Retention time fluctuations during a
measurement are usually caused by the LC system. The most common causes are
1. Pump malfunctions,
e.g. defective check valves.
2. An imprecise gradient,
e.g. by organics at the beginning of chromatography.
How can this be checked?
1. Error analysis of the
pump system, e.g. Replacing check valves, repairing pump heads, fixing leaks.
2. Wash solution may be
mixed with sample (unlikely) or column is not completely backwashed.