Question

An open tubular column with a diameter of 197 μm and a stationary phase thickness on the inner wall of 0.85 μm passes unretained solute through in 51 s. A particular solute has a retention time of 407 s. What is the partition coefficient for this solute? What fraction of time does this solute spend in the stationary phase?

Answer 1

Column diameter = 197 micometer = 0.197 mm

inner wall = 0.85 micrometer = 0.085 mm

k = 407-51/51 = 6.98

We can write for partition coefficient,

K = Cs/Cm with Cs and Cm be concentration in stationary and mobile phase

or, in terms of volume,

K = k(Vm/Vs)

Vm = Vcyllinder = pi x (d^2/4)L = 3.1416 x (0.197^2/4]]L = 0.0305 L

Vs = Vtube = [3.1416 x 0.197 x 0.00085]L = 0.000526 L

Partition coefficient K = 6.98 x (0.0305 L/0.000526 L) = 404.7

Fraction of time spent in stationary phase = time spent in stationary phase/total time spent

= (407 - 51/0.197) = 0.8747 = 87.47%