Bioanalysis of Oligonucleotide by LC-MS: Effects of Ion Pairing Regents and Recent Advances in Ion-Pairing-Free Analytical Strategies

Oligonucleotides (OGNs) are relatively new modalities that offer unique opportunities to expand the therapeutic targets. Reliable and high-throughput bioanalytical methods are pivotal for preclinical and clinical investigations of therapeutic OGNs. Liquid chromatography-mass spectrometry (LC-MS) is now evolving into being the method of choice for the bioanalysis of OGNs. Ion paring reversed-phase liquid chromatography (IP-RPLC) has been widely used in sample preparation and LC-MS analysis of OGNs; however, there are technical issues associated with these methods. IP-free methods, such as hydrophilic interaction liquid chromatography (HILIC) and anion-exchange techniques, have emerged as promising approaches for the bioanalysis of OGNs. In this review, the state-of-the-art IP-RPLC-MS bioanalytical methods of OGNs and their metabolites published in the past 10 years (2012-2022) are critically reviewed. Recent advances in IP-reagent-free LC-MS bioanalysis methods are discussed. Finally, we describe future opportunities for developing new methods that can be used for the comprehensive bioanalysis of OGNs.

Automated summary

Oligonucleotides (OGNs) are a relatively new modality that provides unique opportunities for expanding therapeutic targets. Liquid chromatography-mass spectrometry (LC-MS) is now becoming the preferred method for bioanalysis of OGNs. While ion pairing reversed-phase liquid chromatography (IP-RPLC) has been widely used, there are technical issues associated with these methods. IP-free methods, such as hydrophilic interaction liquid chromatography (HILIC) and anion-exchange techniques, have emerged as promising approaches. In this review, the state-of-the-art IP-RPLC-MS bioanalytical methods for OGNs and their metabolites published in the past 10 years (2012-2022) are critically reviewed. Recent advances in IP-reagent-free LC-MS bioanalysis methods are discussed. Finally, future opportunities for developing new methods for comprehensive bioanalysis of OGNs are described.