A cell separator design is presented for rapid, efficient separation of analytical quality plasma samples from whole blood for use in a continuous segmented flow point-of-care testing system. ...Sedimentation theory for multiple species suspensions, modified to account for continuity and rouleau formation, is used to model the separation process and optimize the separation chamber geometry. Model predictions, relating the sample separation time to a chamber taper angle, indicate respective separation times of 37–28
s for a chamber with a taper angle ranging from 16 to 20°, while maintaining sample volumes in the 1–1.5
ml range. Experimental observations of separation time agree to within 25% of theoretical predictions resulting in complete separation in 40
s, showing the ability to separate small 1–1.5
ml samples in less than 1
min. Results of characterization experiments conducted using the separator indicate indiscernible hemolysis when compared with hemoglobin levels measured from samples prepared in a bench-top centrifuge. Results show that cellular carryover is reduced in seven clean-in-place wash steps to 0.00063% of the original cellular content, and theory based on these results predicts no carryover in 11 steps.
Theoretical analytical sedimentation patterns have been computed for ligand-mediated heterogeneous association-dissociation reactions between macromolecules. Involvement of either a single kind of ...ligand or two different ligands acting in a stepwise fashion has been considered. Self-association, mediated in a stepwise fashion by two different ligands, has also been examined. The conclusion reached is that such interactions have the potentiality for exhibiting as many as three or four sedimenting peaks despite rapid rates of reaction. In general, the peaks correspond to different equilibrium compositions and not to individual macromolecular species; that is to say, they constitute a reaction boundary. Their resolution depends upon generation of concentration gradients of ligand(s) along the centrifuge cell by chemical reequilibration during sedimentation of the several macromolecular species. The implications of these findings for fundamental studies on subunit proteins and protein assemblies and for conventional applications of ultracentrifugation are discussed.
