Retention Factor Calculator Formula
Understand the math behind the retention factor calculator. Each variable explained with a worked example.
Formulas Used
Retention Factor (k')
k_prime = (tr - t0) / t0Variables
| Variable | Description | Default |
|---|---|---|
tr | Retention Time (tR)(min) | 8.5 |
t0 | Void Time (t0)(min) | 2 |
How It Works
Retention Factor (Capacity Factor)
The retention factor k' describes how strongly a compound is retained by the stationary phase relative to the mobile phase.
Formula
k' = (tR - t0) / t0
where tR is the retention time of the analyte and t0 is the void (dead) time. Ideal k' values are 2-10. Below 1, peaks elute near the void and separation is poor. Above 20, peaks are broad and run time is long.
Worked Example
A peak at tR = 8.5 min with void time t0 = 2.0 min.
tr = 8.5t0 = 2
- 01k' = (8.5 - 2.0) / 2.0 = 6.5 / 2.0 = 3.25
- 02The compound spends 3.25 times more time in the stationary phase than the mobile phase.
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