Membrane transfer method and tool

A method of transferring a filter membrane bearing a retentate to a reagent pad, wherein:

• the membrane is mounted in a support frame having a shoulder and a skirt projecting from the shoulder;
• the pad having a membrane contact surface that is substantially flat, the pad being mounted on a cassette of complementary form to said skirt, the pad not being a gel growth medium;
• the skirt being adapted to slide sealingly on the cassette until it comes into abutment formed by the shoulder;
• the method comprising:
• sealingly engaging the skirt of the membrane support frame on the cassette;
• establishing a predetermined pressure difference between the cassette and the membrane support frame such that the membrane takes the form of a dome pointing towards the pad, said pressure difference being a pressure reduction applied in a space between the membrane and the cassette;
• while maintaining the pressure difference, applying a force on the frame so as to make the skirt slide on the cassette until contact is established between the end of the dome and the membrane contact surface of the pad;
• maintaining a force on the frame so as to make the frame move downward until it comes into abutment formed by the shoulder while maintaining the pressure difference, thereby uniformly transferring said filter membrane to said membrane contact surface of the pad.