Capacity Factor Formula:
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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.
The calculator uses the formula:
Where:
Explanation: The formula calculates how much longer the solute is retained compared to the mobile phase.
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.
Tips: Enter the retention time and mobile phase travel time (must be less than retention time). Both values must be > 0.
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 (tm) 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 (tr < tm), 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.