What You Expect What You Got
| Disease | Medicine | |
| Fluctuation of column temperature | Stabilize. Use column oven | |
| Contamination of mobile phase/ | | Use HPLC grade solvent. Degas |
| Air in the detector cell | Clean cell. If necessary use a pressure restrictor at outlet | |
| Plugged detector outlet line | Replace | |
| Default mixing | Check mixer unit. Check flow rate and composition | |
| Plugged detector outlet line | Replace | |
| Strongly retained materials | Flush column with strong solvent | |
| Unoptimized detection | Optimize detector |
Base line noise
What You Expect What You Got
| Disease | Medicine |
| Air (mobile phase, detector cell, pump) | Flush system, prime pumps, degas mobile phase |
| Pump pulse | Use a pulse damper |
| Incomplete mixing | Promote complete mixing |
| Electronic | Check electronic equipment in the same line |
| Leak | Please See No Peaks Or Very Small Peaks |
| Disease | Medicine |
| Leak | Please See No Peaks Or Very Small Peaks |
| Bad quality mobile phase | Use HPLC grade solvents |
| Electronics | Locate problem.Get servicing |
| Cell contaminant | Clean detector cell |
| Weak lamp | Replace detector lamp |
Broad peaks
What You Expect What You Got
| Disease | Medicine |
| Altered mobile phase | Make new |
| Low flow rate | Increase |
| Leak | Please See No Peaks Or Very Small Peaks |
| Incorrect detector settings | Check and correct |
| Column overload | Please see Retention times are not constant |
| Void volume. Tubing too long or to wide | Use 0.010" tubing. Shorten path |
| Low buffer concentration | Increase |
| Column or guard column contamination | Replace |
| Void volume at inlet | Repack |
Change in height
| Disease | Medicine |
| Sample deterioration | Use fresh sample |
| Leak | Please See No Peaks Or Very Small Peaks |
| Non-reproducible sample volume | Ensure loop is completely filled |
| Low detector response | Check detector settings and operating conditions |
Negative peaks
What You Expect What You Got
| Disease | Medicine |
| Recorder connections | Check polarity |
| Refractive index of mobile phase higher than that of solute | Change mobile phase |
| Vacancy peaks | Originate from great difference in composition between sample solvent and mobile phase. Dissolve sample im mobile phase |
| Mobile phase more absortive than sample components | Use mobile phase that is transparent at the wavelength used |
Ghost peaks
What You Expect What You Got
| Disease | Medicine |
| Contamination of injector or column | Always flush injector after each injection. |
| Retained compound from previous injection | Flush colunm with strong solvent after operation to remove late eluting compounds |
Reference:
Prof. Dr. H.J. Chaves das Neves
Universidade Nova de Lisboa
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