Systematic investigation on AlCl3 colorimetric determination of total flavonoids in daylily

The ideal conditions of aluminium chloride colorimetric test affecting detection of total flavonoids from daylily extract have been established using rutin as a reference substance. Effects of AlCl3 concentration, dosage, reaction time, and temperature on the color reaction of total flavonoids with AlCl3 have been systematically investigated. The results indicated the optimal reaction conditions are seen as the following: adding 6 ml 3%AlCl3 solution and reacting for 20min at 30℃ water bath temperature. Under these conditions, the regression equation between the absorbance value and the standard solution of rutin in the range of 0.0043~0.0258 mg/ml was y=25.442x-0.0097, R2 =0.9997. The average recovery of the method was 100.1%, and the relative standard deviations (RSD) of stability, precision, and recovery were 0.29%, 0.08%, and 1.70%, respectively. The method is simple, rapid, and accurate, and can be used to determine total flavonoids in the daylily.