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Current
Current acts on the total cross-sectional area of
all the gels, and in terms of a circuit, the gels
are considered to run in parallel. Therefore, any
current setting for one gel must be multiplied by
the number of gels run. For a gel 1.5 mm thick,
we suggest a starting point current setting of
25 mA. (Two 1.5 mm gels = 50 mA.)
Voltage
The starting voltage for a 1.5 mm slab gel
connected to a power supply set to 25 mA is
usually 80–90 V (for the SE 400 model and a
Laemmli discontinuous buffer system). The final
voltage is typically 200–325 V, depending on the
length of the gel. (See Table 3 on page 20.)
Time
A run is complete when the tracking dye reaches
the bottom of the gel. A 16-cm long, 1.5 mm
thick Laemmli SDS gel, run at 25 mA/gel with-
out cooling, usually requires 5 hours. A 24-cm
gel requires about 8 hours.
Note:
Passive cooling, such
as running the unit in a cold
room, may be required to
reduce the effects of
Joule heating.
Important!
After initial moni-
toring, do not leave the unit
unattended for more than
1 hour without checking the
progress of the bands and the
buffer level.