Enzymatic purification of chemically synthesized oligodeoxyribonucleotides prior to removal from a solid-support

A novel combined solid-phase DNA synthesis and solid-phase DNA purification strategy is described. Removal of all N-, cap-, and phosphate protecting groups while maintaining a 5'-blocking group on the final product followed by a 5'- specific exonuclease digestion of failure sequences with the synthetic DNA still attached to the solid phase yields an essentially pure oligomer.