Laboratory separation method · BEGINNER LESSON
Centrifugation
Centrifugation is a laboratory method for separating substances by density by spinning a sample so particles move outward at different rates. It measures how particles respond to centrifugal force and hydrodynamic drag, which changes their sedimentation or migration behavior.
What it is and what is measured
Centrifugation is a common lab technique for separating substances in a sample by density. A spinning rotor gives particles angular velocity, and the process is judged by how fast they move away from the rotation axis or how they settle in a tube. In centrifugal filtration, the spin also creates transmembrane pressure, which drives liquid through a filter.
[1] Theory‐Guided Low‐Speed Centrifugation for High‐Purity Boron ... [3] Analytical Centrifugal Ultrafiltration as a Tool for High ... - PMC
How separation happens
When a sample spins, particles experience an outward centrifugal force. Their motion is not determined by force alone: the surrounding fluid pushes back with hydrodynamic drag. Because particles can differ in effective mass, size, density, and resistance to moving through fluid, they migrate at different rates. In density-gradient methods, a particle may remain in place where the medium has a similar density, rather than continuing to sink or rise.
[1] Theory‐Guided Low‐Speed Centrifugation for High‐Purity Boron ... [2] Table 4.
Why speed matters
The rotation speed changes both the driving force and the stress on the sample or device. High-speed spinning can help particles sediment faster, but it can also cause problems. One source describes cosedimentation, where similar-density materials separate poorly and end up together. Another source notes that at higher speed in centrifugal ultrafiltration, pressure can damage the filter, causing breakthrough of material that should have been retained.
[1] Theory‐Guided Low‐Speed Centrifugation for High‐Purity Boron ... [3] Analytical Centrifugal Ultrafiltration as a Tool for High ... - PMC
Limitations and trade-offs
Centrifugation is useful, but it is not perfect. Very strong spinning can require specialized equipment, reduce practical throughput, and create mechanical stress. In some cases it can lower purity, reduce yield, or damage fragile particles and filters. The best choice depends on the sample, the size of the particles, and whether the goal is sedimentation, purification, or filtration.
[1] Theory‐Guided Low‐Speed Centrifugation for High‐Purity Boron ... [2] Table 4. [3] Analytical Centrifugal Ultrafiltration as a Tool for High ... - PMC
SEE THE IDEA
How centrifugation separates a sample
A rotor turns the tube or device at a chosen speed.
Particles are driven outward from the rotation axis.
Fluid resistance and particle properties make some move faster than others.
Particles settle, stay in a gradient layer, or pass through a filter differently.
Spinning creates force; force plus drag and density differences produce separation.
Centrifugation links rotation to particle motion, but the final result depends on both sample properties and the device used.
TRY IT YOURSELF
Test your understanding
Choose an answer, then check the explanation.
PUT IT TOGETHER
Match each concept to its meaning
Drag a label onto its description, or select a label and then select a description. This also works with a keyboard.
4 pairs to match
Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.