- PEG contaminant ions observed - easily identified by repeating 44 Da difference between masses
- ACQUITY (Classic, H-Class, or I-Class) with Mass Spectrometer
- nanoACQUITY or M-Class with Mass Spectrometer
- Washing bottles/glassware with soap
- Allowing the UPLC solvents or sinkers to touch the gloves when replacing solvents
FIX or WORKAROUND
For M-Class and nanoACQUITY, use the following protocol:
- Remove the column and replace it with a union, or for a nanoACQUITY or M-Class, plumb a waste line to port 6 of the inject valve.
- Put A and B lines from the LC into the alcohol mix, which is 25/25/25/25 water/isopropyl alcohol/methanol/acetonitrile and 0.2% formic acid.
- 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.
- Change the solvent to IPA and perform the same procedure as in steps 2 and 3.
- Prime and flush with fresh LC/MS-grade or Milli-Q water.
- Put on fresh solvents that are used for the LC. If the solvent bottles were not cleaned for a while, use the alcohol mix to clean out the bottles. Rinse well with fresh solvent.
- Attach the column - preferably a new one.
- Prime and flush the water using the fresh solvents and condition the column.
- Connect LC to MS and inspect for PEG contamination.
For an ACQUITY (H-Class or I-Class), use the following cleaning procedure