How does a laboratory centrifuge work

What Is Centrifugation? Principles of Centrifugation At its core, centrifugation is separation through sedimentation. Centrifugation will displace particles that are even slightly different in density, and is influenced by these four factors: The density of the samples and solution The temperature and viscosity The distance that the particles are displaced The speed of rotation Relative centrifugal force RCF , or G-force, is the amount of acceleration that is applied to the sample.

What Is a Centrifuge Used For? How Does a Centrifuge Work? The Parts of the Centrifuge Machine At the center of the centrifuge is a powerful motor that creates the spin. How to Use a Centrifuge Machine Despite the complex principles at work in the centrifuge, operating the machine itself is quite simple.

To use a centrifuge machine: Insert the test tube sample into one of the portals If needed based on the number of samples you are testing, insert test tubes filled with water for balance Secure the lid and select desired settings Start the centrifuge and wait for it to complete the cycle When the centrifuge has stopped spinning, take out the balances and samples Each sample will now be separated into its various components and ready for analysis Knowing how a centrifuge machine works is key to using it properly.

Balancing the Centrifuge Machine When using a centrifuge machine, it is necessary to balance your samples. Balance the centrifuge machine by: Making sure all tubes are evenly filled with liquids similar in density Ensuring that the masses of the tubes are within 0.

Care and Maintenance for the Centrifuge Machine Ensure your centrifuge receives the proper care and maintenance so it provides reliable results, is safe to use and works for a long time. Regularly perform these checks: Education: Make sure that everyone who uses the centrifuge machine knows how to use it. Teach all laboratory staff how to balance samples, set speeds and take safety measures.

Inspection: An inspection will alert you to any problems with the centrifuge machine. Look at the components for scratches or effects of chemical exposure. All are signs of wear and should be fixed as soon as possible.

Awareness: When using the centrifuge, be aware of signs that something is wrong. This is where the rotor is spun inside a vacuumed chamber. Since there is no air resistance, the rotor can spin much faster. Ultracentrifuges are usually only used for very specific purposes and they are extremely expensive to buy and maintain.

Companies such as Thermo and Beckman Coulter manufacture ultracentrifuges. However, most substances will separate at such lower speeds. For example, a pathologist might spin a tube of whole blood at around 5,xg to separate the red blood cells, known as erythocytes and the plasma.

It is the plasma that the pathologist will use to perform certain clinical chemistry tests to help diagnose health disorders or conditions. Having a basic understanding of centrifugation before carrying out laboratory work is vital. For large-capacity, low-speed applications, low-speed centrifuges reaching approximately x g are available. Benchtop models have a smaller footprint, and general-purpose models are ideal for a wide range of applications.

There are many benchtop models available, including high-speed, microcentrifuge, clinical, and cell washer models. Clinical benchtop models and cell washers typically operate at lower speeds, and are suited to diagnostic applications, and washing debris from red blood cells.

It is essential to select a centrifuge that is suited to the specific application. When purchasing a centrifuge, it is important to consider the following questions:. Running an unbalanced centrifuge may cause significant damage, and injure the operator and other laboratory personnel.

The total mass of each tube should be as close as possible- this becomes increasingly important at very high rotor speeds. Balancing masses to the nearest 0.

For example, do not balance a sample consisting of liquid with a higher or lower density than water with an equal volume of water. A little vibration is normal, but excessive amounts can mean danger. First, double check that the tubes are correctly balanced. This also causes the lighter particles to be displaced and move towards the centre.

These particles are commonly known as pellets, and the clarified solution is coined the supernatant. Although you will probably set a centrifuge to spin at revolutions per minute rpm or rotational speed, it is the acceleration that is the important factor.

This is because two rotors could have different diameters but the same rotational speed. If this is the case the acceleration of the two rotors will not be the same.

Because the acceleration is a product of the radius and the square of the angular momentum, the size of the rotor becomes a contributing factor. Some common applications for centrifuges are listed below:. There are of course many more. What Types of Centrifuge Are Available? There are many types available on the market today, of which the two main factors are rotor speed and centrifuge size. Regular laboratory centrifuges exhibit all the normal properties that have been mentioned and are the standard type of centrifuge available.

Regular centrifuges are the larger centrifuges that you find in a laboratory and are known as floor model centrifuges. These types of centrifuges require more space than benchtop centrifuges , but they can hold a lot more material as the rotors and the centrifuge tubes are larger centrifuge tubes can hold up to ml.