Enrichment and recovery of oligonucleotide impurities by N-Rich twin-column continuous chromatography

N-Rich is a twin-column continuous chromatography technology well suited for small-scale isolation and the enrichment of product related impurities. For the first time, N-Rich was used for impurity isolation from a double-stranded RNA (dsRNA) therapeutic synthetic oligonucleotide (ON), produced by solid-phase synthesis. By employing the N-Rich process, where the desired impurities are recycled and selectively enriched, and interfering substances are depleted, it was possible to obtain substantial amounts of high purity marginal impurities with a reproducible, automatized, and productive method.