Low-Speed Centrifuges. This group comprises the most commonly used centrifuge in medical laboratories, the benchtop centrifuge. They have a variety of uses but are mainly used for spinning down blood and urine samples. They typically have a speed ranging from around 4,000 to 6,000 RPM and an RCF of 3,000 to 7,000 g (more about RPM and RCF later).
High-Speed Centrifuges. These centrifuges are primarily used in more sophisticated biological applications such as DNA and RNA studies. Their speed usually ranges from 15,000 to 20,000 RPM with an RCF between 10,000 to 50,000 g. Normally they are refrigerated since temperature control is essential when working with sensitive biological samples.
Ultracentrifuges. These centrifuges are very sophisticated and expensive. They have a speed of 65,000 RPM and greater with an RCF of 100,000 to one million g. Intense heat is generated because of their high speed, so the spin chamber must be refrigerated and kept under vacuum. Ultracentrifuges may be preparative or analytical.
Microcentrifuges. Also called “microfuges,” these special bench-top centrifuges are used to process small volumes of liquid of 0.2, 0.5, 1.5, and 2.0 mL. They may or may not have refrigeration and spin at a maximum speed of 12,000 to 13,000 RPM (up to 30,000 g). They are mostly used for pelleting nucleic acids and proteins from solution. Pelleting is the term meaning to make into a small solid or densely packed ball or mass.
