In the evacuated tube color-coding system, which color is typically associated with SST tubes used for chemistry tests?

• A. Lavender
• B. Gold
• C. Green
• D. Light Blue

Answer: (B)

SST tubes are designed to provide serum for chemistry tests, and their color signaling uses a gold top. The gold-topped SST tube contains a clot activator and a serum separator gel. After the blood clots and the gel forms a barrier, centrifugation yields clean serum with minimal cellular contamination, which many chemistry assays require. That combination—clot activation to form serum, plus a gel separator for a stable serum/plasma interface—makes the gold color the standard indicator for SST tubes used in chemistry. Other colors indicate different additives and uses: lavender for EDTA in hematology, green for heparin in chemistry using plasma, and light blue for sodium citrate in coagulation studies.