A magnetic stirrer is laboratory equipment that uses a rotating magnetic field to mix one or more solutes with a solvent in an automated way. It is considered the most widely used type of stirrer, since it is silent, efficient and does not have direct contact with the sample.
This equipment has the ability to heat chemical solutions, minimizing the risk of a solution being altered, since generally when the solutions are stirred manually they tend to become contaminated.
This electronic device is commonly used in food manufacturing and chemical research, as well as in research laboratories. There are multiple types of magnetic stirrers, and each of them have specific functions and characteristics.
How is a magnetic stirrer composed?
This type of mixer is made up of a plate with a magnet or a series of electromagnetics, arranged in a circular shape at the bottom, which create a rotating magnetic field that acts by means of an electric motor controlled by an electronic device.
The (magnetic) stir bar, normally covered with an inert film such as Teflon, is placed inside the container and the beaker or container is placed on top of the plate. Once started, the stirring bar begins to rotate, propelled by the electric motor that moves the magnets. The size and shape of the magnetic bar determine the effectiveness of the stirring process, considering a constant speed. Some models of magnetic stirrers also have a heating system – some reach up to 300ºC – to heat the samples at the same time as they are stirred.
Types of magnetic stirrers
- Magnetic stirrers without heating: Useful, if you simply want to stir a sample.
- Heated magnetic stirrers: Very useful when, in addition to shaking the sample, you also need to heat it.
- Magnetic stirrers with heating and temperature probe: Necessary when you need to know the temperature at which the sample is.
- Timer magnetic stirrers: If a solution needs to be stirred for an exact amount of time and the stirring stops automatically at the end of an experiment.
- Multiple magnetic stirrer: Useful when you need to shake several containers at the same time and at the same speed.
What is a laboratory magnetic stirrer for?
As we mentioned, a magnetic stirrer is used to mix liquids with each other or with powders, to produce solutions, fluid or viscous dispersions, as well as suspensions. They are very useful in biology or chemistry laboratories, since these types of tools tend to be needed to carry out many mixtures.
They are silent equipment, they do not break easily because they do not have moving parts that can break. They are also easy to clean thanks to their small size.
This device serves to reduce the contamination of the reagents, normally when using motorized stirrers these need to be lubricated and for this reason there is a risk of contamination.
Uses of a Laboratory Magnetic Stirrer
When using the magnetic stirrer you must place the flask or beaker ready with the content of the solution that you are going to stir on the stirring plate, then insert the magnetic bar into the container and then turn on the device, adjust the speed .
Starting with the slowest speed to increase it progressively you will get the result you want. You must control that the liquid does not spill in the process and when the stirring is finished, remember to return the device to its initial speed and turn off the equipment, finally remove the stirring bar from the container.