104 Creating PowerLine Methods
This line in the gradient table should:
• Be executed by the controller after the separation is complete (run time has elapsed)
and allow enough time for the column to equilibrate
• Change the flow rate to that used in the Initial line of the gradient table
• Have the same eluent composition as the Initial line of the gradient table
Reducing Flow
To conserve eluent, include a final line in the gradient table to reduce the flow rate after
the last injection.
This line in the gradient table should:
• Appear as the last line in the table.
• Be set to a time at least 5 to 10 minutes longer than the time required for another
injection to occur.
• Specify a flow rate of either 0.0 mL/min, or a reduced flow rate, usually 0.1
mL/min.
• Use the eluent composition from the previous line.
• Specify curve #11 (see Analysis Plan and File Sheet) so that the flow rate does not
decrease until the last line is reached. If an injection occurs before this line executes,
the flow rate does not decrease.
Sample Gradient Table
Figure 6-2 is an example of an Auto•Blend gradient table for an analysis with a run time
of 30 minutes. It includes a 5-minute segment that returns the eluent composition to initial
conditions at the end of the run. It also includes a segment that reduces the flow rate to 0.0
mL/min if an injection is not made within 50 minutes of the previous injection.
Figure 6-2 Example of an Auto•Blend Gradient Table
TIME FLOW %A %B %C %D CURVE
Initial 1.00 10 10 0 80 *
30.001.001010800 6
35.00 1.00 10 10 0 80 6
50.00 0.00 10 10 0 80 11
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