Mass spectrometry method and mass spectrometer

1. A mass spectrometry method for generating product ions from a precursor ion derived from a sample component having a hydrocarbon chain, and mass-analyzing the product ion, the mass spectrometry method comprising:

irradiating the precursor ion with an oxygen radical or a hydroxy radical and a nitrogen oxide radical to generate product ions;

separating the product ions according to mass-to-charge ratio, and detecting the product ions; and

inferring a structure of the hydrocarbon chain based on mass-to-charge ratio of the detected product ions.

2. A mass spectrometer for generating a product ion from precursor ions derived from a sample component having a hydrocarbon chain and mass-analyzing the product ion, the mass spectrometer comprising:

a reaction chamber into which the precursor ion is introduced;

a radical generation unit configured to generate an oxygen radical or a hydroxy radical and a nitrogen oxide radical;

a radical irradiation unit configured to irradiate the precursor ion introduced into the reaction chamber with the oxygen radical or the hydroxy radical and the nitrogen oxide radical; and

a separation detection unit configured to separate and detect the product ions generated from the precursor ion by a reaction with the oxygen radical or the hydroxy radical and a reaction with the nitrogen oxide radical according to mass-to-charge ratio.

3. The mass spectrometer according to claim 2 , further comprising a structure inferring unit configured to extract a set of product ions having a mass difference of 29 Da or 31 Da among the detected product ions and infer a position of an unsaturated bond contained in the hydrocarbon chain.

4. The mass spectrometer according to claim 3 , wherein:

the sample component is one in which a substance having a known structure or structure candidate is bound to a hydrocarbon chain,

the mass spectrometer further comprises a compound database in which information on the structure or structure candidate is contained, and

the structure inferring unit is configured to infer a structure of the sample component based on mass-to-charge ratio of the detected product ion and information on the structure or structure candidate contained in the compound database.

5. The mass spectrometer according to claim 3 , wherein the structure inferring unit is configured to infer a type of an unsaturated bond contained in the hydrocarbon chain of the sample component based on a ratio of an intensity of a product ion, which is an adduct ion in which oxygen atoms are added to the precursor ion, to an intensity of the precursor ion.

6. The mass spectrometer according to claim 5 , wherein:

the mass spectrometer further comprises a compound database that contains information on the ratios of a plurality of components that are candidates for the hydrocarbon chain contained in the sample component; and

the structure inferring unit is configured to infer a type of an unsaturated bond contained in the hydrocarbon chain of the sample component by comparing the ratio obtained by the measurement of the sample component with the ratio contained in the compound database.

7. The mass spectrometer according to claim 6 , wherein:

the compound database contains information on the ratios for both cis and trans components that are common except for the type of unsaturated bond; and

the structure inferring unit is configured to compare the ratio obtained by the measurement of the sample component with the ratio contained in the database to infer a proportion of a component having a cis unsaturated bond and a component having a trans unsaturated bond which are contained in the sample component.

8. The mass spectrometer according to claim 2 , wherein the radical generation unit is configured to generate the oxygen radical and the nitrogen oxide radical from a raw gas containing at least one kind of water vapor, nitrogen gas, and air.

9. The mass spectrometer according to claim 2 , wherein the radical generation unit further includes:

a radical generation chamber;

a vacuum exhaust unit for exhausting the radical generation chamber;

a raw gas supply source for introducing a raw gas into the radical generation chamber; and

a vacuum discharge unit for generating a vacuum discharge in the radical generation chamber.

10. The mass spectrometer according to claim 9 , wherein the vacuum discharge unit is a radio-frequency plasma source, a hollow cathode plasma source, or a magnetic field confinement type plasma source.

11. The mass spectrometer according to claim 2 , wherein the mass spectrometer includes a front quadrupole mass filter and a rear quadrupole mass filter, and the reaction chamber is a collision cell provided between the front quadrupole mass filter and the rear quadrupole mass filter.