A rotary evaporator is a complex device with several components. So this is definitely not a simple cleaning project in the lab. However, it is important to clean the rotary evaporator properly. Leaving residues in its components may pose a safety risk or affect the results of subsequent applications.
There are two main methods of cleaning rotary evaporator glassware, which we discuss further below, including their pros and cons:
The "quick and dirty" method: This involves a quick rinse with acetone or another solvent.
Effective cleaning of glassware: In this case, you need to dismantle the equipment before cleaning.
In either case, the rotary evaporator should be cleaned as soon as possible after use. This keeps residue from drying on the glassware and makes cleaning more difficult.
1. The "quick and dirty" method
You may have heard of a quick and easy way to clean rotary evaporator glassware with a quick rinse of acetone. The video below shows how this is done, but here are the general steps:
Fill a small to medium-sized two necked round bottom flask with acetone. (A three-necked flask with a stopper will also work.)
Connect a socket to the rotary evaporator (usually where the evaporating flasks are located). You can hold it in place or hold it with one hand. Note that the flask is not set to spin during this process.
Close the second slot of the double-necked flask with your thumb.
Set the Vacuum Pump to about 250 mbar and turn it on. You should start to see the acetone boil off due to depressurization.
Quickly remove your thumb from the socket and you will see the acetone pass through the rotary evaporator.
Close the outlet with your thumb again and repeat the rinse if needed.
The obvious advantage of this method is that it is very fast. You don't even need to tear down the setup. However, it can cause problems. Quickly pumping solvent into the system means you can fill the Vacuum Pump with solvent. If this gets into the oil at the fuel pump, it will reduce the time between oil changes. If you are using an oil-free pump, such as a Diaphragm Pump, it may be flooded with solvent. If this happens, you'll need to keep it running to help remove the solvent and dry it out.
In either case, in the long run, it's better to skip this cleaning method altogether and dismantle the setup used for cleaning.
2. Effectively clean glassware
The proper way to clean a rotary evaporator is to take it apart and wash each piece individually. Removable and washable parts include evaporating flasks, condensers, collection bottles and vapor tubes.
Many manufacturers will provide recommendations for cleaning specific rotary evaporator components, but here are the basic steps:
Make sure the parts are sufficiently cool (condenser should be at room temperature).
Remove the components and dispose of their contents according to regulations.
Flush components with a suitable solvent. If necessary and according to the manufacturer's instructions, you can use a brush to remove more stubborn residue.
Allow components to dry before reassembling.
Depending on your application, you may wish to autoclave the glassware. Keep in mind that if you are using safety-coated glassware, there may be some limitations on the settings used and how long you can autoclave. In particular, sudden changes in pressure should be avoided as this may cause the coating to peel off the glassware, leaving wrinkles and creases in the coating once the glassware has cooled.
Cleaning other parts of the rotary evaporator
In addition to the glassware, there are other parts of your rotary evaporator that you will need to clean regularly.
The exterior of the rotary evaporator unit: Cleaning the exterior of the rotary evaporator is relatively simple. You can wipe with a cloth dampened with water and a mild detergent, but you should avoid using flammable cleaners, such as ethyl alcohol, on the outside of the unit.
Heated Baths: Also clean with a suitable solvent or water and a mild detergent. Note that some manufacturers recommend against using solvents on the bath, especially those with a Teflon coating. Before cleaning, make sure the Water Bath is turned off and that the evaporating flask is set to a high stop if it is still attached.
Shields: These can be removed and cleaned, but be aware that they may scratch easily, so avoid cleaning with abrasive materials. Covers made of protective glass may be sensitive to some solvents, so are better stuck with water and a mild cleaner.
