QTof Mass Spectral Resolution on mAbs is poor - WKB3880

SYMPTOMS

• There is poor separation between the main peak and the secondary or tertiary peaks.
• The secondary and tertiary peaks are barely visible. 
• The valley between groups of peaks may not reach the baseline. 

ENVIRONMENT

• ACQUITY QTof LC/MS systems
• Xevo QTof
• Xevo G2 QTof
• Xevo G2-S
• Xevo G2XS
• Synapt G1
• Synapt G2
• Synapt G2-S 
• Synapt G2-Si
• ACQUITY
• Intact protein
• Heavy chain
• Light chain

CAUSE

The LC is dirty.

FIX or WORKAROUND

1. Remove the column and replace it with a union.
2. Put A and B lines from the ACQUITY into the alcohol mix, which is 25/25/25/25 water/isopropyl alcohol/methanol/acetonitrile and 0.2% formic acid.
3. Flush the system by priming for five minutes, and then pumping for at least two hours at a flow rate that gives at least 6000 psi pressure.
4. Prime and flush with fresh LC/MS-grade or Milli-Q water. 
5. Put on fresh solvents that are used for the mAb analysis. If the solvent bottles have not been cleaned for a while, use the alcohol mix to clean out the bottles. Rinse well with fresh solvent afterward. 
6. Attach your new column.
7. Prime and flush out the water using the fresh solvents.
8. Run the mAbs again. 

ADDITIONAL INFORMATION