Bio-Rad Rotofor® and Mini Rotofor Cells - Manual (Page 5)

Section 3
Setting Up for a Run
Assemble the electrodes first. Each electrode assembly consists of an inner
and outer component, two grey silicone rubber gaskets, one ion exchange mem-
brane, two small O-rings, one large O-ring, and a vent button. To seal the elec-
trolyte within the chamber, one small O-ring is placed around the central shaft
of each component. To seal the sample within the focusing chamber, one large
O-ring is placed on the side of the inner component facing the sample.
Fig. 1. Outer (left) and inner components of the electrode assemblies. Arrows indi-
cate the O-rings. Electrolyte solutions should just cover the central shaft when filled.
Note that alignment pins prevent misassembly of the two chambers. The
four grey rubber gaskets can be used in either electrode assembly.
Ion exchange membranes are used in the electrode assemblies to separate the
electrolytes from the sample while allowing current to pass through and set up
the pH gradient. There are two types of ion exchange membranes. The anion
exchange membranes are notched to fit only the cathode electrode assembly
(black button) and the cation exchange membranes will fit only the anode elec-
trode assembly (red button). For your convenience, the membranes are pre-
equilibrated in anode and cathode electrolyte solutions.
Anion Exchange Membranes are equilibrated in 0.1 M NaOH. Use this
solution in the cathode chamber.
Cation Exchange Membranes are equilibrated in 0.1 M H
3
PO
4
. Use this
solution in the anode chamber.
3
Outer component
Inner component
Large o-ring
Central shaft
LIT603B 7/10/98 11:56 AM Page 3