lab-rotovap

Solvent extraction and distillation are the most common processes in chemistry labs. These processes make it possible to separate the debris from the valuable materials. As such, laboratories have special machinery to accommodate these procedures in their research.

Many types of lab equipment can perform these processes. However, most chemists prefer rotary evaporators, also known as rotovap. But what is a rotovap? And how does a rotovap work?

What is a rotovap?


A rotary evaporator—or rotovap—is a standard tool in extraction laboratories that gently and effectively evaporates solvents from samples through high temperatures and reduced pressure levels. The rotary evaporation technique is popular for its superior extraction and distillation capabilities.

This method typically separates substances, especially when working with "low boiling" solvents that are solid at room temperature and pressure. Examples of these solvent types are butane and ethyl alcohol. Rotary evaporation may also extract solvents from other samples such as organic, inorganic, and polymeric materials.

Rotovaps are also helpful in various processes such as concentration, crystallization, drying, separation, and solvent recovery. As such, rotovaps have multiple applications in the pharmaceutical, chemical, and biotechnology industries.

How does a rotovap work?


The idea behind rotary evaporators is that different solvents have different boiling points that can decrease when you lower the pressure. 

The components of a solvent separate as the evaporation flask rotates at a specific speed. This event causes the samples to cover the flask's inner walls, forming a thin film. Evenly heating the flask with a heated fluid bath, which often consists of water, will cause the components with a lower boiling point to evaporate quickly. 

The distilling solvent is captured in a condensate-collecting flask at the bottom of the condenser after the solvent re-condenses. Once done, a motorized mechanism lifts the evaporation flask from the heating bath. Other vital parts of the rotovap include the motor unit, vapor duct, and vacuum system.

A vacuum pump is sometimes necessary for rotary evaporation as a heat source for distillation, but working with non-toxic solvents doesn't usually require complicated vacuum systems. These solvents may even be processed in a water aspirator with a trap submerged in a cold bath. 

However, other types of solvents may need a more robust vacuum system. It may have a complex structure controlled by a mechanical vacuum pump and a refrigerated trap.

How to Choose a Rotovap for Your Lab


If you're planning to invest in a rotary evaporator for your laboratory, consider the following factors to ensure your choice suits the processes and solvents you frequently work with.

1. Solvent type

The solvent type informs the solvent's properties, enabling you to understand better the total vacuum needed. For example, the boiling point of ethanol is 78°C without a vacuum, but this reduces to 31.5°C at 100 mmHg vacuum pressure. A rotary evaporator's vacuum pump reduces a solvent's pressure and lowers its boiling point.

2. Evaporation speed

Many factors can affect a rotovap's evaporation speed. These considerations include the sample bottle's rotation speed, the rotovap's degree of vacuum, the water bath's temperature, and the efficiency of the condensation recovery unit.

Precise control over the rotational speed of an evaporation flask is crucial since the rotating motion agitates the water bath and solution, causing the heat transfer from the flask to the solvent to speed up.

However, some samples are highly sensitive to heat and may get ruined. In such cases, balancing all evaporation speed factors is vital. Additionally, you need to monitor samples with low boiling points to ensure the bath temperature doesn't exceed the optimal threshold.

3. Materials

Some lab samples may contain corrosive fluids like acids and bases. However, these sample types can harm the material of your evaporator. 

As such, you need to know what comprises the inside of your rotary evaporator. If you're testing corrosive fluids, getting a rotary evaporator made of steel or materials that can withstand acids is your best alternative.

4. Volume of sample

The sample volume helps in determining the flask size needed. Rotary evaporators on the market come in varying volumes, ranging from 0.25 to 50 liters. 

Smaller models are best suited when working with only a few samples. However, bigger batches may require an industrial model that can hold a large volume at a time. This model may also be beneficial if you need to scale up.

5. Available space

It's also essential to consider the available space in your laboratory. Rotary evaporators may require additional space for their paraphernalia. This space consumption issue may become problematic if you use other lab equipment. 

Measuring the available space in your lab before making any purchases would be best. You can choose from either a benchtop model or one that can stand on its own on the floor. Whatever you choose, ensure that it doesn't disrupt your lab's workflow.

Work with the Right Lab Equipment


Frequent solvent extraction and distillation processes call for rotary evaporators in laboratories. It's a piece of equipment that can help when doing research work, and understanding these machines and their work can help maximize their use. 

To fully reap its benefits, choose a reliable lab equipment manufacturer that produces quality rotovaps capable of improving research accuracy without worrying about equipment fragility. 

If you want to upgrade your equipment, Across International offers a wide range of rotary evaporators and other lab equipment. Our UL/CSA-certified and CE-compliant rotovaps offer high distillation rates and are easy to operate. They come with adapters that allow for various flask sizes, depending on the distilling solvent's volume. Our rotovap models range from 2 to 50 liters, addressing your varying distillation needs. 

Give your lab a boost in efficiency! Check out our rotary evaporators or request a quote today.