SWAMI DAYANAND POST GRADUATE INSTITUTE OF PHARMACEUTICAL SCIENCES, PGIMS, ROHTAK
SOP OF ROTA EVAPORATOR
1. Read the SDS for all materials are
2. Inspect the rota evaporator and all pieces of glassware to ensure that there are no cracks, chips, or defects.
3. Make sure that the solvent trap and bump trap are empty and clean.
4. Fill the hot water bath with DI water if not already filled.
5. Fill the cold trap (e.g., dry ice/acetone).
6. Cool the receiving flask
7. Connect the bump trap to the rota evaporator and secure with the metal clip or a keck clip depending on the model of rota evaporator. The bump trap should be kept clean, it provides a receptacle in case the solution splashes or boils beyond the flask. A clean bump trap can allow for recovery of any solution that “bumps”.
8. Pre-weight a round bottom flask; fill it less than halfway with the solution to be evaporated.
9. Connect the round bottom flask containing the solvent to the bump trap and secure with a neck clip.
10. Turn on the vacuum. You should hear a hissing sound if the stopcock on the evaporator is not closed. Slowly close the stopcock on the evaporator, once closed the sound should stop.
11. Begin rotating the flask. Ensure that the solution does not foam or boil too much.
12. Wait until the rotation and apparatus equilibrate to proper reduced pressure and speed. Keep a watchful eye on the evaporation (boiling) of the solvent (vent or change speed as needed).
13. Allow the solution to evaporate. The solvent should collect in the solvent reservoir.
14. Once the flask changes in temperature and becomes cool to the touch, lower the mechanism into the water bath or lift the water bath to the evaporation flask (depending on the rota evaporator you are using). Make sure that the solvent level is equal to the
water bath level. Never put the flask so low that the Keck clip touches the water.
15. If needed you should start to heat the water bath. [Keep in mind that the sample is under vacuum, this will lower the boiling point]
Never have the water bath temperature higher than the boiling point of the solvent
16. Keep a watchful eye on the evaporation of the solvent. If the sample is boiling too vigorously, remove it from the water bath, decrease the temperature, or change the rotation speed.
17. Allow the solution to evaporate until the product has been isolated or until the desired amount of volatiles have been removed. When the sample appears to be completely done evaporating allow the flask to remain at reduced pressure, while heating, and rotating for at least a few minutes to ensure that all of the volatiles are removed.
18. Once the evaporation is complete conduct the same steps in the reverse order: turn off the hot water bath, remove the flask from the water, stop the rotation, turn off the vacuum, slowly open the stopcock to vent the system (remove residual vacuum) while holding the flask (to avoid it falling and breaking), and remove the flask.
19. Make sure to empty the solvent reservoir into the appropriate waste container and clean the bump trap. Remove the water from the hot water bath when finished using the rota evaporator, this will prevent it from evaporating and leaving behind a residue.
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