ANALYTICAL-SCALE AND PREPARATIVE-SCALE CHROMATOGRAPHIC-SEPARATION OF PHENYLALANINE FROM ASPARTAME USING A NEW POLYMERIC SORBENT

A new, large-pore, cross-linked, polymethacrylate stationary phase separates Phe from Aspartame in 10% aqueous ethanol by reversed-phase chromatography. Batch equilibrium data at 30, 50 and 70-degrees-C, obtained with 165-mu-m particle size material showed linear sorption at loadings of up to 140 mg/g stationary phase, and corresponded to a mobile phase adsorbate concentration approaching the solubility limits. Column runs with 40-, 60-, 117-, and 165-mu-m particle size materials at 30-70-degrees-C showed retention behavior that was predictable from batch equilibrium data, and was independent of particle size at sample volumes as high as 80% of the column void volume and at outlet concentrations of 5-10 mg/ml. The relatively large pores (250 angstrom) of the stationary phase allowed free access of small molecules, with the methacrylate structure promoting strong sorption of aromatic amino acids. These characteristics permitted the ready calculation of column retention times, and facilitated extrapolation of analytical-scale results obtained with small particle size material to preparative-scale separations carried out under volume overload conditions with a large particle size stationary phase.