Consider the chromatography of n C12H26 on a 25 m long 0 53 mm diameter open tubular column of 5 phenyl 95 methyl polysiloxane with a stationary phase thickness of 3 0 m and He carrier gas at 125C The observed retention factor for n C12H26 is 8 0 Measurements were made of plate height, H, at variou...

The van Deemter equation has the form H B u x Cu x B u x C s C m u x where k retention fa ...

Consider the chromatography of n-C12H26 on a 25-m-long 0.53-mm-diameter open tubular column of 5% phenyl-95% methyl

Question:

Consider the chromatography of n-C12H26 on a 25-m-long × 0.53-mm-diameter open tubular column of 5% phenyl-95% methyl polysiloxane with a stationary-phase thickness of 3.0 μm and He carrier gas at 125°C. The observed retention factor for n-C12H26 is 8.0. Measurements were made of plate height, H, at various values of linear velocity, ux (m/s). A least-squares curve through the data points is given by
H (m) = (6.0 × 10-5 m2/s)/ ux (2.09 × 10-3s)ux
From the coefficients of the van Deemter equation, find the diffusion coefficient of n C12H26 in the mobile and stationary phases. Why is one of these diffusion coefficients so much greater than he other?