Bio-Rad Criterion™ Blotter - Manual (Page 6)

4. Set up the gel/membrane sandwich:
a. Pour chilled transfer buffer into each compartment of the gel/blot assembly tray.
b. Place the membrane (nitrocellulose, PVDF, etc.) in the front/small compartment of
the tray. Let it soak while you set up steps c–g.
c. Place the cassette in the back/large compartment of the tray: Open the cassette so
that the red side with the handle is vertical (anode) and the black side (cathode) is
laying horizontal and submerged in transfer buffer.
d. Place a fiber pad on top of the black side of the cassette, submerged in buffer. Push
on the fiber pad with gloved finger tips to thoroughly soak the pad.
e. Place a piece of filter paper on top of the fiber pad (it will wet immediately).
f. Gently place the pre-equilibrated gel on top of the filter paper. Use the roller to remove
any air bubbles that may be trapped underneath the gel.
g. Take the membrane from the front compartment and place it on top of the gel taking
care not to trap any air bubbles. The membrane should not be moved or adjusted
once it touches the gel because this can cause data ghost prints and artifacts. If you
feel that you must adjust the membrane placement, use a fresh pre-wetted membrane.
Use the roller to roll out bubbles (see figure).
4
Fiber pad
Blot absorbant paper
Membrane
Gel
Blot absorbant paper
Fiber pad