Particle interaction effects on blood cell sedimentation and separations

Abstract

Experiments with a continuous centrifuge reveal that the separation of leukocytes (WBCs) and platelets from erythrocytes (RBCs) is maximized at a lower than normal RBC concentration or hematocrit (HCT). Conventional hindered settling models are unsatisfactory in the explanation of this behavior because they do not adequately account for differences in cell size, density, deformability and electrical charge on the membrane surface. In this paper a new approach is taken where an effective porosity is used to account for the differences in the micro-environment of each particle type. Introduction of effective porosities into various sedimentation equations is useful in allowing better prediction of the optimum separation conditions observed in experimental data. Further adjustment of parameters is necessary for some models to shift optimums in settling curves to align with experimental trends.