High-sensitivity workflow for LC–MS-based analysis of GalNAc-conjugated oligonucleotides: a case study

Aim: Mass-selective quantitation is a powerful attribute of LC–MS as a platform for bioanalysis. Here, a sensitive LC–MS approach has been validated for an oligonucleotide having chemical modifications (e.g., N-acetylgalactosamine [GalNAc] conjugated), to distinguish between the conjugated and unconjugated forms of the oligonucleotide, thereby enabling a nuanced view of the pharmacokinetic profile. Results: A high-sensitivity methodology for mass-specific measurement of AZD8233, a GalNAc-conjugated 16-mer oligonucleotide, using LLE-SPE with optimized LC conditions and detection of a low-mass fragment ion was successfully validated in the range of 0.20–100 ng/ml in human plasma. Conclusion: The AZD8233 LC–MS methodology adds valuable insight on the GalNAc linker’s in vivo stability to the program and should be broadly applicable to oligonucleotides requiring high sensitivity and mass-selective measurement for quantitative discrimination from metabolites and endogenous interferences.

GENERAL CHARACTERISTICS OF INTERMEDIATE MASS FRAGMENT INCLUSIVE CROSS SECTIONS IN 20Ne INDUCED INTERACTIONS

Inclusive integrated cross sections of intermediate mass fragments have been measured in 20Ne induced reactions on silver and gold targets at 20, 30, 40, 50 and 60 MeV/nucleon incident energies. Whereas the production yields remain approximately constant for the Ne+Ag system, for incident energies greater than 30 MeV/nucleon, they increase by a factor of 3.5 for the Ne+Au system over the full energy range studied.