Final answer:
EDTA, an anticoagulant, is used in blood collection tubes that are usually identified by their lavender or purple tops. These tubes prevent coagulation and are essential for obtaining plasma for diagnostic tests.
Step-by-step explanation:
The anticoagulant EDTA is commonly used in blood collection tubes to prevent coagulation and maintain the blood sample in a state suitable for analysis. When it comes to the color top of these tubes, EDTA tubes are typically recognized by their lavender or purple caps. These tubes contain either K2EDTA or dipotassium ethylenediaminetetra-acetic acid, which bind to calcium ions in the blood to prevent clotting. Once collected, blood samples are centrifuged to obtain plasma, which can then be used for various diagnostic tests.