7. While observing the flow at the outlet of the SPE column/plate, increase the pressure by
tapping the
Single Up Arrow
(each tap increases the pressure by 0.1 psi). Continue this
action until you observe a desired flow rate through the SPE column/plate. If a higher
pressure is clearly needed due to high flow resistance, tap the
Double Up Arrow
.
Notice:
While attempting to expel the last drop of an SPE consumable, do not
increase the pressure too greatly through the column/plate. A flow rate of gas
that is too high may cause sample or liquid in the collection or waste plates to
splash up against the manifold, leading to carryover issues.
8.
Note:
It is common in SPE processes for a sudden "burst" of pressure to be required to
push out the very last drop from the consumable. You can accomplish this burst by
increasing the pressure dramatically just before tapping DONE, or add this action to be
performed later as an edit to the profile.
Once all of the liquid has exited the SPE column, tap
Done
.
9. Save the profile, which is the “draft” profile to be executed for that step in the method.
Waters recommends that you save the profile with a descriptive name that corresponds to
the step in the method (for example, “Vitamin D Conditioning Step”).
10. Tap
Open Manifold
.
11. Slide the SPE consumable out from underneath the pressure manifold.
5.2.2 Executing the pressure profile
To confirm the effectiveness of the profile, you can execute it without intervention using the
sequence below.
To execute the pressure profile:
1. Load more liquid into the SPE consumable.
2. Slide the consumable under the manifold.
3. On the tablet touchscreen, tap
Close Manifold
.
4. Tap
Run
.
Result:
The previously saved protocol executes automatically.
5. Observe the process to verify performance of the newly created profile. If the performance
of the profile is not precisely as desired, you can load the profile from the Pressure Profiles
screen, and then edit it within the Draw Profile screen.
5.3 Building an SPE method
Once appropriate pressure profiles for each method protocol step are created as previously
described, you are ready to build a method.
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