Bio-Rad Model 491 Prep Cell and Mini Prep Cell - Manual (Page 20)

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3.6 Cooling the Gel
First, determine which setting on the buffer recircu lation pump will provide a flow rate of ~100 ml/min. Next,
using the tubing pro vided with the Model 491 prep cell, connect the outlet of the buffer pump to the inlet
(stopcock) of the lower buffer chamber. Then connect the tubing exiting from the top of the cooling core to
the inlet of the buffer pump. Open the valve and set the pump speed at the maximal setting for a few
minutes to purge air from the lines. Then, reset the pump speed to 80–100 ml/min.
For separation of native proteins where colder temperatures are desirable a 2–3 me ter length of tubing can
be submerged in an ice bath, or an external re frigerator bath. The extra tubing should be placed in line
between the buffer recirculation pump outlet and the inlet to the lower buffer chamber. The Model 491 prep
cell can also be run in a cold room to keep fractions cold once they have been collected.
Fig. 9. Cooling pathway during electrophoresis. Heat generated in the gel during elec trophoresis is drawn off by means of both the
cooling core and the lower buffer cham ber. Electrophoresis buffer from the lower buffer chamber is pumped through the cooling core
which main tains an even cross sectional temperature within the gel.
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