It depends upon the plant material (sample) and method you follow.

generally for tender leafs 100- 250 mg will be taken. The most important is your isolation procedure whether its sand or some thing else.

here is some suggestion for you Rocío Cecilia Arce , Methods Mol Biol. 2011;684:321-5. doi: 10.1007/978-1-60761-925-3_24. hope you find it useful.

It depends on the material you are working with and the methodology involved. Normally, 200mg should be adequate. However, you might want to optimize according to analytical procedures, reagent availability as well as your research focus.

Thanks.

Mohammed Anwar Ali Pascal Chukwuebuka Okoye Thank you so much. I work with tobaco, so its leaf is very tender. I will consider your suggestions.

As said by others, it depends on the material that is used, but other factors have to be considered. Thus, you may need more material if you want to extract and purify a substance or make functional studies (grams and above). For simple biochemical characterization, 0.1 to 0.5 g should be adequate.