Hoefer SG15 - Manual (Page 5)

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1
Make sure all parts are clean and liquid flows freely
through all channels, stopcocks and tubing.
2
Add a magnetic stir bar of the appropriate dimensions
to the mixing chamber (Table 1) and place the unit
on a magnetic stirrer. If volumes will be less than half
the capacity of the unit, an identical stir bar should
be placed in the reservoir chamber as well to balance
the displacement and prevent backflow into the reser-
voir when the chambers are first connected. Connect
tubing to the outlet connector and pump, and adjust
pump speed, if used. Position or connect the tubing
to the receiving vessel (gel casting unit, centrifuge
tube, etc.).
3
Close both stopcocks (handles up) and add the
required volume of the final solution to the reservoir
(back) chamber.
4
Carefully open the connector stopcock and allow just
enough solution to flow through the connector channel
to fill it to the edge of the mixing chamber, then close
the stopcock. Be sure no large bubbles remain to
obstruct flow through the channel.
5
Add the required volume of the starting solution to the
mixing chamber and start the magnetic stirrer.
6
Open the delivery stopcock.
7
Simultaneously open the connector stopcock and start
the pump.
Note: If there is a substantial
difference in densities between
the two solutions, there will be
a sudden flow from the denser
chamber to the lighter chamber
to bring the two into hydro-
static balance. This will result
in the gradient not being fully
linear. To avoid this, add equal
weights, rather than volumes,
of the solutions to the appropri-
ate chambers.