Over the past decade, there has been increased research oligonucleotides therapies (ONTs). With improved target specificity of next-generation oligonucleotides, demand for LC-MS bioanalytical assays in support of their research and development has also increased.
Developing robust, sensitive and selective sample preparation and LC-MS methods for ONTs remains quite challenging, due to their size, poly-anionic nature, physiochemical diversity, and stability, which often results in poor sample recovery from biomatrices, poor MS sensitivity due to limited ionization/fragmentation, and resolution from endogenous matrix interferences due to poor RP chromatographic retention.
This work described herein provides a single, simple method for the quantification of various oligonucleotides (15-35mer) from serum, using RP and mixed-mode µElution SPE sample preparation and analytical scale sub-2µm LC. This method achieves high recovery and low matrix effects, while achieving LODs as low as 0.5-1.0 ng/mL extracted from plasma/sera.