Method for detecting purity of oligonucleotide compounds and related substances in oligonucleotide compounds by LC-MS (liquid chromatography-mass spectrometry)

The invention discloses a method for detecting the purity of oligonucleotide compounds and related substances in the oligonucleotide compounds by LC-MS (liquid chromatography-mass spectrometry). The method provided by the invention comprises the following steps: dissolving or diluting a to-be-detected sample with water to prepare a to-be-detected solution; performing liquid chromatography detection on the to-be-detected solution, feeding the to-be-detected solution into a mass spectrometry detector, and analyzing the part which does not reach baseline separation in a liquid chromatogram through mass spectrometry; and quantitatively analyzing the purity of the oligonucleotide compounds in the sample and the related substances in the oligonucleotide compounds according to the detection results of the liquid chromatography and the mass spectrometry. The method provided by the invention solves the problem that the CpG ODN target sequence is difficult to distinguish from N +, N-and P = O impurities, and realizes a