Breaking Down the Science: How Centrifuges Separate Substances

Breaking Down the Science: How Centrifuges Separate Substances


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  • Source: Microbioz India

  • Date: 25 Jan,2024

Centrifugation is a laboratory procedure that employs the centrifugal force to distinguish components of mixture based on their mass, size and shape. This method is extensively used in different scientific and medical disciplines for undertaking useful functions such as separation of particles from liquid, extraction of cellular components, purification of substances among others.

Here is how centrifuges work:

Basic Principle:

Centrifugal Force:

Centrifugation depends on the principle of centrifugal force which is an outward force acting on a body moving in a circular path. In centrifuge, this force arises from spinning a sample rapidly about central axis.

The Centrifuge Setup:


The sample is placed within a container referred to as rotor which is connected to the central axis of the centrifuge. Depending on different types of samples and centrifuge machines, rotors are differently designed.


The acceleration phase occurs when the centrifuge starts running over time by gradually increasing its rotational speed. As this speed increases so does the resultant centrifugal force on the sample.

Separation Mechanisms:


Denser particles in a sample tube or centrifuge container move away from its axis of rotation towards its bottom due to centrifugal forces called sedimentation.


Upon reaching constant speed, balance gets established in the course of which particles within this sample undergo two mutual forces – outward-directed centrifugal one or buoyant opposing them.

Pellet Formation:

Components or particles in front part (the rear) do settle down at tube’s bottom as a pellet while those less dense stay near its top.

Types of Centrifugation:

Differential Centrifugation:

To separate components according to differences in their density through use of increasing speeds which is performed over a number of times it employs a technique referred to as differential centrifugation thus often utilized in biological research including separation of cellular organelles.

Density Gradient Centrifugation:

This involves addition of density gradient medium into the sample whereby as the spinning takes place, particles will move through it resulting in defined bands with varying densities meaning that for particles with similar sizes but different densities separation will occur because of this.

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