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  • Chemistry  (37)
  • Adsorption kinetics  (7)
  • Column liquid chromatography  (4)
  • 1
    Electronic Resource
    Electronic Resource
    On the importance of the purity of surfactant solutions in determining their adsorption kinetics (1982)
    Springer
    Colloid & polymer science 260 (1982), S. 1148-1150 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; model of diffusion-kinetic-controlled adsorption ; effect of impurities on adsorption kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract By means of a theoretical experiment it is demonstrated, that a barrier in the adsorption kinetics of a surfactant can be simulated by the presence of surface-active impurities. Hence, the application of models for the diffusion-kinetic-controlled and/or kinetic controlled adsorption presumes the proof of the surface chemical purity of the surfactant solution under investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411238
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  • 2
    Electronic Resource
    Electronic Resource
    Adsorption kinetics measurements of some nonionic surfactants (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 357-361 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; ring and plate method ; nonionic surfactants at solution/ air interface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Dynamic surface tension values of aqueous surfactant solutions were measured by using the ring and plate method. The mean diffusion coefficients calculated on the basis of the purely diffusion controlled adsorption model vary between 2 · 10−6 to 7 · 10−6 cm2/s for all surfactants studied:n-alkanols,n-alkanoic acids, dimethyl and diethyln-alkyl phosphine oxides. That means the surfactants investigated adsorb with a purely diffusion controlled adsorption mechanism and no barriers excist to hinder sorption processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01418196
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of carbidopa and levodopa in human plasma by high-performance liquid chromatography with electrochemical detection (1993)
    Springer
    Chromatographia 35 (1993), S. 607-612 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carbidopa and levodopa in plasma ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A validated reversed-phase high-performance liquid chromatographic procedure employing electrochemical detection (LCEC) for the analysis of carbidopa and levodopa in human plasma is reported. The method is sensitive and specific with amperometric detection at a glassy carbon working electrode with Eapp=0.75 V vs. Ag/AgCl. The retention times of levodopa, internal standard, and carbidopa are 3.3, 4.5, and 9.7 minutes, respectively, with an overall chromatographic run time of 12.0 minutes. The peak height ratio versus plasma concentration is linear over the range of 5.0 to 500 ng/mL for each analyte and exhibits correlation coefficients of 0.9957 or better (n=9). The mean absolute recovery of carbidopa and levodopa using the described assay is 36.6 and 66.0%, respectively. The inter- and intra-day accuracy and precision are within 11.8% of the actual values for all concentrations. Also, due to the demonstrated instability of carbidopa and levodopa in plasma a procedure is provided to circumvent this. Blood collected in pre-treated Vacutainer tubes can be stored in an ice bath for up to 4 hours without any significant degradation, thereby providing a practical means for processing several clinical samples simultaneously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267924
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  • 4
    Electronic Resource
    Electronic Resource
    On the application of quantitative models of diffusion-controlled adsorption kinetics at fluid interfaces (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 532-538 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; surfactant transport ; Langmuir isotherm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The model of diffusion-controlled adsorption kinetics can be solved by different mathematical procedures. For the most important case of a Langmuir isotherm, useful solutions are summarized and extended and the ranges of application are given. New approximations are presented which can be applied to most experiments in practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420764
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  • 5
    Electronic Resource
    Electronic Resource
    On the theory of adsorption kinetics of ionic sufactants at fluid interfaces 4. Deceleration of the adsorption rate due to non-equilibrium distribution of adsorbed ions in the diffuse layer (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 548-553 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; ionic surfactants ; non-equilibrium electric double layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An approximate analytical solution is obtained for the adsorption kinetics equation derived earlier. On the basis of these relations the importance of the consideration of a non-equilibrium diffuse layer has been shown. To describe the retarded adsorption kinetics the distribution of adsorbed ions in the diffuse layer section of multivalent surfactant ions has been taken into account. The rate of adsorption calculated for a non-ionic surfactant is compared with the adsorption rate for monovalent and bivalent ionic surfactants, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00653220
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  • 6
    Electronic Resource
    Electronic Resource
    On the theory of adsorption kinetics of ionic surfactants at fluid interfaces (1983)
    Springer
    Colloid & polymer science 261 (1983), S. 335-339 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; ionic surfactants ; influence of the electric double layer ; theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of the electric field caused by an electric double layer (DL) on the adsorption kinetics of charged surfactant molecules at fluid interfaces is described for the case of high surface potentials and a quasi-equilibrium state of the DL. Known relations for the description of the transport of molecules in the diffusion layer and the DL respectively are used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01413940
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  • 7
    Electronic Resource
    Electronic Resource
    Adsorption kinetics of alkyl phosphine oxides in water/alkane systems with transfer across the interface (1997)
    Springer
    Colloid & polymer science 105 (1997), S. 346-350 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; surfactants ; transfer across ; interface ; interfacial tension ; water/hexane ; n-alkyl dimethyl phosphine oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The adsorption kinetics of alkyl phosphine oxides soluble both in water and in alkanes has been experimentally studied by measuring the dynamic interfacial tension. To this aim the pendant drop method was used with an automatic acquisition of the drop shape (ASTRA). The experimental results show that under particular geometrical and initial conditions, the dynamic interfacial tension exhibits a minimum. This nonmonotonic behaviour can be explained by considering the transfer of matter through the surface during the adsorption and the depletion of one phase necessary to establish the partition equilibrium. These data can be interpreted on the basis of a diffusion controlled adsorption model involving two finite phases. Moreover a particular experimental procedure for measuring the partition coefficient has been used based on the equilibrium surface tension measurements and on the evaluation of the adsorption isotherm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01188976
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  • 8
    Electronic Resource
    Electronic Resource
    Adsorption kinetics of surfactants from micellar solutions (1981)
    Springer
    Colloid & polymer science 259 (1981), S. 1124-1128 
    Details
    ISSN: 1435-1536
    Keywords: Adsorption kinetics ; surfactants ; micellar solutions ; theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Es wird ein Modell für die diffusionskontrollierte Adsorption von Tensiden aus mizellaren Lösungen angegeben und numerisch gelöst. Das dabei zugrundegelegte Modell für die Mizellkinetik entspricht einem Bildungs-Auflösungs-Mechanismus. Es wird der Einfluß von Parametern wie Mizellkonzentration, Assoziationsgrad, Geschwindigkeitskonstanten der Mizellkinetik auf die Adsorptionskinetik diskutiert.
    Notes: Summary A model of diffusion controlled adsorption of surfactants from micellar solutions is given and numerically solved. The model used to describe the micelle kinetics corresponds to a formation-dissolution mechanism. Parameters like micelle concentration, aggregation number, rate constant of formation or dissolution of micelles influencing the adsorption process are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01524900
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  • 9
    Electronic Resource
    Electronic Resource
    High performance liquid chromatography (HPLC) of natural products part VI.For part V, see [1] Sulfoxides of penicillin N and cephalosporin c and their role in biosynthesis of β-lactam antibiotics (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 876-884 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pure pencillin N α-sulfoxide (1) and penicillin N β-sulfoxide (2) were obtained by HPLC and tested as substrates for deacetoxycephalosporin C synthetase (DXCS). Neither one of the sulfoxides was utilized under conditions of conversion of penicillin N (8) to deacetoxycephalosporin C (9). The cephalosporin C α and β-sulfoxides (3 and 4, resp.) were also prepared. Relative stabilities of the sulfoxides 3 and 4 are discussed by interpretation of the 13C-NMR spectra.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670329
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  • 10
    Electronic Resource
    Electronic Resource
    High Performance Liquid Chromatography (HPLC.) of Natural Products. III [1]. Isolation of New Tripeptides from the Fermentation Broth of P. Chrysogenum1. Mitt.: [1], 2. Mitt.: [2]. (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 1119-1129 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-Aminoadipoyl-alanyl-valine, α-aminoadipoyl-serinyl-valine and α-aminoadipoyl-serinyl-isodehydrovaline have been isolated from the fermentation broth of P. chrysogenum. The configuration of α-aminoadipoyl-serinyl-valine has been shown to be L, L, D.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630503
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