Check these publications and link for help

http://www.slideshare.net/rahulbs89/extraction-of-plant-contituents

According to polarity i have choose the solvent system

Dear Ali

You start with non-polar solvent, then gradually increase the polarity to most polar. You will get various successive extract. From which you can explore the solubility pattern of different phytoconstituent. Please refer attached table for polarity index of solvents.

http://www.monzir-pal.net/Instrumental%20Analysis/Lectures/Lectures%2021-/L41_files/image002.jpg

If you know something about the compound that needs extraction, one can choose a solvent.

Methanol and ethanol are commonly used since they extract a wide range of compounds.

Another set of solvents is hexane (or petroleum ether), followed by dichloromethane, ethyl acetate, methanol (or ethanol), and finally water. Depending on the compound(s) that show biological activity, it can be in more than one of the extracts depending on its solubility in the different solvents. These solvents are commonly used, and is essentially the advice given above.

First you check the phytochemical profile then find the desired constituent. If it is alkaloid then refer isolation procedure of alkaloid and other compound  you can refer ideal procedure for isolation of compound as mentioned in paulok mukharji, paridhavi reference book

Check these publications and link for help

http://www.slideshare.net/rahulbs89/extraction-of-plant-contituents

You should follow successive solvent extraction with solvents in the increasing order of polarity. Soxhlet apparatus can be used. Start with Hexane/Petroleum ether followed by solvents of increasing polarity like ethyl acetate, chloroform, acetone, ethanol, methanol and water. This will help you to fractionate the phytoconstituents effectively and these fractions can be used for isolation as well as in vitro and in vivo studies.  

Regards 

Dear Researchers,

Selection of solvent for plant extract preparation depends solely on your inclination towards type of phytoconstituents you are willing to separate. If you are not that sure about the nature of phytoconstituents that you are willing to separate, then in such a case, my advice would be to first use an intermediary polar solvent which will behave as a borderline solvent. One such example might be 50% Aquo-ethanolic (1:1) mixture. 

Regards

Pallavi Thakur

Researcher, DRDO

I would go for a solvent system to ensure the extraction of different products. Check this procedure we use in our lab, it can help:

Please also have a look at this ResearchGate link.

https://www.researchgate.net/post/Which_is_the_best_solvent_for_herbal_extraction#post-comment-editor

You can try organic solvents Such as Methanol (lower boiling point) or ethanol (somewhat higher boiling point), pure acetone or acetone/water mixtures.

start with non polar solvent like ( Petroleum ether) >

then continue with Mid Polar like (Acetone) >

finally by polar like ( ethanol).

The choice of solvent depends on the type of compounds you want to separate, but if you don't have any information about the plant and you want to know what compounds the plant contains, you can use methanol initially, then you can make different extracts from the original using solvents with different polarity.

You can choose according to the polarity of solvents

Solvent depends on the type of compounds you want to separate, you can begin with the safe solvent, the ethanol.

For sequential extraction, try hexane followed by ethyl acetate, followed by methanol, and finally water.