Abstract
Rutin was taken as reference substance, and the conditions of aluminum chloride colorimetric assay for determining total flavonoids in leek extract were optimized. The effects of several parameters, such as dosage of color developing agent, buffer dosage, pH and reaction temperature and time, on the color development reaction of total flavonoids were evaluated. The optimum conditions were as follows: 1 mL appropriate concentrationor of leek extract, added 1 mL of HAc-NaAc buffer (pH4.8), 2mL of 0.1mol·L-1AlCl3 solution, volume calibration with 70% ethanol to 10 mL and mixing, and 12 min of water bath at 40°C. Under the optimum conditions, the maximum absorption wavelengths of standard rutin solution and leek extract coincided (407nm), with the absorbances reaching maxima also. The method has high stability, reproducibility and recovery. Compared with the commonly used NaNO2-Al (NO3) 3-NaOH colorimetric method, it is considered that the method of determination of total flavonoids in leek by AlCl3 colorimetric assay is more suitable when rutin was taken as reference substance
