Question

A sample containing anthracene dissolved in methane was separated using gas chromatography. Methane was detected at 42.5 seconds (tm) and anthracene was detected at 173.6 seconds (tr). If the manufacturer of the column states that the volume of the mobile phase (Vm) is 7.0 times the volume of the stationary phase (Vs), calculate both the retention factor (k) and the partition coefficient (K) for anthracene in this separation.

1) k= ?

2) K= ?

Answer 1

a) k = 4.085

b) K = 0.143

Step-by-step explanation:

gas chromatography:

∴ tm = 42.5 s

∴ tr = 173.6 s

∴ Vm = 7 Vs

a) retention factor (k):

∴ k = tr/tm

⇒ k = 173.6/42.5 = 4.085

b) partition coefficient (K):

∴ K ≅ Vs/Vm

⇒ K = 1/7 = 0.143