Development of SPE Method for the Extraction of Phosphorothioate Oligonucleotides from Serum Samples

Comprehensive development of a method for SPE extraction of antisense phosphorothioate oligonucleotide and its metabolites and their determination with the use of UHPLC.Polymer-based adsorbent and high percentage of methanol in elution solvent provided high recoveries compared with silica-based octadecyl cartridge. As to the type and concentration of ion pair reagent and organic solvent, the mixture of 5 mM of N,N-dimethylbutylamine/150 mM of 1,1,1,3,3,3-hexafluoroisopropanol and methanol was selected. Relatively high recoveries in the range of 79.2-81.2% with the SDs of 3.4-6.2% were obtained for the oligonucleotide and its metabolites extracted from human serum.The developed method may be successfully applied for routine analysis of antisense oligonucleotides in serum since it is relatively easy, quick and reliable.