Study on the optimization of aquoues two-phase extraction of total flavonoids from cotton leaves using response surface methodology

An aqueous two-phase system composed of 23% ethanol and 22%(NH4)2SO4was used to extract total flavonoids from cotton leaves. Mass fraction of crude extract,pH and mass fraction of NaCl on the extraction efficiency of total flavonoids were explored by one-factor-at-a-time and Box-Benhnken design methods. The results showed that the optimal conditions were as follows :crude extract concentration 31%,pH4,NaCl concentration 3%. Under the above conditions the confirmed tests indicated that the extraction rate of total flavonoids was 76.32% which had close relation with the predicted yield of the extraction rate of total flavonoids was 78.02%. The study would provide reference for the effective utilization of flavonoids from cotton leaves.