A van Deemter plot for the separation of neutral dyes by micellar electrokinetic chromatography is shown below.62

(a) Explain why plate height increases at low and high velocities.
(b) The irregular flow path term, A, in the van Deemter equation should really be 0 for the ideal case of micellar electrokinetic chromatography. The observed value of A is 2.32 μm, which accounts for two-thirds of the band broadening at the optimum velocity. Suggest some reasons why A is not 0.

Transcribed Image Text:

6.0 5.5 5.0 E 4.5 4.0 03.5 E 4.5 3.0E 2.5 0.5 Electroosmotic velocity (mm/s)