Bio-Rad PROTEAN II XL Cell - Manual (Page 23)

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6. Turn the central cooling core to its other side, and repeat steps 1 through 5 to attach the second gel
sandwich to it.
Note: When the gel sandwich has been properly installed, the shorter inside glass plate will be forced
against the notch in the U-shaped gasket to create a leak-proof seal. Always inspect the contact between
the gasket and glass plate to make sure the glass plate is butted against the notch in the gasket and is
not resting on top of or below this notch. Improper installation of the gel sandwich can result in buffer leak-
age during the run. As a standard procedure, pour buffer into the upper buffer compartment, and check
for buffer leaks prior to a run. In addition, we recommend marking the level of the upper buffer on the glass
plates prior to electrophoresis. Checking this level after 1-2 hours will show whether a slow leak is occur-
ring. This is especially important when the electrophoresis cell is being used for overnight experiments.
5.2 Use of the Buffer Dam
If only one gel is to be run, the acrylic buffer dam must be attached to the cooling core on the other side to
form the complete upper buffer chamber. Position the acrylic plate between two clamps by matching the
notches on the clamps to the notches on the acrylic plate (as in Section 3.1, steps 2-3), and then slide the
dam up each clamp as far as possible. No further alignment is necessary. The acrylic buffer dam fits both 16
and 20 cm clamps.
Note: We do not recommend the use of the acrylic buffer dam at elevated temperatures as the block may warp
and cause buffer leaks.
Note: Failure to slide the dam up completely to the top of the clamp will result in an upper buffer leak.