Patent Application
20190025123
This application claims priority and the benefit of Japan Patent Application No. JP 2017-142237, by SAKUTA, filed Jul. 21, 2017, which is hereby incorporated by reference in its entirety into this application.
The present invention relates to a spectral data processing apparatus and a spectral data processing method.
With respect to a mass spectrometry, an analysis such as identification of a substance is performed using a mass spectrum. The mass spectrum is a two dimensional spectrum in which a horizontal axis represents a mass-to-charge ratio (m/z) and a vertical axis represents signal intensity.
In LC/MS spectrometry or GC/MS spectrometry, a technology has been developed in which various analysis results such as a chromatogram and a mass spectrum are obtained, and these analysis results are displayed in association with each other to allow visualization thereof to be realized (Patent Document 1).
(Patent document 1) Japan Patent Application Publication No. 2014-219317
A thermal desorption ionization mass spectrometer ionizes a gas component evolved by heating a sample, thereby performing mass spectrometry. Herein, the timing of thermal desorption of the gas component contained in the sample is different depending on molecular species or heating conditions, and there is a possibility that information of components actually contained in the sample can be read from a change in the mass spectrum over time. For example, when different peaks of a mass-to-charge ratio occur at the same time, these peaks are likely to be fragments derived from the same material. In addition, it is highly likely that components that are always detected regardless of change in heating temperature over time are impurities (contamination) or noise.
However, considering the characteristics of a chromatogram (total ion chromatogram; compiling signal intensities for each mass-to-charge ratio and showing a change in signal intensity over time) or a mass spectrum, analysis and visual recognition thereof are difficult to achieve.
For example, as shown in
However, when the number of peaks in the mass spectrum is large, it is difficult to superimpose the mass spectra for each point of time on the same screen, and it is also difficult to display the mass spectra every short time interval in a limited screen space. For this reason, it is difficult to easily and carefully analyze a change in time of the mass spectrum in two dimensions.
The present invention has been made to solve the above problems and it is an object of the present invention to provide an apparatus for processing spectra data and a method of processing spectra data, to allow a relationship between time, signal intensity, and a prescribed parameter of three dimensional spectral data, to be easily understood visually in two dimensions.
In order to achieve the above object, a spectral data processing apparatus according to the present invention, in which a particular spectrum is displayed on a display on a basis of three dimensional spectral data having time, signal intensities, and a prescribed parameter, includes a two dimensional spectrum calculating unit compiling the signal intensities for each point of the time and calculating a two dimensional spectrum of the signal intensities and the prescribed parameter, on a basis of the spectral data; a signal intensity-time change calculating unit calculating a change in the signal intensity over time for each value of the prescribed parameter, on a basis of the spectral data; and a display controlling unit displaying the two dimensional spectrum on the display, and displaying the change in the signal intensity over time in a superimposed manner on the display using multicolor, light and shading, or a change in brightness, in such a way that the prescribed parameter of the two dimensional spectrum are consistent and an axis of the signal intensities of the two dimensional spectrum represents the time.
According to the spectral data processing apparatus, since the change in signal intensity over time is two-dimensionally displayed in a superimposed manner, in such a way that the parameter of the two dimensional spectrum is consistent, a relationship between time, signal intensity, and parameter of the three dimensional spectral data may be easily understood visually in detail in two dimensions.
In the spectral data processing apparatus of the present invention, the spectral data may be mass spectrometry data, the parameter may be a mass-to-charge ratio, and the two dimensional spectrum may be a mass spectrum.
In the spectral data processing apparatus of the present invention, the spectral data may be mass spectrometry data of an organic compound.
In the spectral data processing apparatus of the present invention, the spectral data may include fragmentation ions generated from the organic compound.
In the spectral data processing apparatus of the present invention, the display controlling unit may be configured to display the two dimensional spectrum and the signal intensities on the display in a superimposed manner, and display a chromatogram representing a relationship between time and signal intensity on the display in a superimposed manner.
A spectral data processing method according to the present invention, in which a particular spectrum is displayed on a display on a basis of three dimensional spectral data having time, signal intensities, and a prescribed parameter, includes: a two dimensional spectrum calculating step compiling the signal intensities for each point of the time and calculating a two dimensional spectrum of the signal intensities and the prescribed parameter, on a basis of the spectral data; a signal intensity-time change calculating step calculating a change in the signal intensity over time for each value of the prescribed parameter, on a basis of the spectral data; and a display controlling step displaying the two dimensional spectrum on the display, and displaying the change in the signal intensity over time in a superimposed manner on the display using multicolor, light and shading, or a change in brightness, in such a way that the prescribed parameter of the two dimensional spectrum are consistent and an axis of the signal intensities of the two dimensional spectrum represents the time.
According to the present invention, a relationship between time, signal intensity, and parameter of three dimensional spectral data can be easily understood visually in detail in two dimensions.
The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
The present invention will be described in detail below with reference to the accompanying drawings. Repeated descriptions and descriptions of known functions and configurations which have been deemed to make the gist of the present invention unnecessarily obscure will be omitted below. The embodiments of the present invention are intended to fully describe the present invention to a person having ordinary knowledge in the art to which the present invention pertains. Accordingly, the shapes, sizes, etc. of components in the drawings may be exaggerated to make the description clearer.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The evolved-gas analysis apparatus 200 includes a body unit 202 that is a housing, an attaching unit 204 for a gas evolving unit, the attaching unit having a box shape and attached at a front of the body unit 202, and a computer (controlling unit) 210 for control thereof. The computer 210 has a CPU for performing data processing, a storage 215 for storing computer programs or data, a display 220 such as a liquid crystal monitor, an input unit such as a keyboard, and the like.
In the attaching unit 204 for the gas evolving unit, there are a heating furnace 10 having a cylinder shape, a sample holder 20, a cooling unit 30, a splitter 40 splitting gas, an ion source 50, and an inert gas flow passage 19f as a gas evolving unit 100 of a single assembly. In addition, in the body unit 202, a mass spectrometer 110 for analyzing a gas component evolved by heating a sample is received.
As shown in
In addition, for example, when the sample holder 20 is moved on a movement rail 204L (described later) by a stepping motor, etc. controlled by the computer 210, the sample holder 20 may be automatically moved into or from the heating furnace 10.
Hereinafter, referring to
First, the heating furnace 10 is attached to an attaching plate 204a of the attaching unit 204 by being parallel to the axis O. The heating furnace includes a heating chamber 12 having a cylinder shape and being opened on the axis O; a heating block 14; and a heat retaining jacket 16.
The heating block 14 surrounds the heating chamber 12, and the heat retaining jacket 16 surrounds the heating block 14. The heating block 14 is made of aluminum, and is heated by electricity from a pair of heater electrodes 14a (see
In addition, the attaching plate 204a extends in a direction perpendicular to the axis O. The splitter 40 and the ion source 50 are attached to the heating furnace 10. In addition, a supporter 204b extends in a vertical direction of the attaching unit 204, and the ion source 50 is supported by the supporter 204b.
The splitter 40 is connected to an opposite side (right side in
In addition, a mixed gas channel 41 communicates with a cross section on the opposite side (the right side in
Meanwhile, as shown in
The sample holder 20 includes a stage 22 that moves on the movement rail 204L attached to an inner upper surface of the attaching unit 204; a bracket 24c attached on the stage 22 and extending in a vertical direction; insulators 24b and 26 attached to a front surface of the bracket 24c; a sample holding unit 24a extending from the bracket 24c in a direction of the axis O in the heating chamber 12; a sample heater 27 provided just below the sample holding unit 24a, and a sample plate 28 provided on an upper surface of the sample holding unit 24a above the heater 27, wherein the sample is placed on the sample plate.
Herein, the movement rail 204L extends in a direction of the axis O (horizontal direction of
In addition, the bracket 24c has a long rectangular shape having a semicircular upper portion. Referring, to
The bracket 24c has a diameter slightly larger than a diameter of the heating chamber 12 such that the bracket 24c seals the heating chamber 12. The sample holding unit 24a is located in the heating chamber 12.
In addition, the sample placed on the sample plate 28 in the heating chamber 12 is heated in the heating furnace 10 such that the gas component G is evolved.
The cooling unit 30 faces the bracket 24c of the sample holder 20, and is located at an outside of the heating furnace 10 (left side of the heating furnace 10 in
In addition, when the sample holder 20 moves in a direction of the axis O on the movement rail 204L toward a left side of
As shown in
In this embodiment, a filter 42b is provided between the branching channel 42 and the back pressure controller 42a to remove impurities from the mixed gas. Without mounting a valve for regulating the back pressure such as the mass flow controller 42a or the like, the branching channel 42 may be a pipe with an exposed end.
As shown in
The mixed gas channel 41 may have a straight line shape extending in a direction of axis O from the heating chamber 12 connected with the gas channel to the end part 41e. Alternatively, depending on a positional relationship with the heating chamber 12 or with the ion source 50, the mixed gas channel 41 may have a variously curved shape, a line shape having an angle to the axis O, etc.
As shown in
As shown in
In addition, the inert gas T from the inert gas flow passage 19f is mixed with the mixed gas M introduced into the merging portion 45 near the small hole 53c from the end part 41e, so that the resulting gas M+T flows into the discharge needle 56 and the gas component G of the resulting gas M+T is ionized by the discharge needle 56.
The ion source 50 is a well-known device. According to the exemplary embodiment of the present invention, atmospheric pressure chemical ionization (APCI) is applied to the ion source. APCI causes minimal fragmentation of the gas component G, such that a fragmentation peak does not occur. Therefore, it is possible to detect the measurement target without separating the gas component G by using a chromatograph, etc.
The gas component G ionized at the ion source 50, the carrier gas C and the inert gas T are introduced to the mass spectrometer 110, and are analyzed.
In addition, the ion source 50 is contained in the ionizer heat retaining unit 54.
The sample S is heated in the heating chamber 12 of the heating furnace 10, and the gas component G is evolved. Heating condition (temperature rising rate, maximum temperature, etc.) of the heating furnace 10 is controlled by a heating control unit 212 of the computer 210.
The gas component G is mixed with the carrier gas C introduced in the heating chamber 12 to be a mixed gas M, and the mixed gas M is introduced in the splitter 40. A portion of the mixed gas M is discharged from the branching channel 42 to the outside.
The remainder of the mixed gas M is mixed with the inert gas T from the inert gas flow passage 19f to be a total gas (M+T), the total gas is introduced in the ion source 50, and the gas component G is ionized.
A detection signal determining unit 214 of the computer 210 receives a detection signal from a detector 118 (described later) of the mass spectrometer 110.
A flow rate control unit 216 determines whether or not peak intensity of the detection signal received from the detection signal determining unit 214 is within a threshold range. When the peak intensity is out of the threshold range, the flow rate control unit 216 controls the opening ratio of the valve 19v. Therefore, flow rate of the mixed gas M discharged from the splitter 40 to an outside through the branching channel 42 is controlled, and further, flow rate of the mixed gas M introduced from the mixed gas channel 41 into the ion source 50 is controlled, thereby optimizing a detection accuracy of the mass spectrometer 110.
The mass spectrometer 110 includes a first minute hole 111 through which the gas component G ionized at the ion source 50 is introduced; a second minute hole 112 through which the gas component G flows, after flowing through the first minute hole 111; an ion guide 114; a quadrupole mass filter 116; and the detector 118 detecting the gas component G discharged from the quadrupole mass filter 116.
The quadrupole mass filter 116 varies an applied high frequency voltage such that mass is scanned. The quadrupole mass filter generates a quadrupole electric field, and detects ions by moving the ions like a pendulum swinging within the quadrupole electric field. The quadrupole mass filter 116 functions as a mass separator passing only gas component G within a certain mass range such that the detector 118 may identify and quantify the gas component G.
In this example, the inert gas T is caused to flow in the mixed gas channel 41 that is downstream from the branching channel 42, whereby flow resistance is caused to suppress the flow rate of the mixed gas M introduced into the mass spectrometer 110 and the flow rate of the mixed gas M discharged from the branching channel 42 is adjusted. Specifically, the larger the flow rate of the inert gas T, the larger the flow rate of the mixed gas M discharged from the branching channel 42.
Accordingly, when a large amount of a gas component is evolved so that the gas concentration becomes too high, the flow rate of the mixed gas discharged from the branching channel to the outside is increased, whereby it is possible to prevent the measurement from being inaccurate due to overscaled detection signal caused by exceeding the detection range of the detection means.
Next, with reference to
The computer 210 of
First, in this embodiment, a case of measuring the mass spectrum in the scan mode is taken as an example. In the scan mode, a detection signal determining unit 214 acquires a mass spectrum (signal intensity for each mass-to-charge ratio (m/z)) for each point of time. The acquired data is three dimensional mass spectrometry data having time, signal intensities, and mass-to-charge ratio (m/z), and is stored in a storage 215 such as a hard disk.
The mass spectrometry data and the mass-to-charge ratio correspond to “three dimensional spectrum data” and “parameter” of the claims, respectively.
Next, a two dimensional spectrum calculating unit 217 of the computer 210 reads the mass spectrometry data of the storage 215, compiles the signal intensities for each point of time, and calculates a two dimensional spectrum (i.e., mass spectrum) of the signal intensity and the mass-to-charge ratio.
In addition, a signal intensity-time change calculating unit 218 of the computer 210 reads the mass spectrometry data of the storage 215 and calculates a change in signal intensity over time TC for each mass-to-charge ratio.
In
Next, a display controlling unit 219 of the computer 210 displays the mass spectrum MS and the change in signal intensity over time TC in a superimposed manner on the display 220.
That is, as shown in
As shown in
It is needless to say that the change in signal intensity over time TC is similarly displayed in a superimposed manner with respect to other peaks Q of the mass spectrum MS. In addition, “display in a superimposed manner” is preferably to cause the change in signal intensity over time TC to be displayed on the mass spectrum MS not to be overlaid with the peaks of the mass spectrum MS.
Further, when compiling the signal intensity and calculating the mass spectrum for each point of time, all the data (for example, all the data for each point of time in the scan mode) are complied in the entire time from the start to the end of the measurement. Alternatively, the data may be thinned out and compiled at a preset time interval.
As described above, according to the present embodiment, since the change in signal intensity over time is two-dimensionally displayed in a superimposed manner, in such a way that the mass-to-charge ratio of the mass spectrum is consistent, a relationship between time, signal intensities, and mass-to-charge ratio of the three dimensional mass spectrometry data may be easily understood visually in detail in two dimensions.
For example, even though it is assumed that two peaks F are caused due to fragmentation of the component P1 in a normal mass spectrum of
Thus, as shown in
As shown in
As shown in
In addition,
On the other hand,
In
Even though the chromatogram CH is a total ion chromatogram in
The processing in
First, the signal intensity-time change calculating unit 218 of the computer 210 reads the mass spectrometry data of the storage 215 and obtains a chromatogram (total ion chromatogram) CH. In the case of the chromatogram CH of the specific peak P, the change in signal intensity over time TC at the peak P of the mass-to-charge ratio is calculated.
Next, the display controlling unit 219 of the computer 210 displays the change in signal intensity over time TC and the mass spectrum MS in a superimposed manner on the display 220 as described above, and displays the chromatogram CH in a superimposed manner, in such a way that the chromatogram CH is displayed to match the time axis of the change in signal intensity over time TC.
The display controlling unit 219 may determine the position at which the chromatogram CH is displayed on the display unit 220 as a default, but a chart of the peak P or the change in signal intensity over time TC may be possibly superimposed with the chromatogram CH. Accordingly, for example, the operator moves the chromatogram CH to a predetermined position by designation (click, etc.) to allow the display controlling unit 219 to read out the movement information thereof. As such, the chromatogram CH may be displayed at a position in which it is not be superimposed with the peak T or the change in signal intensity over time TC.
The present invention is not limited to the above-described embodiment, but includes various variations and equivalents included in the spirit and scope of the present invention.
The three dimensional spectral data is not limited to the data of the mass spectrometry.
The parameter is not limited to the mass-to-charge ratio, but may be a parameter according to three dimensional spectral data.
The method of displaying the change in signal intensity over time TC is not limited to the use of light and shading. For example, the change in signal intensity over time TC may be displayed in multiple colors by assigning the color according to the signal intensity display (such as color mapping), or as a change in brightness by assigning a brightness according to a signal intensity.
The signal intensity, a change in color, light and shading, or a change in brightness do not need to be proportional, and nonlinear processing such as logarithmic conversion may be performed to emphasize a weak signal intensity.
The method of introducing the sample in the case of mass spectrometry is not limited to the method of evolving the gas component by thermally decomposing the sample in the heating furnace described above, but may be, for example, GC/MS or LC/MS of solvent extraction type that introduces solvent containing a gas component, and generating gas component while volatilizing the solvent.
The ion source 50 is not limited to the type of APCI.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-142237 | Jul 2017 | JP | national |
