Hoefer SG500 - Manual (Page 4)

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1. Generating linear gradients
To generate a linear gradient between two
concentrations, equal volumes of solutions of the
two concentrations are measured into the two
chambers of the gradient maker. As solution is
delivered out of the mixing chamber, an equal
volume flows in from the reservoir chamber
where it is rapidly diluted and mixed to unifor-
mity by a magnetic stir bar. The initial concen-
tration delivered will be that of the solution in
the mixing chamber, the final concentration will
be that of the reservoir chamber. For the most
consistent delivery of gradients, a peristaltic
pump is recommended.
1
Make sure all parts are clean and liquid flows freely
through all the connecting channel of the slide valve
and pump and delivery tubing.
2
Add a magnetic stir bar of the appropriate dimensions
(20–30 mm long) to the mixing chamber 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 reservoir 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,
column, etc.).
3
Close the slide valve (out on side of white slide stop
button, Fig 2). If the outlet tubing is not controlled
by a pump, clamp it off near the gradient former.
Add the required volume of the final solution to the
reservoir (back) chamber.
open
closed
Fig 2. Open and closed positions
of slide valve.