174 Creating Gradient Controller Time-Based Tables
10.1.1 Documenting the Gradient Table
Define the information you want in a gradient table before you actually program a gradient
table. This minimizes the need for you to reprogram the table later.
Using the Analysis Plan and File Sheet
Appendix C, Analysis Plan, contains an Analysis Plan and File Sheet to assist you in
defining and documenting gradient-table information.
1. Make a photocopy of the Analysis Plan and File Sheet.
2. On each line of the Analysis Plan and File Sheet, write:
• Gradient segment time (time is cumulative from injection)
• Flow rate
• Eluent composition
• Gradient profile curve number
The number of changes needed to execute the gradient determines the total number
of lines in the table. The gradient table can contain up to 15 lines (14 plus initial
conditions).
Note: A gradient table with isocratic pump parameters consists of a single line.
See Section 10.1.2, Programming the Gradient Table.
3. When the table entries are complete, keep the Analysis Plan and File Sheet as a
permanent record of your gradient table.
Returning to Initial Conditions
When making multiple injections that require flow or eluent compositional gradients,
include a line in the gradient table to return the system to initial conditions or to
reequilibrate the system before the next injection.
This line in the gradient table should:
• Be executed by the controller after the separation is complete (run time elapsed) and
allow enough time for the column to equilibrate
• Specify the same flow rate as the Initial line of the table
• Specify the same eluent composition as the Initial line of the gradient table
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