| Continous - detector lamp problem or dirty flow cell | Replace UV lamp( each should last 2000 h); clean and flush flow cell |
| Gradient or isocratic proportioning - lack of solvent mixing | Use proper mixing device; check proportioning precision by spiking one solvent with UV absorbing compound and mointor UV absorbance detector output |
| Gradient or isocratic proportioning - malfunctioning proportioning valves | Clean or replace proportioning precision valves; partially remix solvents |
| Occasional sharp spikes - external electrical interference | Use voltage stabilizer for LC system; use independent electrical circuit |
| Periodic - pump pulses | Service or replace pulse damper; purge air from pump; clean or replace check valves. |
| Random - contamination buildup | Flush column with strong solvent; clean up sample; use HPLC grade solvent |
| Spikes - bubble in detector | Degas mobile phase; use back pressure restrictor at detector outlet |
| Spikes - column temperature higher than boiling point of solvent | Use lower column temperature |