The tubes contain EDTA, preventing blood from clotting by binding calcium ions.
Anticoagulant: EDTA potassium salt (ethylenediaminetetraacetate).
Specimen: whole blood.
Immediately after the specimen is collected, gently invert the EDTA tube 9-10 times to mix thoroughly.
Insufficient mixing could lead to platelet aggregation, microclot formation or coagulation.