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  • Biochemistry and Biotechnology  (11)
  • Capillary zone electrophoresis  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Separation of α-hydroxy acid enantiomers by high performance capillary electrophoresis using copper(II)-L-amino acid and copper(II)-aspartame complexes as chiral selectors in the background electrolyte (1994)
    Weinheim : Wiley-Blackwell
    Electrophoresis 15 (1994), S. 864-869 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Optical isomers of some α-hydroxy acids, namely 2-, 3-phenyllactic acid, mandelic, p-hydroxy-, m-hydroxy and 3,4-di-hydroxymandelic acid, were separated by means of capillary zone electrophoresis in free solution, using copper (II) complexes with L-amino acid or aspartame ligands in the background electrolyte. The concentration and the pH dependence of the enantiomer separations have been studied in the cases of different chiral ligands and/or analytes. With the use of L-proline as ligand only the optical isomers of 3-phenyllactic acid were resolvable, whereas using L-hydroxyproline the D and L forms of all compounds, except for 2-phenyllactic acid, were separated. Better results were obtained with aspartame as chiral ligand.Part of this work was presented at the 5th International Symposium on High Performance Capillary Electrophoresis, January 25-28, 1993, Orlando, FL, USA.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501501122
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  • 2
    Electronic Resource
    Electronic Resource
    Capillary electrophoresis quantitation of l-L-folinic acid in the presence of its inactive d-L-form (1993)
    Weinheim : Wiley-Blackwell
    Electrophoresis 14 (1993), S. 823-825 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The diastereomers d-L and l-L-folinic acid were separated by capillary electrophoresis, using heptakis (2,3-di-O-methyl)-β-cyclodextrin as a chiral active component in the background electrolyte. The method proved suitable for the quantitation of these compounds in one commercial pharmaceutical preparation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501401129
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  • 3
    Electronic Resource
    Electronic Resource
    Use of a Hepta-tyr glycopeptide antibiotic as chiral selector in capillary electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1742-1751 
    Details
    ISSN: 0173-0835
    Keywords: Antibiotics ; Chiral separations ; Enantiomers ; Drugs ; Herbicides ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A new glycopeptide antibiotic, MDL 63,246 (Hepta-tyr), of the teicoplanin family, has been evaluated in capillary electrophoresis for the resolution of chiral compounds of pharmaceutical and environmental interest. Electrophoretic separations were carried out in a polyacrylamide-coated capillary using the partial filling-counter current mode with aqueous-organic buffers in the pH range 4-6. Experimental parameters affecting resolution, such as antibiotic concentration, buffer pH, organic modifier type and capillary temperature, were studied. The Hepta-tyr antibiotic exhibited a high enantiorecognition capability towards the studied compounds at very low concentrations (1-2 mg/mL). The optimum experimental conditions were achieved by using a buffer at pH 5 containing acetonitrile at 25°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191036
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  • 4
    Electronic Resource
    Electronic Resource
    Quantitative analysis of synthetic dyes in lipstick by micellar electrokinetic capillary chromatography (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1478-1483 
    Details
    ISSN: 0173-0835
    Keywords: Micellar electrokinetic capillary chromatography ; Dyes ; Cosmetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The separation of synthetic dyes, used as color additives in cosmetics, by micellar electrokinetic capillary chromatography (MEKC) is described in this study. The separation of seven dyes, namely eosine, erythrosine, cyanosine, rhodamine B, orange II, chromotrope FB and tartrazine has been achieved in about 3 min in an untreated fused silica capillary containing as background electrolyte a 25 mM tetraborate/phosphate buffer, pH 8.0, and 30 mM sodium dodecyl sulfate. The electrophoretic method exhibits precision and relatively high sensitivity. A detection limit (LOD, signal/noise = 3) in the range of 5-7.5 × 10-7 M of standard compounds was recorded. Intra-day repeatability of all the studied dye determinations (8 runs) gave the following results (limit values), % standard deviation: 0.24-1.54% for migration time, 0.99-1.24% for corrected peak areas, 0.99-1.24% for corrected peak area ratio (analyte/internal standard) and 1.56-2.74% for peak areas. The optimized method was successfully applied to the analysis of a lipstick sample where eosine and cyanosine were present.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190844
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  • 5
    Electronic Resource
    Electronic Resource
    Atrazine and simazine determination in river water samples by micellar electrokinetic capillary chromatography (1992)
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 698-700 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A rapid and sensitive micellar electrokinetic capillary chromatography analytical method was used for the determination of chlorotriazine herbicides in river water samples. Several electrolyte systems in the pH range 7-10 were tested in order to optimize the separation. The two compounds were separated in less than 10 min and the determination limit was about 0.4 ppb for each herbicide. Recovery values of the method were in the range 80%-117%.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501301148
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  • 6
    Electronic Resource
    Electronic Resource
    Stereoselective analysis of herbicides by capillary electrophoresis using sulfobutyl ether β-cyclodextrin as chiral selector (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 227-234 
    Details
    ISSN: 0173-0835
    Keywords: Herbicides ; Enantiomers ; Cyclodextrin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary zone electrophoresis has been used for the enantiomeric separation of several herbicides. Different β-cyclodextrin (CD) derivatives have been investigated for chiral separations and among them the negatively charged sulfobutyl ether β-cyclodextrin (SBE-β-CD) proved to be effective for the stereoselective resolutions of the investigated herbicides. The effect of CD concentration, buffer pH and organic modifier on effective mobilities, resolution and selectivity of the analytes have been studied. Addition of SBE-β-CD (5-50 mg/mL) to the buffer at pH 9 resulted in a general increase of migration times as well as resolution. A CD concentration as low as 5 mg/mL was effective to completely resolve napropamide and ethofumesate enantiomers. Buffer solutions containing 40 mg/mL of SBE-β-CD were chosen to study the effect of buffer pH (7, 8, and 9) on chiral separation of the herbicides. No great differences in resolution and effective mobilities have been found in the pH 7-9 range. The addition of different organic modifiers to the background electrolyte at pH 9, containing 20 mg/mL of SBE-β-CD, showed different effects. Methanol was the most effective in improving resolution but in some cases total loss in enantiomeric separation was observed. The qualitative analysis of an enantiomerically pure herbicide (flamprop isopropyl) commercial preparation is also shown.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150180209
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  • 7
    Electronic Resource
    Electronic Resource
    Use of cyclodextrins in capillary electrophoresis: Resolution of tramadol enantiomers (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2883-2889 
    Details
    ISSN: 0173-0835
    Keywords: Tramadol ; Enantiomers ; Cyclodextrins ; Capillary zone electrophoresis ; Validation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary zone electrophoresis was successfully applied to the enantiomeric resolution of racemic tramadol. Both uncoated and polyacrylamide-coated capillaries were tested for method optimization using either negatively charged or native cyclodextrins (CD) added to the background electrolyte (BGE). The resolution was strongly influenced by the CD type and concentration as well as by the pH and the concentration of the BGE. Among the CDs tested, carboxymethylated-β-cyclodextrin allowed the baseline separation of tramadol enantiomers. After the method was optimized, it was validated in a coated capillary for enantiomeric analysis of tramadol enantiomers in pharmaceutical formulation, including specificity and elution order, linearity, accuracy and precision, determination of limit of detection (LOD) and quantification (LOQ), enantiomeric purity linearity, freedom from interference, and stability of sample solutions. Precision at the target concentration was less than 2%, with an accuracy higher than 99%. Furthermore, the method was able to detect 0.3% and to quantify 1% of the minor enantiomer in the presence of the major one at the target value.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191614
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of mephenytoin, 4-hydroxymephenytoin and 4-hydroxyphenytoin enantiomers in human urine by cyclodextrin micellar electrokinetic capillary chromatography: Simple determination of a hydroxylation polymorphism in man (1994)
    Weinheim : Wiley-Blackwell
    Electrophoresis 15 (1994), S. 87-93 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Using cyclodextrin micellar electrokinetic capillary chromatography (CD-MECC), baseline separation of mephenytoin, 4-hydroxymephenytoin and 4-hydroxyphenytoin enantiomers in urine was effected with β-cyclodextrin. After single-dose administration of 100 mg of racemic mephenytoin, the 0-8 h urine was collected, and enzymatically hydrolyzed urine specimens were applied. For extensive metabolizers, a single peak for 4-hydroxymephenytoin was detected corresponding to the S-enantiomer. This peak was either very small or undectable in samples of poor metabolizers. Typically, mephenytoin could not be detected in these samples. However, application of undeglucu-ronidated extracts revealed the presence of free S-4-hydroxymephenytoin and R,S-mephenytoin and thus permitted phenotyping via both the urinary S:R enantiomeric ratio of mephenytoin and the hydroxylated metabolite. Application of enzymatically hydrolyzed and extracted urines after phenytoin administration (100 mg; 0-8 h urine collection) revealed the presence of S-4-hydroxyphenytoin. Thus, CD- MECC is shown to be a simple and attractive approach for (i) the confirmation of the stereoselectivity of the aromatic hydroxylation of mephenytoin and phenytoin, (ii) the simple and rapid differentiation between extensive and poor metabolizers for mephenytoin, and (iii) assessment of compliance.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150150113
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  • 9
    Electronic Resource
    Electronic Resource
    Cyclodextrin modified micellar electrokinetic chromatography for the chiral direct resolution of (+), (-)-trans-1,2-dihydrodiol metabolite of chrysene in vitro activated by rat liver microsome S9 fraction (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 784-788 
    Details
    ISSN: 0173-0835
    Keywords: Cyclodextrin modified - micellar electrokinetic chromatography ; Chiral separation ; Chrysene metabolism ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A γ-cyclodextrin (γ-CD) modified electrokinetic micellar capillary chromatography (MEKC) method was used for the enantiomer separation of a racemic trans-1,2-dihydro-1,2-dihydroxy-chrysene (chry-trans-1,2-diOH) mixture. The chiral resolution was strongly influenced by several important parameters: surfactant concentration and addition of organic modifier to the background electrolyte (BGE). An optimized electrophoretic system was used, consisting of the following conditions: 25 mM phosphate buffer, pH 7.8, 50 mM sodium dodecyl sulfate, 20 mM γ-CD, 7.4% V/V 2-propanol as BGE; the applied voltage, 18 kV, corresponded to 37 μA at a constant temperature of 25°C. This electrophoretic method was applied for monitoring the chry-trans-1,2-diOH enantiomer formation in a real sample, obtained from in vitro metabolic activation of chrysene by phenobarbital-ß-naphthoflavone-induced rat microsomes. The (+) and (-) enantiomers were identified by the racemate and the single enantiomer standard addition method and by spectra comparison with the synthetic compound. Under the experimental conditions used for chrysene activation, the (+) optical isomer was the prevailing form. The CD-MEKC system showed high reproducibility and selectivity, allowing a fast and interference-free analysis even of the in vitro metabolic sample extract, without any pretreatment.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501601128
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  • 10
    Electronic Resource
    Electronic Resource
    “Schizophrenic” behavior of zones in capillary zone electrophoresis: Explanation of an old problem (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 701-706 
    Details
    ISSN: 0173-0835
    Keywords: Migration behavior of zones in CZE ; Physico-chemical description of zones ; Fronting and tailing of zones ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Background electrolyte (BGE) systems with two coions are frequently used in capillary zone electrophoresis (CZE), especially in cases where indirect optical detection is employed. This study investigates the behavior of analytes, which possess mobilities intermediate to those of the BGE coions used. Besides the expected behavior, where the analytes provide either tailing or fronting zones, unusual behavior with extraordinary zone broadening is also observed in some cases. The explanation for this effect is that binary BGE systems involve, as a physico-chemical rule, a region where the analytes are forced by one coion to give tailing zones and simultaneously by the other coion to give fronting zones. The result of this “schizophrenic” situation is extraordinary zone broadening and deterioration of the detection record. A series of experiments is presented showing in a telling way the electromigration behavior of the discussed type of zones as well as the ways to remedy the deterioration of the peak shape by a mere slight changing of the quantitative composition of the BGE used.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190517
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