What is retention time?
Definition
Retention time is how long a compound takes to travel through an HPLC column to the detector; it is characteristic of a compound only under one specific method.
What determines retention time
In reversed-phase HPLC, a compound stays bound to the hydrophobic column packing until the solvent becomes organic enough to release it. More hydrophobic compounds are retained longer. Column type, solvent gradient, flow rate and temperature all change the value, so retention times are comparable only between runs using the same method.
Selank retention time
Limits
A matching retention time supports, but does not prove, identity. Identity is confirmed separately by mass spectrometry.