# Calculate Retention Factor in Chromatography: Detailed Explanation and Formula

In a chromatogram, tm is 1.81 minutes and t′r is 8.13 minutes. Calculate the retention factor k. Answer should be rounded to nearest 0.01.

## Understanding Retention Factor in Chromatography

**The retention factor (k) is approximately 4.49 (rounded to the nearest 0.01).**Retention factor (k) in chromatography is a crucial parameter that helps in understanding the behavior of substances in a column. It is defined as the ratio of the time a substance is retained in the column to the time taken for an unretained substance to pass through the column. The formula to calculate the retention factor is:

**k = (t′r - t₀) / (t_m - t₀)**Where: - t′r: retention time of the solute - t_m: retention time of the solvent front - t₀: dead time (considered negligible in this case) Using the given values: - tm = 1.81 minutes - t′r = 8.13 minutes - t₀ = 0 Plugging these values into the formula: k = (8.13 - 0) / (1.81 - 0) k = 8.13 / 1.81 k ≈ 4.49 Therefore, the retention factor (k) is approximately 4.49 (rounded to the nearest 0.01).

**Retention factor (k) = 4.49 (rounded to the nearest 0.01)**