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CombiFlash NextGen Systems
Section 2 Preparation
Figure 2-18 Automatic Run Extension Examples
2-20
Note
This option requires the system to be configured for network
operation and a connection to a printer on the network. Net-
work settings are discussed in Section 4. Do not select this
option for these initial installation steps.
Default Run Units – Run units are displayed along the X-axis
of the chromatogram. Select Time (in minutes) or Column
Volumes (CVs). A column volume unit is the time it takes to
pump enough solvent to exchange the volume held by the
column. The duration in minutes will vary according to the
column media and size, and the flow rate.
Pressure Units – You can choose between PSI and Bar.
Enable Run Length Extension – When enabled, this option
automatically extends the run if a peak is eluting at the end of
the maximum %B gradient. This ensures that a late-eluting peak
fully comes off the column and is collected.
An automatic run extension is a five-minute isocratic hold added
to the end of the run's maximum %B gradient profile. During the
extension, the system continues to pump the maximum %B
solvent mixture. Should the system still detect a peak after an
extension, the system will add another, up to a maximum of three
extensions.
Occasionally, compounds might come off the column once the %B
returns to the minimum value at the end of a run. If the R
L
E
is enabled, it will automatically extend the
ENGTH
XTENSION
run one time to clear the column and plumbing of any remaining
material.
Figure 2-18 illustrates the possible run extensions. The original
method was programmed to rise to the maximum %B over seven
minutes, hold for two minutes, and return to the minimum %B
for a final minute. At nine minutes, a peak was eluting. The
system extended the run, holding the %B at the maximum level
for another five minutes. This also occurred at fourteen and
nineteen minutes, resulting in the second and third extensions.
At twenty-four minutes, the %B solvent strength returned to
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UN
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