BACKGROUND: As an important extraction technique, aqueous two-phase extraction is especially applicable to bioseparation. This work has focused on using a novel kind of aqueous two-phase system (ATPS), for the enantioseparation of tryptophan.
RESULTS: Only limited kinds of salts could form effective phases with ethanol. The salting-out abilities of various salts and the final characteristics of ATPS were investigated. The results show that increase in the amount of phase-forming componentsand decrease in pH from 6 to 2.5 are both beneficial for the enantioseparation of tryptophan; enantioselective extraction and partitioning behavior are mainly dependent on the pH of solution, the type of chiral extractant and its concentration. Furthermore, salt, ethanol and temperature also have some effects on the enantioseparation. Finally, the most reasonable extraction mechanism of the tryptophan enantiomers was suggested.
CONCLUSION:The novel ATPS composed of ethanol/ammonium sulfate proposed in this studyhas good ability for the extraction of tryptophan enantiomers.
Effect of the type and concentration of β-CDsThe type of chiral selector is an important influencing factor. β-CD shows negligible solubilities in organic solvents and positive solubilities in aqueous solution, which is promising for its use as
Influence of temperatureThe influence of temperature on the distribution behavior was investigated in the range of 5-50 • C. The results show that the K wileyonlinelibrary.com/jctb
Taking two-dimensional random variable as the research object, we dig the profound connotation of independence and reveal the true nature of it. Then, from the point of view of entropy in information theory, we explore the relationship between each component of two-dimensional random variable and the equivalence between independence and non-correlation of them.
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