Packing characteristics of winged shaped polymer fiber supports for preparative chromatography.

Polymer fibers have been identified as a promising alternative support material for liquid chromatography. Area enhanced fibers may overcome the shortcomings of conventional fiber supports with respect to binding capacity and packing efficiency. One type of area enhanced fiber supports are winged shaped microfibers, which have a more than tenfold higher surface area than round fibers, and can be manufactured via inexpensive, conventional extrusion techniques. In the present study, the packing characteristics of native and grafted winged shaped fiber supports have been investigated. A suspension based packing technique was used to pack short winged shaped polyamide 6 (PA6) fibers into small laboratory scale columns. Low column-to-column variabilities in porosities, plate heights, axial dispersion coefficients, and peak asymmetries were observed. Peak asymmetries were within typical ranges of preparative columns, and plate heights were at the lower end of those reported for other fiber supports. Packing density was found to be the main parameter that affected column performance. Lower packing densities were associated with lower plate heights, while increases in bed height resulted in more symmetric peak shapes. Packing density was also found to have a strong impact on the performance of poly (glycidyl methacrylate) (PGMA) grafted and sulfonated (SO) winged shaped PA6 fibers. Higher packing densities resulted in higher dynamic binding capacities (DBCs), but led to a decrease in capacity utilization and resolution. A comparison to conventional perfusive and diffusive adsorbents revealed that under optimized packing conditions such adsorbents can achieve a better resolution than conventional adsorbents at high mobile phase velocities. Overall, these results suggest, that winged shaped fibers have strong potential as supports for preparative chromatography. Further improvements may be possible via adjustments in the fiber dimensions.