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:

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

Where

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

References

1. 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.