Final answer:
Potassium Citrate is not typically used as an anticoagulant in blood collection tubes, unlike Lithium Heparin, Sodium Heparin, and EDTA, which are common anticoagulants used to prevent clotting by binding calcium or enhancing antithrombin activity.
Step-by-step explanation:
The question involves identifying which substance listed is not an anticoagulant used in blood collection tubes. Anticoagulants like lithium heparin, sodium heparin, and EDTA (ethylenediaminetetra-acetic acid) are commonly used in blood collection tubes to prevent clotting by various mechanisms. For instance, EDTA works by binding to calcium ions, which are necessary for the coagulation cascade, thus inhibiting the process of clotting. Both forms of heparin act as anticoagulants by enhancing the activity of antithrombin, which in turn inactivates thrombin and other clotting factors. Hence, Potassium Citrate is the correct answer since it is typically not used for anticoagulation in blood collection tubes; it is a citrate salt, which can act as an anticoagulant by a mechanism similar to EDTA, but it's not commonly used in collection tubes for plasma processing as the options listed.