Dear researchers,
I used the following solvent system for isolation of phytoconstituents from plant extract using column chromatogram.
the volume of the solvent used is varied (for colourless compounds, solvents are checked TLC. For coloured compounds, up to getting colourlessness of each solvent ratio). when I am following this procedure, some plant extract is completely extracted (packed silica is returned to its original colour that is the colour of silica before loading of sample). but some plant extract unable to extract completely (white silica turned brown after running of the following 14 solvent ratio also).
Solvent system Ratio Fraction
Hexane 100% 1
Hexane: Ethyl acetate 10:1 2
Hexane: Ethyl acetate 5:1 3
Hexane: Ethyl acetate 1:1 4
Hexane: Ethyl acetate 1:5 5
Hexane: Ethyl acetate 1:10 6
Ethyl acetate 100% 7
Ethyl acetate: Methanol 10:1 8
Ethyl acetate: Methanol 5:1 9
Ethyl acetate: Methanol 1:1 10
Ethyl acetate: Methanol 1:5 11
Ethyl acetate: Methanol 1:10 12
Methanol 100% 13
water 100% 14
my doubt is the brown coloured one is plant constituent left out during extraction procedure? if so what solvent mixture and raio shouldi use?
or the brown colour may be due to silica gel underwent some chemical modification (some X plant constituent may react with silica) ?
Article Isolation and characterization of phytoconstituents from Chl...
Some polar compounds bind "react" irreversibly to normal phase silica. In general, you cant expect to retrieve 100% of your loaded sample column chromatography, collecting 80% of the loaded sample is considered good enough to me at least. Unless your sample is a hexane extract (highly non-polar steroids and triterpenes!), you shouldnt be surprised that the silica turned brown. Good luck
Extraction and isolation of new compounds from traditional herbal medicine; Clerodendrum phlomidis Linn. Future Journal of
Pharmaceutical Science, Elsevier, 3; 2: 118-123.
Isolation, characterization and antimicrobial evaluation of a novel compound N-octacosan 7β ol, from Fumaria parviflora Lam. BMC complementary and alternative medicine 14: 98; 1-9.
- Badges
- Science topic
- Similar topics
- Analytical Chemistry
- Extraction