120
1260 Infinity Binary LC - System User Guide
6
Appendix
Setting Up a Method using Edit Entire Method
•
Solvents
defines the mobile phases that are available and the percentage
proportions that are pumped on the two channels, A and B. On each
channel, a drop- down box allows the selection of a solvent from a list so
that the pump control uses the optimum compressibility settings. This will
optimize the flow characteristics as described in
Configuration for 2.1 mm i.d. Columns”
on page 43. A second text box
allows a description of the mobile phase to be entered. If the solvent
selection valve is installed in the pump, each channel has two solvent
options and the correct option for the method is selected with the radio
button to the left of the solvent description. The pump will form binary
mixtures of the selected A and B channels, for example A2 and B1; it is
not possible to mix A1 with A2 or B1 with B2. The value that is 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 acetonitrile
at 60 %. A will be 40 %.
•
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 that
are 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 set up a simple
gradient, first clear the timetable with the
Clear all
button if it is not
already empty, then add a line and enter the time and solvent
composition required. 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
