JP2008298517A - Mass spectrometry data analysis method and apparatus - Google Patents

Abstract

A molecular weight related ion of a target compound is found with high accuracy among many peaks appearing in a mass spectrum.
A mass spectrum of positive ions and a mass spectrum of negative ions measured substantially simultaneously by a mass spectrometer capable of analyzing with high mass accuracy are used, and one mass spectrum on each mass spectrum is used. The mass difference between the masses of the peaks is calculated, and a pair of peaks is searched for so that the mass difference falls within a predetermined range centered on the theoretical mass (2.0146 Da) of two protons. Since it can be estimated that the pair to be outlined is a proton addition ion (M + H) ⁺ and a proton elimination ion (M−H) ⁻ of the same compound, these are extracted as molecular weight related ions and labeled on the corresponding peak of the mass spectrum. At the same time, the molecular weight of the target compound is estimated to identify the compound.
[Selection] Figure 4

Description

  The present invention relates to a mass spectrometry data analysis method and apparatus for analyzing and processing mass spectrum data collected by mass spectrometry, and more specifically, collected by an atmospheric pressure ionization mass spectrometer that is often used in combination with a liquid chromatograph. The present invention relates to a mass spectrometry data analysis method and apparatus suitable for analyzing the obtained data.

  In a liquid chromatograph mass spectrometer (LC / MS), in order to ionize a liquid sample whose components are separated by a column of the liquid chromatograph, a large amount of electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) is used. Barometric ionization is used. A liquid chromatograph mass spectrometer using such an atmospheric pressure ion source has conventionally been configured to selectively perform positive ion measurement and negative ion measurement (see, for example, Patent Document 1).

For example, in the positive ion measurement mode, in addition to the proton-added ion (mass: molecular weight of the compound + 1) in which one proton (H ⁺ ) is added to the target compound, ions existing in the mobile phase used in the liquid chromatograph In addition, ions formed by adding metal ions in the pipe to the target compound are detected. For example, when adding sodium (Na), the molecular weight of the target compound is M + 23, when adding ammonia (NH ₄ ), the molecular weight of the target compound is M + 18, and when adding both proton and methanol, the molecular weight of the target compound is M + 33. The added ions are detected. On the other hand, in the negative ion measurement mode, in addition to proton desorption ions (mass: molecular weight of compound −1) from which one proton is desorbed from the target compound, acetic acid (CH ₃ COOH) and formic acid (HCOOH) in the mobile phase Addition ions added by the above are detected.

  The tendency of these ion addition and desorption reactions varies depending on the properties of the target compound. If the compound contained in the sample is unknown, any kind of addition (or desorption) ion is detected. It is difficult to predict in advance. It is also difficult to control the reaction of addition / desorption of such ions. Therefore, the task of extracting the peak of ions derived from the target compound (generally collectively referred to as molecular weight related ions) from the obtained mass spectrum and calculating the molecular weight of the target compound is based on the judgment and knowledge of the analyst. It was often done manually. However, such work requires abundant knowledge and experience of the person in charge of analysis, and there is a problem that a person who lacks knowledge and experience cannot perform analysis with high accuracy. In addition, even when an experienced analyst performs analysis work, there is a problem that manual work takes time and throughput is low.

  On the other hand, for example, Patent Document 2 discloses an apparatus for analyzing mass spectrum data using a computer without depending on the manual operation as described above. In this device, various components added to a compound during atmospheric pressure ionization are predicted and registered in a database, and the mass difference between multiple peaks appearing in a mass spectrum obtained by mass analysis of an unknown sample is recorded. Is calculated and collated with the database to identify the additional ions. In Patent Document 3, a candidate for a composition formula of each additional ion is estimated from the masses of the plurality of additional ions detected on the mass spectrum, and the remaining portions obtained by removing the adduct from each of the plurality of composition formula candidates are described. An apparatus for estimating the composition formula of a target compound by comparison is disclosed. Again, the peak mass difference is used to detect additional ions.

  In the conventional additional ion identification method as described above, components in the sample are well separated by liquid chromatography, and only one or a few peaks derived from ions derived from the target compound appear in one mass spectrum. In some cases, additional ions can be identified with relatively high accuracy. However, for example, when component separation in a liquid chromatograph is not good or when a plurality of components with originally close retention times are mixed, peaks of ions derived from a large number of compounds appear in the mass spectrum, There is a problem that the accuracy of identification of additional ions is reduced. If the adduct ion cannot be accurately detected on the mass spectrum, it will hinder the estimation and identification of the molecular weight of the target compound itself.

JP 2001-099821 A JP 2004-271185 A JP-A-2005-221250

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to quickly and accurately obtain ions derived from a target compound from mass spectrum data without relying on the knowledge and experience of an analyst. It is an object of the present invention to provide a mass spectrometric data analysis method and apparatus capable of finding the peak of the above and thereby obtaining the molecular weight of the target compound with high accuracy. Another object of the present invention is to provide a mass spectrometry data analysis method capable of finding a target compound-derived ion, that is, a molecular weight related ion with high accuracy even when peaks of ions derived from a plurality of compounds appear in a mass spectrum. And providing an apparatus.

The first invention made to solve the above problems is mass spectrometry data for analyzing and processing mass spectrum data acquired by a mass spectrometer capable of measuring positive ions and negative ions derived from the same sample simultaneously or separately. An analysis method,
a) calculating a mass difference between one peak appearing in a mass spectrum for positive ions and one peak appearing in a mass spectrum for negative ions, and the mass difference matches or includes a predetermined value Mass difference investigation step for determining whether or not to enter,
b) a molecular weight related ion extraction step for extracting two peaks that have passed the mass difference investigation as molecular weight related ions of the target compound;
The molecular weight of the target compound is estimated and / or the target compound is identified based on information on molecular weight related ions.

In addition, the second invention, which embodies the mass spectrometry data analysis method according to the first invention, analyzes mass spectrum data acquired by a mass spectrometer capable of measuring positive ions and negative ions derived from the same sample simultaneously or separately. A mass spectrometry data analysis device for processing,
a) calculating a mass difference between one peak appearing in a mass spectrum for positive ions and one peak appearing in a mass spectrum for negative ions, and the mass difference matches or includes a predetermined value Mass difference investigation means for determining whether or not to enter,
b) a molecular weight related ion extracting means for extracting two peaks that passed the mass difference investigation as molecular weight related ions of the target compound;
The molecular weight of a target compound is estimated and / or the target compound is identified based on information on molecular weight related ions.

  The mass spectrometer used here needs to have a high mass resolution and mass accuracy. For example, it is desirable that the mass error be within a few mDa. Therefore, in general, a time-of-flight mass separator (TOF-MS) is preferably used as the mass separator. In addition, the ion source of the mass spectrometer may perform soft ionization without adding a specific substance to the compound or desorbing the specific substance from the compound without cleaving the compound upon ionization. desirable. Examples of ion sources that perform such ionization include those that perform atmospheric pressure ionization such as electrospray ionization and atmospheric pressure chemical ionization.

  It is preferable that the positive ion measurement and the negative ion measurement can be performed at the same time. For example, the positive ion measurement is first performed on a certain sample, and then the negative ion measurement is performed on the same sample. Measurement may be performed.

  The functions of the mass spectrometry data analysis method according to the first invention and the mass spectrometry data analysis apparatus according to the second invention can be achieved by operating a predetermined program on a computer.

  In the mass spectrometric data analysis method according to the first invention and the mass spectrometric data analysis apparatus according to the second invention, there is a peak between the mass spectrum obtained by the positive ion measurement and the mass spectrum obtained by the negative ion measurement on the same sample. By determining the mass difference, it is determined whether or not the peak is a molecular weight related ion peak.

  For example, when one proton is added to the target compound and becomes a positive ion during ionization, the mass is increased by 1.0073 per proton than the mass of the compound. On the other hand, when one proton is desorbed from the target compound and becomes a negative ion, the mass becomes smaller by 1.0073 per proton than the mass of the compound. Therefore, the mass difference between proton-added ions and proton-desorbed ions derived from this compound should be a value corresponding to twice the mass of protons. Therefore, it is only necessary to search for two peaks corresponding to 2.0146 Da, in which the mass difference corresponds to twice the theoretical mass of protons. However, in practice, the mass error of the apparatus is unavoidable. Search for two peaks such that falls within a predetermined tolerance for 2.0146 Da.

  As described above, if the mass accuracy of measurement is high, it can be estimated with high accuracy that two peaks whose mass difference falls within the allowable range are a pair of proton addition ion and proton desorption ion derived from the same compound. Therefore, these are extracted by regarding them as the molecular weight related ions of the target compound, and for example, a label is displayed on the corresponding peak on the mass spectrum displayed on the screen. Further, the target compound can be identified by estimating the molecular weight of the target compound based on this information and collating the molecular weight with a previously registered database.

  However, in some cases, two peaks that are not derived from the same compound may be erroneously extracted. Therefore, in order to increase the reliability, an addition of another substance derived from the same compound, that is, a substance other than proton added to the compound. It is useful to take advantage of the presence of ion peaks. That is, in the mass spectrum for positive ions or the mass spectrum for negative ions, two peaks corresponding to the mass difference between proton-added ions or proton-desorbed ions and adducted ions are searched for and used as described above. In addition, it is possible to confirm the peak of the pair obtained by the mass spectrum obtained by measuring the positive and negative ions. In addition, two peaks corresponding to the mass difference between proton addition ions or proton desorption ions and addition ions can be extracted as molecular weight related ions of the target compound.

  Furthermore, there is a case where only one of the proton addition ion and the proton desorption ion can be observed. In such a case, one peak appearing in the mass spectrum for the positive ion and 1 appearing in the mass spectrum for the negative ion. Determine whether the mass difference between one peak matches a value corresponding to the sum of the masses of a particular adduct and another adduct, or falls within a predetermined range including that value, and You may make it find a peak. For example, it is examined whether two peaks having a mass difference corresponding to the mass difference between a positive ion in which ammonia or sodium is added to a certain compound and a negative ion in which protons are eliminated from the same compound are present. be able to.

  According to the mass spectrometry data analysis method according to the first invention and the mass spectrometry data analysis apparatus according to the second invention, the molecular weight related ions are extracted using information on positive ions and negative ions derived from the same compound. The molecular weight related ions can be extracted with higher accuracy than before. As a result, the molecular weight of the target compound can be determined with high accuracy, the identification accuracy can be improved, and further, omission of identification can be reduced.

  In addition, according to the mass spectrometry data analysis method according to the first invention and the mass spectrometry data analysis apparatus according to the second invention, there is no need for the analyst to find molecular weight related ions manually and automatically Since molecular weight-related ions are extracted with high accuracy, it is easy to improve the analysis throughput without the analysis result being influenced by the knowledge and experience of the analyst.

  Hereinafter, an embodiment of a mass spectrometry data analysis apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a mass spectrometer equipped with a data analysis apparatus according to this embodiment.

  Although not shown, a liquid chromatograph is provided in the front stage of the mass spectrometer, and a liquid sample whose components are temporally separated by the column of the liquid chromatograph is introduced into the mass spectrometer. The liquid sample is sprayed from the electrospray nozzle 1 into the ionization chamber 2 which is an atmosphere of approximately atmospheric pressure, whereby the component molecules in the liquid sample are ionized, and the generated ions pass through the heating pipe 3 and have a low vacuum atmosphere. It is fed into the first intermediate vacuum chamber 4. In the ionization chamber 2, in addition to electrospray ionization, another atmospheric pressure ionization method such as atmospheric pressure chemical ionization may be employed, or they may be used in combination. In any case, the ions are converged by the first ion lens 5 disposed in the first intermediate vacuum chamber 4 and are sent to the second intermediate vacuum chamber 6 which is an intermediate vacuum atmosphere. While being converged by the second ion lens 7 arranged, it is fed into the analysis chamber 8 which is a high vacuum atmosphere.

  In the analysis chamber 8, the ions are temporarily accumulated in the ion trap 9, discharged from the ion trap 9 at a predetermined timing and introduced into the time-of-flight mass separator 10. The time-of-flight mass separator 10 is a reflectron type including a reflectron 11 that reflects ions by an electrostatic field, and ions are separated according to mass (strictly, mass-to-charge ratio m / z) during the return flight. The ions with smaller mass reach the ion detector 12 earlier. The ion detector 12 includes, for example, a combination of a conversion dynode that converts ions into electrons and a secondary electron multiplier, and outputs an electrical signal corresponding to the amount of ions that have reached. The detection signal is converted into a digital value by the A / D converter 13 and input to the data processing unit 14. In addition, an operation unit 16 such as a keyboard and a mouse, and a display unit 17 such as an LCD display are connected to the control unit 15 that controls each unit in order to execute the mass spectrometry operation as described above. The substance of the data processing unit 14 and the control unit 15 is a computer, and functions as the data processing unit 14 and the control unit 15 are exhibited by executing a dedicated control / processing program installed in the computer. .

  In the mass spectrometer, ions generated during a predetermined period are accumulated in the ion trap 9, and mass analysis over a predetermined mass range for the accumulated ions is performed by the time-of-flight mass separator 10. This operation is repeated at a predetermined period, and mass spectrum data constituting the mass spectrum is given to the data processing unit 14 for each period. In addition, this mass spectrometer can switch between the positive ion measurement mode and the negative ion measurement mode at high speed, and substantially realizes the simultaneous measurement of positive and negative ions, and the mass spectrum of positive ions at a certain point in time. And the mass spectrum of negative ions can be acquired in parallel.

  Specific examples of the mass spectrometer include a liquid chromatograph mass spectrometer LCMS-IT-TOF manufactured by Shimadzu Corporation (Internet <http://www.an.shimadzu.co.jp/products/lcms/it -tof.htm>) can be used.

  In the mass spectrometer, the atmospheric pressure ionization method is a relatively soft ionization method in which a substance in a mobile phase (solvent) is added to a target compound in a liquid sample, or other metals are added. A relatively large amount of added ions are generated. For this reason, peaks of various additional ions derived from the target compound appear in the mass spectrum.

FIG. 3 is a schematic diagram of a mass spectrum showing peaks of molecular weight-related ions that are generally well observed. (A) is a mass spectrum of positive ions, and (b) is a mass spectrum of negative ions. The numerical value in the figure is an approximate increase / decrease in mass relative to the target compound. In the positive ion, a proton-added ion (M + H) ^{+ in} which one proton is mainly added is observed, and in the negative ion, a proton-desorbed ion (MH) ^{− in} which one proton is mainly released is observed. In addition, ammonia-added ions (M + NH ₄ ) ⁺ and sodium-added ions (M + Na) ⁺ are observed for positive ions, and chlorine-added ions (M + ³⁵ Cl) ⁻ , (M + ³⁷ Cl) for negative ions. ^-, acetate adduct ion ^{_{(M + CH 3 COO) -}} , formate adduct ion (M + HCOO) ^-, etc. are observed. Although only monovalent ions are shown here, divalent ions (such as (M + 2H) ²⁺ ) and dimer ions (such as (2M + H) ⁺ ) may be generated. However, which of these additional ions (including proton desorption ions is included in the additional ions) depends on the properties of the compound, the type of mobile phase, or other analysis conditions.

  Next, characteristic data analysis processing operations executed mainly by the data processing unit 14 will be described with reference to the flowchart of FIG. 2 and the mass spectra of FIGS.

  First, the liquid chromatograph mass analysis operation as described above is performed under the control of the control unit 15, and the data processing unit 14 collects mass spectrum data and stores it in a storage unit (not shown) (step S1). Next, the data processing unit 14 determines whether or not to limit the analysis processing target mass spectrum (step S2). Whether or not to limit the analysis processing target mass spectrum and whether to perform the operation manually or automatically when limiting is assumed to be input in advance from the operation unit 16 as one of the analysis processing conditions.

  When the analysis target mass spectrum is not limited, the process proceeds from step S2 to step S13, and all the mass spectrum data stored in the storage unit (that is, the time when the mass spectrum is collected is not limited) are read. Peak detection is performed for each spectrum. And the mass of the ion corresponding to a peak is calculated | required and the list | wrist of the mass of the ion detected for every positive ion mass spectrum and negative ion mass spectrum is created (step S14). Since detailed processing at this time is the same as step S7 described later, description thereof is omitted here.

  If it is determined in step S2 that the analysis target mass spectrum is limited, it is next determined whether or not to manually specify the mass spectrum (step S3). In the case of manual designation, the person in charge of analysis displays, for example, a total ion chromatogram on the screen of the display unit 17 and designates a chromatogram peak to be analyzed on the screen or designates a holding time. The positive ion mass spectrum and the negative ion mass spectrum are designated (step S4). On the other hand, if not manually specified in step S3, peak detection is performed on the total ion chromatogram (or mass chromatogram for a specific mass) to automatically select an appropriate mass spectrum, and the peak detection is performed. Based on the result, a positive ion mass spectrum and a negative ion mass spectrum are set (step S15).

  When the mass spectrum to be analyzed is determined as a pair of positive ions and negative ions, either manually or automatically (step S5), the corresponding mass spectrum data is read from the storage unit and prepared for processing. (Step S6). Then, similarly to step S14, peak detection is performed for each mass spectrum, the mass of ions corresponding to the peak is obtained, and a list of ion masses is created for each positive ion mass spectrum and negative ion mass spectrum (step S7). ). Here, after performing peak detection, it is determined whether or not the signal strength at the peak top is equal to or higher than a predetermined threshold, and peaks whose signal strength is lower than the threshold are regarded as noise and may be excluded from the list. .

In addition, here, it is also possible to perform monoisotopic determination utilizing determination of valence and specificity of isotope ratio. For example, as shown in FIG. 3 (b), about 2 Da is required for the added ion (M + ³⁵ Cl) ⁻ to which normal Cl ( ³⁵ Cl) is added and the isotope ³⁷ Cl (M + ³⁷ Cl) ⁻ to be added. There is a mass difference. In addition, the intensity ratio of the peaks of both should be almost the same as the abundance ratio of Cl isotopes. Therefore, the peak of the two additional ions can be estimated using this. In addition, in the case of an ion having a valence of 2, since a peak appears every 0.5 Da instead of every 1 Da, the valence of the ion of that peak can be estimated using this. In addition to simply listing ion masses in this way, supplementary information such as valence and monoisotopic (or isotopes) is added to facilitate identification of additional ions performed later. Reliability is also improved.

  Next, the ion mass list for each positive ion and negative ion is compared, and the mass difference is made one-to-one (that is, one peak of the mass spectrum of the positive ion and one peak of the mass spectrum of the negative ion). Find a pair whose mass difference falls within a mass range that allows for a predetermined tolerance with a theoretical mass difference of 2.0146 Da for two protons as the center. This tolerance can be determined in consideration of the mass accuracy of the mass spectrometer itself, but if it is too narrow, a pair of proton-added ions and proton-desorbed ions derived from the same compound cannot be detected (detection miss). On the contrary, if it is too wide, there is a high possibility that ions that are not derived from the same compound will be erroneously detected as a pair. For example, an allowable error may be determined in consideration of a mass error of about several mDa.

Here, it is assumed that the allowable error is 5 mDa. In the case of a mass spectrum of positive and negative ions as shown in FIG. 4, when searching for a pair whose mass difference is determined by a tolerance of 0.005 Da centering on 2.0146 Da, three pairs shown in the figure are confirmed. it can. Therefore, the ions forming a pair are estimated to be proton addition ions and proton desorption ions derived from the same compound and extracted as molecular weight related ions (step S8). In the figure, (M + H) ⁺ and (M−H) ⁻ are labeled, but this is displayed as a result of the processing in step S11 described later, and is displayed in the steps up to step S8. It has not been.

  Next, for each of the ion mass list of positive ions and the ion mass list of negative ions, the mass difference between the two ions is obtained, and the mass difference is predetermined with the theoretical mass of the adduct known (registered in the database) as the center. Search for pairs that fall within the mass range that allows for the tolerance of. Then, a pair of ions entering this is presumed to be a proton addition ion or a proton desorption ion and another addition ion, and extracted as a molecular weight related ion (step S9). The adducts referred to here are components (substances) such as ammonia, sodium, potassium, acetic acid, formic acid, etc., and these may be stored in a database in advance.

  For example, in the case of the mass spectrum of positive and negative ions as shown in FIG. 5, in the process of step S8, a pair whose mass difference is within a mass range determined by a tolerance of 0.005 Da centering on 2.0146 Da is searched. Then, only one pair of m / z = 466.0329 and 464.0163 shown in the figure can be confirmed. On the other hand, the positive ions at m / z = 483.0590 and 488.141 have no negative ions corresponding to them, and thus are not estimated to be proton-added ions. Next, when the determination of additional ions is performed in the process of step S9, in the positive ion mass spectrum, the mass difference of 17.0261 Da between m / z = 4666.0329 and m / z = 483.0590 is ammonia addition, It is estimated that the mass difference of 21.9812 Da between the same m / z = 466.0329 and m / z = 488.141 is sodium addition. Since the ion at m / z = 466.0329 has already been determined to be a proton addition ion, the above two ions are extracted as molecular weight related ions as ammonia addition ions and sodium addition ions for this compound.

  Furthermore, the ion mass lists for each positive ion and negative ion are compared, and a mass difference is obtained between one peak of the mass spectrum of the positive ion and one peak of the mass spectrum of the negative ion. Search for a pair that falls within the mass range with a given tolerance around the sum of the mass and the mass of another adduct or the value obtained by subtracting the theoretical mass of the proton from the theoretical mass of the adduct. One of the paired ions to enter is presumed to be a proton addition ion or proton desorption ion, and the other is an addition ion, and extracted as a molecular weight related ion (step S10). In practice, the processing in step S10 may be performed only when the molecular weight related ions cannot be extracted in steps S8 and S9.

  As an example, in the case of a mass spectrum of positive and negative ions as shown in FIG. 6, there is no pair even if the process of step S8 is performed. That is, proton addition ions and proton desorption ions cannot be found. Next, even if the process of step S9 is performed, no pair exists. That is, proton addition ions or proton desorption ions and addition ions cannot be found. Therefore, when the process of step S10 is performed, the mass difference of 19.0394 Da between m / z = 489.0142 in the negative ion mass spectrum and m / z = 508.0536 in the positive ion mass spectrum is the mass of ammonia and proton. It can be seen that it can be estimated to correspond to the added value. Similarly, the mass difference of 23.9946 Da between m / z = 489.0142 in the negative ion mass spectrum and m / z = 513.0088 in the positive ion mass spectrum can be estimated to correspond to the sum of the masses of sodium and proton. I understand. As a result, ions with m / z = 489.0142 in the negative ion mass spectrum are proton desorption ions, and ions with m / z = 508.0536, 513.0088 in the positive ion mass spectrum are ammonia addition ions derived from the same compound. Extracted as molecular weight related ions as sodium addition ions.

  Once the molecular weight related ions have been extracted as described above, each ion is shown in the mass spectrum displayed on the screen of the display unit 17 to show the attribution of the identified additional ions, as depicted in FIGS. The label display indicating the type of is performed on the corresponding peak (step S11). Since the determination process of the molecular weight-related ion assignment of the peak as described above is automatically performed, it is not necessary for the analyst himself to calculate the mass difference or the like.

  Furthermore, if the molecular weight related ion of a certain compound is obtained, the molecular weight of the compound can be estimated with high accuracy, so that the compound can be identified by comparing this molecular weight with a database (step S12). In addition, for example, the composition estimation software for liquid chromatograph mass spectrometer manufactured by Shimadzu Corporation (see the Internet <http://www.an.shimadzu.co.jp/products/lcms/it-tof5.htm>) Then, the composition of the compound can be estimated from molecular weight related ions and adduct information (type of adduct ions). The greater the number of molecular weight related ions for the same compound, the higher the reliability of molecular weight estimation and identification of that compound.

  It should be noted that the above embodiment is merely an example, and it is obvious that modifications, changes, and additions as appropriate within the scope of the present invention are included in the scope of the claims of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS The whole block diagram of the mass spectrometer provided with the data analyzer by one Example of this invention. The flowchart which shows the procedure of the characteristic data-analysis processing operation in the data-analysis apparatus of a present Example. It is the schematic of the mass spectrum which shows the peak of the molecular weight related ion generally observed well, (a) is the mass spectrum of a positive ion, (b) is the mass spectrum of a negative ion. The figure which shows the mass spectrum for demonstrating an example of the data-analysis processing operation by a present Example. The figure which shows the mass spectrum for demonstrating an example of the data-analysis processing operation by a present Example. The figure which shows the mass spectrum for demonstrating an example of the data-analysis processing operation by a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electrospray nozzle 2 ... Ionization chamber 3 ... Heating pipe 4 ... 1st intermediate vacuum chamber 5 ... 1st ion lens 6 ... 2nd intermediate vacuum chamber 7 ... 2nd ion lens 8 ... Analysis chamber 9 ... Ion trap 10 ... Flight Time-type mass separator 11 ... Reflectron 12 ... Ion detector 13 ... A / D converter 14 ... Data processing unit 15 ... Control unit 16 ... Operation unit 17 ... Display unit

Claims (8)

A mass spectrometry data analysis method for analyzing mass spectrum data acquired by a mass spectrometer capable of measuring positive ions and negative ions from the same sample simultaneously or separately,
a) calculating a mass difference between one peak appearing in a mass spectrum for positive ions and one peak appearing in a mass spectrum for negative ions, and the mass difference matches or includes a predetermined value Mass difference investigation step for determining whether or not to enter,
b) a molecular weight related ion extraction step for extracting two peaks that have passed the mass difference investigation as molecular weight related ions of the target compound;
A mass spectrometric data analysis method comprising: estimating a molecular weight of a target compound based on information on molecular weight related ions and / or identifying the target compound.   The mass spectrometric data analysis method according to claim 1, wherein the predetermined value is a value corresponding to twice the mass of the predetermined substance.   The mass spectrometric data analysis method according to claim 2, wherein the predetermined substance is a proton.   In the mass difference investigation step, two mass differences corresponding to a mass difference between a proton addition ion or a proton desorption ion and an addition ion added by a substance other than a proton in a mass spectrum for positive ions or a mass spectrum for negative ions are further provided. 4. The mass spectrometry data analysis method according to claim 1, wherein a peak is searched, and in the molecular weight related ion extraction step, the two peaks are extracted as molecular weight related ions of the target compound. A mass spectrometry data analysis device for analyzing mass spectrum data acquired by a mass spectrometer capable of measuring positive ions and negative ions from the same sample simultaneously or separately,
a) calculating a mass difference between one peak appearing in a mass spectrum for positive ions and one peak appearing in a mass spectrum for negative ions, and the mass difference matches or includes a predetermined value Mass difference investigation means for determining whether or not to enter,
b) a molecular weight related ion extracting means for extracting two peaks that passed the mass difference investigation as molecular weight related ions of the target compound;
A mass spectrometric data analysis apparatus comprising: estimating the molecular weight of a target compound based on information on molecular weight related ions and / or identifying the target compound.   6. The mass spectrometry data analysis apparatus according to claim 5, wherein the predetermined value is a value corresponding to twice the mass of the predetermined substance.   The mass spectrometric data analysis apparatus according to claim 6, wherein the predetermined substance is a proton.   The mass difference investigating means further includes two mass differences corresponding to a mass difference between a proton addition ion or a proton desorption ion and an addition ion added by a substance other than a proton in a mass spectrum for positive ions or a mass spectrum for negative ions. The mass spectrometry data analysis apparatus according to any one of claims 5 to 7, wherein a peak is searched and the molecular weight related ion extraction means extracts the two peaks as molecular weight related ions of the target compound.

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