Effect of radial gradient of temperature on the performance of large-diameter high-performance liquid chromatography columns

A new split-flow injector for preparative liquid chromatography columns. Annular injection system

“…The efficiency is increased from N=3950 to N=8800 with SD=0. 15 The average asymmetry factor, measured at 10% of the peak height, was reduced from 1.7 with the original injector, which is acceptable, to 1.07 with the AIS, which is good.…”

“…It has been shown by Farkas [12] that "the slurry packed columns are heterogeneous, with a wall region in which the column permeability is lower than in the core region". Dapremont [15] and Brandt [16,17] have, moreover, shown the existence in the column of a temperature gradient caused by the flow past the particles. The higher temperature in the core of the column reduces the viscosity of the solvent and so increases its speed.…”

9.08 Use of Industrial Scale Chromatography in Pharmaceutical Manufacturing

“…This results in a separation using a flow rate of 510.4 l h −1 and a load of 21.3 g injection −1 . Typically, as the scale increases, the performance improves as the extra column effects and the column internal thermal radial gradient become less important, 57 providing that the inlet and outlet column distributors are designed properly. …”

“…57,65 Because porous silica beds are notoriously poor heat conductors, a gradient of temperature can be generated inside the column if the eluent and the column jackets are set at different temperatures. Because the retention of a molecule is strongly affected by temperature, a radial and axial gradient of temperature can result in a nonhomogeneous band distribution inside the column.…”

CFD Simulation of Preparative HPLC Columns with Consideration of Nonlinear Isotherms

“…[3,12,13] deal with the influence of temperature gradients, [2,14] with inhomogeneous chromatographic beds and [5,15] with phenomena, which occur due to local maldistributions of the sample coupled with the flow field.…”