Chemically selective NMR imaging of a 3-component (solid-solid-liquid) sedimenting system.

A novel magnetic resonance imaging (MRI) technique which resolves the separate components of the evolving vertical concentration profiles of 3-component non-colloidal suspensions is described. This method exploits the sensitivity of MRI to chemical differences between the three phases to directly image the fluid phase and one of the solid phases, with the third phase obtained by subtraction. 19F spin-echo imaging of a polytetrafluoroethylene (PTFE) oil was interlaced with 1H SPRITE imaging of low-density polyethylene (LDPE) particles. The third phase was comprised of borosilicate glass spheres, which were not visible while imaging the PTFE or LDPE phases. The method is demonstrated by performing measurements on 2-phase materials containing only the floating (LDPE) particles, with the results contrasted to the experimental behaviour of the individual phases in the full 3-phase system. All experiments were performed using nearly monodisperse particles, with initial suspension volume fractions, phi(i), of 0.1.