4.5.5. Total Flavonoid Content Determination

The total flavonoid content was measured using the aluminum chloride colorimetric assay, as described by Marinova et al. [75]. In a test tube, 1 mL of each sample extract was mixed with 4 mL of distilled water. Following this, 0.3 mL 5% sodium nitrite was applied to each test tube. After 5 min, 0.3 mL 10% aluminum chloride was applied to the mixture. At the sixth minute, 2 mL 1 M sodium hydroxide was added. The mixture was then adjusted to 10 mL by adding 2.4 mL distilled water. A vortex machine was used to fully blend the mixture, and the absorbance was determined at 510 nm using a spectrophotometer. The total flavonoid content of the extracts was calculated as mg quercetin equivalents per gram plant material on a dry basis (mg QE/g DW).