JP7312675B2 - Mass spectrum processing apparatus and method - Google Patents

Description

The present invention relates to mass spectrometry processing apparatus and methods, and more particularly to the processing of mass spectrometric trains generated by mass spectrometry.

A mass spectrometry system is composed of, for example, a gas chromatograph and a mass spectrometer. In a gas chromatograph, a sample to be analyzed produces a plurality of temporally separated components, ie, a plurality of compounds. These compounds are sequentially introduced into a mass spectrometer, and mass spectrometry is performed on each compound (see Patent Document 1, for example).

A mass spectrometer is typically composed of a measuring section and an information processing section. The measurement section is composed of an ion source, a mass spectrometry section, and a detection section. The information processing section generates a mass spectrum sequence based on the detection signal from the detection section, and generates a total ion current chromatogram (TICC) based on the mass spectrum sequence. Mass chromatograms for specific masses may be generated instead of, or in conjunction with, TICC.

An information processing device generally has a function of identifying a compound based on a mass spectrum. Specifically, a peak is specified from TICC, a mass spectrum corresponding to the peak is specified, and a compound is specified based on the mass spectrum.

JP-A-2000-54406

In a chromatogram such as TICC, multiple peaks derived from multiple compounds may overlap and appear as one peak. Also, it may not be clear whether a certain peak is a peak derived from a compound or noise. If the peak derived from the compound (which can also be called a true peak) cannot be correctly identified, the mass spectrum corresponding to the compound cannot be correctly identified. If a compound is estimated based on such a mass spectrum, the reliability of compound estimation will be lowered.

An object of the present invention is to provide new information for correctly identifying the mass spectrum corresponding to each compound. Another object of the present invention is to provide a new graph that can be used in qualitative analysis.

A mass spectrum processing apparatus according to the present disclosure includes a calculation means for calculating the temporal stability of a mass spectrum pattern at each time point on a time axis based on a mass spectrum train composed of a plurality of mass spectra obtained by mass spectrometry for a plurality of temporally separated compounds, and a stability graph generation means for generating a stability graph showing a plurality of stability degrees calculated at the plurality of time points on the time axis.

The mass spectrum processing method according to the present disclosure includes the steps of: generating a chromatogram based on a mass spectrum train composed of a plurality of mass spectra obtained by mass spectrometry for a plurality of temporally separated compounds; calculating the temporal stability of the mass spectrum pattern at each time point on the time axis based on the mass spectrum train; generating a stability graph showing a plurality of stabilities calculated at the multiple time points on the time axis; and displaying the chromatogram and the stability graph. Characterized by

According to the present disclosure, new information for correctly identifying mass spectra can be provided. Alternatively, the present disclosure can provide new graphs that can be used in qualitative analysis.

1 is a block diagram showing a mass spectrometry system according to an embodiment; FIG. FIG. 4 is a conceptual diagram showing generation of a stability graph; It is a figure which shows the example of a 1st display. 4 is a flow chart showing a method of generating a stability graph; 10 is a flow chart showing a stability graph processing method; FIG. 10 is a diagram showing peak separation; It is a figure which shows the mass-spectrum estimation method. FIG. 10 is a diagram showing a second display example; FIG. 11 is a diagram showing a third display example;

Hereinafter, embodiments will be described based on the drawings.

(1) Outline of Embodiment A mass spectrum processing apparatus according to an embodiment includes computing means and stability graph generating means. The computing means computes the temporal stability of the mass spectral pattern at each time point on the time axis based on a mass spectrum train composed of a plurality of mass spectra obtained by mass spectrometry for a plurality of temporally separated compounds. The stability graph generating means generates a stability graph indicating a plurality of stabilities calculated at a plurality of points in time on the time axis.

When the same compound continues to be detected in the mass spectrometer, the mass spectral pattern becomes stable over time. That is, the stability becomes higher. On the other hand, when multiple compounds that are temporally close to each other are detected, the mass spectrum pattern changes temporally. That is, the stability is lowered. According to the stability graph, even if multiple compounds overlap on the time axis, the temporal stability of the mass spectrum pattern makes it possible to identify peaks derived from individual compounds with high accuracy. For example, stability graphs facilitate the separation or discrimination of overlapping compound peaks in a chromatograph. Moreover, according to the stability graph, it becomes easy to determine whether the peak in the chromatograph is a peak derived from a compound or noise.

A stability graph may be provided to the user, and the user may analyze or evaluate the stability graph, or apply processing such as peak search to the stability graph. Stability may also be referred to as consistency or constancy. In the embodiment, the computing means, the stability graph generating means, and each means described below are configured by a processor that executes a program.

In an embodiment, the computing means identifies a mass spectrum set including the mass spectrum of interest and adjacent mass spectra adjacent to it at each time point on the time axis. Then, the stability is calculated based on the mass spectrum set. This is to calculate the stability based on a plurality of mass spectra at each time point. Stability may be calculated based on two mass spectra adjacent on the time axis, or may be calculated based on three or more mass spectra consecutive on the time axis.

In an embodiment, the computing means computes the degree of similarity between the mass spectrum of interest and the adjacent mass spectrum. Stability is calculated based on similarity or is similarity. For example, a mass spectrum set includes a first adjacent mass spectrum that is the n−1th mass spectrum, the mass spectrum of interest that is the nth mass spectrum, and a second adjacent mass spectrum that is the n+1th mass spectrum. The computing means computes a first degree of similarity by mutual comparison between the first adjacent mass spectrum and the mass spectrum of interest. Further, the computing means computes a second degree of similarity by mutual comparison between the mass spectrum of interest and the second adjacent mass spectrum. Then, the computing means computes stability based on the first degree of similarity and the second degree of similarity.

If three or more mass spectra are referred to when calculating the stability, it becomes less susceptible to fluctuations and noise. As the degree of similarity, various known degrees of similarity can be used. In calculating the degree of similarity, the entire mass spectrum may be subject to calculation, or part of the mass spectrum may be subject to calculation.

The mass spectrum processing device according to the embodiment further includes chromatogram generation means and display means. A chromatogram generator generates a chromatogram based on the mass spectrum sequence. A display means displays an image including a chromatogram and a stability graph. In that image, the time axis of the chromatogram is associated with the time axis of the stability graph.

The stability graph and the TICC are graphs suitable for qualitative analysis that represent different information. By displaying them in association with each other, the mass spectrometry results can be comprehensively evaluated or analyzed. Alternatively, the content of the chromatogram can be evaluated from the content of the stability graph. The two time axes may be displayed in parallel with their starting points and scales aligned. It is also possible to perfectly match the two time axes in the image.

The mass spectrum processing apparatus according to the embodiment further includes peak detection means and estimation means. The peak detection means detects stability peaks included in the stability graph. The estimator estimates a true mass spectrum corresponding to the stability peak based on the mass spectrum sequence. A stability peak corresponds to a true peak. A mass spectrum estimated based thereon can be regarded as a true mass spectrum.

In an embodiment, the estimating means estimates the true mass spectrum based on the central mass spectrum corresponding to the representative point of the stability peak, the rising mass spectrum corresponding to the rising edge of the stability peak, and the trailing spectrum corresponding to the trailing edge of the stability peak. According to this configuration, when analyzing a certain compound, it is possible to remove or reduce the influence of other compounds detected in temporal proximity to the compound.

The mass spectrum processing apparatus according to the embodiment further includes difference graph generation means. The difference graph generating means generates a difference graph based on the first stability graph generated from the first sample and the second stability graph generated from the second sample. According to the difference graph, it becomes easy to identify the difference between the components contained in the first sample and the components contained in the second sample.

A mass spectrum processing method according to an embodiment includes a chromatogram generation process, a stability calculation process, a stability graph generation process, and a display process. In the chromatogram generation step, a chromatogram is generated based on a mass spectrum train composed of a plurality of mass spectra obtained by mass spectrometry for a plurality of temporally separated compounds. In the stability calculation step, the temporal stability of the mass spectrum pattern is calculated at each point on the time axis based on the mass spectrum sequence. In the stability graph generating step, a stability graph is generated that indicates a plurality of stabilities calculated at a plurality of points in time on the time axis. In the display step, a chromatogram and a stability graph are displayed. Each of the above steps is, in embodiments, performed by a processor.

A program according to an embodiment executes a plurality of functions of the mass spectrum processing apparatus. The plurality of functions includes a function of calculating the temporal stability of a mass spectrum pattern at each time point on the time axis based on a mass spectrum train composed of a plurality of mass spectra obtained by mass spectrometry for a plurality of temporally separated compounds, and a function of generating a stability graph showing a plurality of stabilities calculated at the plurality of time points on the time axis.

The program is installed in the information processing device via a portable storage medium or via a network. The concept of an information processing device includes a computer with a mass spectrum processing function, a mass spectrometer with a mass spectrum processing function, and the like.

(2) Details of Embodiment FIG. 1 shows a mass spectrometry system according to an embodiment. The illustrated mass spectrometry system is composed of a gas chromatograph 10 and a mass spectrometer 11, and is a system for analyzing a sample to be analyzed. The gas chromatograph 10 has a column for temporally separating a plurality of compounds forming a sample. Individual compounds separated in time are sequentially introduced from the gas chromatograph 10 to the mass spectrometer 11 . A liquid chromatograph may be used instead of the gas chromatograph 10 .

The mass spectrometer 11 is composed of a measuring section 12 and an information processing section 14 . The measurement unit 12 has an ion source 16, a mass spectrometer 18, and a detector 20 in the illustrated configuration example. A plurality of temporally separated compounds are sequentially introduced into the ion source 16 . An ion source 16 ionizes individual compounds. Ions are thereby generated. Various methods can be used as the ionization method. The mass spectrometer 18 is composed of a quadrupole mass spectrometer, a time-of-flight mass spectrometer, and the like. Ions entering the mass analyzer 18 are separated or discriminated according to their mass-to-charge ratio (m/z). Ions that have passed through the mass spectrometer 18 are detected by the detector 20 . A detection signal output from the detector 20 is sent to the information processing section 14 . Note that FIG. 1 omits illustration of an electronic circuit including an A/D converter for converting an analog detection signal into a digital detection signal.

The information processing unit 14 is configured by an information processing device such as a computer. The information processing section 14 may be incorporated within the measurement section 12 . A part of the functions of the information processing unit 14 may be performed by another information processing device on the network. The information processing section 14 has a calculation section 22, a display device 36, a storage section 38, and the like. An input unit such as a keyboard is also connected to the computing unit 22, but the illustration thereof is omitted. The information processing section 14 corresponds to a mass spectrum processing device. The information processing section 14 executes the mass spectrum processing method.

The computing unit 22 is composed of a processor, more specifically, a CPU that executes a program. A processor may be comprised by devices, such as GPU and ASIC. The computing unit 22 has multiple functions, which are represented as multiple blocks in FIG. Specifically, the calculation unit 22 has a mass spectrum generation unit 24, a TICC generation unit 26, a stability graph generation unit 28, an analysis unit 32, a display processing unit 34, and the like.

A mass spectrum generator 24 generates a mass spectrum based on the detection signal from the detector 20 . Specifically, the mass spectrum generator 24 sequentially generates mass spectra at regular time intervals. A mass spectrum string is composed of a plurality of mass spectra arranged on a time axis (retention time axis). A mass spectrum generator 24 may be provided in the measurement unit 12 .

A TICC generator 26 generates a total ion current chromatogram (TICC) based on the mass spectrum sequence. That is, the total ion current is calculated by individually integrating mass spectra at individual times. A TICC is generated by mapping multiple total ion currents computed at multiple times. The processing will be described later with reference to FIG. Other chromatograms, such as mass chromatograms, may be generated instead of or in conjunction with TICC.

A stability graph generator 28 generates a stability graph based on the mass spectrum sequence. The stability graph generation unit 28 functions as stability calculation means and stability graph generation means. More specifically, the stability graph generator 28 identifies a mass spectrum set at each time on the time axis and calculates one stability for each mass spectrum set. The stability graph generator 28 generates a stability graph from a plurality of stabilities arranged on the time axis. The processing may be performed by the display processing unit 34 . In an embodiment, the mass spectrum set consists of the nth mass spectrum in the middle, the n−1th mass spectrum one before, and the n+1th mass spectrum one after. n is 1, 2, 3, . . . Stability corresponds to consistency or constancy. Calculation of stability will be described later in detail with reference to FIG.

The analysis unit 32 analyzes the stability graph. Specifically, a peak search is applied to the stability graph to detect a plurality of peaks that satisfy certain conditions included in the stability graph. At that time, a time range (range on the retention time axis) may be specified, and peak detection may be performed within that range, or a group of peaks from the maximum peak to the peak of a predetermined order in the stability graph may be detected. Peak detection will be described later in detail with reference to FIG. The analysis result is sent to the display processing section 34 .

The display processing unit 34 has a function of generating an image to be displayed on the display device 36 . In an embodiment, images are displayed that include TICCs, stability graphs, and mass spectrum listings. A specific example thereof will be described later in detail with reference to FIG. A storage unit 38 is connected to the display processing unit 34 . A plurality of mass spectra lined up on the time axis, that is, a series of mass spectra are stored therein. The storage unit 38 is composed of a semiconductor memory, a hard disk, or the like. The display 36 is configured by an LCD or the like.

The display processing unit 34 generates a plurality of mass spectra corresponding to the detected plurality of stability peaks based on the mass spectrum sequence. These mass spectra constitute a mass spectrum list. A plurality of mass spectra may simply be selected from within a series of mass spectra. Each selected mass spectrum corresponds to a true mass spectrum. For each individual stability peak, a mass spectrum set corresponding to that stability peak may be identified from among the mass spectrum series, and a true mass spectrum may be generated based on that mass spectrum set.

A mass spectrum sequence 40 is shown in the upper part of FIG. A mass spectrum sequence 40 is composed of a plurality of mass spectra 42 arranged on a retention time axis indicating a retention time RT. The horizontal axis of each mass spectrum 42 is the m/z axis and its vertical axis is the intensity axis. In FIG. 2, individual mass spectra 42 are represented in a simplified manner.

TICC 44 and stability graph 46 are shown at the bottom of FIG. They are also abbreviated. A total ion current (TIC: total ion current) is calculated by integrating the mass spectra for each individual mass spectrum. A total ion current chromatogram (TICC) 44 is generated by plotting the calculated multiple TICs on the retention time axis. It contains multiple peaks 54 corresponding to multiple compounds separated in time. The apex of each peak 54 is the peak top 54a.

On the other hand, a mass spectrum set 48 is specified for each time on the retention time axis. A stability 50 is calculated for each mass spectrum set 48 by a method to be described later. A stability graph 46 is generated by plotting a plurality of stability measures 50 on a retention time axis. The horizontal axis of the stability graph 46 indicates the retention time RT, and the vertical axis indicates the stability S. Stability graph 46 includes a plurality of peaks (stability peaks) 52 . The apex of each peak 52 is the peak top 52a.

Peak top 52a occurs in the most stable mass spectrum for a compound. That is, it corresponds to the true compound peak top. It may be assumed that the mass spectrum corresponding to peak top 52a is the true mass spectrum for the compound, but in the embodiment, the true mass spectrum is estimated from a plurality of mass spectra identified based on peak 52. A true mass spectrum is a mass spectrum in which the influence of the mass spectra of other compounds has been removed or reduced.

Instead of the peak top 52a, the center of gravity, middle point, average point, etc. of the peak 52 may be used as representative points of the peak 52. FIG. Instability may be calculated instead of stability. Since the degree of instability indicates a low degree of stability, it is an indicator of stability in a sense.

FIG. 3 shows a first display example. The image 60 displayed on the display includes a TICC 62 , a stability graph 64 and a mass spectrum list 68 . A TICC 62 is generated based on the mass spectrum series as described above, which shows the total ion current at each time instant. The horizontal axis indicates the retention time RT and the vertical axis indicates the intensity I.

A stability graph 64 is generated based on the mass spectral sequence as described above, which indicates the stability of the mass spectral pattern at each time. The horizontal axis indicates the retention time RT, and the vertical axis indicates the stability S. For example, the user designates a retention time range for peak search (peak detection), and peak search is performed within that range. In the illustrated example, seven peaks from peak No. 1 to peak No. 7 are detected. In that case, a predetermined number of peaks from the highest peak to the predetermined peak may be detected. Alternatively, peak search may be performed according to other conditions. Thresholding may be applied to the stability graph 64 prior to peak searching to remove peaks below a threshold. Other pretreatments may be applied.

The TICC 62 and the stability graph 64 are displayed while their horizontal axes are associated with each other. In the illustrated example, the horizontal coordinates of the starting points of the two horizontal axes are the same, and the scales of the two horizontal axes are also the same. The two horizontal axes are parallel. The two horizontal axes may be perfectly matched. In that case, the TICC 62 and the stability graph 64 are displayed in an overlapping manner above the horizontal axis. Alternatively, the TICC 62 is displayed above the common horizontal axis, and the upside down stability graph is displayed below the common horizontal axis.

A mass spectrum list 68 is composed of a plurality of mass spectra corresponding to a plurality of peaks detected by peak search. The number of mass spectra to be displayed may be specified in advance. In the illustrated example, six mass spectra 68A to 68F corresponding to the 1st to 6th peaks are arranged vertically and displayed. The horizontal axis of each mass spectrum 68A-68F indicates m/z, and the vertical axis indicates intensity. The horizontal axes of mass spectra 68A-68F are parallel, and the horizontal coordinates of their starting points coincide. Their scale is also the same.

Each of mass spectra 68A-68F corresponds to a true spectrum. In embodiments, each mass spectrum 68A-68F is estimated from a plurality of mass spectra. As the mass spectra 68A to 68F, mass spectra selected from the mass spectrum series may be displayed, or integrated mass spectra or average mass spectra generated based on the mass spectrum series may be displayed.

Stability graph 64, like TICC 62, is a graph suitable for qualitative analysis. According to the stability graph 64, it is possible to specify for each individual compound the retention time (RT) corresponding to the mass spectrum obtained with the highest stability of ion detection. If the mass spectrum is selected based on the identified retention time, the selection is more reliable and less susceptible to noise than when the mass spectrum is selected based on the retention time at which the peak in TICC62 occurs.

A compound or its constituent components can be estimated by performing a library search based on the exact masses or integer masses specified from the peaks of interest included in each of the mass spectra 68A to 68F.

FIG. 4 shows the stability graph generation method. The mass spectrum at the time of the present attention is the n-th mass spectrum. In S10, a first similarity is calculated between the (n-1)th mass spectrum and the nth mass spectrum. Each mass spectrum is composed of multiple intensity values on the m/z axis. It is considered one vector. Between two adjacent mass spectra, that is, between two adjacent vectors, cos similarity is calculated as a norm, distance or inner product. The first similarity is the cos similarity between the (n−1)th mass spectrum and the nth mass spectrum.

In S12, a second similarity is calculated between the n-th mass spectrum and the (n+1)-th mass spectrum. The second similarity is the cos similarity between the nth mass spectrum and the n+1th mass spectrum. Other similarities may be calculated instead of the cos similarity. For example, correlation values may be computed.

In S14, the n-th degree of stability is calculated based on the first degree of similarity and the second degree of similarity. The stability is, for example, the average value of the first similarity and the second similarity. Of the two degrees of similarity, the lower or the higher may be used as the degree of stability. An added value may be used instead of the average value.

In S16, it is determined whether or not n has reached the final value. If n has not reached the final value, n is incremented by 1 in S18, and each step after S10 is executed again. As described above, a plurality of stability degrees, that is, stability graphs are calculated from the mass spectrum sequence.

FIG. 5 shows the stability graph processing method. At S20, a peak search is performed on the stability graph. Search conditions can be determined as appropriate. The steps after S22 are executed for each peak. In S22, the peak top of the detected peak is specified. In an embodiment, the peak top as well as the rising and falling edges of the detected peaks are specified. The definition of rising edge and the definition of falling edge can be defined as appropriate.

In S24, the mass spectrum corresponding to the peak top (true mass spectrum corresponding to the compound) is estimated. In the embodiment, the true mass spectrum is estimated from three mass spectra: a mass spectrum corresponding to the peak top (peak top mass spectrum), a mass spectrum corresponding to the trailing edge (falling mass spectrum), and a mass spectrum corresponding to the trailing edge (falling mass spectrum). This will be detailed later with reference to FIG.

In S24, the mass spectrum corresponding to the peak top may be selected as it is. Alternatively, a true mass spectrum may be estimated by integrating or averaging a plurality of mass spectra from trailing mass spectra to leading mass spectra. At S26, the estimated new mass spectrum is displayed. It is what constitutes the mass spectrum listing above.

The relationship between TICC 70 and stability graph 78 is shown in FIG. TICC 70 includes peak 72 . Although it is actually composed of two peaks 74 and 76 corresponding to two compounds, one peak 72 appears.

Stability graph 78 includes two peaks 80 and 82 corresponding to peak 72 . Since the stability graph 78 shows the stability of the mass spectrum pattern, there appear two peaks 80, 82 corresponding to the two compounds. Two peaks 80, 82 have peak tops 80a, 82a. Focusing on the peak 80, it can be seen that it has a peak top 80a as well as a rising edge 80b and a falling edge 80c. The rising (rising point) and falling (falling point) are defined by slopes, thresholds, and the like.

According to the stability graph 78, what appears to be one peak in the TICC 70 can be separated into a plurality of peaks. Moreover, even when it is impossible to determine whether the peak included in the TICC 70 is noise, it is possible to easily determine whether the peak is noise.

FIG. 7 shows an example of the mass spectrum estimation method. A mass spectrum 86 is a mass spectrum corresponding to the peak top of the peak of interest in the stability graph. A mass spectrum 84 is a mass spectrum corresponding to the rise of the peak of interest. A mass spectrum 88 is a mass spectrum corresponding to the trailing edge of the peak of interest.

In the embodiment, the intensity i constituting the estimated mass spectrum 90 is calculated for each m/z by the following equation (1).

i=i2-(i1+i3)/2 (1)

Here, the intensity in the mass spectrum 84 corresponding to the rising edge is indicated by i1, the intensity in the mass spectrum 86 corresponding to the peak top is indicated by i2, and the intensity in the mass spectrum 88 corresponding to the trailing edge is indicated by i3. The above formula (1) excludes components corresponding to other compounds from the mass spectrum corresponding to the peak top (corresponding to a certain compound). The above formula (1) is an example, and other calculation formulas may be used. In any event, on the basis of stability peaks, it is possible to estimate the true mass spectrum for each individual compound. By estimating a compound based on such a mass spectrum, the estimation accuracy can be improved.

FIG. 8 shows a second display example. Image 92 includes TICC 94 obtained by mass spectrometry analysis of the first sample and TICC 96 obtained by mass spectrometry analysis of the second sample. The image 92 also includes a stability graph 98 (corresponding to TICC 94) obtained by mass spectrometry of the first sample, a stability graph 100 (corresponding to TICC 96) obtained by mass spectrometry of the second sample, and a difference graph 102.

TICC 94 includes peak 104 . TICC 96 includes a peak 108 corresponding to peak 104 as well as a minor peak 106 . Stability graph 98 includes peak 110 . Stability graph 100 includes peak 112 as well as peak 114 corresponding to peak 110 . Peak 112 corresponds to minor peak 106 .

Difference graph 102 is generated by comparison 116 of stability graph 98 and stability graph 100, and is a graph showing the difference therebetween. It includes a difference peak 118 corresponding to peak 112 . According to the difference graph, it is possible to accurately identify the difference between two samples, for example, trace components. Which stability graph the differential peak 118 is derived from may be expressed by the hue of the differential peak 118 or the like. For example, where stability graph 98 is represented in a first color and stability graph 100 is represented in a second color, individual differential peaks may be represented by the hue of the stability graph that produced them. A mass spectrum corresponding to the differential peak may be displayed.

FIG. 9 shows a third display example. In the image 120, the upper part of FIG. 9 shows the TICC 122 and the stability graph 124 obtained by mass spectrometry of the standard sample. The middle part of FIG. 9 shows TICC 126 and stability graph 128 obtained by mass spectrometric analysis of the first unknown sample. The lower part of FIG. 9 shows TICC 130 and stability graph 132 obtained by mass spectrometry of the second unknown sample.

TICC 122 includes peak 134 and TICCs 126 and 130 include peaks 138 and 142 corresponding to peak 134 . However, TICC 130 also includes a small peak 144 . Stability graph 124 includes peak 136 and stability graphs 128 and 132 include peaks 140 and 146 corresponding to peak 136 . However, stability graph 132 includes peak 148 corresponding to minor peak 144 .

The contents of the stability graph 128 are substantially the same as the contents of the stability graph 124, and a comparison 150 of the two does not produce any significant difference. On the other hand, the contents of stability graph 132 differ from the contents of stability graph 124 , ie, stability graph 132 has a peak 148 that is not included in stability graph 124 . Their comparison 152 produces a differential peak 154 that is superimposed on the stability graph 132 . The vertical axis of the stability graph 132 indicates stability and difference. The same is true if the stability graph 128 includes differential peaks. Instead of displaying differential peaks 154 independently, unique portions in stability graph 132 may be identified and represented.

According to the display method described above, when comparing the mass spectrometry result of each unknown sample with the mass spectrometry result of the standard sample, it becomes easy to identify the unique component or lack of component of each unknown sample.

10 gas chromatograph (GC), 11 mass spectrometer, 12 measurement unit, 14 information processing unit, 24 mass spectrum generation unit, 26 total ion current chromatogram (TICC) generation unit, 28 stability graph generation unit, 32 analysis unit, 34 display processing unit.

Claims (7)

A calculation means for calculating, as a degree of stability, a small temporal change in the mass spectrum pattern at each time point on the time axis based on a mass spectrum train composed of a plurality of mass spectra obtained by mass spectrometry of a plurality of temporally separated compounds, wherein at each time point on the time axis, a mass spectrum set consisting of three or more mass spectra consecutive on the time axis including a mass spectrum of interest at that time point is specified, and a calculation means for calculating the stability based on the mass spectrum set;
Stability graph generating means for generating a stability graph showing a plurality of stability calculated at a plurality of points on the time axis;
detection means for detecting a plurality of stability peaks included in the stability graph by performing a peak search on the stability graph;
list generating means for generating a mass spectrum list consisting of a plurality of mass spectra corresponding to the plurality of stability peaks detected based on the mass spectrum sequence;
display means for displaying the mass spectrum list;
A mass spectrum processing device comprising: The mass spectrum processing apparatus according to claim 1 ,
The mass spectrum set includes a first adjacent mass spectrum that is the n−1th mass spectrum, the mass spectrum of interest that is the nth mass spectrum, and a second adjacent mass spectrum that is the n+1th mass spectrum,
The computing means is
means for calculating a first degree of similarity by mutual comparison of the first adjacent mass spectrum and the mass spectrum of interest;
means for calculating a second degree of similarity by mutual comparison of the mass spectrum of interest and the second adjacent mass spectrum;
means for calculating the stability based on the first degree of similarity and the second degree of similarity;
including,
A mass spectrum processing apparatus characterized by: The mass spectrum processing apparatus according to claim 1,
Chromatogram generating means for generating a chromatogram based on the mass spectrum sequence;
said display means for displaying an image including said mass spectrum list, said chromatogram and said stability graph;
including
In the image, the time axis of the chromatogram and the time axis of the stability graph are associated,
A mass spectrum processing apparatus characterized by: The mass spectrum processing apparatus according to claim 1,
Estimating means for estimating, for each stability peak , a true mass spectrum corresponding to the stability peak based on the mass spectrum sequence;
The estimating means estimates the true mass spectrum based on a central mass spectrum corresponding to a representative point of the stability peak, a leading mass spectrum corresponding to the leading edge of the stability peak, and a trailing mass spectrum corresponding to the trailing edge of the stability peak.
A mass spectrum processing apparatus characterized by: The mass spectrum processing apparatus according to claim 1,
Difference graph generation means for generating a difference graph based on the first stability graph generated from the first sample and the second stability graph generated from the second sample;
the display means for displaying the difference graph;
A mass spectrum processing device comprising: generating a chromatogram based on a mass spectrum train consisting of a plurality of mass spectra obtained by mass spectrometry for a plurality of temporally separated compounds;
Based on the mass spectrum sequence, a step of calculating, as a degree of stability, the degree of little temporal change in the mass spectrum pattern at each time point on the time axis, wherein at each time point on the time axis, a mass spectrum set consisting of three or more continuous mass spectra on the time axis including the mass spectrum of interest at that time point is specified, and the stability is calculated based on the mass spectrum set;
generating a stability graph showing a plurality of stabilities calculated at a plurality of points in time on the time axis;
detection means for detecting a plurality of stability peaks included in the stability graph by performing a peak search on the stability graph;
list generating means for generating a mass spectrum list consisting of a plurality of mass spectra corresponding to the plurality of stability peaks detected based on the mass spectrum sequence;
displaying the mass spectrum list, the chromatogram and the stability graph;
A mass spectrum processing method, comprising: A program executed in an information processing device,
A function of calculating stability as a degree of stability in terms of a small temporal change in the mass spectrum pattern at each time point on the time axis based on a mass spectrum train composed of a plurality of mass spectra obtained by mass spectrometry of a plurality of temporally separated compounds, wherein at each time point on the time axis, a mass spectrum set consisting of three or more mass spectra consecutive on the time axis including the mass spectrum of interest at that time point is specified, and the stability is calculated based on the mass spectrum set;
A function of generating a stability graph showing a plurality of stability calculated at a plurality of points on the time axis;
A function of detecting a plurality of stability peaks included in the stability graph by performing a peak search on the stability graph;
a function of generating a mass spectrum list consisting of a plurality of mass spectra corresponding to the plurality of stability peaks detected based on the mass spectrum sequence;
A program characterized by comprising:

Images