Magnetic Stirrers: A Key Tool for Efficient and Precise Mixing in the Lab

A magnetic stirrer is a common piece of laboratory equipment that uses a rotating magnetic field generated by a rotating magnet or a stationary electromagnet to rotate a stirring bar immersed in a liquid to stir or mix a solution rapidly. It is ideal for stirring scientific work, business, agriculture, healthcare, home brewing, and more. Let's take a look at some frequently asked questions about magnetic stirrers.

Principle of Magnetic Stirrer:

Magnetic stirrers work on the principle that opposites attract and opposites repel. The magnetic field is used to push the stirring bar to rotate so as to achieve the purpose of stirring the liquid. Magnetic stirrers are generally equipped with a temperature control system, which can heat the sample according to the experimental requirements to ensure that the mixture meets the experimental needs.

Composition of Magnetic Stirrer:

Magnetic stirrers have two main components: the stirring bar and the magnetic heating plate.

Generally, they are composed of power cord, cross clamp, stirring bar, temperature-sensitive probe holder, stand and magnetic stirrer.

Components of Magnetic Stirrer:

Top plate/heating plate: Usually stainless steel or ceramic material.

1. Ceramic: Ceramic top heating plates are highly resistant to chemicals, making them ideal for use when dealing with aggressive chemicals that may splash onto the plate surface.

2. Stainless steel: Stainless steel top plates provide a highly potent coupling and stirring action as it does not generate eddy currents (e.g., aluminum).

3. Stirring bar: Used to stir the solution.

4. Fixed solenoid: Located inside the stirrer and helps to generate a magnetic field. It rotates the stirring bar immersed in the liquid, thus stirring at high speed.

5. Speed Knob: The speed knob is used to adjust the speed (rpm) of the stirring bar according to the density of the liquid or the needs of the project.

6. Temperature control knob: The magnetic stirrer has a temperature control knob that controls the temperature according to the size of the vessel, viscosity and volume of the liquid.

Operating Procedure of Magnetic Stirrer:

The use of a magnetic heating stirrer is as follows:

1. Preparation:

Prepare the required reagents or materials into the container or test tube equipped with the magnetic stirrer and make sure the container or test tube is clean and free of impurities.

2. Set the temperature and speed:

According to the experimental needs, set the temperature and speed of the magnetic stirrer through the digital display screen. You can choose the suitable temperature and speed according to the nature of reagents or materials to achieve the stirring effect.

3. Magnetic stirrer setting:

Place the magnetic stirrer on a smooth tabletop and place the magnetic bar of the magnetic stirrer in the container or test tube. Adjust the position of the magnetic bar so that it can just touch the bottom of the container or test tube.

4. Start the magnetic stirrer:

Connect the power supply and press the start button of the magnetic stirrer to start stirring. During the stirring process, you can adjust the speed and temperature as needed.

5. End stirring:

At the end of the experiment, stop the operation of the magnetic stirrer and then unplug the power cord. Remove the container or test tube, clean the container or test tube, and clean and sterilize the magnetic bar.

Types of Magnetic Stirrers

Conventional Magnetic Stirrers

Mini Magnetic Stirrer

Laboratory magnetic stirrers for use in the laboratory are compact and require less space. They have electronic controls that enable the user to manage the speed precisely. It can withstand destructive and corrosive substances in the laboratory. The speed regulator manages the speed per minute (rpm) of the stirrer.

Hotplate Magnetic Stirrer

Hotplate Magnetic Stirrers have a high mixing capacity. They are also very robust and exhibit good chemical resistance. They may be the ideal instrument for precise discovery in the laboratory. Most chemical reactions require a heated magnetic stirrer.

Multi-position Magnetic Stirrer

Application of Magnetic Stirrer:

The magnetic stirrer is a laboratory instrument used for mixing liquids, mainly used for stirring or simultaneous heating and stirring low-viscosity liquids or solid-liquid mixtures. It is widely used in chemical laboratories for chemical experiments and synthesis by mixing two or more ingredients.

Used in microbiology laboratories to prepare media for the cultivation of microorganisms.

Preparation of samples and analyses in chemical and biological experiments.

Used to achieve maximum possible extraction efficiency of plant material by reducing organic solvent consumption.

Other applications include oil analysis, soil suspension, buffer solution preparation, pH measurements, etc., where multiple types of liquids need to be mixed to achieve homogeneous mixing.

Advantages of magnetic stirrers:

It makes it possible to mix reagents at a constant temperature.

Response rate and evaporation rate are improved.

It makes it possible to perform persistent procedures such as protein dialysis.

The mixing process is safer and pollution-free

They guarantee excellent productivity and precision compared to electronic stirrers and are quiet and easy to use.

The absence of moving external parts does not lead to breakage and wear.

Compact size and small footprint.

Limitations of magnetic stirrers

Not suitable for dispersing nanoparticles

Viscous liquids or viscous suspensions are difficult to handle with magnetic stirrers.

Precautions:

Stirring and heating time should not be too long, intermittent use to prolong life, and no heating when not stirring.

When not in use for a long time, please switch off the power and put the item in a dry and ventilated place.