Is your rotary evaporator well configured?

Rotary evaporation to chemists is like washing hands to surgeons or breathing air to the rest of us. The technique is established in so many labs around the world, that it is especially thrilling to have it featured on the blog. I’d like to dig right into the topic by giving you an overview of rotary evaporation in 2020. Do you know all the applications associated with the technique? Do you know how to go about configuring an instrument to fit your needs? Read on to find out more.

My sister can be very stubborn sometimes. For years she has kept on insisting to wash her dishes by hand. I’ve tried so many times to convince her that she wastes a lot of time, water and energy than was she ever to use an actual dishwasher, but to no avail. That is until last week when we went on a little ski holiday and our cottage had a dishwasher. I just got off the phone with her and she happily told me she has bought herself a dishwasher for her kitchen. Well, better late than never.

I guess that’s how scientists fell when the rotary evaporator was invented back in the 50s. Perhaps slightly distrustful of the instrument at first, but soon hooked on its speed and ability to remove large amounts of solvent with little manual work involved.

Just like dishwashers have become a staple in nearly every kitchen, rotary evaporators are found in nearly any chemical laboratory. But did you know you could wash your hairbrush, shin guards and flip flops in your dishwasher? Then are you sure you know all the applications of a rotary evaporator?

Typically, users rely on laboratory evaporation to perform:

  • Distillation
  • Concentration
  • Drying of products
  • Recrystallization
  • Extractions under flux
  • Freeze-drying sample preparation
  • Cannabis applications
  • Gin applications

And there are several things to consider when checking if your rotary evaporator is well equipped to deal with your specific application.

For example, rotary evaporators are often compatible with various condenser types (see image below).

condenser, rotary evaporation, rotary evaporator, distillation

For example, a reflux condenser is beneficial to those performing recrystallization, HP condensers are well suited to cannabis applications, S condensers are ideal for extractions under reflux and level sensors do the job for concentration processes.

How you set up your rotavapor is in large dictated by sample characteristics.

Sample properties such as boiling point, thermal sensitivity, corrosiveness and acidity can have an influence on how your rotary evaporation system is set up. Different condenser types, heating baths, vacuum pumps, chillers and programmable methods can be used in combination to assist work with challenging samples. I will discuss these different components in more detail in future posts.

There are also various specialized accessories to assist with challenges that arise during the evaporation process.

For example, if you experience foaming, you might consider a foam sensor. If you are working with solid samples, you could consider a vapor duct with frit. If you are processing a sample with unknown characteristics, you could try an instrument that has an automatic distillation function. If you have sunlight sensitive samples, then you could use specialized amber glass to protect your sample. If you are performing extractions, then you could add on a Soxhlet accessory to your rotary evaporator.

Last, but not least, the configuration of your rotary evaporation can be influenced by factors that you deem essential to your specific process.

For example, if you are trying to be as efficient as possible, you would likely benefit from scaled-up instruments with large flask sizes, large heating bath sizes, secondary condensers, stronger chillers. If you are trying to be compliant to stringent regulations, you could consider a system that comes with IQ / OQ services. If you are looking to maximize safety, you could invest into accessories such as splash shields and protection shields. If you are looking for greener operation, you could consider using swimming balls, covers and instruments with ECO modes. And if you are trying to minimize hands-on time, look for automated options, such as foam sensors and automated method programming.

Of course, depending on the batch size and frequency of operation, you could also consider other types of rotary evaporation systems, such as parallel evaporation or industrial evaporation.

This was just a quick dive into the many ways a properly configured rotary evaporator could be at your service. I am very excited to dig deeper into these topics in the upcoming months on the blog.

By the way, this is not the first time my sister makes an appearance on the blog. Her son has inspired me to talk about flow rate and column efficiency in chromatography. And picking out a birthday present for him reminded me of important factors to consider when selecting a flash chromatography cartridge. It is also not the first time a dishwasher makes me think of chromatography. The other time was in my post on how ELSD can help overcome limitations in chromatography. Family is just golden.

I know this is a condensed post, but stay chilled, I did not want to pressure you and overheat you with information. The best in rotary evaporation is still to come on the blog.

Till next time,

The Signature of Bart Denoulet at Bart's Blog