Molecular characterization method of nitrogen-containing compound in petroleum fraction based on liquid chromatography-mass spectrometry

The invention discloses a molecular characterization analysis method of a nitrogen-containing compound in a petroleum fraction based on liquid chromatography-high-resolution mass spectrometry. The method comprises the following steps: directly diluting a sample with a solvent, by adopting ultra-high performance liquid chromatography-electrospray ionization source-high-resolution mass spectrometry in a positive ion mode, and realizing rapid analysis and molecular characterization of the nitrogen compounds in the petroleum fractions within 30 minutes. Compared with the prior art, the method has the advantages that complex grading pretreatment on the oil sample is not needed, mass spectrum positive and negative ion modes are not needed for two-time analysis in mass spectrum electrospray ionization, only positive ion mode analysis is combined with liquid chromatography outflow time, and the mass-to-charge ratio m/z is used for correction of the mass axis of the mass spectrometer in the analysis process, and bette