124
Agilent 1290 Infinity LC System Manual and Quick Reference
6
Appendix
Setting Up a Method using Edit Entire Method
channels, for example A2 and B1; it is not possible to mix A1 with A2 or B1
with B2. The value entered for the proportions of A and B defines the
composition of an isocratic method or they define the starting conditions of
a gradient method and the equilibration conditions between gradient runs.
Only the value of B is entered, A will then update to show 100% minus B
when the cursor is moved. For the example separation, set A to water and B
to methanol at 50 %. A will be 50 %.
• Timetable
details the changes that should occur during the run to the
percentage composition of A and B in the mobile phase or, if required, to
the flow rate and maximum pressure allowed. The timetable makes linear
changes to the parameters between the given setpoints. The settings made
elsewhere on this screen act as the initial conditions and will only change if
an entry is made in the timetable. For example, if the flow is constant
during the run then there is no need to make an entry about the flow in the
timetable. To make an entry in the timetable click the
Add
button to add a
line to the timetable; enter the time of the setpoint, select the type of entry
from the drop-down list (composition, flow, pressure) and click the
parameter
box to reveal the entry box for the value. If timetable entries are
made out of logical sequence the entries are automatically re-ordered into
time order. Timetable lines can be edited directly and the
Cut
,
Paste
and
Remove
buttons can be used to add and remove lines. Multiple lines can be
added to give a series of linear gradient segments to create any gradient
profile. To setup a simple gradient for the example separation, first clear
the timetable with the
Clear all
button if it is not already empty, add a line at
4.00 min to change composition to 90 %. The graphical display will show a
linear gradient from 50 % B to 90 % B over 4 min. If a step gradient is
required, it can be formed by making two entries with the ‘before step’ and
‘after step’ settings separated by 0.01 min. This is often used to rapidly
elute strongly retained peaks from a column near the end of a run by
increasing the stronger solvent and/or the flow rate in a step gradient, for
example, the % B might be stepped up from 75 % to 95 %. It is not necessary
to enter the settings for time 0.00 min into the timetable, these values are
picked up from other setpoints on this screen. However, some users like to
see a ‘complete’ list in the timetable and make an entry for 0.00 min. There
is no problem with this but if the initial conditions are ever changed then
the new settings must be entered in both the timetable and the setpoints in
the Solvents section of the screen.
• Show timetable graph
displays the timetable changes graphically when the
box is ticked.
