Mass spectrometry device and mass spectrometry method

Abstract

A precursor ion is reacted with an ammonia molecule or an ammonia radical to generate a product ion, the product ion is separated and detected according to mass-to-charge ratio, and it is estimated whether an aldehyde group is contained in the molecular structure of the precursor ion based on the difference between the mass-to-charge ratio of the detected product ion and the mass-to-charge ratio of the precursor ion. In addition, a mass spectrometry device (1) is provided with a reaction chamber (132) into which a precursor ion is introduced, an ammonia supply portion (5) that supplies an ammonia molecule or an ammonia radical to the reaction chamber, and a separation and detection portion (142, 143, 144, 145) that separates and detects a product ion generated from the precursor ion by reaction with an ammonia molecule or an ammonia radical according to mass-to-charge ratio.

Description

Technical Field

[0001] This invention relates to a mass spectrometry analysis device and a mass spectrometry analysis method. Background Technology

[0002] To identify polymeric compounds in samples or to determine their structures, mass spectrometry is widely used. This involves screening ions with specific mass-to-charge ratios from ions originating from the sample components as precursor ions. These precursor ions are then fragmented to generate various product ions, which are separated and detected based on their mass-to-charge ratios. Collision-induced fragmentation (CID) is the most common method in this mass spectrometry approach. In CID, precursor ions, accelerated by energy (collision energy), are repeatedly collided with inert gases such as argon (collision gases) to accumulate energy and eventually fragment.

[0003] Most polymers are organic compounds with hydrocarbon chains as their main skeleton. To understand the characteristics of these polymers, it is effective to obtain information such as the presence or absence of unsaturated bonds on carbon atoms and the presence or absence of characteristic functional groups.

[0004] However, in energy-accumulating ion fragmentation methods such as collision-induced fragmentation, the energy accumulated in the precursor ion is dispersed throughout the molecule, resulting in low selectivity for the location of precursor ion fragmentation. It is difficult to cause the precursor ion to fragment at the unsaturated bonds of carbon atoms or specific functional groups. Furthermore, the manner in which the precursor ion breaks varies depending on the magnitude of the collision energy and the pressure of the collision gas. Therefore, it is difficult to obtain information related to the unsaturated bonds of carbon atoms or specific functional groups through collision-induced fragmentation.

[0005] Therefore, the following free radical attachment cleavage method has recently been proposed: by attaching free radicals to precursor ions derived from the sample composition, the precursor ions are cleaved at the positions of unsaturated bonds or specific functional groups on carbon atoms. For example, Patent Documents 1 and 2 describe selective cleavage of precursor ions at peptide bond positions by attaching hydrogen free radicals, etc. to the precursor ions. Furthermore, Patent Documents 3 and 4 describe selective cleavage of precursor ions at the positions of unsaturated bonds contained in the hydrocarbon chain by attaching oxygen free radicals, etc. to the precursor ions.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2015 / 133259

[0009] Patent Document 2: International Publication No. 2018 / 186286

[0010] Patent Document 3: International Publication No. 2019 / 155725

[0011] Patent Document 4: International Publication No. 2020 / 240908

[0012] Patent Document 5: Japanese Patent Application Publication No. 2020-177784

[0013] Non-patent literature

[0014] Non-Patent Literature 1: Hidenori Takahashi, Yuji Shimabukuro, Daiki Asakawa, Akihito Korenaga, Masaki Yamada, Shinichi Iwamoto, Motoi Wada, Koichi Tanaka, “Identifying Double Bond Positions in Phospholipids Using Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry Based on Oxygen Attachment Dissociation”, Mass Spectrometry, Vol. 8, No. 2, p. S0080, 2019

[0015] Non-Patent Literature 2: Wolf, S., Schmidt, S., Muller-Hannemann, M., & Neumann, S., “Insilico fragmentation for computer-assisted identification of metabolite massspectra”, BMC Bioinformatics, 11, 148, 2010 Summary of the Invention

[0016] The problem the invention aims to solve

[0017] As mentioned above, although methods for selectively cleaving precursor ions at specific sites using free radical attachment cleavage are being proposed, no effective method has yet been proposed for aldehydes, which are one of the representative functional groups in organic compounds. Techniques for obtaining information about aldehydes are also being sought.

[0018] The problem to be solved by the present invention is to provide a technique for obtaining information about carbon-oxygen double bonds contained in the molecular structure of a sample component.

[0019] Solution for solving the problem

[0020] The mass spectrometry analysis method of the present invention, which addresses the above-mentioned problems, is as follows:

[0021] The precursor ion reacts with ammonia molecules or ammonia free radicals to generate the product ion;

[0022] The product ions are separated and detected based on their mass-to-charge ratio;

[0023] The difference between the mass-to-charge ratio of the detected product ion and the mass-to-charge ratio of the precursor ion is used to estimate whether the precursor ion contains an aldehyde group in its molecular structure.

[0024] In addition, another aspect of the present invention, completed to solve the above-mentioned problems, is a mass spectrometry analysis apparatus that performs mass spectrometry analysis on the generation of product ions from precursor ions, said mass spectrometry analysis apparatus comprising:

[0025] The reaction chamber in which the precursor ions are introduced;

[0026] An ammonia supply unit supplies ammonia molecules or ammonia radicals to the reaction chamber; and

[0027] The separation and detection unit separates and detects product ions generated from the precursor ions through reaction with the ammonia molecules or the ammonia free radicals based on the mass-to-charge ratio.

[0028] The effects of the invention

[0029] In this invention, precursor ions derived from a sample component are reacted with ammonia molecules (NH3) or ammonia radicals (NH radicals or NH2 radicals) to generate product ions. The generated product ions are then separated and detected based on their mass-to-charge ratio. The presence or absence of an aldehyde group in the precursor ion's molecular structure is then estimated based on the difference between the mass-to-charge ratio of the product ion and that of the precursor ion. Alternatively, the analyst may make the estimation of the presence or absence of an aldehyde group. This invention is based on the following insight: when a precursor ion containing an aldehyde group reacts with ammonia molecules or ammonia radicals, these molecules or radicals selectively act on the aldehyde group, changing the carbon-oxygen double bond into a single bond, thereby generating an adduct ion with a hydrogen atom bonded to the carbon atom side and an amino group bonded to the oxygen atom side. When a precursor ion containing an aldehyde group reacts with ammonia molecules or ammonia radicals, a product ion (adduct ion) with a mass increase of 17 Da is generated for each aldehyde group present. Therefore, it is possible to estimate whether an aldehyde group is present in the molecular structure of a precursor ion based on the difference between the mass-to-charge ratio of the product ion generated from the precursor ion and the mass-to-charge ratio of the precursor ion. Attached Figure Description

[0030] Figure 1 This is a structural diagram of the main parts of an embodiment of the mass spectrometry analysis device involved in the present invention.

[0031] Figure 2 This is a schematic diagram of the free radical generation section in the mass spectrometry analysis apparatus of this embodiment.

[0032] Figure 3 This is a schematic diagram of the free radical transport path in the mass spectrometry analysis device of this embodiment.

[0033] Figure 4 It is the molecular structure of an adduct ion generated by the reaction of the molecular structure of aldehyde C-10 (Aldehyde C-10) with ammonia free radicals.

[0034] Figure 5 This is the product ion spectrum of aldehyde C-10 obtained using the mass spectrometry analysis device of this embodiment. Detailed Implementation

[0035] Hereinafter, embodiments of the mass spectrometry analysis apparatus and mass spectrometry analysis method involved in the present invention will be described with reference to the accompanying drawings.

[0036] exist Figure 1 The diagram shows a general structure of the mass spectrometry analysis apparatus 1 of this embodiment. The mass spectrometry analysis apparatus 1 generally consists of a mass spectrometry analysis apparatus body and a control and processing unit 6.

[0037] The main body of the mass spectrometry analyzer includes an ionization chamber 10 at approximately atmospheric pressure and a vacuum chamber. Inside the vacuum chamber, starting from the ionization chamber 10 side, there are a first intermediate vacuum chamber 11, a second intermediate vacuum chamber 12, a third intermediate vacuum chamber 13, and an analysis chamber 14, forming a multi-stage differential exhaust system with increasing vacuum levels in that order.

[0038] An electrospray ionization probe (ESI probe) 101 is provided in the ionization chamber 10 to spray a liquid sample by imparting a charge. The liquid sample can be directly injected into the ESI probe 101, or a sample component separated from other components contained in the liquid sample by a liquid chromatograph column can be introduced into the ESI probe 101.

[0039] The ionization chamber 10 is connected to the first intermediate vacuum chamber 11 via a thin-diameter heating capillary 102. An ion lens 111 is disposed in the first intermediate vacuum chamber 11. The ion lens 111 is composed of multiple annular electrodes of different diameters and is used to converge ions near the central axis of the ion flight path, i.e., the ion optical axis C.

[0040] The first intermediate vacuum chamber 11 and the second intermediate vacuum chamber 12 are separated by a skimmer 112 with a small hole at the top. An ion guide 121 is disposed in the second intermediate vacuum chamber 12. The ion guide 121 is composed of a plurality of rod electrodes arranged in a manner surrounding the ion optical axis C, for converging ions in the vicinity of the ion optical axis C.

[0041] A quadrupole mass filter 131, a collision chamber 132, and an ion guide 134 are disposed in the third intermediate vacuum chamber 13. The quadrupole mass filter 131 separates ions according to their mass-to-charge ratio. The collision chamber 132 has a multi-pole ion guide 133 inside, and the ion guide 134 is used to transport ions emitted from the collision chamber 132. The ion guide 134 is composed of multiple annular electrodes of the same diameter.

[0042] The collision chamber 132 is connected to a collision gas supply unit 4. The collision gas supply unit 4 has a collision gas source 41, a gas inlet flow path 42 for introducing gas from the collision gas source 41 into the collision chamber 132, and a valve 43 for opening or closing the gas inlet flow path 42. The collision gas used is an inert gas such as nitrogen or argon.

[0043] In addition, the collision chamber 132 is also connected to a free radical supply unit 5. The free radical supply unit 5 has the same structure as described in Patent Document 5 and Non-Patent Document 1. Figure 1 and Figure 2 As shown, the free radical supply unit 5 includes: a free radical source 54, which has a free radical generation chamber 51 formed inside; a vacuum pump (not shown) for venting the free radical generation chamber 51; a raw material gas supply source 52 for supplying gas (raw material gas) as a raw material for free radicals; and a high-frequency power supply unit 53. A valve 56 for adjusting the flow rate of the raw material gas is provided in the flow path from the raw material gas supply source 52 to the free radical generation chamber 51.

[0044] exist Figure 2 A cross-sectional view of the radical source 54 is shown. The radical source 54 has a tubular body 541 made of a dielectric material such as alumina (e.g., alumina, quartz, aluminum nitride), the internal space of which is called a radical generation chamber 51. The tubular body 541 is fixed by a plunger 545 in a state of being inserted into the interior of a hollow cylindrical magnet 544. A helical antenna 542 is wound around the outer periphery of the portion of the tubular body 541 located inside the magnet 544. Figure 2 (dashed line).

[0045] In addition, a high-frequency power input section 546 is provided in the free radical source 54. High-frequency power is supplied to the high-frequency power input section 546 from the high-frequency power supply section 53. The free radical source 54 also has a flange 547 for fixing the front end portion of the free radical source 54. A hollow cylindrical magnet 548, which is paired with the magnet 544 and has the same diameter as the magnet 544, is housed inside the flange 547. A magnetic field is generated inside the tubular body 541 (in the free radical generation chamber 51) by the magnets 544 and 548, and the generation and maintenance of plasma are facilitated by the action of the magnetic field.

[0046] The feed gas is a gas capable of generating ammonia radicals (NH radicals or NH2 radicals). For example, a mixture of nitrogen and water vapor can be used as such a feed gas. In this case, nitrogen radicals are generated from nitrogen and hydrogen radicals from water vapor, which combine to generate ammonia radicals. Alternatively, ammonia can be used directly to generate ammonia radicals. Or, various gases (including mixtures) can be used, such as air as a feed gas to generate nitrogen radicals, or hydrogen as a feed gas to generate hydrogen radicals, etc.

[0047] A delivery tube 58 is connected to the outlet end of the free radical source 54 for transporting the free radicals generated in the free radical generation chamber 51 to the collision chamber 132. The delivery tube 58 is an insulating tube, and can be, for example, a quartz glass tube or a borosilicate glass tube.

[0048] like Figure 3 As shown, a plurality of heads 581 are provided in the portion of the delivery pipe 58 arranged along the wall of the collision chamber 132. Each head 581 is provided with an inclined conical inlet to introduce free radicals in a direction intersecting the central axis (ion optical axis C) of the ion flight direction. As a result, free radicals can be uniformly supplied into the interior of the collision chamber 132.

[0049] The mass spectrometry analyzer 1 in this embodiment is configured such that it includes a free radical supply unit 5 as an ammonia supply unit, from which ammonia free radicals are supplied to the interior of the collision chamber 132. However, the mass spectrometry analyzer 1 can also be configured to supply ammonia molecules to the interior of the collision chamber 132 instead of ammonia free radicals. In this case, the raw material gas supply source 52 can be used as the ammonia supply unit and directly connected to the collision chamber 132. For example, ammonia gas or ammonia water vapor can be used as the raw material gas for generating ammonia molecules.

[0050] The analysis chamber 14 includes: an ion transport electrode 141 for transporting ions incident from the third intermediate vacuum chamber 13 to the orthogonal acceleration section; an orthogonal acceleration electrode 142, which consists of a set of push-out electrodes 1421 and a take-in electrode 1422 arranged opposite to each other across the incident optical axis (orthogonal acceleration region) of the ions; an acceleration electrode 143 for accelerating ions sent into the flight space by means of the orthogonal acceleration electrode 142; a reflection electrode 144 for forming a return trajectory of ions in the flight space; an ion detector 145; and a flight tube 146 for defining the outer edge of the flight space.

[0051] The control processing unit 6 has the following functions: controlling the operation of each part, and saving and analyzing the data obtained by the ion detector 145. In addition to the storage unit 61, the control processing unit 6 also includes a measurement control unit 62 and an aldehyde estimation unit 63 as functional blocks. The storage unit 61 stores a method document describing the measurement conditions for performing the measurement (described later) and information for converting the ion's time-of-flight to its mass-to-charge ratio. The control processing unit 6 is essentially a standard personal computer connected to an input unit 7 and a display unit 8, and the aforementioned functional blocks are implemented by executing a pre-installed mass spectrometry analysis program using a processor.

[0052] Next, as an example of the mass spectrometry analysis method according to the present invention, the analysis process using the mass spectrometry analysis apparatus 1 of this embodiment will be described. The measurement control unit 62 controls each part of the mass spectrometry analysis apparatus to perform a series of measurements described below. In this example, firstly, an MS measurement to determine the mass-to-charge ratio of the precursor ion is performed; then, an ammonia radical is attached to the precursor ion to generate a product ion, and an MS / MS measurement to determine its mass-to-charge ratio is performed.

[0053] When the user indicates the start of the analysis through the prescribed input operation, the liquid sample is introduced into the electrospray ionization probe 101 from the syringe (not shown) pre-set with the liquid sample to ionize it.

[0054] Ions generated from the sample are introduced into the first intermediate vacuum chamber 11 through the heated capillary 102 due to the pressure difference between the ionization chamber 10 and the first intermediate vacuum chamber 11. In the first intermediate vacuum chamber 11, ions are focused near the ion optical axis C by the ion lens 111.

[0055] The ions that are focused in the first intermediate vacuum chamber 11 then enter the second intermediate vacuum chamber 12, are focused again near the ion optical axis C by the ion guide 121, and then enter the third intermediate vacuum chamber 13.

[0056] In the case of MS measurement, all ions pass directly through the third intermediate vacuum chamber 13 without activating the quadrupole mass filter 131 and the collision chamber 132. After passing through the collision chamber 132, the ions are focused to the vicinity of the ion optical axis C by the ion guide 134 and then enter the analysis chamber 14.

[0057] Ions entering the analysis chamber 14 are transported to the orthogonal accelerating electrode 142 via the ion transport electrode 141. The orthogonal accelerating electrode 142 applies a voltage at a predetermined period, causing the ion's flight direction to deflect to a direction approximately orthogonal to its previous flight direction. The ions, whose flight direction has been deflected, are accelerated by the accelerating electrode 143 and ejected into the flight space. The ions ejected into the flight space travel along a predetermined flight path defined by the reflecting electrode 144 and the flight tube 146 for a time corresponding to their mass-to-charge ratio, and then incident on the ion detector 145. The ion detector 145 outputs a signal corresponding to the amount of ion incident each time an ion is incident. The output signals from the ion detector 145 are sequentially stored in the storage unit 61. The storage unit 61 stores measurement data along the ion flight time and ion detection intensity axes.

[0058] When the measurement is completed, the measurement control unit 62 reads the measurement data stored in the storage unit 61 and the information used to convert the flight time of the ions into the mass-to-charge ratio of the ions, and converts it into mass spectrometry data with the mass-to-charge ratio of the ions and the detection intensity of the ions as the axes.

[0059] The measurement control unit 62 then identifies the peak with the highest intensity in the mass spectrometry data and obtains its mass-to-charge ratio. In the electrospray ionization probe 101 used in this embodiment, the proton-adding ions obtained by adding protons to sample molecules are typically the most abundant. Therefore, in this embodiment, the proton-adding ions are identified as the precursor ions corresponding to the peak with the highest intensity.

[0060] After determining the mass-to-charge ratio of the precursor ions, the measurement control unit 62 then performs MS / MS measurement. First, the interior of the radical generation chamber 51 is evacuated to a predetermined vacuum level using a vacuum pump, and a raw material gas (in this embodiment, a mixture of nitrogen and water vapor) is introduced into the radical generation chamber 51 from the raw material gas supply source 52. Next, a high-frequency voltage is supplied to the helical antenna 542 from the high-frequency power supply unit 53, generating plasma in the radical generation chamber 51. Nitrogen radicals and hydrogen radicals are thus generated from the raw material gas supplied to the radical generation chamber 51. These radicals combine inside the radical generation chamber 51 or during their transport from the radical generation chamber 51 to the collision chamber 132 to form ammonia radicals.

[0061] As described above, in this embodiment, ammonia radicals are generated and attached to the precursor ions, but ammonia molecules can also be attached to the precursor ions instead of ammonia radicals. In this case, instead of the above-described steps involved in the generation of ammonia radicals, ammonia molecules are supplied from the raw material gas supply source 52 into the interior of the collision chamber 132.

[0062] After free radicals are generated in the free radical supply section 5 (or in parallel with the generation of free radicals), the liquid sample is introduced into the electrospray ionization probe 101 from a syringe pre-set with the liquid sample and ionized.

[0063] Similar to MS measurements, ions generated from the sample are focused near the ion optical axis C during passage through the first intermediate vacuum chamber 11 and the second intermediate vacuum chamber 12 before entering the third intermediate vacuum chamber 13.

[0064] In the third intermediate vacuum chamber 13, ions with the mass-to-charge ratio determined based on the MS measurement described above are screened as precursor ions using a quadrupole mass filter 131 and introduced into the collision chamber 132. As described above, ammonia radicals are introduced into the collision chamber 132, thereby attaching to the precursor ions. At this time, the ammonia radicals selectively attach to the positions of the aldehyde groups contained in the molecular structure of the precursor ions. As a result, the carbon-oxygen double bond constituting the aldehyde group changes to a single bond, with hydrogen combining on the carbon side and amino group combining on the oxygen side, to generate product ions (addition ions). The product ions generated in the collision chamber 132 are focused near the ion optical axis C by the ion guide 134 and then enter the analysis chamber 14.

[0065] In the analysis chamber 14, similar to MS measurements, the product ions travel along a predetermined flight path defined by the reflective electrode 144 and the flight tube 146 for a time corresponding to the mass-to-charge ratio of each ion, and then incident on the ion detector 145. The ion detector 145 outputs a signal corresponding to the incident ion quantity each time an ion is incident. The output signals from the ion detector 145 are sequentially stored in the storage unit 61. The storage unit 61 stores measurement data with the ion flight time and ion detection intensity as axes.

[0066] When the measurement is completed, the aldehyde estimation unit 63 reads the measurement data stored in the storage unit 61 and the information used to convert the flight time of the ions into the mass-to-charge ratio of the ions, and converts it into mass spectrometry (product ion spectrum) data with the mass-to-charge ratio of the ions and the detection intensity of the ions as the axes.

[0067] When mass spectrometry data is generated, the aldehyde estimation unit 63 extracts information about the mass peaks contained in the mass spectrum. Next, it extracts a mass peak (mass peak of the adduct ion) whose mass difference from the precursor ion is 17 Da (17 in the case of a monovalent ion) greater than that of the precursor ion, which is n times (n is a natural number). Then, it determines the aforementioned n of the product ion with the largest mass-to-charge ratio. After determining n, the aldehyde estimation unit 63 displays the product ion spectrum obtained by marking the mass peaks of the precursor ion and the adduct ion with predetermined labels on the display unit 8, along with the value of n. On the other hand, if there is no mass peak with a mass difference of 17 Da (17 in the case of a monovalent ion) greater than that of the precursor ion among the mass peaks with mass ratios greater than that of the precursor ion, it is estimated that the molecular structure of the sample component does not contain an aldehyde group.

[0068] Here, the results obtained by determining aldehyde C-10 using the above procedure are explained. Figure 4 The upper part is the molecular structure of the precursor ion generated from the C-10 aldehyde, and the lower part is the molecular structure of the product ion (adduct ion) generated by the attachment of an amino radical. Additionally, Figure 5 It is the product ion spectrum obtained by measurement.

[0069] exist Figure 5 In the product ion spectrum shown, the mass peak with a mass-to-charge ratio of 151.1591 is the mass peak of the precursor ion (proton addition ion). Additionally, a mass peak appears at a position where the mass-to-charge ratio is 17.0263 greater than that of the precursor ion. This is the mass peak of the adduct ion formed by the reaction of the ammonia radical with the precursor ion. Therefore, based on this product ion spectrum, it is estimated that the molecular structure of the sample component (aldehyde C-10) contains one aldehyde group.

[0070] Previously, the following method was used to resolve the molecular structure of precursor ions: collision-induced fragmentation (CID) of the precursor ions to generate product ions, and the resulting product ion spectra were compared with those of products in a database to identify the sample component based on their consistency. However, the CID method has low selectivity for the location of precursor ion fragmentation, making it difficult to obtain identical product ion spectra even when mass spectrometry analysis is performed under the same conditions as product ion spectra in the database. Therefore, if one wants to identify compounds, for example, through spectral matching, the following problem exists: multiple candidate compounds with the same score (mass spectrometry consistency) exist, making it difficult to identify which one is the sample component.

[0071] In contrast, if the above determination is performed using the mass spectrometry analysis apparatus of this embodiment, the number of aldehyde groups contained in the compound that is a sample component can be determined to narrow down the range of candidate compounds, thus enabling more accurate identification of the sample component. Furthermore, when the precursor ion reacts with an ammonia radical or ammonia molecule, the selectivity of the precursor ion fragmentation site is high, and compared to the CID method, it is easier to obtain a mass spectrum close to the mass spectra recorded in the database, thus improving the accuracy of compound identification based on spectral matching.

[0072] The above embodiment is an example and can be appropriately modified according to the spirit of the present invention. In the above embodiment, only the determination of the product ion spectrum obtained by attaching ammonia free radicals, which is characteristic of the present invention, has been described. However, it is preferable to obtain the product ion spectrum by CID method in conjunction with this determination, and to identify the sample components based on the two product ion spectra.

[0073] In the above embodiments, a time-of-flight (TOF) type mass separator is used as the subsequent mass filter, but other types of mass separators, such as quadrupole mass filters, can also be used. However, by using a TOF type mass separator as in the above embodiments, the precise mass of the product ions can be measured, thus enabling more reliable determination of adduct ions generated by the attachment of ammonia radicals.

[0074] Furthermore, in the above embodiments, the sample components in the liquid sample are ionized using the electrospray ionization probe 101, but other ionization sources such as atmospheric pressure chemical ionization (APCI) probes can also be used. Additionally, the structure is not limited to liquid samples; it can also be used to ionize sample components in solid or gaseous samples using appropriate ionization sources.

[0075] Furthermore, in the above embodiment, the structure is configured to introduce precursor ions into the collision chamber 132 and allow ammonia radicals to attach to the precursor ions, but it can also be configured to introduce precursor ions into the ion trap.

[0076] [Way]

[0077] Those skilled in the art will understand that the above-described exemplary embodiments are specific examples of the following approaches.

[0078] (First item)

[0079] One approach involves mass spectrometry analysis methods, wherein,

[0080] The precursor ion reacts with ammonia molecules or ammonia free radicals to generate the product ion;

[0081] The product ions are separated and detected based on their mass-to-charge ratio;

[0082] The difference between the mass-to-charge ratio of the detected product ion and the mass-to-charge ratio of the precursor ion is used to estimate whether the precursor ion contains an aldehyde group in its molecular structure.

[0083] (Second item)

[0084] A mass spectrometry analysis apparatus involved in one method performs mass spectrometry analysis from precursor ions to product ions, said mass spectrometry analysis apparatus comprising:

[0085] The reaction chamber in which the precursor ions are introduced;

[0086] An ammonia supply unit supplies ammonia molecules or ammonia radicals to the reaction chamber; and

[0087] The separation and detection unit separates and detects product ions generated from the precursor ions through reaction with the ammonia molecules or the ammonia free radicals based on the mass-to-charge ratio.

[0088] In the mass spectrometry method of the first item and the mass spectrometry apparatus of the second item, a precursor ion derived from a sample component reacts with ammonia molecules (NH3) or ammonia radicals (NH radicals or NH2 radicals) to generate product ions. The generated product ions are separated and detected based on their mass-to-charge ratio. Then, based on the difference between the mass-to-charge ratio of the product ion and the mass-to-charge ratio of the precursor ion, the presence of an aldehyde group in the molecular structure of the precursor ion is estimated. The mass spectrometry method of the first item and the mass spectrometry apparatus of the second item are based on the following insight: when a precursor ion containing an aldehyde group reacts with ammonia molecules or ammonia radicals, these ammonia molecules or ammonia radicals selectively act on the aldehyde group, changing the carbon-oxygen double bond into a single bond, thereby generating an adduct ion with a hydrogen atom bonded to the carbon atom side and an ammonia atom bonded to the oxygen atom side. When a precursor ion containing an aldehyde group reacts with ammonia molecules or ammonia radicals, a product ion (adduct ion) is generated with a mass increase of 17 Da for each aldehyde group. Therefore, it is possible to estimate whether an aldehyde group is present in the molecular structure of a precursor ion based on the difference between the mass-to-charge ratio of the product ion generated from the precursor ion and the mass-to-charge ratio of the precursor ion.

[0089] (Third item)

[0090] In the mass spectrometry analysis apparatus described in the second item, wherein,

[0091] It also includes an aldehyde group estimation unit, which estimates whether an aldehyde group is present in the molecular structure of the precursor ion based on the difference between the mass-to-charge ratio of the detected product ion and the mass-to-charge ratio of the precursor ion.

[0092] In the mass spectrometry analysis apparatus described in the third item, the presence or absence of aldehyde groups is estimated by the aldehyde group estimation unit. Therefore, the user does not need to manually analyze the difference between the mass-to-charge ratio of the product ions and the mass-to-charge ratio of the precursor ions, and can easily obtain information about the presence or absence of aldehyde groups.

[0093] (Item 4)

[0094] In the mass spectrometry analysis apparatus described in the third item, wherein,

[0095] The aldehyde group estimation unit estimates that the difference in mass-to-charge ratio contains one aldehyde group per 17 Da.

[0096] The mass spectrometry analysis device described in the fourth item can obtain not only information about the presence or absence of aldehyde groups, but also information about the quantity of aldehyde groups.

[0097] (Item 5)

[0098] In any of the mass spectrometry analysis apparatuses described in items two through four, wherein,

[0099] The ammonia supply unit includes a radical generation unit for generating ammonia free radicals.

[0100] In the mass spectrometry apparatus described in the fifth item, ammonia radicals are generated via a radical generation section to react with precursor ions. Since radicals are chemically more reactive than neutral molecules, they can react with more precursor ions to generate product ions compared to reacting precursor ions with ammonia molecules.

[0101] (Item 6)

[0102] In the mass spectrometry analysis apparatus described in item five, wherein,

[0103] The radical generation section generates nitrogen radicals, as well as hydrogen radicals or hydrogen atoms.

[0104] (Seventh item)

[0105] In the mass spectrometry analysis apparatus described in item 5 or 6, wherein,

[0106] The free radical generation section uses nitrogen and water vapor as raw material gases to generate free radicals.

[0107] In the mass spectrometry apparatus described in item six, ammonia radicals are generated from nitrogen radicals and hydrogen radicals or hydrogen atoms. These radicals or atoms can be generated from various feed gases, thus allowing the selection of feed gases considering factors such as gas processing, availability, and price. As a combination of feed gases taking these factors into account, for example, a mixture of nitrogen and water vapor can be used as the feed gas, as in the mass spectrometry apparatus described in item seven.

[0108] Explanation of reference numerals in the attached figures

[0109] 1: Mass spectrometry analyzer; 10: Ionization chamber; 101: Electrospray ionization probe; 11: First intermediate vacuum chamber; 111: Ion lens; 12: Second intermediate vacuum chamber; 121: Ion guide; 13: Third intermediate vacuum chamber; 131: Quadrupole mass filter; 132: Collision chamber; 133: Multipolar ion guide; 134: Ion guide; 14: Analysis chamber; 141: Ion transport electrode; 142: Orthogonal accelerating electrode; 143: Accelerating electrode; 144: Reflection electrode; 145: Ion detector; 146: Flight tube; 4: Collision gas supply unit; 5: Free radical supply unit; 51: Free radical generation chamber; 52: Raw material gas supply source; 53: High-frequency power supply unit; 54: Free radical source; 58: Delivery tube; 581: Head; 6: Control and processing unit; 61: Storage unit; 62: Measurement and control unit; 63: Aldehyde group estimation unit; 7: Input unit; 8: Display unit.

Claims

1. A mass spectrometry analysis method, wherein, The precursor ion reacts with ammonia molecules or ammonia free radicals to generate the product ion; The product ions are separated and detected based on their mass-to-charge ratio; Based on the detection of product ions whose mass difference from the precursor ion is an integer multiple of 17 Da, it is estimated that the precursor ion contains an aldehyde group in its molecular structure.

2. A mass spectrometry analysis apparatus for performing mass spectrometry analysis on the generation of product ions from precursor ions, the mass spectrometry analysis apparatus comprising: The reaction chamber in which the precursor ions are introduced; An ammonia supply unit supplies ammonia molecules or ammonia free radicals to the reaction chamber; A separation and detection unit that separates and detects product ions generated from the precursor ions through reaction with the ammonia molecules or the ammonia radicals based on their mass-to-charge ratio; and The aldehyde group estimation unit estimates that the precursor ion contains an aldehyde group in its molecular structure based on the detection of a product ion whose mass difference from the precursor ion is an integer multiple of 17 Da.

3. The mass spectrometry analysis apparatus according to claim 2, wherein, The aldehyde group estimation unit estimates that the mass difference contains 1 aldehyde group per 17 Da.

4. The mass spectrometry analysis apparatus according to claim 2, wherein, The ammonia supply unit includes a radical generation unit for generating ammonia free radicals.

5. The mass spectrometry analysis apparatus according to claim 4, wherein, The radical generation section generates nitrogen radicals, as well as hydrogen radicals or hydrogen atoms.

6. The mass spectrometry analysis apparatus according to claim 4, wherein, The free radical generation section uses nitrogen and water vapor as raw material gases to generate free radicals.

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