I use to follow the following method by Eom et al. (2007). (Eom, S.H., Cheng, W.J., Hyoung, J.P. Kim, E.H., Chung, M.I., Kim, M.J., Yu, C.Y. and Cho, D.H. 2007. Far infrared ray irradiation stimulates antioxidant activity in Vitis flexuosa Thunb. Berries. Kor. J. Med. Crop Sci. 15: 319.323. )
An aliquot of 0.5 ml of sample (1 mg/ml) was mixed with 0.1 ml of 10% aluminium chloride and 0.1 ml of potassium acetate (1 M). In this mixture, 4.3 ml of 80% methanol was added to make 5 ml volume. This mixture was vortexed and the absorbance was measured spectrophotometrically at 415 nm.
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I have gone through many protocols for flavonoid estimation. What I am following is I am mixing plant extract with 2% Aluminium chloride and incubating it at room temprature and reading it against Quercetin standard at 420 nm.
I use to follow the following method by Eom et al. (2007). (Eom, S.H., Cheng, W.J., Hyoung, J.P. Kim, E.H., Chung, M.I., Kim, M.J., Yu, C.Y. and Cho, D.H. 2007. Far infrared ray irradiation stimulates antioxidant activity in Vitis flexuosa Thunb. Berries. Kor. J. Med. Crop Sci. 15: 319.323. )
An aliquot of 0.5 ml of sample (1 mg/ml) was mixed with 0.1 ml of 10% aluminium chloride and 0.1 ml of potassium acetate (1 M). In this mixture, 4.3 ml of 80% methanol was added to make 5 ml volume. This mixture was vortexed and the absorbance was measured spectrophotometrically at 415 nm.
If my answer really helps you, please do vote for my answer.