I've experimented the analytical evaporation through rotary evaporator, and noticed the rate of evaporate was so fast. I could say in a minute all the solvent mixture have dried out. The solvent mixture I used was 50ml v/v DCM:hexane ratio 1:1 in extraction of sonication process. The water bath I used should be less than 30celcius, but the water bath could not reach down than 34celcius because the chiller of evaporator only provide 10celcius. Does it got any standard to set the rotary either on pressure bar, chiller, solvent setting in rotary either DCM or hexane, vapour pressure, water bath temperature and other
I guess your system is connected to a vacuum pump. If so, do not close the vacuum valve completely such that you control the evaporation rate with this valve.
The evaporation process in rotary evaporator is influenced by the pressure and temperature employed. The lower the pressure and higher temperature will enhance the evaporation process, which is what we want to optimise. The choice of solvents also play an important role. Hexane and DCM have low boiling point, when subjected to low pressure and high temp, the boiling points of solvents will be lowered, hence, explaining why your solvents evaporated in just one minute. the rotation of RBF also enhance the evaporation rate as it increases the surface area.
Does the fast evaporation is not desirable?
thank you for the answers. Yes, the fast evaporation did not matter, as the purpose is to concentrate the extract. I just startle to see it could be that fast. Because I've tried using the DCM: methanol before with 6:4 ratio and it takes several hours.
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