Final answer:
For a chemistry test requiring serum, use an SST as it allows the blood to clot and the serum to be separated from the clot. EDTA, PST, and SPS are not suitable for collecting serum as they are either anticoagulants or used for other types of testing.
Step-by-step explanation:
When collecting a blood sample for a chemistry test that requires serum, the appropriate tube to use is an SST (Serum Separator Tube). Serum is the liquid fraction of blood after the blood has clotted and the clotting factors have been removed. This differs from plasma, which is obtained from blood that has been treated with anticoagulants such as EDTA (Ethylenediaminetetraacetic acid) and has not been allowed to clot.
The other options listed, such as EDTA, PST, and SPS (Sodium Polyanethol Sulfonate), serve different purposes. EDTA is an anticoagulant that is primarily used to preserve blood cells and prevent clotting, thus it is used for obtaining plasma, not serum. PST refers to Plasma Separator Tubes that contain heparin, which also prevents clotting and is used for plasma collection. SPS is used for microbiology testing and is not suitable for chemistry tests that require serum.