Selection of the extraction method depends on the nature of your plant material, nature of the compound you are looking for and the facilities you have. Usually if it is dried plant powder and the compounds are not that much thermolabile, Soxlet extraction is the preferred one. If you are looking for a highly thermolabile compound, super critical fluid extraction may be the best method. For highly volatile fragrances such as that of some flower heads, solid phase micro extraction will do.

However, to start with, use a non polar solvent like hexane, then meduim polar solvent like chloroform and finally polar one like methanol or ethanol. This will give you all the kind of compounds. Please see the note on extraction attached.

Many thanks for your effort 

If the compound to be extracted in not certain, then the best method to extract a plant material is to follow an ellutropic series of solvent.

Dear, Dr. what about the best one to liberation them?

Hi, at our lab. for extracting phytochemicals we use solvent(s) and method(s) that suitable for the known target compounds; it could be very different for different target compounds (generally we can search via Google or other data base). I agree with the comments of Rameshkumar and Vivekanand if the target compounds are unknown or we want to extract most of the metabolites; We did usually at first extracted the samples using petroleum ether, then residue will be extracted by acetone and at finally methanol; sometimes we did also as described above : hexane then chloroform/dichloromethane  finally methanol, best regards

thanks for previous replies, but we really still have to add another factor to the extraction systems, which called the mechanical assistant such as using the ultrasonic machines. So, using the best solvent with the suitable concentration applied to well-grounded materials with ultrasonic assistance will the key of your phytochemicals extraction. 

That's right Dr. Gunawan.

I will extract the plant material with pet. ether 60-80, dry the marc, and extract with toluene. After drying the marc, I will extract it with chloroform, subsequently ethyl acetate, acetone, and then with absolute ethanol, followed by water.

In doing all these extractions, care must be taken that all solvent have been freshly purified and dried.

Dear Ibrahem Khalifa,

This is true, lots of methods for determination for flavonoids,  as one example of phytochemicals. But why there are hundreds methods, simply because more than 5000 flavonoid compounds have been existed. So these compounds are found in different plant tissues from fruits, vegetables, tea and cereals. So it is a big world. lots of challenges have been found for determination of flavonoids. For example,  determination of myricetin and using a suitable gradient elution, wavelength, aqueous methanol, type of detector, spectrum stuydy, HPLC-MS .  As an expert in identifying flavonoids HPLC based, I would suggest our developed method in the UK labs attached.

Dear Ibrahem Khalifa,

Please find the rest of the method attached.

A.R. Abdel-Moemin, To investigate the antioxidant properties of dietary flavonoids in human metabolism (Ph.D. Thesis, The Queen’s University of Belfast, United Kingdom, 2004)

All the best

Aly

I believe the answer provided by Rameshkumar K B  should be helpful. The entire project design should include evaluation of different solvent of increasing polarity. If you are interented in absolutes, you will observe that some solvents are more effective in extracting some phytochemicals than others. See also:

Boonyadist Vongsak et al (2013) Maximizing total phenolics, total flavonoids contents and antioxidant activity of Moringa oleifera leaf extract by the appropriate extraction method. Industrial Crops and Products 44: 566– 571

Some phytochemicals that contains antimicrobial active components were heat labile, thus I suggest non Soxlet extraction method for assaying these compounds. Please go through the attachment.