Capillary Chromatography - Capillary Column Theory 5
Consequently, the contribution from the resistance to mass transfer in the stationary phase, for all practical purposes, can be ignored. The resistance to Mass Transfer Ratio for a larger column is shown in figure 16.
It is seen from figure 16 that the larger diameter column exhibits an even grater resistance to mass transfer ratio and at a (k') of unity the resistance to mass transfer in the stationary phase contributes to less than 2% of the total resistance to mass transfer and at practical exit velocities (i.e., 20-30 cm/sec) the fraction is reduced to less than 1.5 %
Column Length 15 m Column Diameter 300 mm
Figure 16. Graph of Resistance to Mass Transfer Ratio against Mobile Phase Exit Velocity.
It is clear, that for all practical purposes the resistance to mass transfer in the stationary phase can be ignored and equation (2) can be reduced to,