Flavonoid Content During the Growth and Floral Development of Calendula officinalis L.

Here, we present the aluminum chloride colorimetric method, a direct analytical technique to determine flavonoids in calendula quantitatively. This approach utilizes a straightforward chemical reaction involving treating the calendula extract with an aluminum chloride reagent, forming a colored complex. The color intensity, assessed using spectrophotometry, correlates with the flavonoid concentration.