How
to operate rotary evaporator
The
rotary evaporator is an expensive piece of apparatus that needs to be used with
great care. If you follow the instructions carefully, it is the fastest, most
efficient and most environmentally friendly way of removing a volatile solvent
from a non-volatile sample.
Step 1 - Switch on the chiller.
Step 2 - Wait for 10 minute to allow the chiller to cool the condenser.
Step 3 - Mean while wash the rotary evaporator by acetone to avoid contamination.
Clean the receiving flask. The receiving flask of the unit should
always be emptied prior use to prevent accidentally mixing of incompatible
chemicals.
Step 4 - Add sufficient ice and chilled water in trap bucket carefully.
Step 5 - Check the water level
of the water bath. If more water is needed, top it up with distilled water, if
it's too hot, let it cool or add a little ice.
Step 6 - Once condenser became cool, keep on the stopcock
and switch on the vacuum
pump.
Step 7 - Attach the round bottom (RB) flask containing sufficient amount of
solution to be evaporated with the help of suitable reducing adapter. Attach a
proper Keck clip for safety purpose.
Step 8 - The solution in RBF should be around 40% of total volume of RBF i.e. for
100 ml RBF the solution in RBF should be approximately 40 ml.
Step 10 - Place your finger or
thumb over the vent hole and use it to control the vacuum. If the sample starts
to boil too vigorously, release the pressure by removing your finger. Once the
boiling of solution has stopped, reapply your finger over the vent hole and
repeat the process until the sample "calms down".
Step 11 - Once the solution calms
down, close the stopcock to generate a vacuum in the apparatus (but keep your
hand on the tap and ready to adjust the tap in case the solution starts to boil
vigorously) - now carefully lower the RB flask until the lower surface of the
glass is just submerged into the water bath by using lift knob control.
Step 12 - If the solution boils
vigorously, release the vacuum with the stopcock. Once the RB flask is
"stable" then you can remove your hand from the tap and leave the
solution to evaporate.
Step 13 - If evaporation is slow,
then turn on the water bath and adjust the required temperature accordingly -
remember that the apparatus is under vacuum so the water bath does not need to
be set at the normal boiling point of the solvent, the 40 to 50°C is usually
sufficient. The temperature
of water bath should be 20 to 30°C less than the boiling point of solvent to be
evaporated.
Step 14 - After evaporation
completed, raise the apparatus out of the water bath using the lift knob
control. Then stop the rotation. Hold the RB flask with your right hand and
release the vacuum with the stopcock with your left hand, wait for 1 minute and then switch off the vacuum pump.
Remove the RB flask.
Step 15 - Remember to empty to
receiver flask of any waste solvent.
Step 16 - Clean the rotary evaporator by acetone. Switch off the
water bath. Switch off the chiller.
Step 17 - Make an entry in register.