Catch and release method utilizing polymer-support was investigated in the separation of 1alpha,25-(OH)(2) pre- and provitamin D-3. Polymer-supported alkyldiisopropylsityl triflate selectively captured the previtamin D-3 from a 26:74 mixture of pre- and provitamin D-3 produced by photoisomerization of provitamin D-3. (C) 2004 Elsevier Ltd. All rights reserved.