Methanol and other organic solvents extract oils and resins from organic materials. When you concentrate the extract you end up with anything from and an oily liquid to a sticky resin or wax. It is not residual water that is making it oily or sticky, so you cannot dry it any further because it has almost no water in it. The oily/resin/waxy substance is the extract you are looking for.

Dear Abdul,

I suggest you to dry the residual methanol in extract using vacuum assisted drying.

Under vacuum assisted drying, you can set the temperature at 25-30 deg C to evaporate the residual solvent. Furthermore, if you want to quantify the residual methanol in your extract, go for GC-MS analysis.

All the best for your work.

If you have gone for methanolic extract directly with the plant material then there may be the problem of resins and fatty acids interference which may also prevent the extract from drying. you can try the following ideas:

1.  Try by applying vacuum which will ease the drying process (no need to go for 60 degree but can achieve at 30 itself with applied vacuum)

2. Defat the material initially with petroleum ether or hexane before extraction with methanol.

3. if still it doesnt dry you have to fractionate with non polar solvents to get dry powder.

All the best.

wow guys..really appreciate all your responses..very much thank you =)

You are right if you put your evaporator at 60°C you will destroy all labile molecules.

As Rohit suggest, you can use the vacuum assisted drying.

You also ensures that your excerpts do not contain chlorophyll. If this is the case, you must first extract with petroleum ether or hexane andpass it on activated carbon.

another alternative, At the end of evaporation you can add a little water it will create a azeotropic and then you freeze and lyophilized extract

Hi Abdul

When you say that you extract is still "wet" do you mean that it contains liquid water (which is very likely if your made the extract from a material that contained water), or is it a thick, or oily, or other type of liquid ?.  Or does it still contain methanol ?  If residual methanol is the problem then run it in a rotovap at room temperature, or blow off the methanol with a stream of dry nitrogen.  If is is a non-aqueous liquid, then test it as is (it is the extract they you wanted after all). Residual water should not be a problem: unless your cell line can miraculously grow in the absence of water it already has a lot of water in its growth medium.

Hi Peter

The extract was like thicky and oily. for your information, the extract was from freeze dried mushroom fruiting bodies.

Thanks for your reply

Thanks also to Lamoussa for the reply

Hi Abdul

Then you can use it as is. There might be a problem with getting it to dissolved in water if it contains a high fraction of fats and oils. Good luck.

Hi Peter..

Thank you very much for your reply

Have a nice day

Same happen to my sample. I used freeze dried pineapple's pulp with methanol. Is it possible, if I'm rotavape until constant weight and dilute with distilled water then freeze dried again? 

Methanol and other organic solvents extract oils and resins from organic materials. When you concentrate the extract you end up with anything from and an oily liquid to a sticky resin or wax. It is not residual water that is making it oily or sticky, so you cannot dry it any further because it has almost no water in it. The oily/resin/waxy substance is the extract you are looking for.

Thanks Peter for a great explanation.

use lyophilizer freeze drying

I can recommend one of the easiest and most economic methods , you can put the extract in small layer in a Petri dish in a well ventilated place. you can recover the dry extract after complete dryness by using a flat end spatula. I used this method successfully for heat sensitive extracts.

Your extract contains oily phyto-constituents, hence cant be rotary evaporated. However, the vehicle to be used for administration should thoroughly considered for better result. Aqueous vehicle cant be used in this case.

better to search for another techniques with high volatile concentration such as Supercritical carbon dioxide