A rotary evaporator (rotovap or rotatvap) refers to a kind of equipment for solvent evaporation under reduced pressure, which is composed of a vacuum system, a heated water or oil bath, a condenser and a motor that rotates the evaporation flask. As its name suggests, what is special is that the evaporation flask can rotate.
Rotary Evaporators’ Extraction Method
Rotary evaporators extract and concentrate substances from mixtures by heating and evaporating sample materials according to the different boiling points of substances within mixtures. The basic principle of rotary evaporators is the vacuum distillation of the distillation flask under continuous rotation. Many people still wonder the very specific details of rotary evaporators’ extraction method, which will be introduced next.
The extraction process starts with the water oil bath. Firstly, set up the heating temperature of the water oil bath, which are supposed to be same as the boiling point of the components to be extracted. Due to the boiling points will be reduced with decreasing pressure, the components’s boiling points will lower than that under normal pressure. After the components to be extracted get evaporated successfully, it will be transferred into the condenser where gas-phase substance will be cooled down and becomes liquid-phase. The liquid-phase substance is easier to be collected than the gas-phase substance. Finally, after the gas-phase becomes liquid-phase, the extracted substance will go into the receiving flask, which is easy for users to collect.
Improvement of Rotary Evaporators’ Extraction Method
The rotary evaporator method, liquid-liquid extraction can extract substances efficiently, but it still has some disadvantages. So people use solid phase extraction (SPE), which was used for the formulation of several radiopharmaceuticals for a better use. Due to its high efficiency, reliability, and low consumption of reagents, it has replaced traditional liquid-liquid extraction in many fields and has become an effective means for sample preparation.
How does a Rotary Evaporator Work?
A rotavap evaporates solvents from samples by utilizing the principle that the solvent will have a lower boiling point at a reduced pressure. Specifically speaking, the stepless speed regulation is adopted to make the evaporation flask rotate at a constant speed. By the rotation, materials can form a large area of uniform thin film on the inner wall of the flask. The evaporation flask is heated evenly by a water or oil bath, and materials, with a lower boiling point, is evaporated rapidly under the vacuum condition. The solvent steam is recycled in the receiving flask after being cooled by the high efficiency glass condenser.