Liu, X. F., Liu, L., Wang, Y. G., Leng, F. F., Wang, S. V., and Li, Y. C
Response surface methodology (RSM) was applied to predict optimum conditions for extraction of flavonoid from Coreopsis tinctoria Nutt. A central composite design (CCD) was used to monitor the effect of extraction temperature, extraction time, and water-to-material ratio on yield of total flavonoids. The optimal extraction conditions were obtained as water-to-material ratio of 55 ml gā1, extraction temperature of 80 °C and extraction time of 70 minutes. Under these conditions, the average total flavonoids yield, according to the mass of raw material, was 9.0 ± 0.6 %, which corresponds to the predicted value of 8.9 %. Thus, the extraction method was applied successfully to extract total flavonoids from C. tinctoria.