Viscous fingering in chromatography visualized via magnetic resonance imaging

Magnetic resonance imaging (MRI) and chromatographic peak shape analysis have been used to study the elution of bovine serum albumin (BSA) and glycerol in size-exclusion chromatography columns. Chromatograms of BSA samples show evidence of dramatic fingering at concentrations above 30–50 mg/ml. However, MRI of BSA samples reveals eluent fingers invading the sample band inside the column at concentrations as low as 10 mg/ml. Growth rates of fingers increase with protein concentration and the impact of fingering on chromatograms at lower concentrations is reduced because of dispersion. MRI analysis of glycerol samples demonstrates similar behavior, although finger widths are larger. Fingering in high concentration samples of glycerol causes portions of a sample to trail and separate from the main sample band. Nonuniform flow at the inlet and a self-correcting leading edge of the sample band were noted and attributed to viscous effects.