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.