Abstract: An improved device and process of assuring separation of an anticoagulant type fluid from a saline type fluid each of which is utilized in the process and operation of a plasma-pheresis apparatus or the process of collecting donor blood, is disclosed. The improvement includes a cross-spike prevention receptacle which is dimensioned, and installed positionally in reference to a plasmapheresis or blood donor apparatus, to receive an anticoagulant fluid container to which a proper respective supply communication line will connect, and to exclude and not receive a saline fluid container or container holding a similar type of fluid, whose fluid line will not reach and connect to the installed cross-spike prevention receptacle.