Particle magnetic susceptibility determination using analytical split-flowthin fractionation

Magnetic split-flow thin (SPLITT) fractionation is a newly developed SPLITT fractionation subtechnique for separating magnetically susceptible particl es. Here, we describe determination of particle magnetic susceptibilities u sing a novel method, analytical magnetic SPLITT fractionation. This method is based on particle retrieval calculation under known flow-rates and magne tic field strengths. The flow axis of separation channel was oriented paral lel to gravity to exclude gravitational effects on separation. Various carr ier magnetic susceptibilities, magnet interpolar gap widths, and ion-labele d particles were studied experimentally, resulting in successful determinat ion of magnetic susceptibilities for magnetically susceptible particles and various ion-labeled particles. The minimum level of particle magnetic susc eptibility (chi) that could be determined in this study was about 5.0(.)10( -7) (cgs). The minimum number of erbium labeling ions per particle required for silica susceptibility determination was found to be 1.57(.)10(10). The se determined values were consistent with relative standard deviations with in 8% variation and within 9% of standard reference measurements using a su perconducting quantum interference device magnometer. Analytical magnetic S PLITT fractionation shows good potential for use in simple determination of particle magnetic susceptibilities. (C) 2001 Elsevier Science B.V. All rig hts reserved.