A device particularly suited for collecting and dispensing an arterial blood sample. A needle is connected to a flexible transparent tube that includes an air exit vent with a nonwet filter so air, but not blood, can exit the vent under arterial blood pressure. A special needle adapter prevents formation of air bubbles, and a baffle system in the needle minimizes blood and air mixing. A clamp on the reservoir pinches off an air contaminated blood segment and can longitudinally strip a different blood segment which is not air contaminated. The tubular reservoir has an oxygen blocking coating, and its internal surface includes a dry anticoagulant coating.