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  • Column liquid chromatography  (3)
  • Sampling techniques  (3)
  • Enantiomeric separation  (2)
  • Liver  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Different effects of early endotoxaemia on hepatic and small intestinal oxygenation in pigs (1996)
    Springer
    Intensive care medicine 22 (1996), S. 795-804 
    Details
    ISSN: 1432-1238
    Keywords: Key words Lipopolysaccharide ; Liver ; Small intestinal serosa and mucosa ; Tissue oxygen tension ; Acid ; base balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract   Objective:  Study on simultaneous O2 supply/uptake relationships in liver and gut during endotoxaemia, to determine whether signs of dysoxia develop uniformly in the splanchnic region. Design: Animal study to assess the early effects of endotoxaemia on oxygenation of both liver and small intestine. Interventions: Eight anaesthetized pigs received a continuous portal venous infusion of lipopolysaccharide (0.5 μg⋅kg-1⋅h-1) for 6 h. Systemic, pulmonary and splanchnic haemodynamics as well as systemic and splanchnic O2 supply/uptake relationships were determined. Results: There was a multiphasic haemodynamic response pattern characterized by an early (within the 1st h) and a subsequent more prolonged phase (between the 2nd and 6th h) of decreases and recovery of hepatic arterial, portal venous and superior mesenteric arterial blood flows (electromagnetic flow probes) and splanchnic O2 deliveries. Unrelated to perfusion pressure and O2 delivery, there were early and sustained decreases in ileal mucosal surface partial pressure of oxygen (PO2) (multiwire PO2 electrode) and pH (tonometry). This was not reflected by ileal serosal surface PO2, O2 uptake and arteriomesenteric venous pH and partial pressure of carbon dioxide (PCO2) gradients. There was little evidence of concomitant hepatic dysoxia as evaluated by surface PO2. Conclusions: The study demonstrates early and sustained regional (mucosa) intestinal hypoxia with little evidence of simultaneous hepatic dysoxia during initial endotoxaemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01709523
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  • 2
    Electronic Resource
    Electronic Resource
    Different effects of early endotoxaemia on hepatic and small intestinal oxygenation in pigs (1996)
    Springer
    Intensive care medicine 22 (1996), S. 795-804 
    Details
    ISSN: 1432-1238
    Keywords: Lipopolysaccharide ; Liver ; Small intestinal serosa and mucosa ; Tissue oxygen tension ; Acid-base balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective Study on simultaneous O2 supply/uptake relationships in liver and gut during endotoxaemia, to determine whether signs of dysoxia develop uniformly in the splanchnic region. Design Animal study to assess the early effects of endotoxaemia on oxygenation of both liver and small intestine. Interventions Eight anaesthetized pigs received a continuous portal venous infusion of lipopolysaccharide (0.5 μg·kg−1·h−1) for 6 h. Systemic, pulmonary and splanchnic haemodynamics as well as systemic and splanchnic O2 supply/uptake relationships were determined. Results There was a multiphasic haemodynamic response pattern characterized by an early (within the 1st h) and a subsequent more prolonged phase (between the 2nd and 6th h) of decreases and recovery of hepatic arterial, portal venous and superior mesenteric arterial blood flows (electromagnetic flow probes) and splanchnic O2 deliveries. Unrelated to perfusion pressure and O2 delivery, there were early and sustained decreases in ileal mucosal surface partial pressure of oxygen (PO2) (multiwire PO2 electrode) and pH (tonometry). This was not reflected by ileal serosal surface PO2, O2 uptake and arteriomesenteric venous pH and partial pressure of carbon dioxide (PCO2) gradients. There was little evidence of concomitant hepatic dysoxia as evaluated by surface PO2. Conclusions The study demonstrates early and sustained regional (mucosa) intestinal hypoxia with little evidence of simultaneous hepatic dysoxia during initial endotoxaemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01709523
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    New polymer coated anion-exchange HPLC-phases: Immobilization of poly (2-hydroxy, 3N-ethylenediamino) butadiene on silica and alumina (1987)
    Springer
    Chromatographia 23 (1987), S. 435-441 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange stationary phases ; Polymer coating ; Cross-linking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary PHEB=POLY(2-hydroxy, 3N-ethylenediamino)butadiene has been synthesized. This unsaturated pre-polymer can be immobilized on different, preferably inorganic supports of suitable porosity such as silica or alumina by cross-linking. Weak anion-exchange phase are obtained. Such phases do not have the disadvantages of organic polymeric phases, regarding pressure stability and swelling by solvent influence. The ion-exchange capacity and the retentivity of IE-separations can deliberately be varied via the thickness of the cross-linked polymer layer. Alumina can also be coated with PHEB applying the same cross-linking procedure. Such phases exhibit an exceptional chemical stability even when operated with mobile phases at very high pH-values. Separations of excellent selectivity are achieved for inorganic anions, as well as with mixtures of aliphatic and aromatic free acids also including hydroxy- (mono- or poly)carboxylic acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311821
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  • 4
    Electronic Resource
    Electronic Resource
    HPLC-separation of enantiomers using quinine, covalently bonded to silica as stationary phase (1988)
    Springer
    Chromatographia 25 (1988), S. 265-271 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02324699
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  • 5
    Electronic Resource
    Electronic Resource
    Chiral stationary phases for LC and SFC obtained by “Polymer coating” (1988)
    Springer
    Chromatographia 26 (1988), S. 19-28 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral LC and SFC phases ; Polymer coating ; Chemical bonding ; Polysiloxane pre-polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chirally substituted Si−H-containing polysiloxanes were synthesized, which can be immobilized on small particle silica gel as well as on the smooth surfaces of fused silica capillaries. Immobilization is achieved either by crosslinking or by chemical bonding to the surfaces via silanol groups; both reactions can only be performed by addition of H2PtCl6, which acts as catalyst for hydrosilylation and as stoichiometric reagent for crosslinking. Chiral substituents of systematically varied chemical structure were introduced into the polysiloxanes by hydrosilylation. The mechanism of immobilization was investigated by spectroscopic methods, notably29Si-NMR. Homogenous stationary-phase coatings of variable film thickness and corresponding retentivity can easily be achieved. The enantioselectivity of the phase systems was characterized in dependency on the chemical structure of the chiral selectors attached to the polysiloxane chain of the chiral stationary phases and also in terms of the functional groups introduced into the solutes by derivatisation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268119
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  • 6
    Electronic Resource
    Electronic Resource
    Modified GC-phases for the enantiomeric separation of optically active compounds: Crosslinking experiments with polymeric chiral compounds (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 391-394 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography, GC ; Capillary columns ; Crosslinking ; Enantiomeric separation ; Polymeric chiral phases ; Polysiloxane skeleton ; Polyethylene glycol skeleton ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crosslinking experiments for immobilization of the well-known chiral stationary phases XE 60-L-valine-(S)- and XE 60-L-valine-(R)-α-phenylethylamide within capillary columns have been successfully carried out. Crosslinking was also obtained with mixtures of the chiral compound acrylyl-L-valine-(S)-α-phenylethylamide and the polyethylene glycol Carbowax 20M. Immobilization of 75% to 90% was achieved by crosslinking the polymeric chiral phases, but sometimes up to 100% of these phases remained within the columns after the usual subsequent solvent treatment. The crosslinking of Carbowax 20M with acrylyl-L-valine-(S)-α-phenylethylamide led to a chiral polymer of a polarity different from that of the common siloxane type chiral phases.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240080806
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  • 7
    Electronic Resource
    Electronic Resource
    Crosslinked chiral phases in GC capillary columns (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 191-192 
    Details
    ISSN: 0935-6304
    Keywords: Gas Chromatography, GC ; Capillary columns ; Polymeric chiral phases ; Crosslinking ; Enantiomeric separation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240080408
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  • 8
    Electronic Resource
    Electronic Resource
    Instrumentation for SFC systems: Different sampling and restriction designs (1988)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 191-197 
    Details
    ISSN: 0935-6304
    Keywords: Capillary SFC ; Instrumentation ; Sampling techniques ; Restrictors ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Different designs of injection and restriction devices for capillary supercritical fluid chromatography (SFC) have been investigated with respect to their practical applicability and usefulness for reproducible and accurate qualitative and quantitative analyses. In combination with a self-made instrument a fast switching valve is preferable as an injection device compared to a split-injector, and an integral restrictor made from the end of the fused silica (FS) separation column was superior to a linear restrictor made by coupling a small diameter FS-column to the separation column.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240110210
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  • 9
    Electronic Resource
    Electronic Resource
    Quantitation in miniaturized GC and SFC systems (1989)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 12 (1989), S. 142-148 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; Capillary SFC ; Narrow bore capillary columns ; Sampling techniques ; Quantitation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Separations of high efficiency and/or speed can be achieved in capillary GC by capillary columns of lower internal diameter (〈 50 μm). Sampling techniques for the analytical application of narrow bore fused silica columns have been evaluated with regard to quantitation. On-column injection cannot be applied. Therefore liquid samples have to be vaporized in external devices before they enter the chromatographic system. Sample introduction by syringe with subsequent splitting must and can be applied but requires special syringes with perfect piston sealing because of the high inlet pressures needed even with hydrogen as carrier gas. For general analytical applications, valve systems should be developed to eliminate both the syringe and the septum from instrumental GC set-up's.In SFC using either narrow bore capillary or packed microbore columns, time-controlled valve sampling with partial displacement of the sample from the loop seems to be an adequate technique because of the very high inlet pressures involved. Splitting in combination with valve operation can also be applied in capillary SFC at least to samples of good solubility in the mobile phase. A disadvantage of splitting in SFC is that another restriction for the adjustment of the split flow is necessary.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240120306
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  • 10
    Electronic Resource
    Electronic Resource
    Sampling techniques for SFC using peak focusing by pressure and/or temperature programming (1989)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 12 (1989), S. 218-225 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical fluid chromatography, SFC ; Sampling techniques ; Peak focusing ; Pressure programming ; Temperature optimization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In analogy to the focusing effective in capillary GC, performed with temperature programming but also with sectional cooling of the column inlet as in multidimensional capillary GC, peak focusing can easily be attained in SFC by adjustment of the mobile phase pressure as well as the column temperature. This may be of practical use in connection with sampling techniques giving poor, i.e. broad and unsymmetrical, peak shapes. Such disturbances may occur, for example, in time controlled valve sampling over longer switching times. Generally, all other negative influences on peak shape can be suppressed or compensated by trapping within the column inlet. Special trapping devices and “retention gaps” may also be coupled to the column inlet in order to create narrow starting plug widths. Positive pressure (density) and negative temperature programs give rise to peak compression besides the increase of peak capacity of the separation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240120406
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