Carthamus Yellow

Carthamus Yellow
Synonyms : Safflower yellow, CI Natural Yellow 5
Definition : Carthamus Yellow is obtained from the petals of carthamus tinctorius L. (fam. compositae).
Contents : Yellow pigments, mainly Safflomin A (Hydroxysafflor yellow A) and Safflomin B (Safflor yellow B) with other minor allied pigments.

Identification:
Solubility : Very soluble in water, practically insoluble in ether and ethanol.
Spectrophotometry : A solution of the sample in water is yellow and shows absorption maximum at 394-400 nm.

Thin layer chromatography:
Adsorbent : Silica gel 60F254 pre-coated TLC plate (Merck)
Chromatography solvent : Butanol: Acetic acid: water (4: 1: 2)
Spots : Safflomin A (Rf 0.33), Safflomin B (Rf 0.42)

Colour reaction : Make the solution of the sample in water alkaline by 10% sodium hydroxide solution; the colour changes from yellow to orange-yellow
Stability : Safflower yellow pigments are relatively stable at acidic pH. Safflomin A (Hydroxysafflor yellow A) is the most stable yellow pigment.