Oligonucleotide research has exploded in recent years, requiring new and sophisticated techniques not only in their application, but also analysis. Phosphorothioate modification of oligonucleotides (S-oligos) is a technique used to improve stability and slow degradation by nucleases. In the synthesis of S-oligos it is imperative that modifications are as directed, whether it be a partially or fully modified S-oligo. COSMOCORE C₁₈ columns are shown here in a method to elucidate minute differences in chemical modification with excellent resolution.

Figure 1: Overlaid chromatograms of fully and partially phosphorothioated DNA oligos. Excellent resolution is observed between oligos of the same length and differing number of modifications.

Data courtesy of Nacalai USA.