Plate height desorption

Z/mc plate height due to sorption/desorption micellar kinetics... 

Calculate the plate height contributed by sorption-desorption mass transfer (nonequilibrium) through a uniform liquid layer (configuration factor q = 2/3) of thickness 1.0 x 10 3 cm coated on the inside of an open tubular (capillary) column. The gas velocity v is 10 cm/s. The solute retention ratio is 0.10 and its diffusion coefficient Ds through the stationary liquid is 1.0 x 10 5 cm2/s. 

The plate height lumps together the contributions of fluid dynamic nonidealities (e.g., axial dispersion), mass transfer resistances, and finite adsorption and desorption rates, which all contribute to undesired band broadening. It can be defined as the rate of the local gradient of the width of a Gaussian peak (Equation 2.31) ... 

From a quantitative point of view vis-a-vis the chromatographic operation, if the plate height is controlled hy pore diffusion (in the stagnant mobile phase, equation (7.1.107h)) and /or stationary-phase sorption-desorption, the plate height H oc d v. Since N = [L/H), for a fixed L,... 

In equation (6) is the width at the base of the peak, measiued in the same units as tj.. The theoretical plate model assumes the column to be made of a series of plates. The distribution of the analyte between the mobile and stationary phase occurs at each plate. Therefore, the higher the number of plates, the better the separation since more sorption-desorption cycles occur. Coliunn efficiency can also be expressed in terms of Height Equivalent to a Theoretical Plate value (HETP or H-value) ... 

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