Secondary metabolites | Reagents | Reaction indicating that the test is positive |
alkaloids | Dragendorff | Precipitate or orange colouring |
flavonoids | Cyanidine | Reddish-brown precipitate |
polyphenols | Ferric chloride | Heat then pink-orange or purplished colouring |
quinones | Bornstraegen | Blackish-blue or green ± dark colouring |
saponosides | Foam Test | Persistent foam, higher than 1cm |
sterols and polyterpenes | Liebermann | Crimson or purple ring, changing blue then green |
tanins | Stiasny | Catechic precipitate in large flakes Gallic blue-black deep colouring |