Quantitative Analysis and Determination of Molecular Weight of siRNA Type Oligonucleotides by LCMS™-8060

Introduction

Nucleic acid drugs are synthetic oligonucleotides which are designed to bond specifically with target RNA or proteins. Although most nucleic acid drugs approved to date are the antisense type, the aptamer type and siRNA type have also been approved. Many nucleic acid drugs consist of around 20 bases and have molecular weights on the order of 6,000. Precision mass analysis techniques such as MALDI-TOF type and Q-TOF type LC/MS are used in measurements of the molecular weight of drug substances. On the other hand, the triple quadrupole mass spectrometer is generally used in quantitative analysis such as analysis of the fate of drugs in the blood, as this instrument offers high sensitivity in combination with a wide dynamic range. This article introduces an example of analysis of synthetic double-strand oligonucleotides using a Shimadzu LCMS- 8060 triple quadrupole mass spectrometer, assuming analysis of the drug substances of siRNA type nucleic acid drugs. Quantitativity was confirmed by SIM (selected ion monitoring). In preparation of the calibration curve by the SIM mode, linearity was confirmed in the range of 1 fmol to 10 pmol. In addition, the molecular weights were determined by deconvolution of a multivalent ion mass spectrum.

July 30, 2020 GMT