High system pressure on ACQUITY - WKB28736

SYMPTOMS

• System pressure is 3000 psi higher than normal

ENVIRONMENT

• ACQUITY
• ACQUITY I-Class
• ACQUITY H-Class

CAUSE

Buildup in the system

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 (can go up to 1% formic acid).
3. Flush the system by priming for five minutes, and then pump for at least two hours (preferably overnight) at a flow rate that gives at least 6,000-psi pressure.
4. Place the alcohol mix into a vial and make five injections.
5. Prime and flush with fresh LC/MS-grade or Milli-Q water. 
6. Put on fresh LCMS-grade solvents that are used for the LCMS analysis. If the solvent bottles were not cleaned recently, use the alcohol mix to clean out the bottles, and then rinse them well with fresh solvent. 
7. Attach a new column.
8. Prime and flush out the water using the fresh solvents.
9. Run the LCMS analysis again. 

ADDITIONAL INFORMATION