[Alex koosha]

Before, I started to evaporate my solvent (butanol) by using rotary evaporator, I greased the ground glass joint holding my flask and *Ignore me, I am impatient* trapper. Subsequently, I secured my flask sample and the trapper with Keck clip . Is there any possibility that my sample may have been contaminated by grease?

[TheUnassuming]

Yes, very good chance you have grease in your sample.
In general its not a good idea to grease anything that will be coming into direct contact with your sample flask.  I'll grease the ground glass stopcocks and joint to the collection flask under the condenser, but nothing else.  Like this I can usually get down low enough to pull off toluene without warming the flask over ambient temp. 

[Dan]

You will definitely have grease contamination. The only thing I ever grease is taps on high vacuum lines.

You should be able to hit 10-20 mbar without greasing anything, which is plenty for butanol. I evaporated 100 mL of n-BuOH earlier this week.

In my experience, the weakest seal in a rotavap is usually not the ground glass joints but the seal around the rotating shaft, or the seal between the condenser shaft and the rotor. Greasing the ground glass rarely improves a rotavap.

[Alex koosha]

Thank you for your reply. May I ask is there any other way than rotary evaporator to get rid of n-BuOH?

[TheUnassuming]

Depending on the set-up you might be able to lyophilize it, though I've never done it myself.

[kriggy]

Lyophilization should work.
Also, I dont grease the rotovap and we are getting about 30 mbar, it works fine without it on all the solvents we use. If we need to evaporate something less volatile then we use external pump and we can get maybe 3-10 mbar (not realy sure, never used it)

[Alex koosha]

Is there any threat of explosion while evaporating 1 and 2 butanol by using a rotary evaporator and turing on the external pump?