If you are located in an institute which has organic synthesis labs, try to see if any of them have a "rotavapor". That according to me is the easiest way to remove organic solvents. I work in a natural products/analytical chem lab and if you too are working with organic extracts of natural material I would strongly suggest your lab to invest in one of these.

http://www.buchi.com/rotary-evaporator_rotavapor.4695.0.html

Essentially what you need to do, is provide some sort of mechanical stirring along with the vacuum in order to facilitate the evaporation to be faster. If I have small sample size i.e < 1ml I sometimes would keep them, uncapped in an incubator with sahking at 50-60rpm at Room Temp or 37C whichever you are more comfortable with. The constant air flow inside the incubator along with the shaking accelerates the process - but it will still take some time (proportional to the amount of solvent).

Thank you all for your comments.

I am currently working with bacterial metabolites extracted in ethyl acetate and therefore I have very small amount of sample, that's why I didn't use the vacuum in the rotavapor.

I cannot use the heating bath from the rotavapor (which would be great otherwise) but I will try to see if there is a liophilizer in another lab.

Thanks :)

If its only a small volume of sample just dry it in under a gentle stream of nitrogen gas. If its a large volume go with rotorevaporator.

evaporate with dry nitrogen using a room temperature bath to bring thermal to the sample. We use an Organomation N-Evap, a very convenient device for this purpose, but you can rig up a nitrogen evaporator with a tank regulator, tubing and a pasteur pipette. Trick is to adjust the flow by holding a beaker with water under the pipette (or long syringe needle) so that only a slight dent on the water is made by the nitrogen flow, so you won't blow your sample out of the container. You can also use Argon.

I am not sure if Lyophilisation is going to work with organic samples. Its normally used for samples that can be frozen i.e. has a high content of water in them. If you are working with a small amount of sample the incubator method or Justin's idea works pretty well.

@Justin, @Parag, yes, my initial idea was to use nitrogen flow but I don't have a Schlenk line yet and yes, I just checked and liophilization is out of the question for my samples.

@Roger, it is very interesting your idea, could you elaborate a bit more?

Thank you

I have lyophilized lipid samples by suspending the sample in benzene (probably ethyl acetate would also work), freezing with liquid nitrogen, and using vacuum with a liquid nitrogen trap to capture the vapors before the vacuum pump. Just set up the system with the liquid nitrogen on your sample and the trap ready, start the pump and remove the liquid nitrogen from outside the sample vial. But nitrogen is easier!!

@Roger, thank you very much, I was attempting something like it, but I didn't freeze them and it also takes a while, so I will try to get some nitrogen and if I don't succeed I will try the alternative :)

There are two ways that I suggest.

First is a nitrogen evaporator at 35-45 C. The problem is you have cooling of the sample as you try to evaporate it, hence a little heat and a steady, but not vigorous stream of nitrogen would work. You could rig one up with a tank of N2 gas, a regulator, a piece of tubing and a Pastuer pipet. Use a heating block on low heat. While those of us in the field have fancy nitrogen evaporators dedicated to this purpose to do multiple samples, this alternative would work.

Second is a Speed Vac. With a medium amount of heat you can easily take off the ethyl acetate.

Most lipids are not incredibly heat labile, but as you haven't defined what are your target molecules it is hard to say.

So, my answer echos Roger's at LSU, but the key is to heat the sample. Remember, the sample is actually cooling due to evaporation, so the net impact on the actual lipids is pretty minimal. We know that PG, FA, and PL are all quite heat stable.

You can use a piece of rubber r polypropylene tubing of a suitable diameter to attach a 2 mL HPLC vial to a rotary evaporator. The splash guard/adapter on the rotary evaporator should end with a small diameter ground glass joint (i.e. 14/20 - see Aldrich cat.# Z549118). Use the rotation, the vacuum and the water bath without any heating whatsoever. During the evaporation under vacuum the sample cools so the water bath keeps about ambient temperature. Since the vial volumes are small you should go against the rules and start the rotation on the rotary evaporator before the vacuum to prevent splashing. Just make sure to use plastic clip to hold the splash guard to the rotary evaporator. One mL ethyl acetate should be gone in about 10 min.

Did you try with a flow of nitrogen?

Dry it with a gentle stream of pure nitrogen gas at ambient temperature utntil complete dryness.

@ Eric Murphy

Thank you very much, actually I am working with lipopeptides, so they are not very heat-friendly, but I will try to rig the N2 tank version of N-evap :)

@ Jonathan Bisson

Yes, I normally inject them directly and I haven't had any issues either, but this time I was aiming to do also an assay measuring biological activity and I was afraid that ethyl acetate would be interfering.

@all

Thank you for all your comments, I will try the nitrogen stream (the low-tech version) and I hope it works (fingers crossed).

You may find N-Evap and Speed-vac to very useful tools for removal of organic solvents.

You may try to blow slowly with nitrogen gas through a sharp nozzle. This is more gentle and cheap too.

for this application best equipment is Turvo vap(Caliper)

@All

I finally succeeded to evaporate the ethyl acetate. As it turns out, another lab had a Speedvac laying around that can handle ethyl acetate (thank you Dr. Murphy) ... and it worked like a charm :)

Thank you all for the advices, I appreciated all the suggestions and learned a lot... for the times when I won't have a Speedvac around.

Usually rotary evaporator will be a good choice.try at 50 to 60 centigrade not more. You can evaporate it easily .

generally, lipid should be dried under a low trmperature to avoid oxidasition. you can use a simple equipment described in "Y. Zhang et al. / Analytica Chimica Acta 752 (2012) 106– 111". the vent pipe and heating block were not needed this time. it will be better if the cold trap was in liquid nitrogen bath. hope you get good results.