Baseline hump and ghost peaks

Baseline hump and ghost peak are two irregularities seen in chromatograms in HPLC (High-Performance Liquid Chromatography).

Baseline Hump:
A baseline hump is a broad, gradual rise in the baseline of the chromatogram, often appearing like a "hill" or "wave".

Causes:
1. Gradient changes (especially in gradient elution).
2. Temperature fluctuations.
3. Contaminants in solvent or glassware.
4. Detector noise or response to solvent mismatch.

Possible Solution:
1. Use fresh, high-purity solvents (HPLC grade), filter & degas all mobile phases.
2. Ensure proper re-equilibration between runs; optimize gradient program.
3. Use a column oven to maintain constant temperature.
4. Flush the system with strong solvents (e.g., methanol, acetonitrile).


Ghost Peak:
A ghost peak is a sudden, unexpected peak that appears intermittently in the chromatogram, without a corresponding analyte or injection.

Causes:
1. Carryover from previous sample.
2. Contamination in injector, vial, or column.
3. Air bubbles or particulate matter.
4. Mobile phase contamination.

Possible Solution:
1. Rinse injection needle and loop thoroughly; use needle wash step.
2. Clean injector thoroughly.
3. Prepare fresh sample; use light-protected or cold storage if needed.
4. Replace with freshly prepared, high-purity solvent.