A. Felinger et G. Guiochon, THE CHANGE OF PRESSURE-DROP DURING LARGE-SCALE CHROMATOGRAPHY OF VISCOUS SAMPLES, Biotechnology progress, 9(5), 1993, pp. 450-455
The variation of the inlet pressure during the injection and the eluti
on of a band of a viscous compound, or pressure-drop profile, was calc
ulated in overloaded elution chromatography, assuming a significant di
fference between the viscosities of the solvent and the pure solute. T
he viscosity of the mixture was calculated using the Grunberg-Nissan e
quation. By means of the numerical integration of the mass balance equ
ation, the concentration profile along the length of the column was ca
lculated. Then, using the instantaneous concentration profile to deriv
e the local viscosity, hence the local pressure gradient, the pressure
drop was determined by integrating the local pressure gradient along
the column. The change of pressure drop calculated is significant only
when the concentration of the injected sample is very high. If a dilu
te sample is injected, even large sample volumes will not really chang
e the pressure drop. The maximum pressure drop observed in each case i
s practically independent of the absorption isotherm. The only determi
ning factors are the solute concentration in the sample, the amount of
sample injected, and the solute diffusivity.