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  • 1
    Electronic Resource
    Electronic Resource
    Separation of nucleoside mono-, di- and triphosphates by capillary electrophoresis via cadmium complexation (1999)
    Springer
    Chromatographia 49 (1999), S. 379-384 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Nucleotides ; Cadmium complexation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The CE separation of twelve nucleotides (5′-mono-, di-, triphosphates of adenosine, guanosine, cytidine and uridine) was improved by adding cadmium ion to the ammonium citrate/citric acid buffer (pH 5, ionic strength 100 mM). Cadmium ion acts as a complexing agent for some nucleotides (ATP, CTP, GTP, UTP, GDP). In order to accelerate the separation, the electroosmotic flow was reversed by flushing the fused-silica capillary with 0.2 % aqueous solution of the polycationic surfactant hexadimethrine bromide. A good separation of the twelve nucleotides studied was then achieved on a dynamically coated capillary in less than 5 min by using an ammonium citrate/citric acid buffer (pH 5, ionic strength 100 mM) to which 2 mM cadmium ion has been added. High peak efficiencies were obtained (210 000 theoretical plates) and the resolution between two adjacent peaks was always greater than 1.5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467610
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  • 2
    Electronic Resource
    Electronic Resource
    Capillary electrophoretic study of the complexation of nucleotides with magnesium and calcium ions (1998)
    Springer
    Chromatographia 48 (1998), S. 739-744 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; Nucleotides ; Inorganic cations ; Complexation with Mg and Ca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The complexation equilibrium between nucleotides (ATP, ADP) and inorganic cations (Mg2+, Ca2+) has been studied by capillary electrophoresis. The equilibrium constant and the stoichiometry of nucleotide-inorganic cation complexes can be deduced from the dependence of the electrophoretic mobility of each nucleotide on the negative logarithm of the inorganic cation concentration. The experimental values of complexation constants determined by CE compare favorably with those in the literature. As expected, Mg2+ forms more stable complexes with ATP (logK=2.30 and 4.10 at pH 5 and 8, respectively) than with ADP (logK=1.92 and 3.15 at pH 5 and 8, respectively). In the pH range 4–8, the stoichiometry of ADP-Mg2+ and ADP-Ca2+ complexes is always 1∶1 whereas that of the complexes between these cations and ATP depends on pH-hence ATP-Mg2+ and ATP-Ca2+ complexes have 1∶1 stoichiometry at pH 5 and 1∶2 at pH 8.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467641
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of weak (2.0–2.5) dissociation constants of non-UV absorbing solutes by capillary electrophoresis (1998)
    Springer
    Chromatographia 48 (1998), S. 529-534 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; pK A determination ; Indirect UV detection ; Alkyl-alkyl phosphonic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capillary electrophoresis (CE) has proved to be a fast and convenient method for the determination of the dissociation constants of non-UV absorbing solutes in the acidic pK A range (2.0–2.5). The electroosmotic flow was reversed by washing the capillary with 0.2% polybren aqueous solution. A series of background electrolytes was prepared with phenylphosphonic acid (pK A=1.29) and β-alanine (pK A=3.55) with the same ionic strength and a high buffer capacity in order to improve the repeatability (0.1–0.2 %) of the electrophoretic mobility and to determine the values of pK A accurately. This procedure was applied to the determination of the dissociation constants of several alkyl-alkylphosphonic acids whose pK A values have not yet been published in the literature. In this work, their dissociation constants have been found to vary between 1.91 and 2.34 for alkyl-methylphosphonic acids and between 2.10 and 2.38 for alkyl-ethylphosphonic acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466645
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  • 4
    Electronic Resource
    Electronic Resource
    Carbon dioxide supercritical fluid chromatography-Fourier transform infrared spectrometry (1986)
    Springer
    Chromatographia 21 (1986), S. 523-530 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography (SFC) ; Fourier transform infrared spectrometry (FTIR) ; Packed columns ; Fermi resonance bands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The coupling of carbon dioxide supercritical fluid chromatography with Fourier transform infrared spectrometry (SFC-FTIR) is a powerful tool for the separation and on-line identification of non-volatile compounds. The IR transparency of carbon dioxide in the Fermi resonance bands region versus its density has been studied. Functional groups with stretching vibrations outside the transparent window of carbon dioxide are examined. SFC-FTIR separations allow Gram-Schmidt reconstruction chromatograms or IR window chemigrams with high quality spectra to be obtained. This SFC-FTIR lightpipe (flow cell, beam condensing optics, narrow band detector) has allowed detection limits of 250ng for benzonitrile and 70ng for methyl benzoate to be reached. The feasibility of very rapid SFC-FTIR separations is shown along with the subsequent peak spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02310540
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  • 5
    Electronic Resource
    Electronic Resource
    Ion-pair reversed-phase liquid chromatography of arsenic species on polymeric styrene-divinylbenzene packed columns with an alkaline aqueous mobile phase (1992)
    Springer
    Chromatographia 33 (1992), S. 581-585 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Arsenic compounds ; Polymeric styrene divinylbenzene phase ; Ion-pairing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolving power of an ion-pair reversed-phase liquid chromatography method, on a polymeric stationary phase (PRP-1) with an alkaline aqueous mobile phase (pH=9) containing tetrabutylammonium cation as ion-pairing agent, is compared with a traditional ion-pairing system using an octadecyl-modified silica column and a neutral aqueous mobile phase (pH=7.3). This chromatographic system (PRP-1 column) provides a rapid means for the determination of two of the most important arsenic species, arsenobetaine and arsenite. Addition of methanol (5%) to the aqueous mobile phase allows the differentation of arsenobetaine from the system peak when using UV detection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262252
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Fast Separation of Nucleosides by Capillary Electrochromatography on Non-Endcapped Phenyl-Bonded Silica Phase Using Short-End Injection Method (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 138-142 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrochromatography ; nucleosides ; short-end injection ; phenyl-bonded silica ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The influence of several experimental parameters (pH, ionic strength, organic modifier content of hydro-organic buffer) upon EOF, migration time, and retention factor has been studied in CEC with a phenyl-bonded silica column on a model mixture of five nucleosides. This paper illustrates the current interest in CEC as a method of resolving complex mixtures of neutral and ionic solutes and demonstrates the potential of the short-end injection method as a means of reducing analysis time.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Influence of temperature on FTIR spectra of various organic compounds analyzed by on-line carbon dioxide SFC/FTIR (1988)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 697-705 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical Fluid Chromatography (SFC) ; Fourier Transform Infrared Spectrometry (FTIR) ; Influence of temperature ; FTIR spectrum ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The development of an on-line SFC-FTIR method with supercritical carbon dioxide as mobile phase requires information about the nature of the FTIR spectrum of a solute dissolved in supercritical or liquid CO2. The wavenumber of maximum absorbance of the carbonyl stretching vibration was quantitatively studied versus temperature and CO2 density. FTIR spectra recorded in supercritical or liquid CO2 have been compared to their vapor-phase and condensed-phase spectra for various solutes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240111004
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  • 8
    Electronic Resource
    Electronic Resource
    Liquid Chromatography of Unstable Zinc Dithiocarbamates. Application to Rubber Gloves Analysis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 565-566 
    Details
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; zinc dithiocarbamate ; vulcanization accelerator ; rubber gloves ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    Micellar electrokinetic capillary chromatography of glucosinolates and desulfoglucosinolates with a cationic surfactant (1992)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 271-275 
    Details
    ISSN: 0935-6304
    Keywords: Electrokinetic capillary chromatography ; Micelles ; Cetyltrimethyl ammonium bromide ; Glucosinolates ; Desulfoglucosinolates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240150412
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Adjusting the selectivity of inorganic anion separation by capillary electrophoresis (1996)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 5-16 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240190102
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