Centrifuge tubes spinning

Laboratory centrifuges use centrifugal force to separate components of liquid mixtures, such as blood or DNA, essential in clinical analyses and research.

About this subject

A laboratory centrifuge spins sample tubes at high speed to separate materials by density. The centrifugal force pushes denser particles to the bottom, forming a pellet, while the supernatant remains on top. This technique is essential in molecular biology for purifying DNA, RNA, or proteins, and in clinical labs for separating plasma or serum from whole blood.

Centrifuges vary from bench-top microcentrifuges (up to 15,000 rpm) to ultracentrifuges (over 100,000 rpm) for isolating cell organelles or viruses. Routine lab centrifuges operate at 3,000, 5,000 rpm, enough to sediment blood cells within minutes. The choice of rotor (fixed-angle, swing-bucket) depends on sample volume and required g-force.

Safety rules include balancing tubes in pairs to avoid rotor damage, using sealed lids, and inspecting tubes for cracks. The first practical centrifuge was built by Alexander Prudden in the 19th century, but modern refrigerated models with digital controls have made it a staple in diagnostics and research.

Frequently Asked Questions

What is a laboratory centrifuge used for?

It separates components of liquid mixtures by density, such as pelleting cells, precipitating DNA, or purifying proteins, commonly in clinical and research labs.

How does centrifugation work?

The device spins sample tubes rapidly, generating centrifugal force that pushes denser particles to the bottom while the less dense liquid stays on top.

What safety precautions are needed when using a centrifuge?

Balance tubes in pairs, inspect tubes and rotor for cracks, never exceed the maximum speed, and always use a sealed lid to prevent spills.