What is a primary function of sodium citrate in phlebotomy?

Sodium citrate serves as an anticoagulant in phlebotomy, primarily through its ability to chelate calcium. Calcium ions are crucial for blood coagulation; when they are bound by sodium citrate, the clotting process is effectively inhibited. This makes sodium citrate particularly useful for collecting blood samples intended for certain laboratory tests, such as coagulation studies, where it is essential to maintain the blood in a liquid state to obtain accurate results.

The other options do not accurately describe the role of sodium citrate in phlebotomy. Enhancing blood flow relates more to factors like vein assessment and patient positioning, while sterilization of the sample involves antiseptics or other methods rather than sodium citrate. Additionally, providing nutrients to the blood sample is not the function of sodium citrate, as its role focuses specifically on preventing clotting rather than nourishing the sample.