Note: This is the last of 3 posts on rotary evaporation. Please note the post date of each article, some older information may be used as reference. Here are links to the previous 2 roto instructionals:
With rotary evaporation at Summit, we have been educating & training our customers for years on how to properly integrate rotary evaporators into their process. We don’t focus on low-power packages that offer little to no recovery speeds. We’ve pioneered a rotary evaporator operating process that has made progressive waves within the industry. What was once a long and arduous process, is now publicly corrected and simplified, here at Summit Research.
Note: For maximum continuous evaporation, utilizing a Summit Research SVC-1 Vacuum Controller and CT-1 Cold Trap is highly recommended, if not required. Here is a diagram.
Setup Steps:
Assemble Rotovap
- Remove all packing around coils with compressed air and/or appropriate solvents, clean and make unit near sterile.
- Make sure rotovap is placed on a flat, level surface, and utilizes an appropriately rated electrical circuit.
- If additional assembly help is needed, video walk-throughs are available on YouTube.
Connect Chiller
- Connect cold output line from chiller, to top port of lower-condenser coil.
- Connect coolant output from lower-condenser coil, to top port of upper-condenser coil.
- Connect output of upper-condenser coil, to chiller return port.
Configure Vacuum System
- Connect vacuum lines from rotovap vacuum manifold, to discharge flask top valve and top port of upper-condenser body.
- Connect vacuum line from vacuum manifold, to Summit Research CT-1 cold trap.
- Connect CT-1 cold trap output port, to Summit Research SVC-1 vacuum controller port labeled ‘System’.
- Connect vacuum pump to SVC-1 controller port labeled ‘Vacuum Pump’.
Operating Steps:
Warmup
- Turn on rotovap, set water bath temperature from 35 to 75°C.
- Turn on chiller, set temperature from 0 to 5°C.
Set SVC-1 vacuum controller to right outside expected solvent evaporation point (generally 75 Torr or 100 mbar) - Turn on vacuum pump and begin system pump-down.
- Allow chiller, water bath, and vacuum pump to reach their set points before proceeding.
Initial Operation
- After equipment has equalized, turn on rotation and set speed between 25 and 130 RPM.
- Adjust vacuum set-point 15-20% lower.
- Feed in small amount of solvent solution:
a. 5 liter rotovap — ~100ml
b. 10 liter rotovap — 100-200ml
c. 20 liter rotovap — 200-500ml
Note: As evaporation begins, watch the condenser/discharge side to get a sense of your solvent recovery rate.
- Slowly feed solvent solution into rotovap and match solvent feed rate, to rotovap discharge rate.
- Reduce feed rate by 1-3%. You want approximately 1.5% more coming out, than going in.
Fine Tuning
After system is feeding and operating, set the Summit SVC-1 vacuum controller set-point as low as you can, while watching both the condenser and the CT-1 cold trap for vapor. Adjust vacuum so that vapor remains in the rotovap and does not exit through the condenser vacuum port.
Note: Ramping down vacuum should be done only after initial operation is completed. The reason is increasing vacuum can increase heat loads exponentially to the chilling system if done improperly.
- Ensure feed line is continuously pulling solvent solution from bottle at appropriate rate; replace bottle as needed. Also keep CT-1 cold trap full of dry ice and preferred solvent.
- Empty solvent discharge ball at bottom of rotovap condenser as needed through process. Only empty evaporation ball as needed.
This process is called batch-feeding and can be run nonstop until the desired amount of material is in the evaporation ball. You will be able to achieve the fastest recovery times possible with these methods. Running in this configuration requires a solid understanding of how to operate non-stop and ability to properly match up system components.
Note: Please know that with mismatched equipment, any weak or inefficient hardware will either overheat, or stop working properly. Summit Research has done a terrific job at pioneering this process and matching correct components with equipment and customer requirements. If you require even faster speeds, please contact us to discuss custom solutions we offer to large-scale labs.
Additional Performance Tips:
Increase Evaporation Rate
- Fill a 5-gallon bucket with water, preferably hot.
- Place a 25 foot, 3/8” OD, thin-wall stainless coil (commonly called a wort chiller) into the bucket.
- Attach an 800 watt (or stronger) sous-vide heater to the bucket and ensure unit is submerged and water is kept at appropriate level.
- Set sous-vide heater between 50 to 75°C.
- Feed solvent solution through the heated coil before it enters the rotovap to greatly aid in rotary evaporation. This also decreases load on the water bath heating elements.
Boost Chiller Performance
- Fill a 5-gallon bucket approximately 30% full with water, preferably cold.
- Place a 25 foot, 3/8” OD, thin-wall stainless coil (commonly called a wort chiller) into the bucket.
- Fill remainder of bucket with wet ice (water ice).
- Attach rotovap condenser coolant output to one side of stainless coil.
- Attach other side of stainless coil to chiller return port. This significantly lowers the load on the chiller, allowing increased vacuum and faster evaporation.
Reduce Leaks
- Apply food-grade silicone vacuum grease to all O-rings and gaskets while assembling the rotovap. This will reduce the load on the pump and can help facilitate reaching even lower vacuum set points, increasing output.
Questions about rotary evaporation or more advanced processes? Please visit the Resources page from our website or contact us. We love when customers visit our showroom in Scotts Valley to view the latest, most efficient innovations & exclusive equipment offers. Summit Laboratory Supply:
103 Whispering Pines Dr.
Suite A
Scotts Valley, CA 95066