Possible Cause Solution
| Contamination | Flush column to remove contaminatint; use HPLC-grade solvent |
| Elution of analytes retained from previous injection | Flush column with strong solvent at end of run; end gradient at higher solvent concentration. |
| Ion-pair chromatography - upset equilibrium | Prepare sample in mobile phase; reduce injection volume |
| Oxidation of trifluoroacetic acid in peptide mapping | Prepare trifluoroacetic acid solutions fresh daily; use antioxidant |
| Reversed-phase chromatography - contaminated water | Check suitability of water by running different amounts through column and measure peak height of interferences as function of enrichment time; clean water by running it through old reversed-phase column; use HPLC-grade water. |
| Unknown interferences in sample | Use sample cleanup or prefractionation before injection. |