Page 139 - phytochemistry general program

Fractional chromatography is a case of multiple development in which the polarity .3
of the system is increased stepwise in each run.

Visualization methods .1

For colorless substances.
The detection methods could be

1. Physical.
2. Chemical.
3. Enzymatic.
4. Biological.
5. Radioactivity.
Physical detection methods
a) Colors (in the day light)
b) Ultraviolet light, they may exhibit different fluorescence colors when subjected to
either short (254 nm) or long (366 nm) UV light.

Chemical detection methods .2
By spraying the chromatogram with the proper reagent.
(a) Iodine gives a brown color with organic compounds.
(b) Dragendorff’s reagent gives an orange color with alkaloids .
(c) Ferric chloride gives a series of colors e.g. simple phenols, flavonoids and

tannins.
(d) Ninhydrin gives with amino acids colors ranging from blue to purple or pink.

(e) Antimony chloride for the detection of steroids and terpenoids.
(g) Alkalis give red colors with anthraquinones and yellow with flavonoids.

Practically, chemical detection methods are carried out by :

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