How to improve peak shape using passivation with ACQUITY UPLC HSS C18 columns - WKB31187

SYMPTOMS

• Peak shape for some alkaloid-type compounds can be suboptimal using ACQUITY UPLC HSS C-18 columns

ENVIRONMENT

• ACQUITY UPLC HSS C-18 columns
• Alkaloid-type compounds such as chloroquine, hydroxychloroquine, and pheniramine

CAUSE

Unclean injector (caused by repeated analysis of these types of compounds)

FIX or WORKAROUND

Employ a passivation technique:

1. Disconnect the column from the mass spectrometer, leaving only the LC flow input.
2. Make three 10-µL injections of 2% phosphoric acid (H₃PO₄). This is the passivation step.
3. Make ten 10-µL injections of blank mobile phase to flush out the H₃PO₄.
4. (Optional) Store the column in initial mobile phase for three days.
5. Reconnect the column to the mass spectrometer and analyze samples.

ADDITIONAL INFORMATION

NOTE: This instruction is for INJECTIONS only.  DO NOT USE 2% Phosphoric acid as mobile phase. 

For additional information see Can I flush my column with 2 percent Phosphoric acid to passivate the column?