Challenge: Typical oligonucleotides used as therapeutics or potential therapeutic compounds are 15 to 30 nucleotides (nt) long. Oligonucleotides <15 nt can be readily resolved by HPLC technology, however the separation of longer sequences are more challenging. Ion-pair reversed-phase (IP-RP) HPLC has been traditionally used for oligonucleotides analysis. The traditional IP-RPLC eluent system typically uses TEA or TEAA or HFIP and the ion-pairing agent triethylammonium ion and a C18, column at 60oC. Under such conditions, the column's hydrolytic stability becomes crucial and is important to prevent the potential contribution of the oligonucleotide secondary structure from impacting retention.