Bio-Rad Rotofor® and Mini Rotofor Cells User Manual

Page 9

Section 2
Description of Major Components

Fig. 2.1. Rotofor components. Harvesting apparatus (1), safety cover (2), housing (3), cooling finger
(4), electrode assemblies (5), O-rings (6), ion exchange membranes (7), vent buttons (8), sealing tape
(9), membrane core (10), focusing chamber (11), cell covers (12), test tube rack (13).

Focusing chambers - Two focusing chambers are available with the Rotofor

cell. The Mini focusing chamber holds 18 ml of sample and should be used for
fractionating micrograms to milligrams of total protein. The Mini chamber is also
ideal for refractionation. The standard chamber holds from 35 to 60 ml of sample
and is used to fractionate milligrams to 3 grams of total protein. The focusing
chambers are machined acrylic cylinders 120 mm long. Twenty evenly-spaced
ports are bored in opposite sides for sample filling and collection.

Membrane core - The membrane core divides the focusing chamber into 20

compartments. The core assembly is a stack of 19 membrane units made from
monofilament polyester screens of 10 µm nominal pore size. This assembly is
inserted in the focusing chamber to stabilize the zones of focused proteins.

Electrode assemblies - There are two electrode assemblies. The assemblies

hold the cathode and anode electrolyte solutions and provide electrical contact
between the focusing chamber and the power supply. They are not interchangeable;
alignment pins prevent improper assembly. Ion exchange membranes, inserted in
the assemblies, isolate the electrolytes from the sample in the focusing chamber
while allowing establishment of an electrical field across the chamber. A plastic gear
mounted on the cathode assembly engages the drive motor to rotate the focusing
chamber.

Ion exchange membranes - Ion exchange membranes are used in the electrode

assemblies to separate the electrolytes from the sample while allowing current