- Peptides come off the column not resolved
- Hydrophobic peptides elute together
- Hydrophyllic peptides elute later than usual and not resolved
- ACQUITY UPLC M-Class
- Flow controller needs to be re-zeroed
- Setting for "Loop Offline" parameter is incorrect
FIX or WORKAROUND
- Perform "Auto Zero Flow Transducers" procedure for both pumps A and B.
- Verify that the "Loop Offline" setting for M-Class Sample Manager parameters in the Inlet Method is either set to "Disabled" or there is sufficient time to allow complete sample load out of the loop and onto the column.
Prior to performing the "Auto Zero Flow Transducers" procedure, ensure that the pump has been flowing 50% A : 50% B for some time to prevent backflow of solvents and incorrect results of the procedure.