AbstractAmberlite XAD-4, a nonpolar adsorbent with a particle size of 62 to 177 μm, was packed into 58 mm i.d. x 294 mm columns and radially compressed in the Waters Prep 500 preparative liquid chromatograph. Efficiency, loading capacity (multigram samples), resolution, recovery, and types of mobile phases were major parameters studied. Since XAD-4 is chemically inert mixed solvent and pH control from 1 to 13 can be successfully used in the mobile phase. Separations illustrating these advantages and the scope of the 58 mm i.d. column are described.