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..

Equation

The equation is:

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

Where

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