Question

A sample containing anthracene dissolved in methane was separated using gas chromatography on a column with mobile phase (????m) and stationary phase (????s) volumes of 24.7 mL and 9.88 mL, respectively. For this particular column, anthracene has a retention volume (????r) of 54.53 mL. Calculate the retention factor (????) and the partition coefficient (K) for anthracene in this separation.

Answer 1

Explanation:

Formula to calculate retention factor is as follows.

               Retention factor (k) = $\frac{V^{'}_{R}}{V_{m}}$

where,    $V^{'}_{R}$ = adjusted retention volume = $V_{R} - V_{m}$

              $V_{m}$ = hold up volume

              $V_{R}$ = total retention volume

Therefore, putting the given values into the above formula as follows.

      Retention factor (k) = $\frac{V^{'}_{R}}{V_{m}}$

or,  Retention factor (k) = $\frac{V_{R} - V_{m}}{V_{m}}$

                                      = $\frac{54.53 ml - 24.7 ml}{24.7 ml}$

                                      = 1.21

Now, partition coefficient (K) will be calculated as follows.

                k = $K \times \frac{V_{s}}{V_{m}}$

             $K = k \times \frac{V_{m}}{V_{s}}$

                     = $1.21 \times \frac{24.7 ml}{9.88 ml}$

                     = 3.025

Thus, we can conclude that the value of retention factor is 1.21 and partition coefficient (K) is 3.025.