Alliance system pressure fluctuates in water/aqueous conditions - WKB57411

SYMPTOMS

• Alliance pressure fluctuations with high delta (~200 psi at 1500 psi) in aqueous conditions with any composition of water

  • Instrument has had PM and rebuild several times

  • Pump tray swapped and GPV replaced without resolution

  • Flow rate accuracy unstable

• 100% line C in methanol at 1 mL/min, the system is operating and stable at ~500+ psi with delta of ~10 psi

  • 100% line D in methanol gives same stable operating conditions

  • Flow rate accurate in methanol

• Swapping lines between water and methanol, the observed pressure fluctuations move with aqueous mobile phase

  • Water mobile phase is freshly prepared (18 meg ohm purity)

  • Degasser operating correctly at 0.5 psia

    • Degassed by vacuum filtration and sonicated

ENVIRONMENT

• Alliance 2695 Separations Module

CAUSE

Microbial growth and contamination of the system's wetted surfaces

FIX or WORKAROUND

1. Passivate the system with 30% phosphoric acid.
   • See article on "How to clean and flush the Alliance HPLC System to remove contamination"

ADDITIONAL INFORMATION