I want to freeze dry some of my plant samples. How long I should place the samples in freeze drying system, and under what conditions like Temperature and Pressure etc.?
If your samples are aqueous extracts, then only you should opt for freeze drying. Under freeze drying conditions (-40 C under vacuum, sample size of 100 ml), it may take 10-14 h to sublime the water. It also depends on the volume of sample to be freeze dried and capacity of the equipment.
If your samples are organic solvent based extracts, try rotary evaporator or nitrogen evaporator.
The following discussion may help to identify further useful references: https://www.researchgate.net/post/Does_anyone_know_of_a_good_review_paper_on_freeze_drying