Retention time (revision 4)
Old revision·15:42, 18 Sep 2024·GroupBuyGalen
| Retention time | |
|---|---|
| Symbol | t_R |
| Depends on | Column, mobile phase, gradient, flow, temperature |
| Relative measure | Relative retention time, against a reference peak |
| Topic infobox · conventions | |
Retention time is the interval between injection and the appearance of a component's peak maximum at the detector. Under fixed conditions it is characteristic of a substance and reproducible, which makes it the basis of chromatographic identification.[1]
It is not a property of the substance alone. Column chemistry and dimensions, mobile-phase composition, gradient profile, flow rate, temperature and even instrument dwell volume all change it, so a retention time is only meaningful alongside the conditions that produced it.[1]
What it can identify
[edit]Matching a sample peak's retention to that of a reference standard run under identical conditions on the same day is the ordinary chromatographic identification. It is weak evidence on its own: many species can share a retention time on a given system.[2]
Co-injection strengthens it substantially. Spiking the sample with the standard should enlarge the existing peak without producing a shoulder; a shoulder indicates two species.