In rotary evaporation, as in a lot of other things happening in your lab, time is of the essence. Maybe you need those APIs purified ASAP, or maybe your clients needed that ethanol removed from the cannabis they sent you yesterday. Bottom line is a rotary evaporator can only spin so fast, but we got your back. In today’s blog post we’ll give you a few tips and tricks to speed up your rotary evaporation process.

Increase your Vessel Size

It might  sound counterintuitive to use a vessel that is considerably larger than your sample size. However, increasing your vessel size is the way to go if you’re aiming for a more efficient process. A larger vessel means an increased surface area, which means that a bigger portion of your flask will be in contact with the water in the water bath, which paves the way for a quicker and more even heating process. At the same time, using a large vessel also means that the sample inside of the flask is exposed to more air, making evaporation more efficient!

Increase your Vacuum Level

As discussed in one of our previous blog posts, using a controllable vacuum source gives you the luxury of adjusting the pressure with surgical pressure, thus providing you with your desired evaporation rate. Variating the pressure (increasing it to be more specific), will decrease the pressure, and thus make your process faster. And while this is generally true, you need to avoid a few pitfalls, like bumping and foaming. A sharp decrease in pressure can also lead to a hasty evaporation, not allowing the solvent to evaporate properly. The uncondensed vapor might end up inside of the vacuum pump, which is undesirable to say the least. Oh, and did we mention that sharp drops of pressure in your flask might make it implode?

Increase your Bath Temperature

This one’s pretty straightforward: a higher bath temperature means a higher rate of evaporation, and a more efficient process. Just make sure that your sample can handle an increased temperature without any side reactions occurring, do your best to avoid bumping, and follow the rule of 20 to avoid too much solvent vapor formation.

Increase your Rotation Speed

Last but not least, increasing the rotation speed of your evaporation flask. To better understand how this works, we need to take a closer look at the two main functions achieved by rotating the flask: It improves the heat transfer from the water bath to the solvent and the flask, and it increases the evaporation rate by increasing the surface area of the liquid inside of the flask. However, reaching too high of a speed can lead to the sample being pressed against the sides of the flask, thus greatly reducing the efficiency of the process. You want to aim for 250-280 rpm to reach optimal turbulence.

Years after “Star Wars: Episode 1 – The Phantom Menace ” was released, George Lucas revealed that the title was a reference to Palpatine concealing his identity as an evil Sith Lord behind the façade of a good-willing public servant. And while dry ice slurries aren’t nearly as evil as Sith Lords, they do pack a few “evil” disadvantages that we’ll discuss in today’s blog post (keep reading all the way for a little surprise at the end of the blog).

Rotary evaporators are widely used in chemical and biological laboratories for distillation, solvent removal, and concentration of samples. One of the techniques employed in rotary evaporation is the use of dry ice slurries to maintain low temperature during the process. However, this seemingly routine procedure can pose serious safety hazards if not handled correctly.

A director at BMS recently noted the safety concerns that arise from the use of dry ice. As experienced scientists, we understand the potential risks of exploding condensers when water builds up in the cold finger and is not emptied and/or mistaken for acetone. The resulting rapid expansion of the slurry can lead to shattered condensers, posing the risk of physical injury to the scientists.

Exploding condensers are a significant issue that is not adequately addressed particularly in university Labs. Injuries can range from Minor cuts to serious lacerations that require medical attention. According to a report published by the Centers for Disease Control and Prevention (CDC), from 2001 to 2018 there were 2578 reported lab associated injuries involving rotary evaporators with 20% of these injuries resulting from shattered glassware.

The report also revealed that rotary evaporators were the second most common equipment involved in lab-associated injuries, after pipettes. The most common type of Injuries associated with rotary evaporators were cuts, punctures, and abrasions, with the hand being the most frequently affected body part. In addition to physical injuries, exploding condensers can also lead to equipment damage and downtime, negatively impacting productivity, research progress, and causing delays. Replacing damaged or broken equipment is often costly, and the unavailability of spares can further exacerbate the situation.

To mitigate these risks, it is crucial to ensure that proper training and education are provided to scientists who use rotary evaporators. This includes educating lab personnel on the correct use of the dry ice/acetone slurries, the importance of monitoring for water build-up in the cold finger, and appropriate disposal of the mixture after use. The use of protective gear such as gloves and eye protection should be mandatory to minimize the risk of physical injury.

Expanding on the negative impact of damaged or broken equipment due to exploding condensers, it is essential to highlight the financial cost that can be incurred. Replacing a damaged or broken condenser can be an expensive affair, and in many cases, there may not be any spares readily available in the lab. This can result in a significant delay in replacing the broken part, which can negatively impact productivity and research progress. Even if the replacement part is ordered immediately, it may take several days or weeks to arrive, which can be a major setback for ongoing experiments.

Lab guidelines and procedures should be established to ensure that all laboratory personnel are aware of the risks associated with dry ice/acetone slurries and the necessary precautions to prevent accidents and injuries. Spare parts should be readily available to facilitate the timely replacement of damaged or broken equipment.

In the style of master Yoda:

Widely used in chemical and biological labs, rotary evaporators are, hmmm. For distillation, solvent removal, and concentration of samples, they are employed, yes.

One technique, dry ice slurries, is used to keep temperatures low during the process. Safety hazards, however, can arise if not handled correctly, hmmm.

A director at BMS, safety concerns recently noted. Potential risks of exploding condensers, we understand. When water builds up in the cold finger and is mistaken for acetone or not emptied, rapid expansion of the slurry can lead to shattered condensers, and physical injury to the scientists, posing a significant risk, hmmm.

Not adequately addressed, exploding condensers are, particularly in university labs. Injuries, they can cause, ranging from minor cuts to serious lacerations requiring medical attention. A report by the CDC revealed 2578 lab-associated injuries involving rotary evaporators from 2001 to 2018, with 20% resulting from shattered glassware. The second most common equipment involved in lab-associated injuries, they were, after pipettes.

Cuts, punctures, and abrasions, the most common type of injuries associated with rotary evaporators were, with the hand being the most frequently affected body part. Equipment damage and downtime, they can also lead to, negatively impacting productivity and research progress, and causing delays.

To mitigate these risks, proper training and education are crucial for scientists who use rotary evaporators. Educating lab personnel on the correct use of dry ice/acetone slurries, monitoring for water build-up in the cold finger, and appropriate disposal of the mixture after use is essential. The use of protective gear such as gloves and eye protection should be mandatory to minimize the risk of physical injury.

Expanding on the negative impact of damaged or broken equipment due to exploding condensers, essential it is to highlight the financial cost that can be incurred. An expensive affair, replacing a damaged or broken condenser can be, and in many cases, no spares readily available in the lab there may be. Result in a significant delay in replacing the broken part, this can, productivity and research progress negatively impacting. Even if the replacement part is ordered immediately, several days or weeks to arrive it may take, a major setback for ongoing experiments, this can be.

Lab guidelines and procedures should be established, to ensure that all laboratory personnel are aware of the risks associated with dry ice/acetone slurries, and necessary precautions are taken to prevent accidents and injuries. Spare parts should be readily available to facilitate the timely replacement of damaged or broken equipment, hmmm.

Using a vacuum source with your rotary evaporator comes with a significant set of advantages, like making your processes safer, more efficient, cleaner, and overall, easier. In this blog post, we’re going through all the reasons why owning a rotary evaporator is typically paired with using a vacuum source (either built-in or a vacuum pump).

Depending on the rotary evaporator you’re using, you might already have a built-in vacuum controller and you’ll only need to add a vacuum pump. However, if this isn’t the case, you’ll need to invest in both a pump and a manual (or digital) controller. Controllers don’t come cheap, but there are a few ways to decrease your cost (That we’ll discuss in a future blog post – stay tuned!).  

Controllable vacuum sources allow you to adjust the pressure with surgical precision, providing you with the desired evaporation rate. An increase in evaporation rate can therefore be achieved without having to upscale your bath’s temperature, which will allow you to achieve evaporation rates previously unattainable using a bath alone. Using a vacuum source also leads to improved solvent-product separation thanks to the controlled and even evaporation rate. It also decreases the risk of bumping (the formation of bubbles due to hasty boiling of samples; This can lead to your sample splashing out of the flask.). 

In regard to safety, using a vacuum source mitigates many risks. The decrease in boiling point of certain temperature-sensitive compounds reduces the odds of them reacting in your mixture. By reducing the pressure inside of the flask, and in tandem with it, the boiling point of your solvents, you can remove high boiling solvents in a quicker (we’re talking a few minutes, or even seconds) and safer manner. Inherently, you can work at lower bath temperatures, and use water instead of oil in heating baths. This is a safer option since using oil can leave behind residues in your evaporation flask which constitutes a fire hazard in the presence of flammable gas vapors. 

To sum it up, vacuum makes your processes safer, cheaper, and even easier (specially in cleaning – ever tried cleaning up oil off of your machine?).  

RESEARCH TRIANGLE PARK, NC, May 1, 2022 – NIRvana Sciences, Inc., the leading developer of synthetic bacteriochlorins and chlorins, today announced that it is purchasing an environmentally friendlier chiller for its rotovap system from Ecodyst, a local company in Apex, North Carolina.

Chris MacNevin, VP of Operations, said “We recently retrofitted one of our existing rotovaps with the Ecochyll X1 chiller unit and are very happy with its performance. A simple flip of the switch and the chiller is ready to go in minutes. It’s great to be free from the hassles of dry ice – no more constant refilling of the trap during solvent collection. So far it has worked well with all typical solvents with no noticeable solvent pass through. Convenient temperature control also allows for removal
of water without excessive frost buildup. Thanks to George and the team at Ecodyst for putting together a great product!”

About NIRvana Sciences
NIRvana Sciences is a spin-out from North Carolina State University with a mission to commercialize red and nearinfrared fluorescent dyes and associated probes and beads with narrow spectral properties for use in life science applications. In addition to support from NIH, NIRvana has also received support from angel investors in North and South Carolina, North Carolina Biotechnology Center (NCBC), NC IDEA and Blackstone Entrepreneurs Network. NIRvana facility is located at Alexandria Innovation Center in Research Triangle Park, NC USA.

Source: NIRvana Sciences