For TLC chromatography how we select solvent system via hit and trial method?

Hi, in my opinion, I think it is easier to try finding the solvent systems in the data base instead hit and trial methods, who knows you can find suitable solvents for your compounds in the data base. I attach the link of the Camag TLC data base., Best regards

http://www.camag.com/en/tlc_hptlc/customer_magazine_cbs/ccbs_database.cfm?method=query

Shilpa Varma

thank you for reply sir, but if there is no literature present regarding my plant for tlc then what should i do? please explain

Jack Silver

I think the issue is that you have a complex mixture, and you can't tell which spot is the active compound, or whether it moved down the plate in a given solvent system. There are things one can do to make it easier to identify compounds on the plate.

Do a literature search using your plant genus and species. This lets you know what compounds have already been found. If your biological activity is due to one of those compounds, or a related compound, you can run TLC using the method in the paper. If they don't list TLC conditions, but list the conditions to run a silica column, you may use the silica column solvent system. The retention on a silica column (in column volumes) = 1/Rf where Rf is the TLC plate retention factor. They may not list the elution time, but the Rf should be between 0.2 and 0.5 for good column chromatography for a solvent system used for a column.

I didn't see what biological activity is being evaluated in your extracts, but do a literature search on that biology and see what sort of compounds show activity; I tended to observe alkaloids in central-nervous-system assays, for example. If your extract is active in anti-bacterial/anti-fungal assays, use auto-radiography to determine how your compound(s) run on the TLC plate. The petri-dish is now specific for your compound and you can develop a solvent system, although it will take a bit longer due to the time to see the results. But one can try several plates & solvent systems one day, and fine-tune them the next.

If you are running a biological assay, I've come up with a column screen that systematically runs different columns and solvents, using what I term as "wide polarity range" chromatography. Since we don't know what compounds are active, small test columns are run with a small amount of sample. After assay-directed fractionation, the results can be used to choose a purification strategy- columns and solvent system. See these posters for more detail (although run on an automated flash system, the technique will work with oipen columns with step gradients): http://www.isco.com/WebProductFiles/Applications/101/Poster_and_Paper_Reprints/New_Techniques_In_Extraction_Column_Screening.pdf and http://www.isco.com/WebProductFiles/Applications/101/Poster_and_Paper_Reprints/New_Techniques_in_Extract_Column_Screening_II.pdf

Gunawan Indrayanto

Hi, I agree with the comments of Jack above; if we can not find any TLC system for our compound(s) in the data base(s), generally we did TLC by using published data for its related compound(s), if the compounds are not well separated, we will do some modifications. In the website of Camag you can find many applications. Best regards

http://www.camag.com/en/tlc_hptlc/camag_laboratory/methods.cfm

Shilpa Varma

thanks all for your valuable suggestions....................

Henry Bachmann

Hi, i agree with the former tipps.

i assume you have an idea what class of componds you are looking for:

secondary plant metabolites, as Flavonoids, Alkaloids, Sterols, colorants, vitamins etc. -> then go to Camag literature. they also file specific detection reagents which helps in the identification

Primary plant metabolites are more difficult, but there is also literature with specific color reactions for Sugars, Amino acids etc

O. Aldulaimi

hexane:ethyl acetate 7.5:2.5 or chloroform:methanol 8:2 then increase the polarity gradually, two directions TLC may be suitable sometimes

Mini Shobi

Use gradient solvent system starting from low polarity to high polarity and check its combined effect as well.

Petroleum ether/Hexane - Non polar solvents

Chloroform/Ethyl acetate - Medium polar solvents

Ethanol/Methanol/Acetone - High polar solvents

Water- High polar solvent (exceptional)

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