Ecole Supérieure de Physique et de Chimie Industrielles, Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMH-UMR 7636 CNRS-ESPCI ParisTech-Université Pierre et Marie Curie-Université Paris-Diderot), 10 rue Vauquelin, 75231 Paris Cedex 05, France.
J Chromatogr A. 2011 Jul 8;1218(27):4117-25. doi: 10.1016/j.chroma.2011.01.010. Epub 2011 Jan 12.
Elution time measurements of colloidal particles injected in a symmetrical flow field-flow fractionation (flow FFF) system when the inlet and outlet cross-flow connections are closed have been performed. This no-field method has been proposed earlier for void time (and void volume) determination in flow FFF Giddings et al. (1977). The elution times observed were much larger than expected on the basis of the channel geometrical volume and the flow rate. In order to explain these discrepancies, a flow model allowing the carrier liquid to flow through the porous walls toward the reservoirs located behind the porous elements and along these reservoirs was developed. The ratio between the observed elution time and expected one is found to depend only on a parameter which is a function of the effective permeability and thickness of the porous elements and of the channel thickness and length. The permeabilities of the frits used in the system were measured. Their values lead to predicted elution times in reasonable agreement with experimental ones, taking into account likely membrane protrusion inside the channel on system assembly. They comfort the basic feature of the flow model, in the no-field case. The carrier liquid mostly bypasses the channel to flow along the system mainly in the reservoir. It flows through the porous walls toward the reservoirs near channel inlet and again through the porous walls from the reservoirs to the channel near channel outlet before exiting the system. In order to estimate the extent of this bypassing process, it is desirable that the hydrodynamic characteristics of the permeable elements (permeability and thickness) are provided by flow FFF manufacturers. The model applies to symmetrical as well as asymmetrical flow FFF systems.
已对注入对称流场流分离（流 FFF）系统的胶体颗粒的洗脱时间进行了测量，此时入口和出口交叉流连接已关闭。这种无场方法早先曾用于流 FFF Giddings 等人的空隙时间（和空隙体积）确定。（1977）。观察到的洗脱时间比根据通道几何体积和流速预期的洗脱时间大得多。为了解释这些差异，开发了一种流动模型，允许载液通过多孔壁流向位于多孔元件后面的储液器，并沿这些储液器流动。观察到的洗脱时间与预期洗脱时间的比值仅取决于一个参数，该参数是多孔元件的有效渗透率和厚度以及通道厚度和长度的函数。测量了系统中使用的滤器的渗透率。考虑到在系统组装过程中通道内可能存在膜突出，将其值与实验值进行了比较，得出的预测洗脱时间与实验值吻合良好。它们支持无场情况下流动模型的基本特征。载液主要绕过通道，沿系统主要在储液器中流动。它从入口附近的通道通过多孔壁流向储液器，然后再次从储液器通过多孔壁从储液器流向出口附近的通道，然后再从系统中流出。为了估计这种绕过过程的程度，希望流动 FFF 制造商提供可渗透元件的流体动力学特性（渗透率和厚度）。该模型适用于对称和非对称流 FFF 系统。
