24
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Chiral separation ; Selenium amino acids ; Vancomycin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Baseline separation of the enantiomers of the negatively charged 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatives of cystine, methionine, ethionine, and their seleno analogs can be achieved in 3-5 min with capillary electrophoresis in polyacrylamide coated capillaries and submillimolar concentrations of vancomycin as the chiral selector.In addition to the vancomycin concentration, the separation is affected by the type, concentration and pH of the buffer. Good buffers are more suitable than phosphate buffer. At pH values above the isoelectric point of vancomycin the mobility difference between the enantiomers becomes smaller. This effect is larger than would be expected from the reversal of the vancomycin migration alone.
    Additional Material: 3 Ill.
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  • 25
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electroanalysis 8 (1996), S. 722-725 
    ISSN: 1040-0397
    Keywords: Conductometry ; Detection ; Capillary electrophoresis ; Capillary HPLC ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple electrochemical cell has been constructed for conductometric detection in capillary electrophoresis or HPLC. A platinum ring electrode is chemically deposited at the capillary end and the other electrode, a platinum wire, is immersed, together with the capillary, in a vessel containing the running buffer or the mobile phase used. The cell has been tested on a model system and its operational parameters have been discussed. The measurement is very sensitive (a limit of determination of ca. 3 × 10-9 M for potassium ions) and the detector response is rapid, comparable with that of the UV photometric detector. The dynamic range is wide (at least five concentration decades) but is nonlinear at high concentrations.
    Additional Material: 3 Ill.
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  • 26
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 131-136 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Kraft process liquors ; Inorganic anions ; Sulfur specification ; Direct and indirect detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various sulfur containing anions (sulfate, sulfite, and thiosulfate) in Kraft pulping process liquors are determined by capillary electrophoresis. In addition, other inorganic anions (hydroxide, chloride, oxalate, carbonate) are analyzed with the developed method. Through optimization of the separation conditions it is possible to simultaneously determine these anionic species in pulping liquors with direct and indirect UV detection at 185, 214, and 254 nm. To ensure short separation times a migration of the anionic analytes in the same direction as the electroosmotic flow (co-electroosmotic CE) is established by reversal of the electroosmotic flow with 1,5-dimethyl-1,5-diazaundecamethylene polymethobromide (hexadimethrine bromide; HDB; polybrene™) which is added to the electrolyte as EOF modifier. The impact of acetonitrile as organic modifier to improve the selectivity of the anionic analytes is also investigated. The developed method is then applied to analyze and quantify various anions in pulping liquors (white and black liquors). By simultaneously determining the hydroxide concentration it is possible to calculate effective alkalinity and sulfidity with the measured concentrations without the need of volumetric methods.
    Additional Material: 9 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 225-226 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Chiral separation ; Ergot alkaloids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 28
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 5-16 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Inorganic anions ; Decamethonium hydroxide ; Potassium dichromate ; Indirect UV detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separation of the principal inorganic anions (bromide, carbonate, chlorate, chloride, fluoride, nitrate, nitrite, sulfate, phosphate) has been achieved using a capillary electrophoresis system with indirect UV detection at 260 nm. Several types of cationic surfactants (quaternary ammonium, phosphonium or methonium) were tested as electroosmotic flow modifiers and added to a chromatebased buffer prepared from potassium dichromate. The influence of many physicochemical parameters such as nature and concentration of cationic surfactant, buffer pH, dichromate concentration buffer, voltage and temperature upon the migration time of an analyte anion, peak efficiency, asymmetry factor, and finally resolution has been investigated. A linear relationship between the corrected area and the anion concentration in the 2.5-50 ppm range was obtained, thus allowing the quantitative analysis of anions in mineral water. Finally, by increasing the hydrodynamic injection time, the separation of inorganic anions at a low concentration level of 50 ng/ml was achieved without any loss of resolution.
    Additional Material: 10 Ill.
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  • 29
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 322-326 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Enantiomer separation ; Drugs ; Loxiglumide ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vancomycin has been used as chiral selector for the enantiomers separation of D, L-loxiglumide, a new drug proposed for the treatment of gastrointestinal pathology. The chiral selector, dissolved at very low concentration in the running buffer, filled only part of the capillary (polyacrylamide coated) and allowed chiral resolution in less than 12 min using a 50 mM phosphate buffer at pH 6. The partial separation technique allowed to obtain a detection limit of 0.5 μg/ml for each enantiomer avoiding the drop in sensitivity due to the strong UV absorption of vancomycin when present in the detector path. The effects of vancomycin concentration and buffer pH on enantiomers resolution have been studied in order to find the optimum experimental conditions for the chiral purity control of drug. The optimized method, using the internal standard, showed good reproducibility for both migration times and normalized peak area ratio and for linearity. Under the studied operating conditions it was possible to detect 0.2 % (w/w) of L-loxiglumide as a chiral impurity. Analysis of pharmaceutical preparations of D-loxiglumide did not reveal the presence of the impurity (L-isomer).
    Additional Material: 3 Ill.
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  • 30
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 347-351 
    ISSN: 0173-0835
    Keywords: Aldoses ; Reductive amination ; Acid catalysis ; Capillary electrophoresis ; Laser-induced fluorescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The reductive amination of monosaccharides with 8-aminopyrene-1,3,6-trisulfonate (APTS) in seven different organic acids including the commonly used acetic acid was investigated by capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection. The correlation between the yields of the saccharide-APTS adducts and pKa of the organic acid catalyst is consistent with general acid catalysis of the rate-determining step of the reductive amination reaction. Derivatization in the presence of organic acids of higher strength than acetic acid produced substantially higher yields of APTS-sugar adducts, an effect which is more pronounced for N-acetylamino sugars. Optimum yields were obtained using citric acid as a catalyst. Conversion of a few nanomoles of neutral saccharides to the APTS derivatives is achieved at 75°C in less than 60 min.
    Additional Material: 4 Ill.
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  • 31
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Laser-induced fluorescence detection ; Carbohydrates ; Dansylhydrazine ; Tear fluid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A mixture of mono- and disaccharides was derivatized with dansylhydrazine in a relatively fast chemical reaction (15 min) which is selective toward aldehydes and ketones. The products of the derivatization reaction were then separated by capillary electrophoresis (CE) using laser-induced fluorescence (LIF) as the detection mode. The smallest amount of carbohydrate derivatized and determined by CE/LIF was 10 pmol contained in 100 μL of the final reaction mixture. The CE/LIF method provided a linear response for the carbohydrates tested (over 2-3 orders of magnitude), with a limit of detection of 100 amol. Separation efficiencies over 250 000 theoretical plates were obtained. The procedure was used to analyze a tear fluid sample to demonstrate the applicability of the method for the glucose determination in small volumes of biological samples.
    Additional Material: 7 Ill.
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  • 32
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 401-405 
    ISSN: 0173-0835
    Keywords: Cations ; Purity ; Capillary electrophoresis ; Heparin ; Dermatan sulfate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: High performance capillary electrophoresis was used to determine impurities in glycosaminoglycans. The counterion of glycosaminoglycans was analyzed with indirect UV-detection using a 40 mM 4-aminopyridine buffer. Calcium, lithium, potassium and sodium could be resolved. A linear correlation between the area under the curve and the concentration of sodium (r2 = 0.98) and calcium (r2 = 0.99) was found. Using enzymatic depolymerization, chondroitin sulfates were cleaved to disaccharides. The resulting disaccharides, with the structure 4-deoxy-α-L-threo-hex-4-enopyranosyl uronic acid (ΔUA) 2 × (1 → 3)-D-GalNY6X (X = H, sulfate and Y = acetyl, sulfate) for dermatan sulfate, were detected selectively at 230 nm using capillary electrophoresis. Dermatan sulfate disaccharides were analyzed using a 50 cm long fused silica capillary (75 μm ID). The buffer used was 10 mM sodium tetraborate and 50 mM SDS, pH 8.8. The detection was at 230 nm. Using the main peak ΔUA (1 → 3)-D-GalNAc4S as standard, between 1 and 80% dermatan sulfate in heparin preparations were analyzed. The disaccharide showed a linear correlation of the peak area versus the concentration with a correlation coefficient r2 = 0.98. The methods are useful in characterizing the identity and concentration of the counterion of glycosaminoglycans after chondroitinase degradation.
    Additional Material: 5 Ill.
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  • 33
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Peptides ; Thymosin ; High performance liquid chromatography ; Edman degradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A combination of high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) spiking, Edman degradation, amino acid analysis and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) was applied for the analysis of the primary structure of β-thymosins. CE has been used to resolve peaks which coelute on HPLC, as well as to help establish the identity of tryptic fragments in the peptide mapping experiments of the two highly homologous β-thymosins.
    Additional Material: 9 Ill.
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  • 34
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 766-770 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Imaging detection ; Proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A simple home-built electrophoretic unit and a commercially available chargecoupled device (CCD) camera with image acquisition and analysis software were used to study the separation process in zone electrophoresis experiments in 4 cm long, round capillaries (inside diameter 0.2 mm). Several capillaries could be investigated simultaneously. The absorption imaging system was used not only to follow the course of the separation but also to study the interaction between biologically active substances (proteins, detergents, enzymes and substrate). Since the system allows visual on-line observation of the separation one can rapidly decide when the analysis is finished, which often shortens the analysis time. The electrophoresis method presented is suitable also for preparative runs, since direct visualizations of a solute zone allows it to be excised and then used for further studies.
    Additional Material: 6 Ill.
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  • 35
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Micellar electrokinetic chromatography ; Macromolecular branched chain polypeptides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Amphoteric poly(Lys-[Glu1.0-DL-Ala4.1]), (EAK) and anionic poly(Lys-Ac-Glu0.98-DL-Ala3.98]), (AcEAK) branched chain polypeptides were analyzed by capillary electrophoresis (CE) and micellar elektrokinetic chromatography (MEKC) in the following buffers. A1: 0.25 N triethyl ammonium phosphate (TEAP) buffer (pH 2.25); A2: 100 mM sodium dodecyl sulfate (SDS) in buffer A1; B1: Na-borate buffer (pH 7.7); B2: 100 mM SDS in buffer B1; C1: Na-borate buffer (pH 11.0); C2: 100 mM SDS in buffer C1. Both EAK and AcEAK could be separated by a CE mechanism at pH 2.25 and by an MEKC mechanism at pH 11.0. Optimum results were achieved with CE in buffer A1 and with MEKC in buffer C2.
    Additional Material: 3 Ill.
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  • 36
    ISSN: 0173-0835
    Keywords: DNA ; Capillary electrophoresis ; Slab electrophoresis ; Thermoreversible matrices ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We demonstrate the feasibility of temperature-sensitive polymers as novel matrices for capillary and slab electrophoresis of DNA. These matrices combine the ease-of-use of agarose with resolution properties of polyacrylamide. Two classes of matrices are used: (i) aqueous suspensions of gel microspheres and (ii) solutions containing uncross-linked temperature-sensitive polymers. When heated, the viscosity of these solutions drops dramatically because of the phase transition behavior of these polymers, and therefore these formulations are easy to pour or load. Results are presented for separation of double-stranded DNA fragments (〈 2000 bp) in capillary, tube, and slab electrophoresis. Preliminary results are also presented for separation of single-stranded sequencing fragments by capillary electrophoresis. In the tube format, good resolution was obtained for ΦX174/HaeIII fragments. In the slab format, excellent resolution of double-stranded DNA was obtained, including simulaneous separation of a 10 bp ladder up to 150 base pairs. In the capillary format, pBR322/MspI fragments were completely resolved, and single-base resolution of sequencing fragments was obtained up to 150 bases. We believer that temperature-sensitive polymers represent a new and promising class of electrophoretic media.
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  • 37
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Polymer solutions ; Polymerase chain reaction ; T-cell receptor (TCRγ) ; Gene rearrangements ; Laser-induced fluorescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The rapid increase in the number of DNA-based clinical diagnostic procedures, particularly polymerase chain reaction (PCR)-based assays, has generated interest in analytical techniques that are less time-consuming and labor-intensive than traditional procedures such as polyacrylamide gel electrophoresis (PAGE). Capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection, which allows for rapid and sensitive detection of DNA fragments in an automated format, is well-suited for DNA-based clinical assays. In this study, we demonstrate the potential of CE-LIF for the detection of PCR products from T-cell receptor gamma (TCRγ) gene rearrangements present in monoclonal populations of lymphocytes. The presence of monoclonal populations of T-cells is associated (but not always synonymous) with lymphocytic malignancies. Analysis of 31 patient samples, as well as sensitivity controls, demonstrated that CE-LIF detection of monoclonal lymphocytic populations is comparable to that of PAGE-SYBR Green I staining, and that CE-LIF detection can be accomplished in less than 20 min. These preliminary results illustrate the potential feasibility of a CE-based diagnostic assay for the detection of T-cell gene rearrangements.
    Additional Material: 5 Ill.
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  • 38
    ISSN: 0173-0835
    Keywords: Random amplified polymorphic DNA ; Capillary electrophoresis ; Polymorphism ; DNA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The random amplified polymorphic DNA technique (RAPD) has found wide use in molecular genetics because of its speed and ease of use. For various reasons, with this method the amplified DNA fragments are produced at different concentrations between genotypes and even between polymerase chain reaction (PCR) runs. Since the detection of the multiple amplified fragments is performed routinely by agarose gel, and seldom by acrylamide gel electrophoresis, we have found that by capillary zone electrophoresis (CZE), which is more sensitive and accurate than gel electrophoresis, it is possible to unequivocally detect amplified fragments even at low concentration, avoiding polymorphism misinterpretation. CZE is also useful to make more potentially polymorphic fragments evident per random primer used, with obvious economical benefits.
    Additional Material: 2 Ill.
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  • 39
    ISSN: 0173-0835
    Keywords: Isoelectric focusing ; Capillary electrophoresis ; Hemoglobin ; Glycated hemoglobin ; Diabetes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A precise and reproducible method for assessment of glycated hemoglobin in human adult red blood cells is reported, based on capillary isoelectric focusing (IEF). In order to obtan baseline resolution between adult hemoglobin (Hb A) and its glycated form (Hb A1c), two species which differ by minute ΔpI values, 〈 0.03 pH units, the following procedure was adopted: the focusing mixture consisted of 5% Ampholine, pH 6-8, 0.5% Pharmalyte, pH 3-10, 3% short-chain liquid polyacrylamide and an equimolar mixture of two “separators”, 0.33 M β-alanine and 0.33 M 6-aminocaproic acid. The last two compounds flatten the pH gradient in the pI region of the two Hbs, thus allowing full separation. Additionally, the Hb samples, instead of being pulse-loaded, are uniformly distributed in the background electrolyte. A longer capillary lifetime is obtained if all nonbuffering ions are eliminated; thus, as catholyte, 50 mM Lys (pH 9.7) is utilized and as anolyte 50 mM acetic acid (pH 3.5) is adopted. The percentages of Hb A1c, as obtained by capillary IEF, are in good agreement (±6%) with data obtained by one of the standard zone electrophoretic methods in clinical chemistry, i.e., the Helena REP Glyco gel system.
    Additional Material: 5 Ill.
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  • 40
    ISSN: 0173-0835
    Keywords: DNA sequencing ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary electrophoresis with a replaceable linear polyacrylamide matrix operated at elevated column temperatures of 55° and 60°C was used to exted the separation of DNA sequencing fragments to lengths greater than 800 bases. A solid-state heater was employed to provide stable, uniform temperature control over a significant portion of the capillary. The polymer matrix, 3% w/v linear polyacrylamide in a denaturing buffer, was replaced in the capillary after each run. Using dye-labeled primers and Sequenase chemistry on an M13mp18 single-stranded template, four-color separations for the sequencing products were obtained, with read lengths in excess of 800 bases. This paper also briefly discusses the effects of buffer denaturants and capillary temperature on separation speed, resolution, and gel compression.
    Additional Material: 6 Ill.
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  • 41
    ISSN: 0173-0835
    Keywords: Lactoferrin ; Heparin binding ; Neutrophils ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Human lactoferrin from two different sources: milk and secondary granules of neutrophil granulocytes, was compared with respect to heparin binding by means of affinity capillary electrophoresis. This method is based on analysis of migration pattern shifts induced by various amounts of ligand present in the electrophoresis buffer. Since lactoferrin is a basic molecule, analyses were performed at pH 8 in a capillary with a neutral hydrophilic coating. However, analyzable peaks were only obtained in the presence of heparin in the electrophoresis buffer. Proportionally to the amount of heparin present, these peaks exhibited shape changes and strong migration shifts. In the ensuing analysis it could be demonstrated that the two lactoferrins had comparable migration shifts and peak shape changes. This indicates that also in this respect the two forms of lactoferrin are identical. Affinity capillary electrophoresis is a convenient and fast method to investigate functional characteristics of low amounts of unmodified biomolecules.
    Additional Material: 3 Ill.
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  • 42
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1950-1953 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Chiral separation ; Proteins ; Transferrin ; Drugs ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Stereoselective interaction of drugs with human serum transferrin in capillary zone electrophoresis is described. The substances passed a pseudo-stationary protein zone applied in a coated capillary and the possible chiral separation of the optical isomers was followed. Drugs with different structures were screened and the enantiomers of bupivacaine, propranolol and promethazine as well as the diastereomers of labetalol were resolved. Racemic mixtures of atenolol and pindolol enantiomers could not be resolved under these conditions.
    Additional Material: 6 Ill.
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  • 43
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Cyclodextrin ; Methadone ; Stereoselective metabolism ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Using capillary zone electrophoresis with a phosphate buffer at pH 3, containing 4.3 nM hydroxypropyl-β-cyclodextrin as chiral selector, the simultaneous separation of the enantiomers of methadone and its primary metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), is reported. After solid-phase extraction and analysis of the reconstituted extracts in a 60 cm fused-silica capillary of 50 μm ID within about 25 min, the mean S/R enantiomeric ratio of methadone in the urines of eight patients undergoing methadone therapy is shown to be 0.653 (range: 0.502-0.842). The mean enantiomeric ratio for the metabolite is 0.630 (range: 0.517-0.729). These data document the stereoselectivity of the methadone metabolism. Finally, the EDDP/methadone ratio is shown to vary between 0.357 and 2.917 with a mean value of 1.731. The capillary electrophoretic assay described is simple, inexpensive and neither requires any sample derivatization, nor large amounts of organic solvents or expensive separation columns.
    Additional Material: 5 Ill.
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  • 44
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Furosine ; Food analysis ; Additives ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The electrophoresis of ε-N-2-furoylmethyl-L-lysine (furosine) was studied in an attempt to develop a method for the identification and quantitation of this compound in processed food. The effect of pH and composition of electrolyte solution on both the electrophoretic migration of furosine and the electroosmotic flow in a bare fused-silica capillary of 75 μm internal diameter was investigated. We demonstrate that the addition, to the running electrolyte solution, of N,N,N′,N′-tetramethyl-1,3-butanediamine (TMBD) at concentrations ranging from 20 to 80 mM improves peak efficiency and can be used to modulate the migration time of furosine by controlling the electroosmotic flow which is reversed from cathodic to anodic. In a sample of dried milk subjected to a long period of storage under controlled conditions, furosine could be efficiently and reproducibly separated and quantitated by employing as the running electrolyte 60 mM TMBD titrated to pH 2.5. Capillary electrophoresis is a promising technique for the rapid identification and quantitation of furosine in processed food.
    Additional Material: 3 Ill.
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  • 45
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 310-318 
    ISSN: 0173-0835
    Keywords: Pulsed electrochemical detection ; Electrochemistry ; Capillary electrophoresis ; Carbohydrates ; Integrated pulsed amperometric detection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Pulsed electrochemical detection (PED) following capillary electrophoresis (CE) has been applied to the direct detection of polar aliphatic compounds. These compounds typically have poor optical detection properties and are considered to be electroinactive under constant applied potentials. The voltammetric responses at microelectrodes of model compounds were studied under various buffers and pH conditions. The detection of unsubstituted carbohydrates requires highly alkaline conditions, whereas amine-containing compounds (e.g., glycopeptides, peptides, and amino acids) and thiocompounds can best be detected at mildly alkaline (i.e., pH 9.0) and mildly acidic (i.e., pH 5.5) conditions, respectively. In a comparative study of pulsed amperometric detection (PAD) and integrated pulsed amperometric detection (IPAD), IPAD is determined to be better suited to manage the large oxide-formation backgrounds, which accompany oxide-catalyzed detections of amine- and sulfur- containing compounds. IPAD results in more stable baselines, eliminates oxide-induced artifacts, and often yields lower limits of detection. Mass detection limits under optimal conditions are typically 10 fmole or less. This paper delineates PED waveform parameters for the optimal detection of underivatized nonchromophoric compounds of biological significance in various operating buffers and electrolytes.
    Additional Material: 10 Ill.
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  • 46
    ISSN: 0173-0835
    Keywords: Glycosaminoglycan ; Hyaluronan ; Synovial fluid ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The glycosaminoglycan, hyaluronan, can be detected in human synovial fluid by capillary electrophoresis (CE). Variations in peak shape make this technique unsuitable for quantitative analysis of hyaluronan in raw synovial fluid. Quantitative analysis was achieved by hydrolysis of the polymeric hyaluronan to the tetrasaccharide by the action of testicular hyaluronidase and separation of the product using CE. A UV detector operating at 200 nm was used. The X-ray contrast material, omnipaque, a propriety aqueous solution of iohexol was used as internal standard. A second peak in the electropherogram of synovial fluid was quantified. The variation in concentrations of these two components correlate with the arthritic disease state of a joint.
    Additional Material: 3 Ill.
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  • 47
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 418-422 
    ISSN: 0173-0835
    Keywords: Monoclonal antibodies ; Microheterogeneity ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Based on complex formation of borate with carbohydrates in alkaline solutions, the oligosaccharide microheterogeneity of a monoclonal antibody was studied using capillary zone electrophoresis. In borate buffers characteristic separation patterns were found that could be attributed to the same antibody by their UV spectra, while in a phosphate buffer, under otherwise the same conditions, only a single peak was observed. N- and O-glycans were chemically hydrolyzed by trifluoromethane sulfonic acid, resulting in a completely deglycosylated protein; alternatively, N-glycans were enzymatically cleaved by incubation with peptide N-glycosidase F (PNGase F). In both approaches a changed antibody pattern was detected, indicating that the separation is due to carbohydrate microheterogeneity of the protein. Deglycosylation of the antibody by treatment with PNGase F was investigated by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). A shift to lower molecular masses of approximately 1500 Da for the enzymatically treated protein, compared with the intact glycoprotein, was found. The separation method was validated for linearity and reproducibility of migration time and peak area and optimized in terms of buffer pH, capillary temperature and borate concentration. This technique is sensitive to analyze batch-to-batch consistency in production and to test the stability of galenical formulations. After antibody storage in glass vials for 3 months at 37°C, the separation profile changed distinctly due to degradation at the carbohydrate or sialic acid moiety of the antibody, as indicated by MALDI-TOF-MS.
    Additional Material: 6 Ill.
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  • 48
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 431-437 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Carbohydrate-deficient transferrin ; Transferrin ; Sialic acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The presence of specific transferrin (Tf) glycoforms in human serum has been shown to correlate with certain clinical syndromes. Hence, the ability to separate and quantitatively measure the various forms of human transferrin has become increasingly important. As a means of evaluating the potential for developing a rapid capillary electrophoresis-based assay for the analysis of carbohydrate-deficient transferrins (CDTs), the capillary zone electrophoretic (CZE) analysis of Tfs from several species was evaluated using uncoated capillaries and a separation augmented with cationic additives. With bovine Tf, five peaks (representing different sialylated forms) were partially resolved in borate and baseline-resolved when 1,4-diaminobutane was added to the buffer. These same conditions were found to be inadequate for the resolution of the sialo-forms from other species. Some success was achieved using α,γ-bis-quaternary ammonium alkanes instead of the 1,4-diaminobutane and optimizing the pH for each of the species Tfs. Human Tf was found to be resolved in an uncoated capillary equilibrated with a borate buffer containing millimolar concentrations of decamethonium bromide as a buffer additive. Under these conditions, resolution of the various sialoforms from the iron-saturated Tf was possible and the glycoforms were found to migrate differently than their iron-depleted counterparts. Despite the resolution achievable under these conditions, the lengthy analysis time is incompatible with the requirements for a clinical CZE-based assay.
    Additional Material: 5 Ill.
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  • 49
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Micellar electrokinetic chromatography ; Somatostatin analog peptides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary electrophoresis (CE) and micellar electrokinetic chromatography (MEKC) methods, utilizing uncoated silica capillary and triethyl ammonium phosphate or sodium borate buffers in the pH range of 2.25-11.0, containing sodium dodecyl sulfate (SDS) (0-100 mM) for analysis of somatostatin-analog peptides were developed. The method presented here was compared with the reversed-phase high performance liquid chromatographic (RP-HPLC) and CE methods developed for analysis of peptides. The peptides investigated in this work can be separated by CE on the basis of their electrophoretic mobility in aqueous buffer of low pH value (pH 2.25) or by MEKC on the basis of their hydrophobicity in SDS containing buffer of high pH value (pH 11.0). Optimal MEKC separation of the investigated peptides has been achieved at pH 11.0 in an Na-borate buffer containig 100 mM SDS. CE at pH 2.25 proved insensitive to the hydrophobicity of the peptides investigated. By contrast, results obtained with MEKC at pH 11.0 proved to be anologous to those obtained by RP-HPLC, with highly hydrophobic peptides - migrating slower than peptides without hydrophobic moieties.
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  • 50
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1470-1475 
    ISSN: 0173-0835
    Keywords: Isoelectric buffers ; Capillary electrophoresis ; Oligonucleotides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Analysis of oligonucleotides (especially in regard to assessing the purity of antisense compounds) is typically performed in 18%T sieving liquid polyacrylamide, in 30% formamide and 7 M urea. Up to 600 V/cm have been reported, with transit times, for 20 to 25 oligomers, of 15-20 min. We show that the same analysis can be performed in isoelectric buffers, typically histidine (His), and in more dilute linear polyacrylamides, e.g. 10%T (at 0%C), with much reduced analysis times. A series of His concentrations has been explored, ranging from 25 to 150 mM. Best performance is obtained in 100 mM His (at pH = pI, i.e., 7.47 at 25°C), dissolved in 7 M urea, in presence of 10% sieving liquid linear polyacrylamide. Such a buffer allows delivering 800 V/cm without any loss of resolution due to Joule heating, with retention of very high resolving power down to fragments as short as tetranucleotides. Under these conditions, the analysis time for an antisense oligonucleotide containing fragments from a 10-mer to 18-mer is in a time window of 4-5 min. It is shown that the smallest fragment (10-mer) migrates in the capillary at the remarkable speed of 5 cm/min.
    Additional Material: 4 Ill.
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  • 51
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Laser-induced fluorescence detection ; Intercalation ; Mitochondrial DNA ; Low-stringency single specific primer ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Polymerase chain reaction (PCR)-based DNA typing is routinely used in forensics for identity testing. Those assays that distinguish single nucleotide polymorphisms (SNPs) require other biochemical reactions in addition to PCR to identify the sequence polymorphisms. Low-stringency sequence-specific PCR (LSSP-PCR) is an example of a recent method that does not require additional biochemical treatments. The analysis of LSSP-PCR by capillary electrophoresis (CE) to discriminate the highly polymorphic mitochondrial DNA (mtDNA) D-loop region is described. The DNA from five individuals were amplified (first step) using sequence-specific primers to produce 1021 bp fragments containing the D-loop region. Each fragment was isolated by electroelution using CE and UV detection, and subjected to a second amplification (second step) using a single primer annealed under low stringency conditions. This generated a range or profile of PCR products for each sample, which were resolved and analyzed by CE with the intercalator TOTO-1 and laser-induced fluorescence (LIF) detection. The LSSP-PCR profiles were unique for each individual, indicating that this technique may be applicable for forensic identity testing.
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  • 52
    ISSN: 0173-0835
    Keywords: D1S80 ; Amelogenin ; Capillary electrophoresis ; Laserinduced fluorescence ; Polymerase chain reaction ; Forensic ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In this study, a technique was developed to separate by capillary electrophoresis (CE) the widely varying DNA fragment sizes produced by a multiplex polymerase chain reaction (PCR) amplification of the loci D1S80 and amelogenin. Experiments were performed to analyze different buffer systems and obtain optimal resolution for the separation. A matrix composed of two different molecular weights of the same polymer was constructed to separate the DNA fragments with baseline resolution, and a cubic spline fit was used to estimate the size of DNA fragments over 350 base pairs. Over 100 samples were examined to demonstrate the rapid, robust and precise characteristics of this CE system. An average relative standard deviation of 0.3% was obtained for the sizing of the D1S80 alleles in these samples. DNA from mixed body fluid samples samples subjected to environmental insult, and D1S80 sequence variants were also typed successfully. These results demonstrate that CE is a viable method for analysis of D1S80 and amelogenin forensic DNA samples.
    Additional Material: 5 Ill.
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  • 53
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Capillary isoelectric focusing ; Fourier transform ion cyclotron resonance-mass spectrometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The interfacing of capillary electrophoresis (CE) with Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) and the factors which dictate obtainable performance (i.e., sensitivity, mass resolution, scan rate and duty cycle) are described. We demonstrate the current status of the technique with examples of capillary zone electrophoresis (CZE) and capillary isotachophoresis (CITP) with FTICR analyses of proteins and oligonucleotides, and describe current limitations on sensitivity and scan speed. The first on-line interfacing of capillary isoelectric focusing (CIEF) with FTICR is also demonstrated and shown to be effective for separating minor components of protein mixtures for on-line mass spectral analysis. Finally, the potential for greatly improved performance based upon recent advances in FTICR instrumentation and methods is briefly described.
    Additional Material: 7 Ill.
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  • 54
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; DNA melting ; Kinetics ; Mutation ; Separation efficiency ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Constant denaturant capillary electrophoresis (CDCE) separation takes place in the heated portion of the capillary where faster-moving, unmelted DNA fragments are in equilibrium with slower-moving, partially melted forms. Within a certain temperature range, the position of the melting equilibrium and thus the average electrophoretic mobility of each mutant is different. The resulting difference in mobility allow sequences containing single base pair point mutations to be separated from each other. We report the results of experiments in which we explored the rules defining separation efficiency by varying the parameters of CDCE. We discovered an unusual peak broadening mechanism. In contrast to most other DNA electrophoresis systems, peak width in CDCE steadily decreases with the square root of the separation speed. Moreover, the peak width displays a sharp maximum at a specific temperature. To account for these observations, we use a model which describes CDCE separation as a random walk. According to this model, peaks in CDCE are broad because the kinetics of the melting equilibrium are slow and there-fore the number of random walk steps represented by melting/renaturation transitions is relatively small. In addition to providing a satisfactory interpretation of the data, the model also predicts that separation efficiency will increase as the ionic strength of the running buffer is increased and as the concentration of denaturant in the buffer is decreased. These predictions were verified and were used to establish conditions for high-resolution CDCE suitable for separating complex mixtures of single base pair mutants.
    Additional Material: 7 Ill.
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  • 55
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; pH variation ; Electrode reactions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Electrode reactions during the electrophoretic process may change the pH of the buffer and subsequently the migration behavior of solutes with resultant loss of reproducibility. A theoretical treatment of pH variations due to electrolytic processes is presented. The choice of buffer appears to have a dramatic influence on the pH variations observed, even if substantial buffer action is expected at the pH chosen. The experimental evaluation of the separation of 4-hydroxy-3-methoxycinnamic acid and 3-hydroxybenzoic acid reveals that the quality of the separation decreases continuously from a baseline separation observed in the first experiment to a comigration of the two solutes (resolution = 0) in the ninth experiment. A pH decrease of about 0.05 pH units accounts for the observed changes in mobility.A novel in situ pH measurement approach is presented, in which the mobility, peak area, and peak height of an indicator dye are related to the pH in the capillary. This enables the identification and quantification of pH variations during electrophoretic runs: the pH decreases at the anodic side already after the first experiment and pH variations as small as 0.02 pH units can be measured. The variations in peak height appear to be less suited. The calculated pH variations are in close agreement with the ones obtained experimentally.
    Additional Material: 5 Ill.
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  • 56
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 275-301 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Carhohydrates ; Glycoproteins ; Glycoforms ; Glycopeptides ; Glycosaminoglycans ; Glycolipids ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
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  • 57
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Hydroxyethylcellulose ; Energy transfer ; DNA aggregate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Fluoresence resonance energy transfer (FRET) microscopy is used to observe structures of DNA aggregates formed during electrophoresis in ultradilute hydroxyethylcellulose (HEC). FRET gives evidence of aggregates with a tightly packed core and random entanglement of DNA in the outer portions. HEC concentrations also appear to play a role in aggregate formation. DNA aggregates take longer to assemble in higher HEC concentration solutions and assume a less compact form than those formed at lower HEC concentrations.
    Additional Material: 5 Ill.
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  • 58
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1126-1133 
    ISSN: 0173-0835
    Keywords: Ampholytes ; Buffering capacity ; Capillary electrophoresis ; Numerical modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A numerical model has been used to study the separation of protein mixtures by zone electrophoresis in a nonsieving amphoteric medium. An amphoteric buffer fixes the pH of the solution close to its isoelectric point, where the buffer molecules are uncharged: they thus contribute very little to the conductivity of the solution. This means that high field strengths can be used for rapid separation without sacrificing resolution. The numerical study shows that in this process the band spreading that can reduce resolution is essentially due to differences in migration rate between protein-rich and low-protein zones: both differences in solution conductivity and in protein mobility are involved. Rules for judging the buffer capacity of amphoteric molecules are presented and it is shown how, for a given protein, the effectiveness of this technique varies with the range of pH in which it is applied.
    Additional Material: 11 Ill.
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  • 59
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1151-1160 
    ISSN: 0173-0835
    Keywords: Polyelectrolytes ; Charge density ; Capillary electrophoresis ; Free solution electrophoresis ; Gel electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: To assess the role of charge density on polyelectrolyte mobility, both gel and free solution electrophoresis experiments are performed on poly(acrylic acid) and acrylic acid/acrylamide copolymers. Control of charge density for poly(acrylic acid) is achieved through solution pH, while control for acrylic acid/acrylamide copolymers is obtained through chain composition. In either approach, the effective fraction of charged repeat units can be varied from 0 to 100% without a major interruption of solvent quality. Polyelectrolyte mobility in the presence of a monovalent counterion is observed to rise linearly with charge density when this density is low. A transition to charge density independence then occurs over a surprisingly narrow window of charge density. For vinyl polymers of the sort examined here, the transition occurs when 35-40% of the repeat units are charged. These observations are qualitatively consistent with the free solution electrophoresis model proposed by Manning and several previous data sets. An unexpected overlap of normalized gel and free solution data reveals that the charge density exerts a comparable influence in either environment. Results from the present study help define the experimental conditions in which electrophoresis can provide polymer separation by charge density and those in which the method can provide polymer separation by molecular weight.
    Additional Material: 7 Ill.
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  • 60
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1173-1180 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Resolution ; Solitary wave ; Nonlinear wave ; Laser ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A theoretical study about the generation of solitary waves (SW) in electrophoresis and capillary electrophoresis is performed. Two models that use velocity terms in Fick's first law and absorption and decaying terms in Fick's second law are presented. These models give the time evolution of the band or zone shape in electrophoresis and capillary electrophoresis in the presence of electromagnetic radiation. In particular, the effect of electrophoretic mobility changes of the analytes due to radiation excitation is included in the present models. The analytes are represented either by three-level or four-level systems. It is shown that the resulting system of coupled nonlinear partial differential equations governing the spatial motion of these bands over time exhibits SW solutions for some values of the equation parameters. We analyze the conditions in which these SWs, which propagate with constant velocity, constant area, constant standard deviation, and without change of form, are generated. The results of the present models are compared with those from a previous two-level model (Phys. Rev. Lett. 1995, 75, 1210-1213). The velocities of these SWs are calculated analytically. The time evolution of their standard deviations is shown. The numerical integration of a two-component electrophoresis run shows higher resolutions under some conditions. The expected practical difficulties which may be encountered when observing this phenomenon are discussed. Some practical difficulties that are likely to limit its useful application in electrophoresis and capillary electrophoresis are mentioned.
    Additional Material: 8 Ill.
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  • 61
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 302-309 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Glycopeptides ; Pulsed amperometric detection ; Carbohydrates ; Glycoproteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The utility of capillary electrophoresis with pulsed amperometric detection (CE-PAD) for the analysis of carbohydrate-containing samples from a variety of biological sources is described. CE-PAD was used to separate a mixture of oligosaccharides obtained from bovine fetuin and to monitor the desialylation process used in the characterization of the oligosaccharides. Additionally, the high resolving power of the system was demonstrated using a series of glycopeptides obtained from recombinant coagulation factor VIIa, which possess the same decapeptide core but differ in the extent of sialylation. Deglycosylation of these glycopeptides for characterization purposes resulted in a mixture of carbohydrates and peptides. Unlike CE with UV detection, this system gave good responses for all analytes, demonstrating the unique ability of PAD to respond to the electrochemical features of diverse classes of biomolecules such as carbohydrates and peptides. Finally, CE-PAD was applied to the analysis of a tryptic digest of recombinant tissue plasminogen activator. The use of different detection potentials in sequential runs on a sample gave structural information about the peptides, such as glycosylation. A brief review of prior applications of CE-PAD to the analysis of standard mixtures of simple saccharides is also presented.
    Additional Material: 7 Ill.
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  • 62
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Polysaccharides ; Electrochemical detection ; Cu electrode ; Carbohydrates ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Complex polysaccharide mixtures were analyzed directly without derivatization by capillary zone electrophoresis in strongly alkaline solutions and electrochemical detection at a Cu electrode. The positively charged surfactant cetyltrimethylammonium bromide was included in the electrophoresis medium in order to reverse the electroosmotic flow and permit elution to be in order of increasing polysaccharide size. Carbohydrate samples analyzed by this approach included linear maltoses, enzymatically hydrolyzed starch, and commercially available dextrans of up to an average molecular weight of 18 300. Detection by constant-potential oxidation at a Cu electrode was very sensitive, with detection limits for individual carbohydrates generally below the femtomole level.
    Additional Material: 4 Ill.
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  • 63
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 333-340 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Cyclodextrin ; Indirect detection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary zone electrophoresis (CZE) methods with indirect absorbance detection for analyzing mixtures of α-, β-, and γ-cyclodextrins (CDs) and their derivatives have been developed. Benzylamine, salicylic, sorbic, or 1-naphthylacetic acid (NAA) was utilized as background electrolyte (BGE) and absorbance provider. Separation of α-, β-, and γ-CD could be achieved in less than 18 min when the CZE was run in 2 mM NAA or 5 mM sorbate solution (pH 12.2) and detected by indirect absorbance at 222 or 254 nm, respectively. Mixtures of α- and β-CDs, and dimethyl- and trimethyl-derivatives of β-CD could also be analyzed by CZE, using 50 mM salicylic acid or benzylamine solution (pH 6.0) as BGE with indirect absorbance detection at 230 and 210 nm, respectively. CZE methods for determining the inclusion complex formation constants of various CDs for salicylic acid or benzylamine with either direct or indirect absorbance detection have also been developed. The formation constants of salicylate are in the range from ca. 8 ± 0.3 mole-1 for the complex with α-CD to ca. 99 ± 2 molarity-1 for the complex with methyl-β-CD. The detection limits (determined at a signal-to-noise ratio of 3) for the NAA and the salicylate system are ca. 0.1 mM and 1 mM, respectively.
    Additional Material: 8 Ill.
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  • 64
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 359-366 
    ISSN: 0173-0835
    Keywords: Glycoconjugated antibiotics ; Macrolide antibiotics ; Capillary electrophoresis ; Sodium cholate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary electrophoresis was utilized in the study of the macrolide antibiotics (i.e. pharmaceutical glycoconjugates) clarithromycin, erythromycin, oleandomycin, troleandomycin, and spiramycin. In order to assist in analyte solubilization, two buffer systems using acetonitrile were developed. The first system involved 30 mM sodium cholate and 20% acetonitrile in 80 mM sodium phosphate, pH 6. This buffer permitted the baseline resolution of all five glycoconjugated antibiotics. In addition, erythromycin was separated from its derivatives estolate and ethylsuccinate. In the absence of surfactants, a higher acetonitrile quantity, 65%, was used in the second buffer system, with 35 mM sodium phosphate, pH 6. Selectivity between oleandomycin and clarithromycin was reversed in this system compared to the cholate buffer, indicating solute interaction with the cholate micelles in the previous system. Calibration linearity and detection sensitivity were improved in the high acetonitrile buffer, due to decreased background absorbance. It was demonstrated that both buffer systems can be utilized for the visualization of minor components that may be present in bulk pharmaceuticals.
    Additional Material: 10 Ill.
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  • 65
    ISSN: 0173-0835
    Keywords: Heparin ; Heparan sulfate ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A rapid, sensitive and accurate high-performance capillary electrophoresis method is described for the determination of the sulfation pattern of heparin and heparan sulfate disaccharides. The analysis, performed after enzymic degradation of the polysaccharides with heparinase and heparinases II and III in combination, yields highly UV-absorbing Δ-disaccharides. The separation is performed with reversed polarity using 15 mM phosphate buffer, pH 3.50. This method is superior to others since all known 12 disaccharides carrying N-acetylated, N-sulfated or unsubstituent glucosamine can be separated in a single run of 15 min. At the highest sensitivity the analysis consumes only a few femtograms of glycosaminoglycan and allows a determination of Δ-disaccharides at the attomole level.
    Additional Material: 4 Ill.
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  • 66
    ISSN: 0173-0835
    Keywords: Glycans ; Fetuin ; Monoclonal antibodies ; Capillary electrophoresis ; 2-Aminoacridone ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary electrophoresis and laser-induced fluorescence detection have been used to fingerprint the 2-aminoacridone derivatives of complex glycans released from bovine fetuin and human IgG monoclonal antibodies. The utility of this method in distinguishing between N- and O-linked oligosaccharides and in determining the presence of sialic acid residues in glycan mixtures at an early stage of analysis has been demonstrated.
    Additional Material: 5 Ill.
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  • 67
    ISSN: 0173-0835
    Keywords: Capillary isoelectric focusing ; Recombinant tissue-type plasminogen activator ; Capillary electrophoresis ; Validation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Attempts were made to validate a capillary isoelectric focusing (cIEF) method for a recombinant glycoprotein as an alternative technique to slab gel isoelectric focusing methods routinely used to monitor such charge heterogeneity. The cIEF method principally separates the charged glycoforms of recombinant tissue-type plasminogen activator (rt-PA) on the basis of their sialic acid content. Nine to ten distinct peaks were consistently resolved, with the profile dependent on the class of ampholyte used. The pI of rt-PA measured with synthetic pI standards was in the range pH 6.5-7.5 with the migration of the standards affected by the presence of the protein. The method showed an acceptable recovery of 〉 100% and had good sensitivity where 25 ng of protein could be resolved into constituent peaks. Recovery of both major peaks and total protein measured by peak areas was linear over a wide range from 50-1000 μ/mL. A detailed study showed that when a capillary had been used for some time, capillary age affected peak migration times and, to a lesser extent, resolution. Peak migration times were stable over a temperature range of 15-30°C, and decreased predictably with increasing voltages (400-600 V/cm) and decreasing N, N, N′, N′-tetramethylethylene diamine (TEMED) concentrations (0.4-1.5% v/v). Overall the data indicated that this methodology has the potential to be used in the commercial release of protein pharmaceuticals if variability resulting from capillary age and lot were resolved. Even in its present format the method equals the performance of slab gel IEF whilst offering significant improvements in ease of operation and in time and reagent use.
    Additional Material: 8 Ill.
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  • 68
    ISSN: 0173-0835
    Keywords: Lupinus ; Sodium dodecyl sulphate-gel electrophoresis ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Effective distinction was achieved among a wide range of lupin grain samples by either sodium dodecyl sulphate (SDS)-gel electrophoresis or capillary electrophoresis, based on grain-protein composition. Capillary electrophoresis was faster (〈 1 h) and provided slightly greater distinction between the samples. On the other hand, SDS-gel electrophoresis could provide a greater throughput of samples in a 24 h period. Either technique could be used successfully to distinguish between lupin species and cultivars for taxonomic analysis or seed identification.
    Additional Material: 3 Ill.
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  • 69
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 341-346 
    ISSN: 0173-0835
    Keywords: Glycosaminoglycans ; Capillary electrophoresis ; Copper (II) sulfate ; Oligosaccharides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Glycosaminoglycans including heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate and hyaluronic acid were analyzed by reversed polarity capillary electrophoresis. Detection was achieved at 240 nm based on the formation of a copper (II) complex in copper sulfate solution at low pH. Glycosaminoglycans having a high ratio of iduronic acid to glucuronic acid, as well as ones having lower molecular weight, gave the highest detection sensitivity using this method. Detection of the copper (II)-heparin complex is extremely sensitive, permitting the analysis of as little as 10-9 g. This method was also successfully applied to the analysis of heparin oligosaccharides that lacked a chromophore prepared from heparin using controlled, low pH nitrous acid depolymerization.
    Additional Material: 6 Ill.
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  • 70
    ISSN: 0173-0835
    Keywords: Keywords: Glycosaminoglycans ; Capillary electrophoresis ; Preparative electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We have used various electrophoretic techniques to analyse glycosaminoglycan structure. Capillary electrophoresis has been particularly useful in the determination of the sulphation of glycosaminoglycans (GAG) and the sulphation of partly desulphated glycosaminoglycans produced by methanolysis. This, in conjuction with preparative electrophoresis and enzyme linked immunosorbent assay (ELISA) has permitted us to ascertain the length of the oligosaccharide required for binding and sulphate ester groups required for optimal binding and those essential for antibody binding. From these preliminary studies, we have demonstrated that the minimum length of oligosaccharide required for binding was about 12-14 monosaccharides in length. It appears likely that 6 sulphation is required for strong binding but 4 sulphation is not involved in mimotope binding. We propose on the basis of this evidence that the mimotope does not contain 4-sulphate residues but 3-4 6-sulphate ester groups are essential for binding.
    Additional Material: 9 Ill.
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  • 71
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; DNA restriction fragments ; Polyacrylamide ; Hydroxyethylcellulose ; Hydroxypropylcellulose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Low-viscosity, aqueous solutions of hydrophilic linear polymers have been shown to be useful for the separation of DNA restriction fragments by capillary electrophoresis (CE). However, the choice of polymer type, size, and concentration remains largely empirical, because the mechanism of high-field electrophoretic DNA separations in polymer solutions is not well understood. To assist in elucidating the mechanism of DNA separation, we experimentally investigated the effects of polymer properties such as stiffness (persistence length), average molecular mass, polydispersity, and hydrophilicity on the separation of DNA ranging from 72 bp to 23 kbp. This was accomplished by comparing the results of DNA separations obtained by counter-migration CE in dilute and semidilute solutions of linear polyacrylamide (PAA), hydroxyethylcellulose (HEC), and hydroxypropylcellulose (HPC) polymers of several different average molecular masses.
    Additional Material: 10 Ill.
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  • 72
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Mass spectrometry ; C-terminal modification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: To identify the form of the C-terminal amino acid of a sea anemone toxin, the native protein was compared with two synthetic proteins comprising the same sequence and a free or an amide C-terminal form. Using electrospray ionization-mass spectrometry, capillary electrophoresis and the coupling of both techniques, we assigned the C-terminus of the native protein to be in the free carboxyl form.
    Additional Material: 4 Ill.
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  • 73
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; DNA sequencing ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The mobility of DNA sequencing fragments was measured in Long-Ranger gels at an electric field ranging from 200 to 1200 V cm-1 and in noncross-linked polyacrylamide at electric fields ranging from 100 to 300 V cm-1. In both cases, N*, the fragment length that denotes the onset of biased reptation with orientation, is inversely proportional to electric field. The inverse dependence of N* is inconsistent with the original biased reptation model but is consistent with modern models of DNA migration. While separation speed increases dramatically with electric field, the number of bases determined in a separation decreases in proportion to field strength. We present a DNA sequencing run at an electric field of 1200 V cm-1. Roughly 200 bases of sequence are determined in 3.5 min.
    Additional Material: 12 Ill.
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  • 74
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Uncrosslinked polyacrylamide solutions ; DNA sequencing resolution ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two preparations of linear polyacrylamide with average molecular weights of 0.37 million and 1.14 million Da, and a deuterated preparation with an average molecular weight of 1.71 million Da, were used to study the effects of molecular weight, polydispersity, and concentration on the mesh size of entangled polymers in a DNA sequencing buffer solution and their ability to resolve DNA sequencing reactions by capillary electrophoresis. The polyacrylamide concentrations were above the overlap threshold C*, the concentration above which an entangled polymer network is expected to form. Small angle neutron scattering experiments showed that between 1% and 8% polyacrylamide, the mesh size (ζ) can be expressed by the relation ζ = 2.09C-0.76, where ζ is in Å and C is the polymer concentration in g/mL. The mesh size depended only on the concentration and was independent of the average molecular weight of the polyacrylamide. Consistent with this result, electrophoretic mobilities of DNA moving through the polymer network depended almost entirely on the polyacrylamide concentration and not on its molecular weight or polydispersity. Although separation was little affected, band sharpness persisted to longer DNAs when the polymer network contained a higher fraction of larger polyacrylamide molecuels. We postulate a dispersive effect that depends on the size of the DNA and the resiliency of the polymer network. This interpretation provides a rationale for optimizing the design of polymer solutions to sieve DNA for sequencing by capillary electrophoresis.
    Additional Material: 8 Ill.
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  • 75
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1348-1356 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Electrokinetic chromatography ; Immunassay ; Drugs ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: This paper characterizes competitive binding, electrokinetic capillary-based immunoassays for various drugs in human serum using reagents which were commercialized for fluorescence polarization immunoassays. After incubation of serum with the reactants, a small aliquot of the mixture is applied onto a fused-silica capillary and tracers (fluorescein-labeled drugs) and the antibodytracer complexes are separated and analyzed by micellar electrokinetic capillary chromatography with on-column laser-induced fluorescence detection. Examples studied include serum assays for theophylline, ethosuximide, paracetamol, salicylate and quinidine. With these assays, concentration-dependent peaks produced by the free tracers or the antibody-tracer complexes serve as the basis for quantitation. The sizes of the peaks produced are shown to be dependent on the applied power and the proportions of the reactants and serum employed. The separation medium permits effective characterization of tracers and antibody selectivities. Based on the high selectivity of the antibodies employed, the feasibility of the simultaneous performance of different immunoassays is demonstrated. For capillaries of 50 μm internal diameter (ID), separations are best performed at electric fields 〈 500 V/cm, this resulting in electrokinetic analyses within 4 to 10 min (capillaries of 20 to 50 cm effective length).
    Additional Material: 10 Ill.
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  • 76
    ISSN: 0173-0835
    Keywords: N-Substituted acrylamides ; DNA electrophoresis ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The behavior of N-substituted poly(acrylamides) and of cellulose in the separation of double-stranded DNA by capillary zone electrophoresis (CZE) is evaluated. Contrary to previously held belief, which attributed best separations in poly(acrylamides) to small DNA fragments (typically in the 50-1000 bp size range) and in celluloses to large DNA fragments, we show that also celluloses can achieve fine sieving of short DNA sizes provided they are used at much higher concentrations than previously reported. For example, in the case of hydroxyethylcellulose (HEC), typically used at 0.2-0.8% concentrations, levels of 3% produce excellent patterns, at 25°C, in the 50-600 bp size range. If separations are conducted at 60°C, sieving is lost in most liquid polymers. However, if the concentration of HEC is raised to 6%, and that of hydroxypropylmethylcellulose (HPMC) above 1%, sieving is fully restored. Also, N-substituted acrylamido derivatives, notably N-acryloylaminoethoxyethanol (AAEE) and N-acryloylaminopropanol (AAP) offer excellent performance at both 25° and 60°C, whereas plain poly(acrylamide) irreversibly collapses at high temperatures, possibly due to intrinsic instability of the amido bond under such harsh conditions. Among all the polymers investigated, an 8% solution of poly(AAP) offers the best performance and highest theoretical plates in the 25°-60°C interval. Separations at high temperatures are necessary when dealing with detection of point mutations in temperature-programmed CZE and are preferred in DNA sequencing. Two additional advantages are evident when running DNA separations at 60°C: a marked reduction of analysis times and a linearization of the transit times of the larger (434-587 bp) DNA fragments, in all polymers tested.
    Additional Material: 7 Ill.
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  • 77
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1451-1459 
    ISSN: 0173-0835
    Keywords: DNA sequencing ; Capillary electrophoresis ; Flowable networks ; Polyethylene glycol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A novel class of materials that self-assemble in water into equilibrium network structures with a well-defined mesh size consist of polyethylene glycols (PEG's) end-capped with micelle-forming fluorocarbon tails. These micellar systems form flowable aqueous gel-like networks that permit electrophoretic DNA sequencing in capillary columns. The gels have unusual rheological properties, including netword breakdown under shear, resulting in plug flow that allows colums refill with complete ejection of byproducts of the previous sequencing analysis. In this system, DNA fragment electrophoretic mobilities are unaffected by the hydrophobicity of the polymer tails. Low molecular weight (M) PEG chains (M 8000) show catastrophic resolution loss for DNA fragments larger than 100 bases due to band broadening. For a longer PEG segment (M 35000) separating the end groups, band broadening occurs for DNA fragments larger than 300 bases, implying that the PEG segment length controls the mesh size in the equilibrium network structure. Optimum sequencing results were obtained from a 6% solution of a 1:1 mixture of C6F13 end-capped- and C8F17 end-capped PEG 35000. The resolution limit of fluorescent-dye-labeled sequencing products in this formulation was 450 bases in 75 μm capillaries at 200 V/cm.
    Additional Material: 4 Ill.
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  • 78
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1584-1586 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Pullulan ; Proteins ; Separation mechanism ; Coated capillary ; Sodium dodecyl sulfate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The separation mechanism of capillary electrophoresis of sodium dodecyl sulfate (SDS)-proteins using pullulan with a molecular mass range of 50 000-100 000 as a separation matrix was investigated. The pullulan solution was filled into fused-silica capillaries whose inner walls were coated with linear polyacrylamide through chemically stable Si-C linkages. Baseline separations of SDS proteins were achieved at concentrations ranging from 3-10% w/v of pullulan. The entanglement threshold of pullulan solution was found to be around 0.5% w/v, indiacating migration of SDS-proteins through an entangled pullulan network. Ferguson plots exhibited a linear relationship between log mobility and pullulan concentration. Linear relationships were also obtained for double logarithmic plots of the electrophoretic mobility and protein molecular mass. These results show that the separation is based on mass discrimination in accordance with the Ogston theory.
    Additional Material: 3 Ill.
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  • 79
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1617-1621 
    ISSN: 0173-0835
    Keywords: Micelles ; Retinoids ; Bile salts ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Micellar electrokinetic chromatography (MEKC) using bile salts has been employed to separate retinoids differing in structure and charge; bile salts in MEKC allows the separation of liposoluble molecules but, to the best of our knowledge, there are only few data on the above-mentioned technique for the separation of highly hydrophobic compounds. The three natural vitamin A derivatives, retinal, retinol and retinoic acid, were successfully separated by MEKC using sodium cholate within a relatively short time (ca. 25 min), whereas the separation of these compounds was not successful using sodium dodecyl sulfate or sodium deoxycholate. Several parameters (pH and organic modifiers, in addition to bile salts concentration) have been tested to provide a system that can be extended to synthetic retinoids, which are often used in treating several diseases, including cancer prevention and therapy.
    Additional Material: 9 Ill.
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  • 80
    ISSN: 0173-0835
    Keywords: DNA sequencing ; Capillary electrophoresis ; Confocal fluorescence detection ; Energy transfer primers ; Mitochondrial DNA polymorphisms ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The design, construction and operation of a four-color capillary array electrophoresis scanner are presented. The use of sensitive energy transfer primers facilitates four-color detection of the DNA sequencing fragments following excitation at a single laser wavelength (488 nm). This scanner collects fluorescence data from up to 25 capillaries in parallel. The resulting four-color image files are automatically reduced to four-color line plots, and a base-calling program (Sax) is used to call the sequence. The performance of this system for DNA sequencing is demonstrated by examining twelve different motifs of the hypervariable region I of human mitochondrial (mt) DNA obtained from a Sierra Leone population.
    Additional Material: 3 Ill.
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  • 81
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1884-1889 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; DNA ; Loading capacity ; Resolution ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A serious limitation of capillary electrophoresis in separating mutant from wild-type DNA sequences is the amount of DNA which may be loaded on narrow-bore columns. Because we sought to examine mutant sequences derived from more than 109 human cells, we were obliged to overcome this limitation. Thus we examined the feasibility of using wide-bore capilllaries of 250, 320 and 540 μm in constant denaturant capillary electrophoresis (CDCE) using conditions which successfully limited the effect of Joule heating. Excellent separations were observed using the wide-bore capillaries comparable to those obtained using a 75 μm capillary. DNA loading capacities were increased almost 100-fold as the bore of capillary increased from 75 to 540 μm.
    Additional Material: 4 Ill.
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  • 82
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Light-emitting diodes ; On-capillary absorbance detection ; Linearity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A model which takes into account both stray light and polychromatic light was used to predict and evaluate linearity in on-capillary detection in capillary electrophoresis (CE). According to the model the stray light is the major factor which determines linearity under typical CE operating conditions. By calculating theoretical absorbance versus concentration plots, the influence of different levels of stray light and polychromatic light on linearity is demonstrated. Experimentally, six light-emitting diodes (LEDs) in the range from 563 to 654 nm were examined as light sources for on-capillary detection in CE. Fitting theoretical curves to measured linearity plots enabled determination of the values of both effective path lenght and stray light for a particular detection system. The detector linearity for the four LEDs was compared to mercury and tungsten lamps used with interference filters. For potassium permanganate as the test compound, the linear range for a 563 nm LED was two times greater than that for a mercury lamp operated at 546 nm. The relatively poor linearity of the mercury lamp detector is explained by its high level of stray light. The noise of the LED563-based detector was the same as for the mercury lamp, whereas the other LEDs of higher light intensity gave approximately half the noise of the mercury lamp. The lowest noise level of 3 × 10-5 AU was obtained for the LED at 554 nm (determined at a detector time constant of 0.1 s).
    Additional Material: 7 Ill.
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  • 83
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Affinity electrophoresis ; Peptides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Peptide electrophoretic mobility measured by capillary zone electrophoresis can be regarded as deriving from the mean of mobilities of different protonated forms, each one participating according to its charge, Stokes radius and relative percentage. The percentage is a function of the peptide dissociation constant and solutior pH. Therefore, mobility modifications due to pH variations can be related to peptide dissociation constant, charge, and Stokes radius throughout general binding equations. Thus, not only can peptide dissociation constants be measured, but information about Stokes radius modifications linked to proton loss can also be obtained with picomoles of peptide.
    Additional Material: 7 Ill.
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  • 84
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Polymer solution ; Retardation coefficient ; Field strength ; Band width ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Subjecting particles in the size range of 3 to 1085 nm radius (R) to capillary electrophoresis in buffered solution of entangled uncrosslinked polyacrylamide (Mr 5 × 106), it was found that particle size-dependent retardation (“molecular sieving”) becomes electric field- and particle size range-dependent once the particle size exceeds 15-20 nm in radius. The field strength dependence of the retardation coefficient [KR = d(log mobility)/d(polymer concentration] and the positive or negative sign of dKR/dR suggest the existence of two different mechanisms of molecular sieving depending on the particle size range: particles with diameters less than the screening length (or blob size) of the polymer network are thought to penetrate into the available spaces within a discontinuous polymer network; particles with diameters larger than the screening length (or blob size) of the polymer network are thought to undergo size-dependent retardation by exerting shear stress against polymer chains, and displacing them, so as to cause local deformations in a continuous polymer network. A limit in the separating capacity of molecular sieving, due to a sharp increase in the rate of band widening with polymer concentration, was found when the value of the retardation coefficient exceeded 60 (mL/g).
    Additional Material: 5 Ill.
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  • 85
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1161-1166 
    ISSN: 0173-0835
    Keywords: Free-solution electrophoresis ; Capillary electrophoresis ; End-labeled free-solution electrophoresis ; Polyelectrolyte ; DNA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We propose here a simple procedure to estimate the electrophoretic mobility of composite objects obtained by linking two charged subunits, stressing that this electrophoretic mobility is in general different from the ratio of the total charge to the total friction coefficient. We focus especially on the situation where at least one of the subunits is a polyelectrolyte. Our remarks in particular correct the existing theoretical analysis of separation capabilities of devices in which a buoy (sphere, protein, polymer) is attached to a DNA chain. We also predict that, in some cases, the direction of electrophoretic motion can be reversed by increasing the electric field amplitude.
    Additional Material: 6 Ill.
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  • 86
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Pullulan ; Protein ; Coated capillary ; Sodium dodecyl sulfate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Pullulan was used as a sieving medium in high-performance capillary gel electrophoresis to study the effect of temperature and viscosity on electrophoretic behavior of sodium dodecyl sulfate (SDS)-proteins with molecular masses in the range of 14 400-116 000 Da. The migration time decreased with increasing capillary temperature. Equations were derived relating mobility of SDS-proteins to capillary temperature and viscosity of pullulan solution. Linear relationships were obtained from experiments between logarithm of mobility and reciprocal temperature and between double logarithmic values of mobility and viscosity of pullulan solution. The experimental results agree well with the equations.
    Additional Material: 5 Ill.
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  • 87
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Metal ions ; Iterative regression optimization ; 2-Hydroxyisobutyric acid ; Metal ligand complexes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The iterative regression design developed earlier for high performance liquid chromatography (HPLC) has been applied successfully to the optimization of the separation of 11 metal ions by capillary electrophoresis. The parameters used for optimization were pH (over the range 3.5-5.0) and the concentration of 2-hydroxyisobutyric acid (HIBA) (2-20 mM) used as the complex-forming ligand added to the background electrolyte. Five initial experiments were performed and the response surface was calculated using the relative resolution product as criterion. Three additional experiments were sufficient to establish a stable optimum, with which all 11 metal ions were separated and well spread in the electropherogram. The total analysis time was less than 5 min.
    Additional Material: 4 Ill.
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  • 88
    ISSN: 0173-0835
    Keywords: DNA sequencing ; Capillary electrophoresis ; Noncross-linked polyacrylamide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We present the mobility of DNA sequencing fragments as a function of temperature in 5%T, 0%C noncross-linked polyacrylamide and at an electric field of 150 V/cm. The mobility of the fragments follows the Arrhenius equation. The activation enegry for migration of a fragment through the polymer decreases monotonically with fragment length. The data were also analyzed in terms of the biased reptation model; the onset of biased reption with stretching occurs for longer fragments as the temperature increases. These results are quite different from those observed for separation of DNA in cross-linked gels and represent a fundamental difference in the physics of the cross-linked and noncross-linked polyacrylamide.
    Additional Material: 10 Ill.
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  • 89
    ISSN: 0173-0835
    Keywords: DNA fragments ; Quantitative competitive polymerase chain reaction ; Capillary electrophoresis ; Fluorescence detection ; Bacillus anthracis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Quantitation of DNA fragments amplified by polymerase chain reaction (PCR) is needed for the determination of target DNA in molecular biology. Capillary electrophoresis in entangled polymer solution coupled to laser-induced fluorescence detection was assessed as an alternative technique to conventional slab gel methods to monitor competitive PCR, which consists of amplifying an internal standard fragment under the same conditions as the target fragment. The fluorescence signal was generated either through end-labeling of the fragments using 5′-fluorescein-labeled primers or through intercalation of ethidium bromide along the double strand. It is shown that the more accurate and reliable results were obtained using this latter pathway.
    Additional Material: 7 Ill.
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  • 90
    ISSN: 0173-0835
    Keywords: N-Substituted acrylamides ; N-Acryloylaminopropanol ; Capillary electrophoresis ; DNA separations ; Liquid polymer ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Separation of DNA fragments in a novel polymer network, consisting of N-acryloylaminopropanol (AAP) is reported. The performance of this novel monomer, as a sieving liquid polymer in capillary zone electrophoresis, was evaluated. In 50 μm ID capillaries, an 8% solution of poly(AAP) can afford apex-resolution of the 123/124 bp adjacent pair of DNA fragments in marker V, typically unresolved in any poly(acrylamide) formulation. It is proposed that the distal -OH group in the AAP molecule can form transient H-bonds with the DNA double helix. Molecular modeling shows a meandering structure for poly(AAP), lacing the walls of half a cylinder, with kinks protruding at regular intervals, potentially able to fit into the major groove of DNA. Contrary to previously held beliefs, there seems to be a minimum length of the polymer for proper sieving of DNAs. For poly(acrylamides), a weight average molecular mass Mw 30 000 polymer offers no resolution, whereas a polymer of 250 000 to 400 000 Da exhibits optimum resolving power. For poly(AAP), the optimal length is in excess of 450 000 Da in Mw. Thus, it is shown that both the chemical composition of the monomer and the length of the polymer play a subtle, cooperative role in DNA separation.
    Additional Material: 5 Ill.
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  • 91
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1115-1120 
    ISSN: 0173-0835
    Keywords: Temperature profile ; Capillary electrophoresis ; Convection ; Thermocouple ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Temperature profiles of buffer-filled capillaries (capillary temperature), using both natural and forced air convection for cooling, were obtained both theoretically and experimentally in order to achieve stable capillary electrophoresis for accurate DNA sequencing analysis. The capillary temperature was calculated using the temperature dependency of the buffer resistivity, and the threshold values of the electric field and the capillary temperature for temperature instability were characterized. The capillary temperature became unstable at about 420 V/cm and at about 62°C regardless of the outer diameter of the capillary; these values approximately coincide with the measured values obtained using a very thin thermocouple. The sets of values of electric field, air temperature, and air flow velocity in forced air cooling were obtained to keep the capillary temperature at the 40 ∼ 60°C needed for accurate DNA sequencing in a Tris-boric acid-EDTA buffer.
    Additional Material: 5 Ill.
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  • 92
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1202-1209 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Neutral surfactants ; Polyelectrolytes ; Amphiphilic polymers ; Polymer-surfactant interactions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Hydrophobically modified poly(acrylic acids) (HMPAs) are random copolymers of sodium acrylate and dodecyl acrylamide, containing 0-10% mol/mol of dodecyl grafts. The hydrophobic character of different HMPAs of average molecular weight 150 000 was studied by capillary electrophoresis (CE), using neutral surfactants as buffer additives. The differentiation of the electrophoretic mobilities of HMPAs with their hydrophobicity was achieved through the use of nonionic Brij 35 and zwitterionic DAPS surfactants. A nearly baseline separation of the precursor and three HMPAs derivatives was obtained in a poly(ethylene glycol)-coated capillary with a background electrolyte containing 10 mM N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DAPS) and 10 mM borax (pH 9.2). In addition to CE experiments, the polymer-surfactant interactions were also investigated by means of quasi-elastic light scattering (QELS) and viscosimetric measurements. According to the latter results, the separation mechanism was interpreted as an expansion of the polymer coil in the presence of micelles and subsequent change of its frictional properties. A true micellar electrokinetic capillary chromatography (MEKC) partitioning model was discarded on the basis of the relative sizes of the macromolecule and the micelles.
    Additional Material: 9 Ill.
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  • 93
    ISSN: 0173-0835
    Keywords: Field-inversion gel electrophoresis ; Low-gelling agarose ; Low-melting agarose ; Capillary electrophoresis ; DNA fragments ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Field inversion capillary gel electrophoresis (FICGE) has been used for the separation of 0.1-23 kbp DNA fragments in a low-melting, low-gelling agarose gel. The influence of the amplitude of the voltage pulses, the pulse times and gel concentrations on the separation factor has been studied and found to be similar to that of polyacrylamide gels. Very high resolution can be obtained by altering continuously the pulse times and/or voltage according to a program tailor-made for the size of the DNA molecules to be separated (programmed FICGE). The advantage of these agarose gels in comparsion with polyacrylamide gels is that they are nontoxic, easy to prepare and they have high UV transmission. They give a resolution that is equivalent to or better than that of polyacrylamide gels, and the risk of bubble formation in the gel is small. In addition, they are replaceable and, therefore, very convenient for automated analyses.
    Additional Material: 12 Ill.
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  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1512-1517 
    ISSN: 0173-0835
    Keywords: RNA ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Analytical parameters known to be important for the separation of DNA by capillary electrophoresis, including gel polymer concentration, electrical field strength and temperature, were investigated and optimized for the analysis of RNA molecules from 100 to 2000 bases. Denaturation, essential to obtain uniform and identifiable peaks, was accomplished by heating the sample in 80% formamide prior to electrophoresis and the presence of 2-8 M urea in the electrophoresis buffer. Efficient separations were obtained over a wide range of electrical field strengths and temperatures using the gel polymer hydroxypropylmethylcellulose (HPMC) as separation matrix. Low HPMC concentrations (〈 0.3%) were suited for the separation of high molecular mass RNA (〉 1000 bases) whereas higher HPMC concentrations were required for optimal separation of low molecular mass RNA. An optimized system was applicable for the separation of the predominating RNA populations (small RNA of 60-300 bases (as a group of unseparated peaks), 18S and 28S rRNA) in total RNA from a human glioma cell line. This is the first systematic investigation of electrophoresis of higher molecular mass RNA in capillaries, and motivates further studies to transfer electrophoresis of RNA to the capillary format.
    Additional Material: 7 Ill.
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1587-1589 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Channel width ; Channel fluctuations ; Resolution ; Bandwidth ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Variations in the lateral dimensions of capillaries and ultrathin gels along their length could lead to a distortion of the sample zone because charged particles traveling near the wall must travel a longer distance under a smaller field than particles traveling along the centerline. The size of the effect is computed by solving Laplace's equation for the potential everywhere in a conducting slab with a discontinuity in thelateral dimensions and integrating the travel time along different streamlines.
    Additional Material: 4 Ill.
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  • 96
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Membrane proteins ; Photosystem II light-harvesting complex ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The electrophoretic migration behavior of three closely related hydrophobic intrinsic membrane proteins of the photosystem II light-harvesting complex (LHC II) was investigated in free solution capillary electrophoresis at pH 8.0-10 with running electrolyte solutions containing either anionic, zwitterionic or nonionic detergents. The complete and repeatable separation of these proteins was accomplished with a running electrolyte solution of 25 mM Tris/192 mM glycine, pH 8.8, containing either sodium dodecyl sulfate or n-octyl β-D-glucopyranoside at concentration up to 5.0 and 7.0 mM, respectively. Migration times and resoltuion of the individual LHC II intrinsic membrane proteins were sensitive to the type of detergent. The effect of detergent concentration on the electrophoretic behavior of the LHC II proteins was also investigated. Electroelution of the LHC II components separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to isolate these intrinsic membrane proteins, which were then injected onto the capillary electrophoresis system for peak identification.
    Additional Material: 4 Ill.
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  • 97
    ISSN: 0173-0835
    Keywords: Preconcentration ; Rapid loading ; Capillary electrophoresis ; Mass spectrometry ; Major histocompatibility complex class I peptides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Using a removable membrane preconcentration (mPC) cartridge, large sample volumes can be loaded prior to final assembly of the mPC capillary electrophoresis (CE) capillary. For narrow-bore (≤ 25 μm ID) uncoated mPC-CE capillaries, applied to peptide analysis, efficient moving boundary transient isotachphoresis (tITP) conditions at the onset of electrophoresis are described. The enhancement of mPC-CE-mass spectrometry (MS) technology afforded by rapid sample loading and modified moving boundary tITP conditions are demonstrated by analysis of major histocompatibility complex (MHC) class I peptides that were derived from a Kb precipitation of mouse EL-4 cells. Furthermore, we demonstrate the structural characterization of these immunologically significant molecules by mPC-CE-tandem mass spectrometry (mPC-CE-MS/MS).
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  • 98
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Mass spectrometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A miniaturized, integrated capillary electrophoresis-ultraviolet detection-electrospray ionization-mass spectrometry (CE-UV-ESI-MS) interface has been constructed and evaluated. The device incorporates a fiber optic detection cell close to the electrospray tip to allow UV monitoring of separated zones just prior to their admittance into the mass spectrometer. This configuration provides precise information about the time when UV-active zones enter the electrospray and allows easy location of analyte mass information in the ion current profile. The miniaturized dimensions of the interface allow the use of short capillaries for fast separations.
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  • 99
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Ligase chain reaction products ; Mitochondrial DNA ; Point mutations ; Leber's hereditary optic neuropathy ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: High speed capillary electrophoresis-laser-induced fluorescence (CE-LIF) has been used to separate and detect point mutations using the ligase chain reaction (LCR). The method utilizes short capillary columns (7.5 cm effective length) and fields of 400 V/cm to analyze DNA-ethidium bromide complexes using an He/Ne laser. The method was first demonstrated with a commercially available kit for LCR based on a lacI gene fragment inserted in a Blusescript® II phagemid. LCR-CE-LIF was then applied to detect point mutations in human mitochondrial DNA. resulting in Leber's hereditary optic neuropathy (LHON). Three severe mutations were analyzed in which the original base is substituted by a thymidine base at positions 3460, 11778 and 14459. Appropriate primers were designed with polyT tails for length discrimination of pooled samples. Successful detection of mutated samples was achieved, with appropriate correction for small amounts of nonspecific ligated product. The method is rapid, easy to implement, and automatale.
    Additional Material: 8 Ill.
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  • 100
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; DNA analysis ; Rh ; genotyping ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A safe and reliable method for determining RhD type (positive or negative) and zygosity (D/D or D/d) could have applications, for instance, in the prediction of the D genotype of a father in couples where there is an RhD-negative woman at risk of fetal alloimmunization. Capillary zone electrophoresis (CZE) is proposed as a novel, reliable and powerful method for quantitative evaluation of polymerase chain reaction (PCR) products. RhD is determined by amplifying a 136 bp region common to the RhCcEe and RhD genes and a 186 bp region specific of the RhD gene. RhD positive and negative samples are identified by polyacrylamide gel slab electrophoresis, followed by silver staining of the DNA bands, and by CZE in sieving liquid polymers, with direct on-line peak densitometric evaluation by exploiting the intrinsic UV absorbance of the DNA fragments at 254 nm. The CZE method allows not only a reliable assessment of the RhD type (the presence of both 136 bp and 186 bp fragments indicating an RhD-positive type, the presence of only the 136 bp fragment indicating an RhD-negative type), but also a rapid determination of the zygosity based on the quantitative expression ratio of the 136 bp/186 bp pair. Thus, a 2:1 peak ratio clearly indicates a D/D homozygous individual, whereas a 3:1 peak ratio gives evidence of a D/d heterozygous individual.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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