- Retention factor
- Capacity Factor
K' or capacity factor in chromatography can be used as a guide to help assess if the peak will give reproducible and linear results over time. The definition of interaction with the sorbent or retention in chromatography is that the earliest eluting peak of interest should have a k' of 1 or better; the ideal is 2 or better. This ensures that small errors in mobile phase or pH don't have a large impact on retention time or response.
For full theoretical breakdown, see the text book WAT038216 - HPLC COL THEORY TECH/PRACTICE BOOK, by Uwe D. Neue.
For practical examples, see the following John Dolan LC-GC articles: