CHEMICAL IMAGING OF MULTICOMPONENT VISCOUS FINGERING IN CHROMATOGRAPHY

Resolution in chromatographic separations can be compromised by nonuni form flow distribution, heterogeneous packing, or flow instabilities s uch as viscous fingering. In this work, the displacement of solutes wi thin a chromatographic column was monitored with an advanced magnetic- resonance technique, echo-planar spectroscopic imaging (EPSI). Unlike conventional magnetic-resonance imaging, this approach allows multiple solutes to be observed simultaneously, providing separate ''chemical images'' for each component. Qualitative chemical images were obtained in approximately I min with approximately 1 mm(3) spatial resolution. EPSI allowed us to examine the multicomponent viscous fingering probl em for the first time. While many features of the instability are pres erved solute retention appears to slow the growth of solvent fingers.