1. What is Capacity Factor?

Definition: The Capacity Factor of a compound is a measure of how long it is retained by the column relative to the mobile phase travel time.

Purpose: It helps in chromatography to characterize the retention behavior of solutes and optimize separation conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( k'_{compound} \) — Capacity factor of the compound (dimensionless)
• \( t_r \) — Retention time of the solute (seconds)
• \( t_m \) — Unretained solute travel time (mobile phase time, seconds)

Explanation: The formula calculates how much longer the solute is retained compared to the mobile phase.

3. Importance of Capacity Factor

Details: A good capacity factor (typically between 1-10) indicates proper retention and separation. Values below 1 mean poor retention, while very high values mean excessive retention.

4. Using the Calculator

Tips: Enter the retention time and mobile phase travel time (must be less than retention time). Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a good capacity factor value?
A: Ideal values are typically between 1-10, indicating proper retention without excessive analysis time.

Q2: How is mobile phase time (t_m) determined?
A: It's measured using an unretained compound that moves with the mobile phase velocity.

Q3: What if my capacity factor is too low?
A: Adjust mobile phase composition to increase retention (e.g., decrease solvent strength in HPLC).

Q4: What does a negative capacity factor mean?
A: This indicates an error (t_r < t_m), which is impossible as solutes can't elute before the mobile phase.

Q5: How does capacity factor relate to retention factor?
A: They are essentially the same concept, with capacity factor being the more modern terminology.