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  • 1
    ISSN: 1435-1536
    Keywords: Chitosan ; molecular weight ; light scattering ; viscosity ; gel permeation chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The viscometric constantsa andK in the Mark-Houwink equation were determined in 0.5 M acetic acid-0.5 M.sodium acetate solution for chitosan fractionated by gel filtration. The weight-average molecular weight of each fraction was measured by the light-scattering method. The values obtained area=0.59 andK=0.119 cm3 g−1. The molecular weightsMw andMn for fractionated chitosan were measured by GPC. The value ofMw by GPC was much different from that by light scattering and, therefore, a universal calibration procedure was applied to the data by GPC. It was concluded that, also in the case of a cationic polysaccharide such as chitosan, the universal calibration procedure is effective for obtaining the reliable molecular weight by GPC.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 276 (1998), S. 388-394 
    ISSN: 1435-1536
    Keywords: Key words Hyaluronic acid ; degradation ; molecular weight ; metal surface ; hydroxyl radical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  When the viscosity of hyaluronic acid (HA) solution was measured with a rotational visco-meter, depolymerization occurred only by leaving the sample in the cup of the viscometer, while the solution in a glass test tube at the same temperature, 37 °C, was practically stable during the entire period of investigation. As the parts where the sample solution had contact with the viscometer are stainless steel, the participation of metal ions in the depolymerization was suspected. Therefore, experiments were carried out with stainless-steel beads in the HA solution. The results show that the molecular weight of HA decreased on exposure to the beads under aerobic conditions. The addition of 10 beads to 2 ml of a 0.1% HA solution prepared with 0.2 M NaCl reduced the molecular weight to about 75% of the initial value after 4 h. The degradation rate was proportional to the surface area of the beads. However, no dissolution of metal ion was detected, and therefore, this reaction was thought to proceed at the surface of the metal.
    Type of Medium: Electronic Resource
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