What is in a serum separator tube?

Serum separator tubes (SSTs) are used in blood collection for the purpose of obtaining serum, which is the fluid component of blood that remains after the removal of red blood cells, white blood cells, and platelets. Here's what is typically found in a serum separator tube:

1. Gel Barrier: SSTs contain a gel barrier made of inert material, such as silica-based gel or polymer gel. This gel forms a physical barrier between the clotted blood and the serum during centrifugation.

2. Clot Activator: The tube contains a clot activator, which is usually a chemical substance such as silica particles, kaolin, or glass beads. These particles accelerate the blood clotting process by activating the coagulation cascade.

3. Serum Separator: After centrifugation, the gel barrier forms a firm barrier that separates the clotted blood components (red blood cells, white blood cells, platelets, and fibrin) from the serum. This clear separation allows for easy collection of serum without disturbing the cellular components.

4. Vacuum: SSTs are typically evacuated to create a vacuum within the tube. This vacuum facilitates the flow of blood into the tube, ensuring a proper blood-to-additive ratio and minimizing the risk of hemolysis (rupture of red blood cells).

5. Additives: Some serum separator tubes may contain additives to enhance the quality and stability of the serum. Common additives include:

- Thrombin: This enzyme speeds up the clotting process, ensuring complete separation of serum from the clot.

- Gel Enhancer: This component strengthens the gel barrier, ensuring a clear separation between serum and clot.

- Preservatives: Some SSTs contain preservatives, such as sodium azide or potassium fluoride, to inhibit bacterial or fungal growth and preserve the integrity of the serum for longer durations.

It's important to follow proper blood collection and handling protocols to ensure accurate laboratory results when using serum separator tubes.