Final answer:
Heparin is an anticoagulant substance used to prevent blood from clotting. The dosage of heparin needed depends on the blood volume and specific requirements of the situation.
Step-by-step explanation:
Heparin is an anticoagulant substance that opposes coagulation. It is commonly used in clinical settings to prevent blood from clotting. The amount of heparin needed depends on the blood volume. In this case, you have 2 ml of blood, so you would need to use a certain volume of heparin to prevent coagulation for over 15 minutes.
The exact dosage of heparin would need to be determined by a healthcare professional based on the specific requirements of the situation.