Which color cap is used for serum separator tubes?

The color cap that indicates a serum separator tube is gold or tiger top. These tubes contain a gel that serves as a separator, allowing for the separation of serum from the cellular components of the blood after centrifugation. This separation is crucial for many laboratory tests, as it prevents the cells from interfering with the analysis of serum.

In the context of blood collection, the serum separator tube is specifically designed for the collection of serum, which is the liquid portion of the blood that remains after coagulation. The gel forms a barrier between the serum and the cells following centrifugation, making it easy for laboratory personnel to obtain a pure serum sample for testing.

In contrast, the other colors—green, red, and blue—represent different additive compositions and purposes for blood collection, such as heparin in green, no additives in red, and citrate in blue, which are used for specific tests that do not require serum. This difference highlights the importance of selecting the appropriate tube based on the specific needs of the test being performed. Therefore, the gold or tiger top cap is essential for obtaining serum samples, making it the correct answer in this context.