Bio-Rad Criterion Dodeca Cell - Manual (Page 10)

b) Connect the male fittings from the refrigerated circulator to the female fittings on the
Criterion Dodeca Cell. The cooling coil in the Dodeca Cell has no specific orientation, so
it is not important which direction the flow goes.
A refrigerated circulator is not required for running Tris-HCl, TBE and TBE-Urea gels
because the large volume of buffer serves as a sufficient heat sink. However, a refrigerated
circulator is recommended to maintain a set temperature while running a large number of
Tris-Tricine gels since they produce more heat during electrophoresis. Nonetheless, the
cooling option offers additional control over the running conditions when desired.
Note: The Dodeca Cell MUST be used with a stir bar and stir plate. Stirring the buffer is
essential in maintaining a constant buffer temperature throughout the entire cell. Without this
control, the run times between the twelve gels in the tank may vary, thus altering the
migration patterns of the samples from gel to gel.
Section 3
Maintenance
3.1 General Maintenance
The Criterion Dodeca Cell lid should be rinsed after use. The tank should be rinsed
thoroughly each time it is emptied.
3.2 Draining the Tank
To drain the tank, insert the male quick-connect fitting into the drain port on the end of
the tank and allow to drain by gravity. Be sure that the open end of the tubing is placed into
a receptacle of the appropriate size, since buffer will flow out as soon as the connection is
made. Alternatively, pick up the entire tank and pour off the buffer.
3.3 Guidelines for Reusing Tank Buffer
The buffer in the lower tank may be reused up to 10 times. Sodium azide (final concentration
of 0.02%) is recommended to help minimize contamination.
The number of times the buffer is used depends on the number of gels run each time and
the conditions at which the runs are performed. The primary concern is ion depletion. Prepare
fresh buffer if the following problems appear:
• changes in protein mobility
• decrease in band sharpness
• longer run times
• a band at the bottom of the gel which is difficult or impossible to destain
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