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  • Column liquid chromatography  (124)
  • Gas chromatography  (60)
  • Springer  (182)
  • Cambridge University Press
  • Frontiers Media
  • 2020-2022
  • 1985-1989  (182)
  • 1980-1984
  • 1975-1979
  • 1970-1974
  • 1988  (127)
  • 1985  (55)
  • 1970
Collection
Keywords
Publisher
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  • 2020-2022
  • 1985-1989  (182)
  • 1980-1984
  • 1975-1979
  • 1970-1974
Year
  • 1
    Electronic Resource
    Electronic Resource
    The rapid quantitative analysis of codeine phosphate drug substance by reversed-phase high-performance liquid chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 289-292 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase ; Codeine phosphate drug substance ; Opium alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid procedure for the evaluation of codeine phosphate drug substance derived from poppy straw or opium concentrate is described. The gradient HPLC procedure employs a pH 2.5 phosphate buffer, methanol and acetonitrile mobile phase at 40°C and a μBondapak C-18 column. Eight opium alkaloids, including the four major alkaloids, are separated from each other. The paper describes details of the assay procedure and presents data documenting the linearity, specificity, precision, and sensitivity of the method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02310385
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  • 2
    Electronic Resource
    Electronic Resource
    Spectroscopy and the classification of liquid stationary phases in gas-liquid chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 293-302 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary liquid, choice of ; Physico-chemical data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A table of data for acidity, basicity, polarity and London potential for stationary phases is given. These provide guidance in choosing a stationary phase for a given task from the 26 substances listed. The indices are calculated from infra-red shifts of 1-chlorobutane and the visible wavelength shifts of l2 when they are dissolved in the stationary phases, from NMR estimates of acidity and basicity and from relative retention data. They replace the less reliable data of Burns and Hawkes. Methods of determining the indices are suggested that require only a gas chromatograph and can be applied by technicians with no specialized understanding of solution parameters. An attempt to add electron donoracceptor indices to the table was unsuccessful. A further table is given of the slopes of the log plots d(logt′)/dC for use in extrapolating from one homologue to another on these stationary phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02310386
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  • 3
    Electronic Resource
    Electronic Resource
    The new generation of L. C. columns; A critical evaluation of their systems compatibility and performance (1985)
    Springer
    Chromatographia 20 (1985), S. 335-342 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; External variance determinations ; Column and system compatibility ; Microbore and fast LC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The demand for faster, more economic and convenient high-efficiency LC analyses has led to the development of microbore and fast columns. However, to utilize their benefits, the low column dispersions produced by these new technologies necessitate low external variances in the total system. This paper describes the determination of the external variance of microbore, fast and conventional LC systems by a column method. Compatibility with the relevant column technologies is evaluated by a method involving the comparison of the external and column dispersions. Direct comparison of chromatograms of an 8-component mixture, on a set of columns of various diameters and lengths, shows the relative speed, economy and sensitivity obtainable in practice. The problem of reduced sample loadability is considered and the practical solution of peak compression illustrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269058
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  • 4
    Electronic Resource
    Electronic Resource
    Retention prediction system coupled with a multichannel ultraviolet detector for the identification of polycyclic aromatic hydrocarbons (1985)
    Springer
    Chromatographia 20 (1985), S. 351-356 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention prediction system ; UV multichannel detector ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention prediction system assisted by a micro-computer coupled with an UV multichannel detector has been investigated in the separation of polycyclic aromatic hydrocarbons. The method offered very precise identification of components in NBS-SRM-1647 sample without any standard reference substances. It has been proven that the system makes very precise, non-pollutive and convenient environmental analysis possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269061
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  • 5
    Electronic Resource
    Electronic Resource
    Fast determination of tetracycline antibiotics in different media by high-performance liquid chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 313-322 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Tetracyclines antibiotics ; Quantitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of high-performance liquid chromatography (HPLC) for the identification and determination of tetracycline antibiotics is reviewed. HPLC chromatograms provide fast identification by retention time, tR, and precise quantitation by measurement of peak height or peak area. For separation of tetracycline compounds, most HPLC methods use reversed-phase C18 or C8 columns and UV detection. The HPLC solvent system should have a pH of about 6 to prevent steric changes in the tetracycline molecule. For accurate quantitation it is necessary to avoid tailing and this is accomplished by adding a zwitter ion to the solvent system. Methanol and acetonitrile are frequently used as organic modifiers in these solvent systems. In a single analysis, HPLC methods can be used to separate as many as nine or ten commercially used tetracycline compounds and to determine four to five tetracyclines in commercial tetracycline preparations or in biological fluids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02310389
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  • 6
    Electronic Resource
    Electronic Resource
    A new adsorbent for trace level organic contaminants (1985)
    Springer
    Chromatographia 20 (1985), S. 343-346 
    Details
    ISSN: 1612-1112
    Keywords: Thermosorb ; Tenax GC ; Environmental Analysis ; Trace Organics ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A preliminary study has been carried out to evaluate a new adsorbent, Thermosorb, for trace level organic contaminants. For this purpose, a comparison was made with a well-characterized adsorbent, Tenax GC, using a prepared aqueous solution of trace organic components. In addition, a comparison was made of chromatograms of air contaminants obtained using both of these adsorbents, under equivalent conditions. The results clearly indicated the potential of this thermally stable, inorganic adsorbent for many trace organic substances of environmental interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269059
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of the flame photometric detector in the sulphur mode (1985)
    Springer
    Chromatographia 20 (1985), S. 371-375 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Flame photometric detector ; Sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of experimental conditions such as gas flow rates, detector and column temperatures on sulphur response are discussed. It is concluded that the response of the flame photometric detector is affected by the O/H ratio and the total gas flow. Column temperature has an important influence upon S2 emission. It is shown that the sulphur response of the FPD is dependent on the compound containing the sulphur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269065
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  • 8
    Electronic Resource
    Electronic Resource
    Direct analysis of fenvalerate isomers by liquid chromatography. Application to formulation and residue analysis of fenvalerate (1985)
    Springer
    Chromatographia 20 (1985), S. 376-378 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Resolution of optical isomers ; Chiral column ; Pyrethroids ; Fenvalerate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the optical isomers of fenvalerate [cyano(3-phenoxyphenyl)methyl 2-(4-chlorophenyl)-3-methylbutyrate] has been carried out by high-performance liquid chromatography (HPLC) on a chiral column with (R)-N-3,5-dinitrobenzoyl-phenyl-glycine (DNBPG) covalently bonded on aminopropyl silica and eluted with mixtures of methanol, 2-propanol, and hexane. The system was applied to the analysis of Pydrin®, an emulsifiable concentrate formulation of fenvalerate, and to the residue analysis of fenvalerate in milk samples. For the analysis of Pydrin® the only requirement was the proper dilution of Pydrin® with hexane. For the analysis of residues in milk, fenvalerate was extracted with hexane after precipitating the milk proteins with acetonitrile and removing the precipitate by filtration; the hexane extract was concentrated to small volume and filtered before being analyzed by HPLC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269066
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  • 9
    Electronic Resource
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    A study of the elution of macromolecules from columns of thermally-treated controlled-porosity glasses (1985)
    Springer
    Chromatographia 20 (1985), S. 487-494 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion chromatography ; Controlled-porosity glasses ; Boron-enriched glass surface ; Adsorptive properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Controlled-porosity glasses (CPG) are sieves for macromoleculars, very widely applied in chromatographic columns for the separation of polymers and biopolymers by means of size-exclusion chromatography (SEC) and affinity chromatography. This paper deals with the influence of the thermal treatment of CPG on the elution of polymers in SEC columns. The problem is examined for a few mobile phases and for glasses having different porosities. Additionally, the SEC results obtained are compared with the adsorption properties of the glases investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02344791
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  • 10
    Electronic Resource
    Electronic Resource
    Scintillator-fiber flow-cell radioactivity detector for liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 31-36 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Radioactivity detector ; Solid scintillator ; Fibre-packed flow cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new type of flow-cell radiation detector for use in liquid chromatography which is packed with aligned scintillator fibers is described. A primary advantage of the fiber packed cell is that light generated by the scintillator is absorbed to a much less extent by the fibers than by the powder scintillator used in conventional flow cells. A detection efficiency of 55% has been obtained for carbon-14 using 0.1-mm diameter hand-pulled glass fibers. Computer modeling has shown that even better results can be obtained by using smaller and more uniform diameter fibers which will allow better packing. The fiber cell also demonstrates back pressures which are a factor of 50 less than the conventional cell and much less susceptibility to absorption of compounds because of its lower surface area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311524
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  • 11
    Electronic Resource
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    Turbidimetric titration and gradient high-performance liquid chromatography of polystyrene samples (1988)
    Springer
    Chromatographia 25 (1988), S. 854-860 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polystyrene ; Gradient elution ; Turbidimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polystyrene samples of narrow molecular-weight distribution have been eluted according to their molecular weight from columns packed with bare silica Si50, phenyl, or C18 bonded phase by gradients of methanol and tetrahydrofuran (THF) or ofiso-octane and THF. Among the six combinations investigated,iso-octane/THF with a silica column formed a proper normal-phase system whereas methanol/THF with a C18 column formed a proper reversed-phase system. The combinations of C18 column andiso-octane/THF or of Si50 column and methanol/THF gradient did not correspond to the approved polarity rules in high-performance liquid chromatography but were nevertheless effective in separating polystyrene mixtures by molecular weight. Methanol andiso-octane are nonsolvents for polystyrene whereas THF is a solvent. The solubility of polystyrene as a function of molecular weight and concentration was determined by means of turbidimetric titration of solutions in THF with the nonsolvents used in the gradients. The solubility and elution characteristics were almost identical on C18 columns or in methanol/THF combinations. The elution from phenyl bonded phase and Si50 columns usingiso-octane/THF gradients required more THF than the solubility experiments. Information is also given on the occurrence of multimodal elution patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311417
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  • 12
    Electronic Resource
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    Retention characteristics of alkylated polycyclic aromatic hydrocarbons in normal phase liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 25-30 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polycyclic aromatic compounds ; Alkylated PAC ; Retention characteristics ; Normal phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention characteristics of series of polymethyl and mono-n-alkyl derivatives of benzene and pyrene, and also of parent polycyclic aromatic hydrocarbons (PAH), were studied using silica and aminopropyl- and cyanopropyl-modified silica. Differences in the selectivities for the studied compound groups were found between the three phases. Deviations from linear behaviour in plots of log (k′)vs. carbon number were observed for the methyl series. These are explained in terms of differences in π-electron delocalisation within the aromatic ring systems. Further, the effect of methyl substitution on selectivity decreased with an increasing number of aromatic rings. Results were obtained which indicated that the primary adsorption site in a cyano column used in normal phase mode, at least for PAH molecules, is the cyano group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311523
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  • 13
    Electronic Resource
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    Void volume determination and experimental probes in reversed phase chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 43-50 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Void volume ; Adsorption isotherms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In reversed-phase liquid chromatography with n-alkyl bonded silica, the dead volume (V0) of the column is theoretically indeterminate owing to adsorption of organic modifier on n-alkyl chains and of water on silanol groups. With binary mobile phases, retention volumes of the mobile phase components and of their deuterated species are relaeed to the adsorption isotherms and V0 by equations which can be solved with some assumptions on the adsorbed layer composition. Methanol-water and acetonitrile-water systems are studied. As the experimental excess isotherm shows a linear part in the concentration range 50–80% in organic modifier, the hypothesis of an adsorbed layer of constant composition in this range is possible. When increasing the water content of the mobile phase, adsorption of water occurs up to saturation of silanol groups. Then the assumption of a constant water content for a mobile phase having more than 50% of water is applied. With the hypothesis of a constant adsorbed content of organic modifier when the eluent has more than 80% of organic modifier, V0 and the absolute isotherms are calculated over the entire range of mobile phase composition. Experimental retention behavior of the mobile phase components are totally explained by these V0 determinations. The retention times of commonly used V0 markers are compared with V0 values. It is shown that, when buffering the eluent, no visible effect on the distribution equilibrium is observed, so that injection of concentrated potassium nitrate is a convenient method to measure V0. With a few solutes with are UV detectable it is possible to measure V0 whatever the mobile phase composition in methanol-water and acetonitrile-water systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311526
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  • 14
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    Extended solubility parameters and stationary phase selectivities of anino-, cyano- and diol-silica normal bonded-phase liquid chromatography columns (1988)
    Springer
    Chromatographia 25 (1988), S. 55-60 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Stationary phase solubility parameters ; Cyano-silica ; Amino-silica ; Diol-silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Extended solubility parameters have been determined for aminopropyl, cyanopropyl and 1,2-dihydroxypropyl propyl ether (diol) normal bonded-phase HPLC columns. Parameters were calculated from both the retention data of solutes (partition model) and empirically determined solvent strengths (adsorption-displacement model). The use of solvent strengths to calculate solubility parameters for these silica-based bonded stationary phases appears to be superior, since this technique avoids many of the problems that arise from their inherent heterogeneity. Normalized solubility parameters were also used to position these columns on a stationary phase selectivity triangle. The amino and cyano phases appear in regions of the tringle expected based on the properties of the pure liquids, but an ether linkage in the diol apparently neutralizes some of the acidity expected from this phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311528
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  • 15
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    Simultaneous distillation-extraction (SDE) method in the qualitative and quantitative GC analysis of cheese volatile components (1988)
    Springer
    Chromatographia 25 (1988), S. 861-864 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Simultaneous distillation-extraction ; Cheese volatiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simultaneous distillation-extraction apparatus proposed by Godefroot has been used for the GC study of volatile components of cheese. 5–10 g of cheese provide a fraction that can be directly injected into a GC or a GC/MS. Two capillary columns (SE-30 and SP-1000) were evaluated, the second one being adequate for quantitative determinations. Camphor was used as internal standard. The coefficients of variation ranged from 1.4 to 11.8. The technique can be used as a fast method for the characterization of cheeses from their volatile component concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311418
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  • 16
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    Slope of the log plot of adjusted retention time against carbon number for various homologues serices (1988)
    Springer
    Chromatographia 25 (1988), S. 1087-1088 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Log plot ; Homologous series
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The slope of the log plot of the adjusted retention time of a homologous series usually varies from that of the n-alkane series by no more than 2%, though with unusual interactions between the functional group and the stationary phase the difference may be as high as 7%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259389
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  • 17
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    Comparison of the elution curves of pure components and their mixture and prediction of elution curves by a theoretical plate model in preparative gas-liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 961-964 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Preparative scale separations ; Plate model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two close-boiling materials, diethyl ether (DEE) and dichloromethane (DCM), were separated to investigate the effects of the pure components and the mixture on elution in preparative gas-liquid chromatography. Nitrogen was used as the carrier gas, and the chromatographic column (1 cm I.D. and 0.75m length) was packed with Chromosorb A with different quantities of dinonyl phthalate stationary phase and particle sizes. Below ca. 7% (by wt.) of feed concentration, the experimental elution curves of pure DEE and DCM were almost the same as those of the mixture, and the theoretical plate model can be used successfully to predict the elution curves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259412
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  • 18
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    Reversed-phase HPLC analysis of the semisynthetic macrolide antibiotic azithromycin (1988)
    Springer
    Chromatographia 25 (1988), S. 999-1003 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Macrolide antibiotic azithromycin ; Intermediates of azithromycin ; Optimization of separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC is the most convenient method for the assay of the azithromycin (10-dihydro-10-deoxo-11-methyl-11-azaerythromycin A), a semisynthetic macrolide antibiotic and its reaction intermediates. Data concerning the effects of pH, temperature and column type are presented. The analytical procedures enabling the reliable assay of azithromycin and its intermediates, as well as other impurities are defined. Use of a reversed-phase octadecyl column, a pH of 9.3–9.5, and isocratic mode at ambient temperature are the best conditions of analysis.
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    URL: http://dx.doi.org/10.1007/BF02259419
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  • 19
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    Diagnostic and therapy-control of inborn metabolic disorders by high-performance liquid chromatography: 2,8-dihydroxyadeninuria, xanthinuria (1988)
    Springer
    Chromatographia 25 (1988), S. 205-209 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Metabolic disorders ; Xanthine and 2,8-dihydroxyadenine ; Urine analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 2,8-Dihydroxyadeninuria and xanthinuria are inborn enzyme disorders which must be under lifelong therapeutic control. Quantitative determination of 2,8-DHA and xanthine using reversed phase HPLC was performed. A new application for the separation of purines shortens analysis-time. Examples of the determination of 2,8-DHA and xanthine before and under certain therapies are shown. Long term monitoring of the patients offers the possibility of a reliable prophylaxis against stone recurrence.
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    URL: http://dx.doi.org/10.1007/BF02316445
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  • 20
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    Simulation of induced peaks in indirect detection of non-electrolytes in high-performance liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 107-110 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Indirect detection of non-electrolytes ; Simulation of induced peaks ; RP systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Induced peaks observed in indirect detection of nonelectrolytes in high-performance liquid chromatography are simulated. The equation representing the signal intensity of the induced peaks is derived, and it is verified by the experimental results. The peak area is proportional to (K b ′ +1) k a ′ /| a ′ —k b ′ |, where k a ′ ad k b ′ are the capacity factors of the visualization agent and the analyte, respectively.
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    URL: http://dx.doi.org/10.1007/BF02259025
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  • 21
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    Invetigations into the use of an auxiliary metal ion for indirect amperometri detection (1988)
    Springer
    Chromatographia 25 (1988), S. 162-166 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Analysis of metal ions ; Post column derivatisation ; Amperometric detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for determination of metal ions subsequent to separation by ion chromatography has previously been developed. The method is based on Indirect Amperometric Detection whereby the decrease in the oxidation current, due to a dithiocarbamate ligand added post column, is monitored. Upon elution from the chromatographic column the metal ions are complexed by the ligand. As the complexes formed are electroinactive at the applied potential, the background current decreases according to the metal ion concentration. The method developed in this work involves addition to the reagent of Zn(II) as a auxiliary metal ion to displace the analyte metals from the chromatographic eluent ligand complexes after separation. Sodium bis(2-hydroxy-ethyl) dithiocarbamate was used as the postcolumn derivatising reagent. The addition of Zn(II) to the reagent causes some unforeseen behaviour in the chromatographic system.
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    URL: http://dx.doi.org/10.1007/BF02316437
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  • 22
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    Catecholamine: „On-Line” probenaufarbeitung und nachsäulenderivatisierung (1988)
    Springer
    Chromatographia 25 (1988), S. 199-204 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column switching ; Catecholamines ; Urine ; Serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We developed an automated, two-column HPLC-method that can be used routinely to quantify the catecholamines norepinephrine and epinephrine in body fluids. The method is based on a new, laboratory-prepared SEC-HPAC column material, on the application of a microprocessor-controlled column-switching technique, and on the use of an integrated reaction system for postcolumn derivatization and trihydroxyindol-fluorescence monitoring. It allows the direct injection (upto 500 μl) of an appropriate biological fluid and distinguishes on its integrated sample-processing mode, its practicability, its chemoselectivity and-specivity, its detection limit (2 pg), its within- and between-run precision and its speed of analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02316444
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  • 23
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    On some aspects of the silica surface modification with hexamethylcyclotrisilazane, hexamethyldisilazane and their mixtures (1988)
    Springer
    Chromatographia 25 (1988), S. 404-408 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silica surface modification ; Hexamethylcyclotrisilazane ; Hexamethyldisilazane ; Support materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper is concerned with the structure of an organic layer bonded to the silica surface modified with silazanes. The changes of the retention volumes of hydrocarbons is studied for the silicas modified with hexamethylcyclotrisilazane, hexamethyldisilazane and their mixtures. It is shown that most of the carbon in the layer after hexamethylcyclotrisilazane modification is bonded to the surface by Si−O−Si bonds. This fact supports the assumption of a fragmentation of the cyclosilane used for modification.
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    URL: http://dx.doi.org/10.1007/BF02324782
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  • 24
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    Determination of pheophytinatonickel(II) by reversed-phase highperformance liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 319-323 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pheophytinatonicke(II) ; Chlorophyll ; Pheophytin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC determination of pheophytinatonicke(II) (Pheo-Ni) prepared by the replacement of magnesium(II) in chlorophyll with nicke(II) is described. The good separation of PheoNi was obtained by using chemically bonded C18 as the stationary phase and acetone-methanol (50∶50, vol/vol) as the mobile phase. Conventional spectrophotometric method was also used for the determination of PheoNi. For the synthetic samples prepared by mixing (pheophytinato a) nicke(II) [(Pheo-a) Ni] and (pheophytinato b) nicke(II) [(Pheo-b) Ni], analytical values obtained by the spectrophotometric method were very high compared to those obtained by HPLC. In the proposed HPLC method, (Pheo-a) Ni and (Pheo-b). Ni could be determined in the concentration range of 0.028–30μg/ml and 0.038–30μg/ml with relative standard deviations (n=10) of 3.1% and 0.8%, respectively.
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    URL: http://dx.doi.org/10.1007/BF02324707
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    Testing for linearity in retention time — Carbon number plots for n-alkanes (1988)
    Springer
    Chromatographia 25 (1988), S. 389-392 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Statistical criteria ; Non-linear models ; Constants for n-alkane retention curve ; Multiparametric least-squares adjustment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Multiparametric, least-squares, regression treatment of G.C. data is extended to describe deviations from the usual linear model. Through statistical evaluation of results, four parameters models are generally found adequate and the use of higher degree empirical models is discouraged.
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    URL: http://dx.doi.org/10.1007/BF02324779
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    Chromatographic behaviour of flavonoid compounds in reversed-phase HPLC systems (1988)
    Springer
    Chromatographia 25 (1988), S. 423-429 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flavonoid compounds ; Structure-retention relationships ; Reversed-phase systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase HPLC retention behaviour of different flavonoid compounds in different columns and with a range of methanol-buffer eluents was examined. Repeatibility and reproducibility of logk′ and Δlogk′ values were analyzed. Sharp group contributions, expressed as Δlogk′, were observed. These did not depend significantly on acid modifier type, column packing characteristics (C8 and C18) and dimensions (5,7 and 10μm) or the percentage of methanol in the mobile phase. A list of twelve group contributions is presented which is in agreement with literature data.
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    Process scale high-performance liquid chromatography Part II: Dissolution of silica matrices (1988)
    Springer
    Chromatographia 25 (1988), S. 443-446 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Large scale separations ; Dissolution of silica ; Metallic contaminants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Possible contamination of purified product by the silica matrix is of considerable importance when considering process scale high-performance liquid chromatography (HPLC) as a separation methodology. The stability of silica supports in normal phase, reversed phase and affinity chromatography modes has been examined with organic solvents and water. Both inorganic and organic components were found, contributed by the support, and the chromatographic and distillation equipment. In all cases, based on assumed values of production, they were found to contribute less than 0.01% of impurities. In critical cases crystallisation or dialysis may be considered as a last stage of purification, with re-chromatography to maximise yields.
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    URL: http://dx.doi.org/10.1007/BF02324789
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    Liquid chromatography/fast-atom-bombardement mass spectrometry of nonionic detergents (1988)
    Springer
    Chromatographia 25 (1988), S. 523-525 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fast atom bombardment mass spectrometry ; Nonionic detergents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Microcolumn liquid chromatography (LC) combined with fast-atom-bombardment mass spectrometry (FABMS) was applied to the analysis of nonionic detergents. The porous silver filter attached to the top of the capillary fused-silica tubing worked as the interface for coupling of micro LC and FABMS.
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    URL: http://dx.doi.org/10.1007/BF02324826
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    Calculation of retention indices at an assigned temperature from temperature-programmed data (1988)
    Springer
    Chromatographia 25 (1988), S. 539-542 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Temperature programming ; Retention index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is presented for the calculation of retention indices at an assigned temperature from temperature-programmed data. If the retention times at two different program rates for the solutes and the n-alkanes are known, the retention indices at an assigned temperature can be calculated directly.
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    URL: http://dx.doi.org/10.1007/BF02324830
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    Process scale high performance liquid chromatography part IV—Examples of reversed phase separations (1988)
    Springer
    Chromatographia 25 (1988), S. 577-581 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Process scale ; Examples of separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The flexibility of process scale high performance liquid chromatography is demonstrated by three examples of reversed-phase separations (a) a standard purification (b) isolation of trace compounds, and (c) recovery from crystallisation mother liquors. It was shown that a material, thought to be acceptably pure, contained a toxic impurity, and a remaining impurity, a previously unseen component of potential therapeutic interest. Favourable cost data were indicated for example (3).
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    Quantitative determination of miconzole in human serum by high-performance liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 717-720 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase chromtography ; Antifungla agent ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liqid chromatographic method is reported for the measurement of miconazole in systemic, fungal infectious patients. Pharmacokinetic data are presented for a single patient receiving miconazole therapy. Sample preparation involves protein precipitation by acetonitrile (1:1, vol/vol). Analyses are carried out on a reversed-phae chromatographic system using octadecylsilane stationary phase: a mobile phase consisting of 0.05 M acetate buffer (pH 7.4)acetonitrile (20:80, vol/vol) is used to elaute miconazole is quantified on the basis of ultraviolet absorption at 220 nm. The precision of the method ranged from 3.21% at 0.5 mg/L to 0.85% at 2.0 mg/L. The limit of quantification was established as 0.1 mg/L. Interference from other drugs that are co-adimistered such as amphotericin B, 5-fluorocytosine of ketoconazole and most other comonly encountered drugs was not observed.
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    Investigation of the limitations of saturated fractional factorial experimental designs, with confounding effects for an HPLC ruggedness test (1988)
    Springer
    Chromatographia 25 (1988), S. 769-774 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fractional factorial experimental designs ; Ruggedness test ; Method validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Recently much attention has been directed to the validation of analytical methods. The level of validation will depend on the method application. If a method is developed for general use, for instance by different analysts, instruments or laboratories, then the effect of these changes need evaluation. This is normally referred to as ruggedness testing, where the limitations of the method to changes in the specified conditions are examined. This paper examines the use of Plackett-Burman fractional factorial experiment designs for ruggedness testing in high performance liquid chromatography (HPLC). The ability of these designs to identify confounding effects is applied to the stability indicating analysis of Salbutamol and its major degradation product, AH4045. The results show that confounding effects, proving extremely pertinent to HPLC, can be identified. The assay proved rugged to most tested changes although not to the use of column packing material from different manufacturers.
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    Theoretical background of multicomponent gas chromatography for high concentrations (1988)
    Springer
    Chromatographia 26 (1988), S. 125-132 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Non-equilibrium frontal chromatography ; Nonlinear isotherms ; Variable velocity ; Multicomponent mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper presents a classification of various theoretical models for multicomponent gas chromatography at u=var for high concentrations of the mixture components with consideration of the major distinctive features of the interphase mass exchange inside the porous grains of the adsorbent and outside them within the porous medium of the chromatographic column. It has been shown that the conditions determining a given front behaviour of multicomponent gas mixture at u=var depend on: theoretical models for the kinetics and dynamics of adsorption; the values of mass exchange parameters inside the porous grains and in the porous medium. Formulae have been derived for calculating the values of the quantities characterising the frontal behaviour in the stage of adsorption and desorption of multicomponent mixture at u=var.
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    Solute retention in reversed-phase chromatography as a function of stationary phase properties: Effect of n-alkyl chain length and ligand density (1988)
    Springer
    Chromatographia 26 (1988), S. 115-119 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alkyl-bonded phases ; Retention behaviour ; Ligand density ; n-alkyl chain length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two series of bonded phases were synthesized employing LiChrospher Si 100, 10 μm and n-alkyldimethylmonochlorosilanes as silanizing reagents. In series A the n-alkyl chain length, n, of the bonded phase was varied between 1 and 20 at a constant ligand density of 3.5±0.2μmol·m−2. In series B the ligand density, d, was gradually changed from 0 to 4.1μmol·m−2 on the C1, C4, C6, C8 and C18 bonded phases, respectively. The capacity factors of benzoic acid esters and anilines as solutes were found to increase linearly with the n-alkyl chain length of packings at constant eluent composition (series A) up to a so-called critical chain length, ncrit, where the capacity factor remained constant. ncrit was in the range from 11 to 14. The same pattern was observed when plotting the solute capacity factor against the ligand density of the packing at constant n and constant eluent composition (series B). The critical ligand density, αcrit, varied between 2.3 and 3.2 μmol·m−2 depending on n and the solute. Furthermore, solute retention was slightly higher on RP packings with an even number of carbon atoms in the alkyl chain than on those with an odd number. These findings are consistent with the results of Berendsen and de Galan (J. Chromatogr., 196, 21 (1980)), Dill (J. Phys. Chem., 91, 1980 (1987)) and Simpson and Lau (to be published). The observed phenomena reflect the dynamic structure of RP silicas which are related to the mobility of solvated n-alkyl chains. Due to the lack of a precise conformational analysis of the surface of RP silicas, a semiquantitative model was applied to interprete the described dependencies.
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    Effect of the type of ion-pairing reagent in reversed-phase ion-pair chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 587-590 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair chromatography ; Sulfonate pairing ion ; Adsorption isotherms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention of positively and negatively charged and neutral solutes was studied in an aqueous phosphate buffer eluent, with constant inorganic-counterion concentration, on ODS-Hypersil stationary phase in the presence of various sulfonic acid ion-pairing reagents. The adsorption isotherms of the ion-pairing reagents d-camphor-10-sulfonic acid, sodium cyclohexylsulfamic acid and sodium alkylsulfonates (butyl-, hexyl- and octyl-) were determined by the breakthrough method.
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    The dependence of the properties of liquid crystals on the film thickness and surface quality of capillary columns (1985)
    Springer
    Chromatographia 20 (1985), S. 601-608 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystal ; Capillary columns ; Retention data ; Stationary phase film thickness ; Column surface quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Glass capillary columns were prepared from non-deactivated and deactivated glass and coated with (2-methyl-4-[trans-4-n-propyl-cyclohexylcarbonyloxy]-benzoic acid-[4-n-heptyloxy-phenylester]) as the liqud phase, in different film thicknesses. The columns were tested using substances of different structures and polarities. It was verified that the capacity factors, retention indices and selectivity significantly depend on the thickness of the liquid crystalline stationary phase film and the quality of the tube, particularly in the case of columns with thin films. Trasition temperatures (melting and clearing point) of the liquid crystal are also dependent on these two factors.
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    On line trace enrichment for isolation of vitamin B2 in food samples (1985)
    Springer
    Chromatographia 20 (1985), S. 615-617 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Vitamin B2 in food ; Column switching ; Liquid-solid extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Vitamin B2 was enriched by liquid-solid extraction from large volumes of aqueous samples on a short precolumn. The enriched compounds were transferred onto an analytical reversed-phase column and separated by ion-pair chromatography. The equipment used provides the possibility of automation for routine analysis.
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    An evaluation and comparison of micro-techniques for concentration of volatile components from dilute solutions (1988)
    Springer
    Chromatographia 25 (1988), S. 21-24 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sample concentration ; Chromatographic evaporation ; Solvent effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several micro-techniques for the removal of solvent from dilute solutions of volatile compounds have been compared. Large solute losses were experienced when the conventional blow-down technique was applied. Better yields could be obtained with static evaporation procedures, as long as an effective reflux was maintained. However, careful optimization of the vessel design and operating conditions is necessary. The most efficient volume reduction technique was shown to be chromatographic evaporation. Quantitative recoveries were obtained for the compounds tested and the process was significantly faster than static concentration. Moreover, operating conditions (gas flow, temperature) are less critical. With modifications, the principle can be used for the concentration of large sample volumes down to a few microliters.
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    Esterification of amino acids to n-butyl and isobutyl esters in aqueous solutions for their gas chromatographic analysis (1985)
    Springer
    Chromatographia 20 (1985), S. 652-656 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Amino acids have been esterified with n-butanol and isobutanol in the presence of perchloric acid. It has been established that in the concentration range of [H2O]/[n-BuOH]=0.10–0.40 esterification can be utilized for the determination of alanine, glycine, valine, leucine, proline, methionine, aspartic acid, phenylalanine, tyrosine, glutamic acid, lysine, arginine, histidine and cystine. In the case of [H2O]/[i-BuOH] =0.05–0.20 the esterification yield decreases from 100% to 70%, in proportion to the water content.
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    The influence of the concentration of surface boron atoms on the properties of column packings with bonded C18 groups, prepared from controlled-porosity glasses II. Liquid chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 677-680 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Controlled-porosity glasses ; Chemically bonded phases ; Boron-glass surface enriched
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In the preparation of C18-bonded phases higher coverage densities were obtained using dimethylaminodimethyl-n-octadecylsilane than chlorodimethyl-n-octadecylsilane as the reagents. The HPLC results show the very high hydrophobicity of the materials obtained. The elution mechanism has been found to be independent of the coverage density on the boron-enriched glass surface in the range 2.3–4.0 μmol/m2.
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    A GC-system for the analysis of residual geothermal gases (1985)
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    Chromatographia 20 (1985), S. 681-682 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Geothermal gases ; Molecular sieves ; Low temperature separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gases evolved from geothermal fields, after condensation of H2O, CO2, H2S and NH3 in caustic solution, contain He, H2, Ar, O2, N2, CH4 and higher hydrocarbons. The analysis for the major components in these residual gas mixtures can be achieved by use of two simple gas chromatographs in parallel, and using 5Å molecular sieve. The separation of He and H2 to baseline is achieved by using low temperatures (30°C) coupled with a relatively long column; and the difficult separation of Ar and O2 is achieved by use of a cryogenically cooled column. The use of switching valves to backflush and bypass columns ensures that a minimum time for analysis can be achieved whilst retaining baseline separations of the He/H2 and Ar/O2 pairs.
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    Isolation of new quinidine metabolites and simultaneous determination of quinidine and its metabolites in blood and urine by direct injection HPLC analysis (1985)
    Springer
    Chromatographia 20 (1985), S. 671-676 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Direct injection of biological samples ; New quinitidine metabolites ; Deproteinisation on precolumn ; Column switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New quinidine metabolites, including 10,11-dihydrodiol quinidine N-oxide, 10,11-dihydrodiol quinidine and their glucuronides, were found in human urine. A quinidine monitoring HPLC method including these metabolites, is proposed by the direct injection of body fluid samples onto the precolumn for deproteinization followed by reverse phase separation in the analytical column with a column switching technique. The recovery of spiked quinidine and its metabolites in plasma was quantitative (98–102%) with good reproducibility (C.V.: 1.6–4.0%). Several clinical samples such as whole blood and urine were analyzed by the present method.
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    Formation of derivatives of chlorophenoxy acids and some other herbicides (1985)
    Springer
    Chromatographia 20 (1985), S. 685-688 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fuming sulphuric acid-ethanol esterification ; Ethyl and methyl esters of herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A fuming sulphuric acid-ethanol esterification method has been applied to chlorophenoxy acids and some other herbicides. This method is compared with esterification by iodoethane and diazomethane. The chlorophenoxy acids studied were: 2,4-D, dichlorprop, MCPA, MCPB, mecoprop and 2,4,5-T. Other herbicides studied were: benazolin, bentazone, bromophenoxime, bromoxynil, chlorthal, dicamba, 3,6-dichloropicolinic acid, dinoseb, ethephon, fluroxypyr, glyphosate, haloxyfop, ioxynil, picloram, 2,3,6-TBA and triclopyr. Fuming sulphuric acid-ethanol esterification can be successfully applied to chlorophenoxy acids, benazolin, 3,6-dichloropicolinic acid, dinoseb, fluroxypyr, haloxyfop, picloram and triclopyr. The reproductibility of the method is ±5%.
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    Non-empirical descriptors of sub-molecular polarity and dispersive interactions in reversed-phase HPLC (1985)
    Springer
    Chromatographia 20 (1985), S. 705-708 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Quantitative structure-retention relationships (QSRR) ; CNDO/2-MO Calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention data for 12 aromatic test solutes with functional groups of various polarities were studied on a wellcharacterized monomeric octadecyl stationary phase over a range of methanol/water compositions. CNDO calculations on the solute structures and regression analysis indicated that two terms, the total energy, ET, and the maximal difference of electron excess charge, Cd, correlated well with changes in retention as a function of methanol composition. This approach allowed for the non-empirical calculation of retention data for solutes with a range of polarities, overcoming previous deficiencies in the estimation of molecular polarity for non-homologous solutes based on total dipole moment.
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    The polarity of polyoxyethylene glycol dialkyl ethers and their sulphur analogs as measured by parameters considering intermolecular electric interactions (1988)
    Springer
    Chromatographia 25 (1988), S. 95-98 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phase polarity ; Polarity parameters ; Structure-retention relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The new stationary phase polarity parameters BN and BS evaluated from the concept of the electric intermolecular interactions are used to describe the polarity of polyoxyethylene glycol dialkyl ethers and their sulphur analogs. Relations between the discussed parameters and accepted measures of surfactants' polarity are presented and discussed. The considered parameters are correlated with the compound structures. Structural increments for characteristic fragments of the molecule are calculated and use to predict BN and BS values.
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    Gas chromatographic investigations of the adsorption of n-octane on the surface of sulfur (1988)
    Springer
    Chromatographia 25 (1988), S. 134-138 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sulfur ; n-Octane adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary From the adsorption isotherms of n-octane on the surface of sulfur at 29.8°C and 40.6°C some thermodynamic functions were determined. On the basis of these data the structure of the adsorbed layer of n-octane is postulated. The molecular interactions and adsorption mechanism are also discussed. It is stated that both quasi-liquid and quasi-sold layers may be formed on the surface of sulfur depending on the surface coverage with n-octane.
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    Application of the chromatographic step profile method for determination of water film pressure and surface free energy of quartz (1985)
    Springer
    Chromatographia 20 (1985), S. 724-728 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Step profile method ; Adsorption isotherm ; Water film pressure ; Surface free energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Investigation of water adsorption by the step profile method (Glueckauf method) was carried out with the help of a modified gas chromatography equipped with thermal-conductivity detector. On the basis of the adsorption isotherm obtained, the water film pressure and the polar component of the surface free energy of quartz were calculated. The calculated value of the polar component of the surface free energy of quartz agrees with analogous values obtained by other methods.
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    Reversed-phase and cation-exchange chromatography on a new poly(styrene-divinylbenzene) high capacity, weak cation-exchanger (1985)
    Springer
    Chromatographia 20 (1985), S. 735-738 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Weak cation-exchanger ; Styrene-divinylbenzene copolymer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A weak cation-exchanger for high-performance liquid chromatography is obtained by oxidation of either poly(methylstyrene-divinylbenzene) or of poly(chloromethylstyrene-divinylbenzene). Reaction conditions were optimised to yield an exchange capacity of about 4meqg−1 dry resin. The material was evaluated chromatographically as a function of pH, organic modifier, temperature and flow rate. A combination of ionexchange and hydrophobic interaction between the solutes and the packing material was observed. This could be used to provide more options for realising chromatographic separations. Some chromatograms of heterocyclic bases, nucleosides, nucleotides and amino acids are shown.
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    Time optimization for routine separations, using high-speed microbore HPLC (1985)
    Springer
    Chromatographia 20 (1985), S. 87-96 
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    ISSN: 1612-1112
    Keywords: Time Optimization ; Column liquid chromatography ; Microbore ; Theophylline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Algorithms for the time optimization of an HPLC separation are presented. Resolution, column performance, extra-column variance, capacity factor, and column length are incorporated into these algorithms. Extracolumn variance for a high-speed microbore system (1 mm i. d. column) was assessed using 2nd moment variance and a non-linear extrapolation of tubing length to zero. Extra-column variance, as a function of flowrate, was incorporated into the reduced operating curve of column performance. The use of empirical correction factors for column reproducibility and homogeneity are suggested. Cutting to an optimum length did not degrade column performance. These algorithms were applied to the optimization of a microbore assay for theophylline, in a simple xanthine mixture. Resulting total analysis times were reduced to 10seconds per sample, at a flowrate of 700μl/min.
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    Separtation of metal tetrakis(p-tolyl)porphine complexes by reversed-phase high-performance liquid chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 72-74 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Metal complexes ; Tetrakis(4-methylphenyl)porphine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The feasibility of reversed-phase high-performance liquid chromatography for the separation of several metal complexes ofmeso-tetrakis(p-tolyl)porphine (TTP) is described. A combination of an octadecyl-bonded stationary phase with a non-aqueous polar mobile phase, such as an acetone-acetonitrile mixture, has proved effective for the separation. Thus, the TTP complexes of Mg, VO, Ni, Cu, Zn, and Pd and also TTP free acid were successfully separated in about 10min on a Li-Chrosorb RP-18 column (7μm, 250×4mm i.d.) with a 70∶30 (vol/vol) mixture of acetone and acetonitrile at a flow-rate of 1 mlmin−1.
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    HPLC-separation of enantiomers using quinine, covalently bonded to silica as stationary phase (1988)
    Springer
    Chromatographia 25 (1988), S. 265-271 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral phases ; Polymer coating ; Quinine substituted polysiloxanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Stationary phases for chiral separations have been synthesized by chemical modification of porous small particle silica using new procedures of fixation of the chiral moiety. So called pre-polymers of the methylpolysiloxane polysiloxane type are immobilized on silica surfaces by different procedures. These pre-polymers are substituted by chiral groups. Their synthesis is done externally i.e. not in-situ on the support surface. The immobilization on the silica surface is achieved by crosslinking and/or by chemical bonding. Anchor groups within the pre-polymer (e.g. SiH) as well as on the silica surface (SiOH) give rise to the chemical bonding therewith. Chiral phases with quinine as the chiral moiety were obtained which show high separation efficiency as well as chemical stability, in addition to the enantiomeric selectivity required for the separation of certain types of aliphatic and aromatic alcohols.
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    A new method for the determination of mobile phase volume in normal and reversed-phase liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 288-294 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mobile phase volume ; Ionic solutes ; Eluent electrolyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for the determination of the mobile phase volume (V m) in liquid chromatography is presented based on the model regarding the retention of ionic solutes in the presence of eluent electrolytes. TheV m value can be determined by measuring the retention volumes of two ions that have the same charge in two eluent electrolyte systems. Compared with the methods using isotopically labelled eluent components or inorganic salts asV m markers, the method presented is proved to give more reasonableV m values for both normal and reversed-phase liquid chromatography. As well as in binary mixed solvent systems, theV m values in single solvent systems can be determined by this method.
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    Predicting retention data using the slope of the log adjusted retention time vs. carbon number plot for n-alkanes (1988)
    Springer
    Chromatographia 25 (1988), S. 313-318 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index ; Slope of log plot ; Homologous series ; Partition coefficient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The slope of the n-alkane log plot dt′R/dnc (t′R=adjusted retention time; nc=carbon number) for a stationary phase can be used to obtain the retention index of an unidentified substance in a chromatogram containing only one peak with a known retention index, or to predict the retention time of a substance from that of a different homolog in the same series. It can also be used to translate retention indices into relative retention time, partition coefficient or specific retention volume. Published values of the slope are collected and critically evaluated. Equations are deduced that predict its approximate value at a specified temperature given the value at only one other temperature.
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    Optimization of stepwise gradient elution in columns chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 339-342 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gradient elution ; Prediction of retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A general equation for the final retention of a solute chromatographed under conditions of stepwise gradient elution has been derived. The elution process and the distances travelled by solutes as a function of eluent volume were simulated by computer for the optimization of stepwise gradient prorams from isocratic HPLC data. The validity of the equations was experimentally veritied.
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    Molecular parameters and retention characteristics of unsubstituted polyaromatic hydrocarbons in HPLC (1988)
    Springer
    Chromatographia 25 (1988), S. 272-278 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyaromatic hydrocarbons ; Molecular parameters ; Retention prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The present research studies the possibility of using the correlation dependence between molecular parameters of unsubstituted polyaromatic hydrocarbons (PAH) and their retention in reversed-phase liquid chromatography to optimize the conditions for the separation and identification of unknown peaks on the chromatograms of multicomponent mixtures. A linear correlation equation, that takes the number and environment of the carbon atom in the PAH molecule into account as well as the differences in the specific interactions of isomeric molecules with polar eluent, has been proposed. The adequacy of the proposed PAH retention model was verified by comparing the calculated retention values with the experimental data. The possibility of identifying unsubstituted PAH according to the number of carbon atoms of various types and according to the values of the molecules lengths (calculated on the basis of the retention of these substances under different eluent compositions) was exemplified by various chromatographic systems (reversed phase-eluent-PAH molecules).
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    Olefin group selectivity in non-aqueous reversed-phase LC (1988)
    Springer
    Chromatographia 25 (1988), S. 327-331 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Olefin group selectivity ; Methylene group selectivity ; Non-aqueous reversed-phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effects of mobile phase composition upon olefin group selectivity (the ratio of the retention factor of a n-alkane to 1-olefin of equal carbon number) has been examined for non-aqueous reversed-phase liquid chromatorphy. Under time-normalized conditions, large variations in olefin group selectivities were noted as the mobile phase constitutents were changes. However, methylene group selectivities were found to be insensitive to the nature of the mobile phase under these conditions. Mobile phases containing alcohols demonstrated low olefin group selectivities compared to those containing acetonitrile as weak solvent. The results of this study explain variations previously observed in the LC separation of olive oil triglycerides that differ in the number of methylene groups and double bonds.
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    Silanol group effect of alkylnitrile (cyano) bonded phase in high-performance liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 419-422 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cyano bonded phases ; Residual silanol groups ; Diethyldithiocarbamates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary When a cyano bonded phase is used together with a nonaqueous eluent, it is universal that the silanol groups which remain at the surface of the silica gel after bonding affect the retention of solutes. With solutes containing such atoms as N, S and O, hydrogen bond may form between the solute and the residual silanol group, leading to dual retention mechanism. Based on the understanding of retention mechanism, methods were developed to separate metal-diethyldithiocarbamate (DDTC) chelates and crown ethers on cyano bonded phase, the mobile phase being a nonaqueous solvent containing triethylamine (TEA).
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    Gas chromatographic resolution of enantiomeric and diastereoisomeric amino acid esters on Chirasil-Val capillary column (1988)
    Springer
    Chromatographia 25 (1988), S. 393-396 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Separation of optical isomers ; Chirasil-Val capillary columns ; Amino acid esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary D,L-amino acids were derivatized with (+), (±)-2-butanol or N-trifluoroacetyl-L-prolyl chloride (L-TPC) and then chromatographed. Four optical isomers were separated on a Chirasil-Val capillary column. By this method, the concentration of optical impurities arising from the commercial optically active reagents can be determined. The observed abnormal elution orders of enantiomeric amino acid esters may be caused by a selective intermolecular force.
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    Preparation of active ribosomal proteins by HPLC (1988)
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    Chromatographia 25 (1988), S. 409-412 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Separation of proteins ; Biological activity after separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The proteins of the large ribosomal subunit fromEscherichia coli have been separated by size-exclusion, ion-exchange and reversed-phase high-performance-liquid chromatography (HPLC) using various buffer systems. The biological activity of the isolated proteins was tested via their ability to assemble into active 50S subunits (total reconstitution). The activity of the reconstituted subunits was measured with poly(U)-dependent poly-(Phe) synthesis. Reversed-phase HPLC techniques yielded active proteins (80–100%) by application of 2-propanol or acetonitrile. Proteins prepared by size-exclusion chromatography employing ammonium acetate as buffer also gave highly active proteins (70%). On the other hand, separation of the proteins on ion-exchange columns, using urea containing buffers, resulted in reduced activity (up to 50%).
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    Quantitative determination of phospholipids in amniotic fluid by high-performance liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 497-503 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phospholipids ; Amniotic fluid ; Fetal lung maturity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new quantitative analytical method for the determination of phospholipids in amniotic fluid by high performance liquid chromatography (HPLC) is described. In addition to the main compounds, phosphatidylcholine (lecithin) and sphingomyelin, the so-called minor phospholipids, phosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine can also be determined. Separation is achieved using a guard-column of Lichrosorb Si 60 and an analytical column of Lichrosorb DIOL. Acetonitrile/water is used as mobile phase at an elevated temperature. By determining the recovery rates, the within-run and the between-run precision, it was shown that sufficient accuracy and precision could be achieved for all the parameters examined. The method is highly sensitive, the detection limit for sphingomyelin is 0.2 μg and 0.1 μg for all the other components. A single determination of 5 phospholipids in an amniotic fluid sample takes about two hours. By performing simultaneous extractions it is possible to analyse 5 samples per day.
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    Study on retention behavior of peropyrene-type polycyclic aromatic hydroccrbons with various bonded stationary phases in reversed-phase liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 483-486 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase diphenyl and naphtylethyl bonded phases ; Retention/molecular polarizability relationships ; Peropyrene aromatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behavior of 15 peropyrene-type polycyclic aromatic hydrocarbons was investigated on various bonded stationary phases in reversed-phase liquid chromatography. On diphenyl and naphthylethyl bonded phases, high correlations were obtained between the molecular polarizability of solutes and their retention. However, very low or no correlations were found on various octadecyl bonded phases. These facts are discussed by using the electrostatic interaction concept between the solutes and the stationary phase. We conclude that these observations are due to two reasons: the difference in the degree of planarity of polycyclic aromatic hydrocarbons and the high ability of planarity recognition of octadecyl bonded phases.
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    A new porous polymer for off-line preconcentration of chlorophenols from water (1988)
    Springer
    Chromatographia 25 (1988), S. 504-506 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous polymeric sorbent ; Solid-phase extraction ; Chlorophenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new porous polymer obtained by the copolymerization of two cross-linking agents: 1,4-di(methacryloyloxymethyl) naphthalene and divinylbenzene was used for the off-line preconcentration of chlorophenols from water solutions by solid-phase extraction. In order to establish its applicability to preconcentration the recoveries and breakthrough volumes of phenol, 2-; 3-chlorophenols; 2,3-; 2,4-dichlorophenols and 2,4,6-trichlorophenols were studied. The recoveries of the studied compounds were compared with those obtained for chemically bonded phases containing hexyl and octadecyl groups.
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    Determination of the evaporation rate of essential oils and perfumery compositions using gas chromatography (1988)
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    Chromatographia 25 (1988), S. 520-522 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Essential oils ; Evaporation rate ; Perfume composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple method was developed for the determination of the evaporation rate of essential oils and perfumery composition using gas chromatography with temperature programming. The volatility of 19 essential oils and 17 perfumery composition was evaluated. The method is useful for different comparative measurements.
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    Retention prediction of substituted phenols in reversed-phase HPLC (1988)
    Springer
    Chromatographia 25 (1988), S. 515-519 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention/structure relationships ; Retention prediction ; Substituted phenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A retention prediction system (RPS) for substituted phenols in reversed-phase HPLC using a ternary mobile phase was investigated. The RPS was used to predict the retention times of the phenols, and then evaluated by comparing measured and predicted retention data. Excellent agreement between both values was obtained. In addition, the retention mechanism of the phenols was investigated by means of a correlation analysis relating the parameters of the RPS to the physicochemical properties of the phenols. The three properties investigated (partition coefficient, hydrophobic substituent constant and Hammett's constant) were used to describe quantitatively the structure-retention relationship. Significant correlating equations between these descriptors and the retention data were obtained.
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    Monitoring the preparation of NAD analogs by reversed-phase high-performance liquid chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 543-544 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; NAD analogs ; NAD glycohydrolase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Pig brain NAD glycohydrolase immobilized on Affi-Gel 10 or nylon 6 was used for the conversion of NAD into 3-acetylpyridine adenine dinucleotide (APAD) or 3-aminopyridine adenine dinucleotide (AAD). A reversed-phase chromatographic system consisting of a C18 Resolve column and phosphate buffer (pH 6.2)-methanol as the mobile phase was used to monitor the production of APAD and AAD.
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    An improved method for steroid profile analysis using capillary gas chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 598-602 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Steroid profiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Steroid conjugates are hydrolysed enzymatically using β-glucuronidase after extraction from urine using a solid phase extraction cartridge. After hydrolysis the free steroids are removed from the matrix, again utilising solid phase extraction. Derivatisation of the free hydroxyl groups using Hydrox-Sil AQ produces the respective TMS ethers which are extracted into hexane, in which solvent they are stable for many days. Capillary GC analysis with flame ionisation detection produces a profile of the steroids present in the sample. This technique is suitable for following changes in the urinary excretion profiles of patients undergoing investigation for a variety of steroid production-related diseases.
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    Separation of aliphatic and aromatic amines by the ion interaction reagent RP-HPLC technique (1988)
    Springer
    Chromatographia 25 (1988), S. 603-608 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion interaction reagent HPLC ; Separation of amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ion interaction reagent RP-HPLC has been employed for the separation of some typical aliphatic and aromatic amines. The effects on retention of the alkyl chain length of the eluent, and of the eluent flow-rate have been studied. The use of solutions of hexylaminium-, octylaminium-and decylaminium-salicylate has been tested and compared, employing both conductometric and spectrophotometric detection. On the basis of the results obtained, the optimal experimental conditions can be chosen for each separation. Aliphatic and aromatic mono and diamines can be separated and detected, with an average sensitivity of the order of 40 ng without any pretreatment or derivatization. The retention data obtained for amines, compared with those obtained with the same ion interaction reagents for anions, help in the interpretation of the mechanism involved in the technique.
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    Determination of the triglyceride composition of grapes by HPLC (1988)
    Springer
    Chromatographia 25 (1988), S. 609-612 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Triglyceride composition of grapes ; Identification system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The triglyceride composition of the Tempranillo grape (Vitis vinifera) has been examined by a combination of HPLC and GLC. To identify the triglycerides, equations were applied relating log k′ with the molecular variables: equivalent carbon number, chain length and number of double bonds in each of the fatty acids in the glycerides. Ten triglycerides were found, the principal ones being trilinolein (35.75%), dilinoleyl-olein (21.03%) and dilinoleyl-palmitin (17.02%).
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    High-performance liquid chromatographic assay of bacterial collagenase (1988)
    Springer
    Chromatographia 25 (1988), S. 659-662 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Collagenase ; Enzyme activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The activity of bacterial collagenase Clostridiopeptidase A was estimated using a labelled synthetic peptide, 4-phenylazobenzyloxycarbonyl-L-Pro-L-Leu-Gly-L-Pro-D-Arg, as substrate. The N-protected dipeptide obtained after enzymatic hydrolysis of Leu-Gly peptide bond was quantified by reversed-phase, high-performance liquid chromatography using 4-phenylazobenzyloxycarbonyl-L-Pro-L-Phe as internal standard. The time dependence of the appearance of the hydrolysis product and the dependence of rates of hydrolysis on collagenase concentration were linear. Kinetic parameters for collagenase were determined to test the suitability of the described procedure.
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    The effect of temperature on the resolution of racemates on a chiral bonded packing incorporating N-formylphenylalanine (1988)
    Springer
    Chromatographia 25 (1988), S. 639-642 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Racemic resolution ; Effect of temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of temperature on the resolution of racemates was investigated with respect to the resolution of racemic mixtures of aminoacid esters and 2,2,2-trifluoro-1-(9 anthryl) ethanol. Generally the capacity factor (k′) was found to increase with decreasing temperature. The values of the difference in the standard change of molar Gibbs energy, (ΔΔG), between the more retained and the less retained enantiomer do not appear to vary in a particular fashion. The sign of the enthalpic (ΔΔH) and the entropic, (ΔΔS) quantities for all the mixtures also depend upon the nature of the solute mixture.
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    Influence of structure of alkenes on their retention on different stationary phases (1988)
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    Chromatographia 25 (1988), S. 655-658 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Structure-retention relationships ; Connectivity indices, topological indices ; Alkenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention indices of different alkenes are correlated with connectivity and topological parameters. The appropriate statistically valid relations hips are derived and discussed.
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    Separation and identification ofα, ω-diiodoperfluoroalkanes in gas chromatography (1988)
    Springer
    Chromatographia 25 (1988), S. 735-736 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; α,ω-diiodoperfluoroalkanes ; Separation ; identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of α,ω-diiodoperfluoralkanes on a glass capillary column coated with OV-101 methylsilicone was investigated. Retention indices were determined at three temperatures (140, 150 and 160°C). The correlation between the retention indices and the boiling points of the investigated compounds was studied.
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    The temperature dependence of retention indices in gas chromatography (1988)
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    Chromatographia 25 (1988), S. 731-734 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention Index (l) ; Temperature dependence of Retention Index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A linear dependence of (T−T1)/[1(T)−1(T1)] on temperature (considering the retention index 1(T1) at temperature T1 as a standard value) is derived. Both ther retention index at an assigned temperature and the temperature dependence of the retention index can be calculated from retention data measured at two temperature-programing rates.
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    URL: http://dx.doi.org/10.1007/BF02290481
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    Use of two-dimensional liquid chromatography in the analysis of additives in cellulose acetate polymer (1988)
    Springer
    Chromatographia 25 (1988), S. 791-796 
    Details
    ISSN: 1612-1112
    Keywords: Gel permeation ; Column liquid chromatography ; Column switching ; Additives in cellulose acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The capability of elution-elution multi-dimensional liquid chromatography was investigated. A “column scaling” approach was evaluated for the quantification of low-molecular-weight additives in cellulose acetate. A small-bore (1-mm i.d.) gel-permeation column was used to separate the higher-molecular-weight polymer from the lower-molecular-weight components. Once separated these additives were transferred to a C18 reversed-phase column via a switching valve. The reversed-phase system successfully separated and quantified individual additives. Analysis time for an ultraviolet inhibitor, Tinuvin®P, in cellulose acetate, including re-equilibration, was approximately 30 minutes. Both accuracy and precision were good. Precision over a three day period was about 1.5%.
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    URL: http://dx.doi.org/10.1007/BF02262086
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    Semi-preparative high-performance liquid chromatographic separation of trimedlure isomers (1988)
    Springer
    Chromatographia 25 (1988), S. 811-814 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Separation of trimedlure isomers ; Medfly ; Ceratitis capitata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Semi-preparative high-performance liquid chromatographic procedures on 5 μm silica were developed for the isolation of gram quantities of eight trimedlure isomers (trans: A, B1, B2, and C;cis: V, W, X, and Y) for comparative biological evaluation and NMR studies. Isolations were made from an eight-component 2∶1cis: trans-trimedlure mixture, a four-componentcis-trimedlure mixture, trimedlure-B2:X and trimedlure-C:W epimerization merization mixtures, a trimedlure-B1:Y:B2 mixture, and a trimedlure-A concentrate.
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    URL: http://dx.doi.org/10.1007/BF02262090
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    HPLC with electrochemical detection of metal-flavonoid-complexes isolated from food (1988)
    Springer
    Chromatographia 26 (1988), S. 133-138 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detection ; Flavonoids ; Metal-complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The electrochemical and chromatographic behaviour of flavonoid standards and of flavonoids extracted from food (green tea, black tea and onions) is investigated with respect to metalbinding properties. It is shown that metals such as iron, copper or aluminium are complexed by flavonoids, preferrably by those having an aromatic o-dihydroxy structure. This is confirmed by cyclic voltammetry on HPLC fractions (stopped flow) and by AAS measurement of metals. As the complexing sites of flavonoids are closely related to electrochemical properties, this is used for an indirect detection of metal species at low oxidation potentials. For iron species in particular a sensitive and selective detection is possible. For copper reductive detection can also be used.
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    URL: http://dx.doi.org/10.1007/BF02268137
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    HPLC determination of morphine with amperometric detection at low potentials under basic pH conditions (1988)
    Springer
    Chromatographia 26 (1988), S. 163-167 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detection ; Morphine ; Polymeric column
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, sensitive, accurate and reliable method for morphine determination in biological samples has been developed. It uses reverse-phase HPLC on a polymeric column with an eluent (0.05 mol/L dibasic sodium phosphate: acetonitrile, 85∶15) at pH 9.5, allowing both the suppression of ionization of morphine amine and the promotion of oxidation of the phenolic group. Amperometric detection at mild oxidizing potential (350 mV) proves very selective, and, therefore, only a simple and rapid one-step liquid-liquid sample preparation is required. Under these conditions “clean” chromatograms are obtained even with complex biological matrices such as cadaveric blood, urine and hair. Minimum detectable amount of morphine is about 200 pg injected. A calibration line with a correlation coefficient of 0.99996 has been produced over the range 7.5–250 ng/mL. Precision results comparable to other HPLC methods.
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    URL: http://dx.doi.org/10.1007/BF02268144
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    Analysis of polycyclic aromatic hydrocarbons in solid sample material using a desorption device coupled to a GC/MS system (1988)
    Springer
    Chromatographia 26 (1988), S. 171-177 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; GC/MS analysis ; Polycyclic aromatic hydrocarbons ; Bituminous coal ; Brown coal ; Plant waxes ; Thermodesorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polycyclic aromatic hydrocarbons (PAH) today are ubiquitous detectable constituents of recent sediments. The compounds are adsorbed on particulate emissions and are thus transferred to the environment. To date the analysis of PAH in sediments, dust samples and plant material is based mainly on the application of solvent-extraction methods followed by liquid chromatography and/or gas chromatographic separation of the extracts. An alternative approach for the analysis of PAH in solid samples such as coal, sediments, dust samples and plant waxes is shown in this contribution. A commercially available device for the analysis of volatile compounds present in solid matter is connected on-line to a GC/MS system. The device enables the thermal desorption of hydrocarbons at a temperature of 320°C. Subsequently, the hydrocarbons trapped on the initial part of the capillary column are analyzed by GC/MS. The application of mass chromatography provides the possibility of detection and quantitation of PAH in complex mixtures even when they coelute with other compounds. The sample amount required varies between 1 and 10 mg depending on the hydrocarbon content.
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    URL: http://dx.doi.org/10.1007/BF02268146
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    HPLC characterization of phenolics in lignocellulosic materials (1988)
    Springer
    Chromatographia 26 (1988), S. 191-196 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detector ; Phenolics ; Lignocellulosic materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The application of HPLC with an electrochemical detector for the determination of phenolics in lignocellulosic materials is reported. The separation of phenolic acids and aldehydes (gallic acid, p-hydroxybenzoic acid, vanillic acid, p-coumaric acid, syringic acid, ferulic acid, vanillin, syringaldehyde and p-hydroxybenzaldehyde) on two different columns (reversed phase C6 and styrene-divinylbenzene PLRP-S) is shown. Chromatograms of phenolic compounds in neutral, basic and oxidative extracts of wheat straw treated with NaOH and white rot fungusStropharia rugosoannulata are reported along with quantitative results.
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    URL: http://dx.doi.org/10.1007/BF02268150
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    Isolation and structure determination of minor components of teicoplanin (1988)
    Springer
    Chromatographia 26 (1988), S. 234-236 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative-scale separations ; Teicoplanin ; Structure determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Teicoplanin, a lipoglycopeptide antibiotic active against gram-positive bacteria, is produced as a complex mixture consisting of six major components and four chemically related minor cmmponents. Preparative HPLC was used to isolate small amounts of the pure minor components, in order to determine their structures. In the present paper the isolation procedures are presented, as well as the analytical HPLC conditions. The retention times of the minor components with respect to those of the more abundant compounds, permittedus to make hypotheses on their structures, which were then confirmed by NMR and FAB-MS investigations.
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    URL: http://dx.doi.org/10.1007/BF02268158
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    On-line procedures for the phase-transfer-catalyzed dansylation of phenolic steroids — Application to biological samples (1988)
    Springer
    Chromatographia 26 (1988), S. 267-273 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phase-transfer catalysis ; On-line derivatization ; Phenolic steroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Commercially available equipment from two manufacturers served to set up an automated system for the precolumn phase-transfer-catalyzed dansylation of phenolic steroids, using ethynyl estradiol (EE) and estradiol (E) as model compounds. Using different mixing techniques, the on-line determination of EE and E in 200μl untreated urine samples was achieved at a rate of 3–8 analyses per hour. Detection limits were calculated to be 3–5 ng/ml. Calibration curves in urine were linear over two orders of magnitude with r=0.999 (n=5) for EE and r=0.999 (n=6) for E. The repeatability of the determination of EE in urine (1μg/ml) was 3.9% (RSD; n=20) and of E (1.5μl/ml) 3.8% (RDS; n=10). The use of plasma instead of urine in the on-line procedures was not possible due to rapid formation of emulsions, but E and EE were determined in 100μl plasma samples using a mild off-line mixing procedure in 10min. Detection limits were calculated to be ca 10ng/ml. A reaction detector, based on a solvent-segmented system, was developed for the on-line post-column dansylation of phenols and was coupled with a reversed-phase LC system. The highly selective system showed excellent linearity over at least two orders of magnitude with r=0.9999 (n=6) for both phenol and 2,5-dimethylphenol. The reproducibility was good with RSD values of around 2%. Detection limits for loop injections from standard solutions were calculated to be between 4 and 11ng.
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    URL: http://dx.doi.org/10.1007/BF02268165
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    Direct determination of the enantiomeric purity of oxyphenonium using chiral HPLC with post-column extraction detection (1988)
    Springer
    Chromatographia 26 (1988), S. 281-284 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomeric purity ; Chiral HPLC ; Oxyphenonium ; Post-column extraction detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of the enantiomeric purity (enantiomeric excess) of the anticholinergic drug oxyphenonium. The method for this quaternary ammonium compound is based on the direct HPLC analysis with a chiral stationary phase. Two kinds of α1-acid glycoprotein-bonded phases were used. For the detection a post-column extraction with fluorescence detection of the ion-pair counter ion dimethoxyantracene sulphonate was used.
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    URL: http://dx.doi.org/10.1007/BF02268167
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    Determination of 2-mercaptobenzothiazole in river water by HPLC (1988)
    Springer
    Chromatographia 26 (1988), S. 297-299 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detection ; 2-Mercaptobenzothiazole ; River water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is proposed for the determination of 2-mercaptobenzothiazole in river waters using multi-electrode electrochemical detection HPLC. 2-mercaptobenzothiazole determination is unsatisfactory by gas chromatography as it degrades readily on the column. Multielectrode electrochemical detection HPLC combines sensitivity and the ability to ‘screen out’ other electrochemically active species. The development work leading up to the proposed method is discussed. The method has a limit of detection of 0.798μgl−1 2-mercaptobenzothiazole and a total standard deviation of 2.06μgl−1 2-mercaptobenzothiazole at a concentration of 7.97μgl−1 2-mercaptobenzothiazole in river water.
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    URL: http://dx.doi.org/10.1007/BF02268169
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    Immobilisation of Chirasil-Val on glass capillaries (1988)
    Springer
    Chromatographia 26 (1988), S. 229-233 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Glass capillaries ; Chirasil-Val ; Immobilisation ; Enantiomeric separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Immobilisation methods of the chiral silicone stationary phase Chirasil-L-Val have been studied. In addition to the standard techniques of radical-induced immobilisation with dicumyl peroxide and azo tert-butane, immobilisation was solely achieved by thermal treatment: conditioning at low flow-rates or under stop-flow conditions led to unexpectedly high immobilisation despite mild temperatures. The presence of water vapor in the carrier gas accelerated the immobilisation process. While up to 75% immobilisation was attainable with both ATB and thermal methods, immobilisation with DCUP did not exceed 50%, despite relatively high DCUP concentrations. Whilst all immobilisation methods were accompanied by varying degrees of racemisation at the chiral centre, it was possible to establish conditions that yielded a high immobilisation (in excess of 70%) with a negligible loss in enantiomeric selctivity. The immobilisation reactions also slightly affected the polarity of the stationary phase, reflected in a shift of the Kovats-Indices of amino acid derivatives and in the accompanying “Squalane-Effect”. With respect to immobilisation, racemisation and polarity shift, thermal immobilisation with water-saturated carrier gas proved to be the optimum method.
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    URL: http://dx.doi.org/10.1007/BF02268157
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    RP-HPLC as an evaluation method for the behaviour of urinary trypsin inhibitors (1988)
    Springer
    Chromatographia 26 (1988), S. 369-371 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Urinary trypsin inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Human urine contains a family of trypsin inhibitors. Procedures for their purification and characterization involve laborious techniques and the conclusions are different in the identification of the separated compounds. We report results obtained by applying our RP-HPLC method to some procedures adopted by different authors.
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    URL: http://dx.doi.org/10.1007/BF02268183
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    An improved method for the determination of S-Carboxymethyl-L-cysteine in biological fluids with precolumn derivatization and on-line clean-up (1988)
    Springer
    Chromatographia 26 (1988), S. 377-382 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Determination of S-Carboxymethyl-L-cysteine ; Precolumn derivatization ; HPLC on-line clean-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to follow levels of S-Carboxymethyl-L-cysteine in biological fluids for a period as long as three half-lives after drug administration during pharmacokinetic studies, an improved method for its determination had to be developed. Like the previous one, this method uses a protein precipitation step followed by an O-Phthalaldehyde derivatization step and then an HPLC on-line clean-up. This latter was obtained by means of a switching valve system, including a Nucleosil CN 5 μm (3 cm × 4.6 mm i.d.) precolumn and a Spherisorb ODS 5 μm (15 cm×4.6 mm i.d.) analytical column. The sensitivity limit was improved to 0.1 μg/ml in plasma samples and 0.2 μg/ml in urine samples. This method was applied in studies comparing single (0.75 g) and repeated (0.75 g tid) oral administration of the drug to 30 elderly patients and 20 healthy volunteers. Results showed that the half-life was 40% longer in elderly patients than in healthy volunteers, and that area under the plasma concentration versus time curve (AUC) values in elderly patients were twice those obtained with young subjects.
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    URL: http://dx.doi.org/10.1007/BF02268185
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    An improved energy generator for the study of reactions of thermal-energy electrons with organic compounds (1985)
    Springer
    Chromatographia 20 (1985), S. 149-154 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron-capture ; Thermal-energy electrons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The products resulting from the reaction between thermal energy electrons and organic compounds have been investigated to further our knowledge of the mode of action of the electron-capture detector. Thermal energy electrons were generated by maintaining a corona discharge between a stainless steel cathode and a silver/silver chloride anode. The effects of electrode geometry, gas composition, gas flow rate, and the physical properties of the test substances were investigated. The design of the reactor was modified to minimize losses of unchanged substrate. Reaction products of benzaldehyde, tolualdehydes, chlorobenzaldehydes, and dichlorobenzenes were identified by combined gas chromatography — mass spectrometry.
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    URL: http://dx.doi.org/10.1007/BF02262703
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    Wide-bore capillary columns for gas chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 195-196 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Wide-bore capillaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262711
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    Analysis of nitro-PAHs in diesel exhaust particulate extracts with multicolumn HPLC (1985)
    Springer
    Chromatographia 20 (1985), S. 213-218 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nitro-PAHs ; Diesel particulate extract ; Column switching-HPLC ; Pyrene-butyric acid stationary phase ; π-acceptor ligands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of nitrated polynuclear aromatic hydrocarbons (nitro-PAHs), in particular 1-nitropyrene, in diesel particulate extracts. The method employs a multidimensional HPLC (column switching) technique with final on-line peak identification by UV-VIS spectral comparison with standards. To achieve exceptional chromatographic selectivity for nitro-PAHs, a new pyrene butyric acid amide phase has been prepared which is capable of forming donor-acceptor complexes with them. With this technique it is possible to confirm the presence of 1-nitropyrene in the range 3–100 ng/mg on filter-collected diesel soot. Its utility was demonstrated with diesel exhaust extracts spiked with varying levels of 1-nitropyrene and proved to be highly selective.
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    URL: http://dx.doi.org/10.1007/BF02259689
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    Hydrocarbon group-type analysis with microcapillary-column liquid chromatography/conventional infrared spectrometry (1985)
    Springer
    Chromatographia 20 (1985), S. 279-282 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microcapillary column ; Gasoline group analysis ; Conventional IR detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Slurry-packed microcapillary column liquid chromatography with conventional infrared detection is described for the group-type analysis of gasolines. The results indicate that the three eluted groups, saturates, olefins and aromatics, from the microcapillary column are easily detected by conventional microcomputerized infrared spectrometer coupled with a Teflon flow-cell with a good signal-to-noise ratio. This study shows the feasibility of microcapillary column liquid chromatography combined with a low-cost, conventional infrared spectrometer as a routine tool which allows the analyst to use an LC-IR system effectively and economically.
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    URL: http://dx.doi.org/10.1007/BF02310383
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    A new derivative for improved GLC separation of mannose, galactose and glucose (1985)
    Springer
    Chromatographia 20 (1985), S. 403-406 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Separation of sugars ; Oxime formation ; Silylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The procedure involving oxime formation followed by silylation for the analysis of standard hexoses by GC resulted in unseparated peaks for D-glucose, D-mannose and D-galactose. This procedure was therefore modified to obtain clear separation of hexoses. STOX (hydroxylamine containing phenyl-β-D-glucopyranoside as the internal standard) was mixed with trimethylsilylimidazol or hexamethyldisilazane, and then added to a standard sugar mixture containing D-glucose, D-galactose and D-mannose. The mixture was analyzed by gas chromatography with OV-17/OV-22 as the stationary phase, resulting in three distinct peaks.
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    Esterification of aliphatic hydroxy acids to n-butyl esters in aqueous solutions for their gas chromatographic analysis (1985)
    Springer
    Chromatographia 20 (1985), S. 421-424 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of aliphatic hydroxy acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Aliphatic hydroxy acids were esterified in aqueous solution in the presence of sulfuric acid. Esterification of lactic, tartronic malic and citric acids in water/n-butanol mixtures with mole ratios between 0.02 and 2.53 can be utilized for the determination of these aliphatic hydroxy acids by gas chromatography. Water does not interfere at water/n-butanol mole ratios below 0.02. For mole ratios above 0.02 anhydrous sodium sulfate is used for the binding of water. The mole ratio range was 0.25–2.53 for anhydrous sodium sulfate/water, and 0.32–1.27 for sulfuric acid/anhydrous sodium sulfate.
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    Adsorption isotherms of organic modifiers and the determination of the dead volume in RPLC (1985)
    Springer
    Chromatographia 20 (1985), S. 425-433 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Adsorption isotherm ; Dead volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In RPLC the dead volume can be defined as the difference between the maximum column hold-up volume and the volume of the adsorbed phase. The composition of the adsorbed phase depends on the composition of the mobile phase and therefore, the dead volume also varies with it. In this work, the alkyl bonded phase acetonitrile (ACN)-water mobile phase system is investigated. In the system, deuterated water (D2O) and deuterated acetonitrile (D-ACN) are retained due to the isotopic dilution effect. By means of D2O and D-ACN, the absolute adsorption isotherm of the organic modifier ACN is measured. Based on the isotherm, the chromatographic behaviour of ACN, D-ACN and D2O, the variation of the dead volume with the composition of the mobile phase, and the approach to determine the maximum column hold-up volumn are explained. In addition, the various approaches to determine the dead volume are compared and the recommendations are given for the case of common unbuffered binary systems (MeOH/H2O, THF/H2O and ACN/H2O).
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    Gas chromatographic analysis of the thermal and photochemical reaction products in diethyl ether solutions of nitrogen oxides (1985)
    Springer
    Chromatographia 20 (1985), S. 466-470 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Nitrogen dioxide ; Diethyl ether ; Photo-induced reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary When dissolved in diethyl ether, nitrogen dioxide reacts with the solvent, slowly at room temperature, more rapidly on heating of UV irradiation. A complex mixture of products is formed in which further changes are observed after prolonged storge: these are less pronounced if the unreacted nitrogen oxides are removed. A gas chromatographic method was applied for the identification of the majority of products. Irradiation does not change significantly the qualitative and quantitative composition of the reaction products. The reaction is thus the so-called photo-induced process [ΔG〈0]. Preliminary suggestions are made concerning the reaction mechanism.
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    URL: http://dx.doi.org/10.1007/BF02344787
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    Simultaneous quantitative determination of amiloride hydrochloride and hydrochlorothiazide in tablets by high-performance liquid chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 477-481 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amiloride hydrochloride ; Hydrochlorothiazide ; Quantitative determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure for the simultaneous quantitative determination of amiloride hydrochloride and hydrochlorothiazide by high-performance liquid chromatography is proposed. A reversed-phase LiChrosorb C8 stationary phase is used. The eluent consisted of an acetonitrile/0.1M phosphate buffer pH3 (15∶85) mixture, containing 50mM propylamine hydrochloride. In this system amiloride hydrochloride, a basic drug, eluted with a acceptable asymmetry factor (Asf=2.1). A simple extraction procedure with methanol is used. Relative standard deviations of 0.87% and 1.6% were obtained for amiloride hydrochloride and hydrochlorothiazide respectively. Chlorothiazide, a thiazide diuretic, is a suitable internal standard. Furthermore the method is also specific for other thiazide diuretics, potassium-sparing diuretics and loop diuretics and for the respective hydrolysis productes of both drugs. Analysis time is reduced to a minimum; the chromatographic separation is complete within 6 minutes.
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    Determination of L-tryptophan-serum albumin binding by high-performance liquid chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 495-499 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; L-tryptophan-serum albumin binding ; Bovine serum albumin ; Human serum albumin ; Binding parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two high-performance liquid chromatography (HPLC) techniques were developed for the determination of binding constants in the interaction of serum albumin with L-tryptophan: internal calibration and external calibration. The results obtained were compared with those obtained by the classical method of equilibrium dialysis and by gel filtration. While all the methods are equally reliable, the internal and external calibration techniques seem to be superior in their simplicity, speed and convenience.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02344792
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  • 97
    Electronic Resource
    Electronic Resource
    Liquid chromatographic behaviour of pyrimidine bases on various bonded phases (1985)
    Springer
    Chromatographia 20 (1985), S. 529-532 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Modified silica gels ; Pyrimidines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of the surface chemistry of bonded-phase column material containing alkyl, phenyl, cyano and amino groups on the adsorption of pyrimidine molecules has been studied by HPLC. The dependence of the retention on the chemical structure of the adsorbed molecules was determined. The influence of the substituents at the pyrimidine ring and their position on the retention character is shown for various bonded phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312171
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  • 98
    Electronic Resource
    Electronic Resource
    Determination of free formaldehyde in the presence of donators in cosmetics by HPLC and post-column derivation (1985)
    Springer
    Chromatographia 20 (1985), S. 559-565 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reaction detector ; Formaldehyde determination ; Trace analysis ; Cosmetic products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The determination of free formaldehyde in the presence of its donators in cosmetic samples by a combination of reversed phase chromatography and post column reaction detection is described. The free formaldehyde is separated on a RP column with water as eluent from interfering formaldehyde-containing compounds and consecutively determined by the lutidine method in a reaction detector with knitted open tubes. With detection in the visible (420nm) the minimum detectable quantity is 40 ppb, with fluorimetric detection 15 ppb. The sample clean-up procedure for cosmetic products ranging from mascara to shampoo is by extracting the formaldehyde with water of pH 3, where the decomposition rate of the donators is minimal. Smaller amounts of free formaldehyde are always found compared to the standard lutidine method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312176
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  • 99
    Electronic Resource
    Electronic Resource
    Chromatography in fluidized beds (1985)
    Springer
    Chromatographia 20 (1985), S. 538-542 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fluidized beds ; Industrial chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chromatography is carried out under the conditions of fluidization, in long, straight tubes under organized and non-organized conditions. Under non-organized conditions the column is filled only with a sorbent. In organized conditions, either metal coils are added into the column or a segmented column is utilized with metal grids. The results obtained are compared to those obtained under fixed-bed conditions when the column is completely filled with the sorbent. Organized fluidized beds provide a significant decrease in longitudinal bandspreading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312173
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  • 100
    Electronic Resource
    Electronic Resource
    Simultaneous measurements of formaldehyde and ozone in air by annular denuder-HPLC techniques (1988)
    Springer
    Chromatographia 25 (1988), S. 895-898 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ozone ; Formaldehyde ; Annular denuder ; Air monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A denuder sampling method combined with HPLC analysis for the simultaneous determination of formaldehyde and ozone in ambient air is described. It is based on the reactions of CH2O and O3 with 2,4-dinitrophenylhydrazine (DNPH) and 4-allyl-2-methoxyphenol (eugenol)_respectively, both acting as coatings of two annular denuders connected in series. Formaldehyde released from the ozonolysis of eugenol is quantitatively collected on a third downstream DNPH-coated denuder. The two DNPH denuders are then extracted and analyzed as hydrazone derivative by HPLC with UV absorbance detection. The stoichiometric factor of the eugenol-ozone reaction was found to be 2.0±0.1 moles of O3 per mole of CH2O. The limits of detection are 0.8μgm−3 CH2O and 3μgm−3 O3 for 100l air sampled, corresponding to 1-h sampling at 1.7l min−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311425
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