You can start with either Hexane or Pet. ether with increasing the gradient with portions of Ethylacetate

I advise you with a very intresting book in the Natural products " Natural prducts Isolation" you will find it free on internet

I agree with Pedro, but you can also try hexane with methylene chloride. Also try alumina - often with closely eluting non-polar fractions the use of alumina or C2 reverse phase stationary phase improves the resolution over silica.

Thank you every one for your valuable ideas. I will give update later.

Journal of planar Chromatography, December 1988, p 336 ff, Nyiredi, Toelke, Sticher: The PRISMA system

Hexane: CH2Cl2

I will refer you to Dr Joe Karchesy, an emeritus chemistry and wood science professor at Oregon State University, he is an expert on natural products and holds the patent for nootkatone. [email protected] Good luck with your research, we will be publishing a paper soon on thymoquinone. Thanks for asking my opinion, but I am an entomologist, not a chemist.

Reverse phase chrom is generally good for this group. Initially pl check as suggested Hex-EtOAc and Hex CH2Cl2 on Silicagel TLC. This helps to decide the next course of action.

I agree with Pedro. Hexane and diethyl ether are the best eluent solvents that you can use for TCL. I hope that these suggestions will help you in your work. Good luck!!!!!!

Especially if you'll have a mixture of olefins (or even E/Z mixtures of it) you´ll be in troubles. You can use old E.J. Corey´s trick to dot your silica-TLC layer with Ag(I) salts. I use it once some time ago and it was highly efficient - just bit light sensitive. Unfortunately, I can not find the protocol how to do it (practically). If I have time, I´ll try to find it during the WE. As far as I do remember, I used Ag(I) salt (presumably nitrate) dissolved in CH3CN. TLC plate was then place in it for 1 min and the CH3CN was then evaporated (in dark). Then you do TLC by classical way, using hexan/CH2Cl2 or hexan/Et2O (or MTBE) as solvent. Hope to find the original reference, if not ou should be able to find it in any Practical ORganic Chemistry reference book

Since in a n-hexane extract there will be in general non-polar compounds, the choice of your stationary phase depends on it. An analytical two-dimensional thin layer chromatography seems a first choice to me. Starting with a polar solvent system (methanol/water) in the first direction, and in the second direction (n-hexane/dichloormethane).

The ratio of the solvents is always a trial.

Good luck,

John

I am interested in Dr Kraise' suggestion for using C2 reverse phase stationary phase for non- polar compounds. Please indicate solvent conditions and/or references. Thank you

I am very glad to see your suggestions. Thank you so much. Let me try now with you suggestions and then i will give update.

But I should let you know that I will try to isolate most of the compounds from my Hexane extract but i am more interested for the terpenoids and triterpenoids. thank you again

Hexane: EtOAC:: 20:1 to 10:1 are best solvent systems for terpenoid compound extraction.

I’m fully agree with Dr Pritish Chowdhury; Hexane: EtOAC:: 20:1 to 10:1 are best solvent systems for this type of compounds. Best regards

Today I tried with all of you suggestions. I found good separation with Hexane:Ethyle acetate and Hex: Diethyl ethare. Hex:DEE was the best among them.

Thats good. I am sure you will be successful.

Why to stop at 1:20? We use regularly 1:100 mixture of hex/AcOEt, both for TLC and MPLC... What ist the problem here, is simple fact you're at the edge with the silica as the stationary phase. But if only preconcentration for subsequent HPLC is your task, it will work nicely. My second note is related to the discussed use of Et2O. It will boil in the moment of decompression and form gaseous cavities in silica and thus spoil the separation. MTBE or iPr2O is MUCH better idea. I hate DCM for the same reason, the only exception is use of MPLC with reasonable backpressure regulation (regulator at the column outlet or at least higher flowrate).

can u kindly explain MPLC, Et20, MTBE and iPr20? I am very new in chromatographic works.

I agree with Diderot Noungoue and Matej Babjak that the most promising way forward seems to be to try different combinations of hexane and ethyl acetate. See what works best for your specific extract.

In thin layer chromatography, I would avoid mixtures with diethylether (DEE, Et2O). The main reason is that, each time you open your TLC-tank, a bit of the diethylether evaporates; it's just too volatile. So, after a few plates you end up with a different ratio of hexane:diethylether than the one you started with (and consequently your Rf values will alter too).

I already suggested to use Hexane and EtOAC in different ratios to find out the best possible combination for the respective non polar extract. Even for dichlromethane extract, this combination is good for better separation of the products.

I agree with Dr. Pritish sab but U can also try Hexane and EtOAC( 9:1). I have tried, it gives best results for cannabinoids.

Generally in non polar extracts isolation, lower m.wgt fatty acids, steroids (like sigmasterol, beta sitosterols) will get separated in lower polar solvent

I agree with Dr Pritish that a good system is Hex: EtOAc , you can also try toluen: EtOAc combinations.

somebody suggested that e.j.corey introduced silvernitrate-TLC (argentation chromatography) It was dr SUKHDEV WHO INTRODUCED THIS TECHNIQUE IN 1962.

In my experiences, I used a polar column (silica column) for separation of non polar compounds in the fraction both for analytical (250 x 7 mm) as well as for preparative/semipreparative HPLC (250 x 20 mm), n-hexane - EtOAc (5:1), refractive index detector. Hopefully this information could be useful.

A.K.M. Moyeenul Huq:

"can u kindly explain MPLC, Et20, MTBE and iPr20? I am very new in chromatographic works."

MPLC=medium pressure liquid chromatography (automated flash chromatography), Et2O= diethyl ether, MTBE=methyl tert-butyl ether, iPr2O = di-isopropyl ether

Toluene is another solvent that might work, as well as tetrahydrofuran. Also consider the use of a silica-diol bonded phase column, or alumina column with the solvents suggested by others above.

you can try to use HSCCC...a powerfully technical cromatography

I second Pierre. HSCCC is a powerful technique for such analysis.

Though costlier, you may try reverse phase TLC plates.

If your extract is mostly fats or fatty acids, the fav mobile phase of all phytochemist comes to your help: 50% Methanol. I have tried this with non-polar extract of argemone seed and it shows wonderful bands. By the way i used HPTLC.

Use low polarity solvent mixtures: pentane, hexane (toluene if needed) in mixtures with Et2O or iPr2O. Sometimes CH2Cl2 is also an option

Thanks every one. for my sample I found good separation with Hex:EA 6:3 and Hex:DCM:Actone 5:4:1. Now I want to separate the major compounds which shows the major band in TLC plate by HPTLC.

Another suggestion for TLC of non-polar samples is use n-hexane/AcOEt (8:2 ), (7:3) , CHCl3/MeOH (9:1) or CH2Cl2/MeOH (8:2). These systems are, normally, efficients in routine experiments - with extracts of triterpenes, flavonoids and steroids, for example. Thanks!

you can use petroleumether and acetone like (! :9) or u can change ratio.or CHCl3 : MeOH mixture or petroleumether -ethylacetate may be good for nonpolar extracts.

 HEXANE:  ACETONE 4:1

Methanol-water on normal silica TLC plates will only result in all spots moving to Rf=1

That will hardly improve separation.

I would stick to Hexane-ethylacetate mixtures, but you may play with the pH, e.g. by adding a few drops of triethylamine in your mobile phase

Hexane, petroleum ether or benzene with ethyl acetate in a ratio starting from 20: 1 increasing ethyl acetate. Sometimes you can use chloroform