November 16, 2016, 715004521 Rev. C
Page 36
3.2.1.1 Adding co-solvent to adjust the retention times of sample components
Adding a co-solvent typically decreases a sample’s retention time. System pressure and
temperature also effect retention times.
3.2.2 SM-FL instrument method settings
When setting up the instrument method for the SM-FL, confirm that the injection mode is set to the
default configuration, PLNO (partial loop needle overfill).
Restriction: The ACQUITY UPC
2
system does not support the Full Loop or Partial Loop Pressure
Assist injection modes.
Recommendation: Use your weak-wash solvent, or a solvent weaker than the weak-wash
solvent, as the co-solvent.
When choosing a sample diluent, follow these guidelines:
• Do not dilute a sample in 100% methanol or similar strong solvent. Doing so can cause
retention-time problems, selectivity problems, and split peaks.
• Dilute samples in heptane or similar weak solvents, instead of in methanol.
• You can use as much as 20% methanol with heptane.
• Do not use water as the sample diluent or wash solvent.
3.2.3 Instrument method settings for the column manager
The minimum and maximum temperature settings vary among the various system components.
When configuring the instrument settings for a column manager in an ACQUITY UPC
2
system,
maintain the column-heating temperature between ambient and 60° C.
3.2.4 Instrument method settings for the ccManager
The ccManager sets the ABPR to prevent phase separation in the mobile phase. The minimum
back pressure to maintain CO
2
in a liquid state is 7,584 kPa (75 bar, 1100 psi).
Note: On the UPC
2
system, the minimum back pressure setting is 10,342 kPa (103 bar, 1500 psi).
Notice: To prevent damage to the needle, do not use the Cycle Injection Valve function in
the Method Editor Events table for UPC
2
.
Adding 0 to 20% co-solvent to CO
2
:
As co-solvent
increases
Solvating
power
Retention time
decreases
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