The extract is a mixture of a lot of compounds, including carbohydrates, amino acids, denatured proteins, DNA, lipids etc. So ethanol extracts from plants will always be sticky, and never a nice powder.
How would I be able to weigh it for further in vivo or in vitro works? No papers in literature ever mentioned it! they always say its a powder which they weigh in mg or ug for their experiments!!
Alcohol doesn't freeze, so freeze drying (lyophilization) would not work in theory, using a speed vac should work, though I've never heard of a speed vac lyophilizer before. Speed vac simply draws a vacuum and evaporates the liquid with small amount of heat, speed vacs for DNA preps aren't heated though. If your compound is sensitive to heat, I'd use the cooled speed vac.
Yuvraj is right, ethanol cannot be freeze dried (aka lyophilized), but it can be dried down in a SpeedVac. I assume you heat your sample with the ethanol anyways to extract your metabolites, so you generally don't need a cooled SpeedVac, as heat sensitive metabolites can't be efficiently extracted with ethanol anyways.. Furthermore, your sample will stay decently cool due to evaporation of the ethanol. Just make sure to take out your samples as soon as they are dry, otherwise they WILL heat up.
As for the amount: If you look carfully in publications, you will find that metabolite contents are normalized to either fresh weight (easy, just weigh in your sample before you add the ethanol), dry weight (generally better than fresh weight, as it controls for water content of your sample) or leaf area (easiest if you can use hole punchers to make leaf discs, but the most imprecise normalization method, as it does not control for leaf thickness (and only work with leaves).
Bottom line: metabolite contents are normalized to your starting plant material.
Thank for the info and suggestions... I tried normal lyophilizer before..but it didn't turn out dry... let me try to find the other alternative suggested by all.. I will surely inform you the out come of the results soon....
Kavisa,
remove all fat content using chloroform or hexane. fat content extracted in that sovent. you will get dry powder.
Every plant extract contains water soluble and fat soluble compounds. As recommended by several others, it is necessary to separate them and dry them. former will be in powder form and later will be gel format. There are different ways to remove fat soluble forms as described by others. extensive literature is available on this aspect in pubmed.
What you can do is....you can try to remove the ethanol using rotary evaporator then freeze dry....however, if your compound is sensitive to the heat, chemical structure of the compound might be affected and after freeze driying you will find the dried/powdered form might not completely dissolved in the solvent againt....
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