Final answer:
Potassium oxalate is the anticoagulant additive that binds calcium in blood samples to prevent coagulation.
Step-by-step explanation:
Calcium Binding Anticoagulant Additive
In a laboratory setting, when blood is drawn for testing, anticoagulants are used to prevent coagulation. One such anticoagulant is potassium oxalate, denoted as K2C2O4. Its role is to chelate calcium ions, which are essential for the coagulation process. The question specifically asks which additive binds calcium. From the information provided, potassium oxalate is used to remove calcium as a precipitate of CaC2O4 H2O. Thus, out of the options given, potassium oxalate (option b) is the additive that binds calcium.
Blood serum naturally contains calcium ions (Ca2+) which are necessary for the clotting process. To ensure that blood samples do not coagulate during laboratory tests, it is crucial to reduce the level of these ions significantly. Adding potassium oxalate to a blood sample effectively reduces the Ca2+ levels, preventing coagulation by forming a precipitate with calcium.
In conclusion, when considering the additives mentioned—sodium citrate, potassium oxalate, sodium fluoride, heparin—the one that binds calcium is potassium oxalate.