Extra Column Dispersion - Dispersion in Tubular Conduits > Page 22
The dispersion that takes place in an open tube is described by the Golay equation (7), (see Dispersion in Chromatography Columns ) but under conditions where there is no stationary phase present and thus, k'=0.
As a result, the variance due to an open tube (stu2)will be
|where (u)||is the linear velocity of the mobile phase,|
|(r)||is the radius of the tube,|
|and (Dm)||is the diffusivity of the solute in the mobile phase.|
If u >> Dm/r (which will be true for most practical chromatographic systems, then equation (8) reduces to,