Split/ghost peaks in an isocratic run after PM - WKB109551

SYMPTOMS

• Split peaks occur in the main components
• Ghost peaks occur when sample is injected
• Peak area/height unstable

ENVIRONMENT

• Alliance HPLC System
• 2695 Separations Module
• New column (conditioned and equilibrated)
• Isocratic run
• Buffer mobile phase
• Sample has component that is pH-sensitive

CAUSE

• Expired buffer mobile phase
• Expired needle wash solvent
• Dirty mobile phase solvent bottle

FIX or WORKAROUND

1. Use a clean solvent bottle and ensure that no soap residue remains after washing.
2. Prepare a new buffer mobile phase and ensure that the pH is within the method-specified range.
3. Prepare a new needle wash mobile phase. 

ADDITIONAL INFORMATION

A pH-sensitive component tends to neutralize when the mobile phase or needle wash is out of the specified range, thus creating split and ghost peaks.