Which statement about the retention factor formula is true?

Which statement about the retention factor formula is true?

• A. Relates the retention factor to the retention time and the dead time
• B. Relates the retention factor to the peak width
• C. Relates the retention factor to the sample concentration
• D. Relates the retention factor to the detector response

Answer: (C)

Retention factor measures how long an analyte stays on the column relative to the time the mobile phase takes to pass through (dead time). It uses the retention time of the analyte and the dead time: k' = (tR − tM) / tM. This ties the factor directly to how long the solute interacts with the stationary phase versus simply moving with the mobile phase, so it reflects the chemistry of the interaction, not the amount injected or how sharp the peak is. A higher k' means the analyte interacts more with the stationary phase and is retained longer. Peak width is governed by column efficiency and diffusion, not by the retention factor itself. Sample concentration affects peak area and height, not the time spent on the column in a simple measurement of retention. Detector response changes signal magnitude, not the time the analyte spends in the column.

Retention factor measures how long an analyte stays on the column relative to the time the mobile phase takes to pass through (dead time). It uses the retention time of the analyte and the dead time: k' = (tR − tM) / tM. This ties the factor directly to how long the solute interacts with the stationary phase versus simply moving with the mobile phase, so it reflects the chemistry of the interaction, not the amount injected or how sharp the peak is. A higher k' means the analyte interacts more with the stationary phase and is retained longer.

Peak width is governed by column efficiency and diffusion, not by the retention factor itself. Sample concentration affects peak area and height, not the time spent on the column in a simple measurement of retention. Detector response changes signal magnitude, not the time the analyte spends in the column.