Abstract: An apparatus for analyzing blood comprises a conduit formed with a passageway. The conduit is also formed with an inlet, an outlet and an aperture, each of which are in fluid communication with the passageway. An adapter is threadably engageable with the conduit to hold a membrane therebetween over the aperture. A syringe is engageable with the outlet to draw blood into the passageway through the inlet and into contact with the membrane. The electrode of a blood gas analyzer is engageable with the adapter to position the electrode against the side of the membrane opposite the side in contact with the blood for analyzing the oxygen status of the blood.