Please specify your compounds of interest which you would life to separate. As a thumb rule, use silica plates for separation of polar compounds (normal phase separation). In case you are looking for separation of non polar compounds, you will have to go for reverse phase TLC plates. The choice of the solvents would be again based on your compounds of interest and normal/reverse phase separation.

Plant sample means (plant extract ) than u will start with non polar(hexane, chloroform DCM to polar solvents(ethyl acetate. acetone methanol ) system in different ratio in normal phase TLC and polar to non polar(water: methanol or acetonitrile combination ) in reverse phase TLC system .

Plant sample contains non polar to polar components , you have to vary the polarity say hexane and increase polarity with say ethyl acetate after hit and trial u will get the right mobbile phase for your compound.

It will majorly differ considering your phytoconstituent of interest your experimental parameters will completely change. If the compound of your interest is polar then the carrier gas should be polar, or else it ill not seperate. Also there will be suitable markers to identify if the compound you are targeting are on correct path or no!!!

Dear plant samples contains various compounds from non-polar to highly polar. It totally depends on the compound of interest and type of plant or sample

If you have no idea about sample constituents then try using solvents of differnt polarity. Likewise start with nonpolar solvnets towards polar ones. Like 1, Hexane, 2, chloroform, 3, ethyacetate, 4, methanol and 5, water. then try mixing of above solvents in different ratios 1&2, 3&4 and 4&5.

Methanol is a good one

Which class compounds are you interested in separation? Plants contain various classes of these compounds, you need to be a li'l more specific.!

I'm assuming, like most new projects, you don't know which compound gives the activity. If the plant shows activity and people have already purified compounds active in this assay, try the TLC conditions they employed since your compound is probably a similar class.

Hexane, ethyl acetate, dichloromethane, methanol, some of these solvents with a little water mixed in to deactivate the silica... all have worked for me

You'll have to do trail & error to get the best resolution for whatever you see as spots, and this often means running a lot of TLC plates with different solvent systems.

Recognizing that we don't know what compounds are active in a mixture, I do something I term "Wide Polarity Range" chromatography that allows me to elute a wide range of compounds from a column by chaining several gradients. See: http://www.isco.com/WebProductFiles/Applications/101/Poster_and_Paper_Reprints/Wide%20Polarity%20Range%20Flash%20Purifications.pdf

Hi ariharan, each phyto constituent will elute at diff solvent system

example for detection of glycosides the solvent system is Ethyl acetate: methanol: water (100:13.5:10).. similarly each bioactive constituents will elute at diff solvent systm.. i hope it will useful for u,,

Tannins will resolve well with chloroform: ethylacetate: formic acid (5:4:1) and for low molecular wt polyphenols chloroform:ethyl acetate:acetic acid (50:50:1) may work well. Try some papers here is one http://www.sciencedirect.com/science/article/pii/S0021967398004907

and another

http://www.doiserbia.nb.rs/img/doi/1450-7188/2004/1450-71880435199M.pdf

If at all you dont knw your phytoconstituent of interest then you cqan also select a gradient of mobile phase which will facilitate the elution of many constituent along the gradient

chloroform/methanol/water 10:3:0.2 with me worked very good especially with triterpenes

I would recommend it

For a initial secreening you can use ethyl acetate-methanol-water (100:13.5:10) for the analysis of polar componds: alkaliods, bitter principles, flavonoid, saponins, etc. and toluene-ethyl-acetate (93:7) for the analysis of lipophilic compounds: essential oils, terpenes, napthoquinons, liphophilic acids, etc.

methanol only will be good

Your question is too general and broad based. What plants are you talking about? well, if you have a particular plant in question, you can look into literature to know the extent of phytochemical study that has been done and you can get some ideas on the nature of the phytocontituents that are present in the plant and the kind of solvent system(s) that have been previously used to resolve the components. You can also look into the genera to know the kind of the chemical compounds that are common to it. sincerely, there is no hard and fast rule to TLC solvent systems, you just need to try a range of solvent's compositions to know the best that will be suitable to resolve your complex mixture.

In TLC solvent system, in particular for extraction of medicinal activities, a number of solvents have been tried and to see the result after finding the yield. Usual organic solvents for starting the process are ethanol and acetone.

Go through this article it may help you

Article Antimicrobial activity of the bioactive components of essent...

In TLC , the suitability of solvent depend upon the type of plant origin and nature of process.

Because of toxicity, cost, and flammability concerns, the common solvents are hexanes (or petroleum ethers/ligroin) and ethyl acetate (an ester). Diethyl ether can be used, but it is very flammable and volatile. Alcohols (methanol, ethanol) can be used. Acetic acidcan be used, usually as a small percentage component of the system, since it is corrosive, non-volatile, very polar, and has irritating vapors. Acetone can be used. Methylene chloride or and chloroform (halogenated hydrocarbons) are good solvents, but are toxic and should be avoided whenever possible. If two solvents are equal in performance and toxicity, the more volatile solvent is preferred in chromatography because it will be easier to remove from the desired compound after isolation from a column chromatography procedure.

Usually we mix a non-polar solvent (hexanes) with a polar solvent (ethyl acetate or acetone) in varying percent combinations to make solvent systems of greater and lesser polarity.

For polar compounds in medicinal plants, I found DCM:MeOH (9:1) solvent system

the best.

I have tried methanol: water (50:50) using C-18 reverse phase TLC plates with good results. Viewing is at wavelength 254nm under UV light.