Rodrigues equation

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The Rodrigues equation is an equation used in chromatography to describe the efficiency of a bed of permeable (large-pore) particles. It is thus an extension of Van Deemter's equation. It was developed by Alirio E. Rodrigues et al^[1].

$HETP = A + \frac{B}{u} + C \cdot f( \lambda ) \cdot u$

Where

HETP is the height equivalent to a theoretical plate
A = Eddy diffusion
B = Longitudinal diffusion
C = Resistance to mass transfer
u = Flow rate
$f( \lambda ) = \frac{3}{ \lambda } \left [ \frac{1}{tanh( \lambda )} - \frac{1}{ \lambda } \right ]$
$λ$ = Intraparticular Péclet number

[edit] References

^ Alirio E. Rodrigues (10 October 1997). "Permeable packings and perfusion chromatography in protein separation". Journal of Chromatography B: Biomedical Sciences and Applications 699 (1-2): 47-61. doi:10.1016/S0378-4347(97)00197-7.