We are extracting tannin from plant. The method says that after treating the plant sample with acetone/water (7:3; v/v), solutions are then concentrated, then the aqueous extracts were freeze-dried.
Sadly, we don't have freeze dryer. Can we just use rotary evaporator to remove the solvent, then put it in the freezer afterwards?
Many conventional systems of rotary evaporation will struggle when it comes to removing water. Having said that, my rotary evaporator can remove water thanks to a very good vacuum pump that we use. So, yes you can with a good vacuum pump. If you are going to use the extract for a biological assay, say by weighing few milligrams of the extracted dry matter, make sure that you do not have residual water. That is when we need freeze drying otherwise water can be removed as said above.
I doubt rotary can codense a water based solution. You should test it.
Tannins are relatively heat-resistant, so I think rotary temperature cause no problem. However, you should test if this method give you a solid material
I have dried samples using a rotary evaporator, but it takes a long time and requires relatively high temperatures. One trick that I've found useful is to add a water-miscible solvent that has a lower boiling temperature to speed up evaporation. Try adding methanol or acetone in a 1:1 ratio of the liquid volume and evaporating it, and see if it speeds up the process for you.
Thank you, Mr. Solomon Habtemariam. Yes, we need it for a larval assay (LEIA). What do you suggest we do? Our university has not much instruments.
Thank you,Mr. Seyyed Morteza Hoseini . Should the solid material be as dry as it could be?
It should be without water. You can test the water content by placing 1 g of the sample in oven for 24 h at 70 degree C. The weight of before and after heating must be very similar
Reena Dado, As a first step, you can try to evaporate the water, but under reduced pressure to avoid partial thermal decomposition. The sequence may be either freeze drying or convection drying under reduced pressure. However, it is worth remembering that freeze drying preserves flavor and color, while convection drying does not.
Reena Dadod rota evaporator with strong vacuums will be helpful to dry your samples at low temperature without decomposition.
vacuum spray drying, vacuum microwave drying and vacuum foam drying
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