Rodrigues equation

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]

Equation

The equation is:

$HETP = A %2B \frac{B}{u} %2B C \cdot f( \lambda ) \cdot u$

Where

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

References

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