Magnetic split-flow thin fractionation of magnetically susceptible particles

We recently built a magnetic separation system to extend the applications o f split-flow thin (SPLITT) fractionation to magnetically susceptible partic les. Here, we characterize the magnetic SPLITT system using magnetically su sceptible particles and ion-labeled particles. The flow axis of separation channel was orientated parallel and perpendicular to gravitational forces t o exclude and include, respectively, gravitational effects on separation. B oth operating modes were used to test the theory experimentally, with empha sis on the parallel mode. The magnetic susceptibilities of carrier and ion- labeled particles were varied, and various ion-labeled and unlabeled partic les were studied experimentally, resulting in successful separation of labe led particles, yeasts, and cells from unlabeled ones. The minimal differenc e in magnetic susceptibility (Delta chi) required for complete particle sep aration was about 1.75x10(-5) [cgs], corresponding to about 10(9) labeling ions per particle in this study. The throughput was around 7.2x10(8) partic les/h using the present setup. Magnetic SPLITT fractionation shows good pot ential for use in obtaining particles magnetic susceptibilities from a simp le theoretical treatment. (C) 1999 Elsevier Science B.V. All rights reserve d.