Figure 4.2.

Centrifugation is a common technique used to purify viruses away from cell debris and other small molecules. Low-speed centrifugation (~5000×g) is used to remove cells and large cell debris, leaving virions in the supernatant. Virus can be further purified and concentrated by centrifugation at higher speeds. A gradient of sucrose or glycerol can be used to achieve further purification as materials in the sample will separate into layers depending on their buoyant density.