Thermodynamics of the partition of chondroitin sulfate–hexadecylpyridinium complexes in butanol/aqueous salt biphasic solutions

✍ Scribed by Robert E. Hurst

• Publisher: Wiley (John Wiley & Sons)
• Year: 1978
• Tongue: English
• Weight: 397 KB
• Volume: 17
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1978.360171108

✦ Synopsis

Abstract

The thermodynamics of the partition of chondroitin sulfate–hexadecylpyridinium complexes wee studied in order to gain further insight into the mechanisms responsible for the sensitivity of the relative solubility of these complexes in aqueous slat and butanol phases to small changes in slat concentration. The dependence of the partition coefficient was measured as a function of temperature at three different salt concentrations. Increasing the temperature was found to favor the form of the complex which was soluble n the aqueous phase. Although the transition could be induced by temperature changes, he transition occurred over a 20°C range in temperature. The transition from the aqueous phase to the butanol phase was strongly exothermic, with Δ__H__ = −22.3 kcal/mol polymer. The value of Δ__S__ was found to be dependent on the salt concentration, ranging from −72.7 e.u./mol polymer in 0.05125__M__ NaCl to −77.1 e.u./mol polymer in 0.05375__M__ MaCl. When placed on a disaccharide basis, the corresponding values are Δ__H__ = −402 cal/mol and Δ__S__ = −1.31 to −1.3 e.u./mol. The sharpness of he transition was found to be due t the similarity in magnitude of Δ__H__ and T__Δ__S, and on the dependence of the later upon the salt concentration.