The present invention relates to a process and apparatus for separating blood plasma, having a mixing unit in the form of a first injection having a first connecting tube and a first piston to provide a compartment for a mixture composed of plasma to be separated and the protein-precipitating agent; a separating unit composed of a filtering tube for separating and preserving a solid material after separation. The filtering tube includes a third connecting tube a filter and a third piston, the third connecting tube communicates with the fourth injection tube having a fourth piston for receiving a separated liquid; and a storage unit in the form of a fifth injection tube having a fifth connecting tube, a second connecting valve and a fifth piston.