How long should blood tubes spin to ensure complete separation of serum?

To ensure complete separation of serum from the cellular components of blood, it is generally accepted that centrifugation should occur for about 10 minutes. This time allows for effective separation, enabling the heavier cellular components (like red and white blood cells and platelets) to sediment at the bottom of the tube while the lighter serum remains above them.

Spinning for a shorter duration, such as 5 minutes, may not provide sufficient time for complete separation, leading to mixed samples that can affect test results. If the tubes are spun for 15 or 20 minutes, while they may still achieve separation, the increased spin time could potentially disrupt the serum layer or lead to hemolysis of the cells, which can also compromise the integrity of the sample. Therefore, 10 minutes is considered the optimal time for achieving reliable and consistent separation of serum.