Dispersion in Chromatography Columns - Effect of Mobile Phase Compressibility On the HETP Equation for a Packed GC Column > Page 43

Figure 9. HETP Curves for the Same Column and Solute Using the Average Mobile Phase Velocity and the Exit Velocity

 

The two curves are clearly quite different and, if the results are to be fitted to the HETP equation, only the data obtained using the exit velocity  will give meaningful values for the exclusive dispersion processes. This problem is further emphasized in the graphs shown in figure 10. In figure 10, the individual contributions from the different dispersion processes are obtained by deconvoluting the HETP curve obtained using the average velocity data.