Answer is D (All of the above) Dilution of a sample with heparin can cause erroneously low value for pH, pCO2 and HCO3-. Heparin and Blood Gas Measurements Heparin is the preferred anticoagulant for blood gas specimens Heparin is used in blood gas syringes to avoid coagulation of the blood sample, as clots interfere with the function of the blood gas analyzer. Heparinization of blood sample also limits the deposition of proteins on the electrodes. However excess heparin can affect blood gas analysis by lowering the PaCO2 and calulcated HCO3- by dilutional effect and the pH as heparin is acidic.