94 Purification Solution - Developer's Guide
7
Checkout Procedure
UV/MS Workflow: Focused gradient in Purification software
• MS-based target identification:
• Check in the chromatogram that the correct peak was selected: Ethyl
4-hydroxybenzoate (166.1) is the third major peak of the mixture to
elute.
• Also check that the ethyl 4-hydroxybenzoate peak was identified in
both the UV detector and the MSD target ion species. If the UV and
MSD are not well aligned, then the problem can be in UV/MSD delay
value or integration parameters. If the UV signal is saturated, the
integration parameters may need to be changed.
10 Click Run again to submit the preparative task to the ChemStation run
queue.
11 When the preparative task is completed, check in Preparative Results that the
correct peak was collected.
12 Create a new task:
• Click Add Task.
• Select Add clone of currently selected task and click OK.
13 Set the parameters in Analytical Results:
• Enter the Ta r get ma ss of 194.1 (Caffeine)
• Scale-Up tab: set Minimal target candidate peak height in EIC to 200000.
• Click Re-evaluation to apply the change.
• Set suitable thresholds in the Fraction collection tab:
• MSD detector:
• Display MSD ion species curve in the graph.
• Zoom to baseline and determine its highest level.
• Set the Threshold value to five times the determined analytical
baseline level or 2000, whichever is higher.
• UV detector: set Threshold to 5 or adjust the value to achieve a
threshold of about 5 % of the peak height in the preparative run.
14 Review the Analytical Results (check the settings and the target peak):
• Check in the chromatogram that the correct peak was selected: caffeine
(194.1) is the first major peak of the mixture to elute. Note that caffeine,
as a complexing agent, can create ghost peaks in the MSD signal of
caffeine on positions of other mixture compounds. For this purpose, the
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