Separation of racemic tryptophan using hollow-fiber membranes

CHED 245

Anthony Stender and Daniel M. Besemann, dbesemann@hamline.edu. Department of Chemistry, Hamline University, 1536 Hewitt Avenue, Saint Paul, MN 55104
The efficient separation of enantiomers is a matter of great interest, particularly for the pharmaceutical industry. This work explores the utility of separating tryptophan enantiomers using hollow-fiber membranes. A cylindrical, microporous fiber (polysulfone) with a molecular weight cutoff of 20 – 40 kiloDaltons was used as the hollow-fiber membrane. Bovine serum albumen (BSA, MW = 66kDa) was the chiral selector for L-tryptophan. The hollow-fiber membrane served as a boundary between two aqueous phases that were pumped through a homebuilt column. The feed phase carried racemic tryptophan through the inside of the membrane, and the receiving phase preferentially collected one tryptophan enantiomer on the outside of the membrane. Conditions (concentration of BSA and racemic tryptophan, the location of BSA, the number of columns, and the pH) were varied to determine the optimal configuration for this separation. Results were quantified with chiral high-performance liquid chromatography.