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Figure 2–9:
Waste
Sample
Liquid mobile phase (CO
Gas mobile phase (CO
Air gap
With the injection and auxiliary valves in the inject position, after injecting the sample, the SM-FL
washes the outside and inside of the sample needle. The wash syringes dispense the
programmed amount of strong and weak washes through a single trace in the injection valve and
out through the needle.
2.5
Performing column screening
Before running separations, best practice requires that you first screen the various UPC
chemistries, to determine the most suitable one to use for the compounds you want to separate.
A typical column screening workflow involves these actions:
•
Create a method for each column that you want to screen.
•
In each method, create a gradient consisting of two or three injections. Specify the first
injection, to equilibrate the column, and the second and third injections, to inject the sample.
•
Run the gradient for 5 minutes, starting with a mobile phase mixture of 5% organic solvent
and 95% CO
•
Run the 40% organic solvent for at least 1 minute to wash the column.
Step 7: The SM-FL washes the outside and inside of the needle
Auxiliary valve (inject position)
To column
From pump
Sample loop
Injection valve (inject position)
2)
2)
, and ending with a maximum of 40% organic solvent and 60% CO
2
November 16, 2016, 715004521 Rev. C
Page 32
Waste
Metering syringe
Buffer volume
Sample
Weak wash
Wash
syringes
2
column
.
2
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