Characterization of Non-Specific Crossover in SPLITT Fractionation

• Published in: Analytical chemistry (Washington) Vol. 80; no. 18; pp. 7105 - 7115
• Main Authors: Williams, P. Stephen, Hoyos, Mauricio, Kurowski, Pascal, Salhi, Dorra, Moore, Lee R., Zborowski, Maciej
• Format: Journal Article
• Language: English
• Published: 13-08-2008
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac800841q

Split-flow thin channel (SPLITT) fractionation is a technique for continuous separation of particles or macromolecules in a fluid stream into fractions according to the lateral migration induced by application of a field perpendicular to the direction of flow. Typical applications have involved isolation of different fractions from a polydisperse sample. Some specialized applications involve the separation of the fraction influenced by the transverse field from the fraction that is not. For example, immuno-magnetically labeled biological cells may be separated from non-labeled cells with the application of a transverse magnetic field gradient. In such cases, it may be critically important to minimize contamination of the labeled cells with non-labeled cells while at the same time maximizing the throughput. Such contamination is known as non-specific crossover (NSC) and refers to the real or apparent migration of non-mobile particles or cells across streamlines with the mobile material. The possible mechanisms for NSC are discussed, and experimental results interpreted in terms of shear-induced diffusion (SID) caused by viscous interactions between particles in a sheared flow. It is concluded that SID may contribute to NSC, but that further experiments and mathematical modeling are necessary to more fully explore the phenomenon.