During the extraction process, blood is first collected in a tube containing sodium citrate. Sodium citrate prevents the blood from clotting by binding to calcium ions, which are necessary for the formation of blood clots. This allows for the separation of plasma from the other components of the blood. The plasma is then used for DNA extraction.

Sodium citrate is also used in other applications where anticoagulation is necessary, such as in the collection of blood samples for medical testing or in the preservation of organs for transplant.