Cause Solution
| Blocked frit | Replace or clean frit; install 0.5-um porosity in-line filter between pump and injector to eliminate mobile-phase contaminants or between injector and column to eliminate sample contaminants |
| Coelution of interfering compound | Use sample cleanup or prefractionation; adjust selectivity by changing mobile or stationary phase |
| Coelution of interfering compound from previous injection | Flush column with strong solvent at end of ran; end gradient at higher solvent concentration |
| Column overloaded | Use higher-capacity stationary phase; increase column diameter; decrease sample amount |
| Column void or channeling | Replace column, or, if possible, open top endfitting and clean and fill void with glass beads or same column packing; repack column |
| Injection solvent too strong | Use weaker injection solvent or stronger mobile phase |
| Sample volume too large | Use injection volume equal to one-sixth of column volume when sample prepared in mobile phase for injection |
| Unswept injector flow path | Replace injector rotor |