Mass spectrometry method and analysis method using same for correcting temperature or time change of generated gas

Abstract

To remove a time delay until a gas generated at isothermal or heating time is detected by a mass spectrometer.SOLUTION: Provided are a mass spectrometry method for performing analysis by deconvolution on a strength curve as a function of time or a strength curve as a function of temperature in mass analysis, and an analysis method to correct for a temperature change or a time change of a gas generated at sample heating time, using said mass spectrometry method.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a mass spectrometry method and an analysis method using the same that corrects for temperature changes or time changes in generated gas. [Background technology]

[0002] Heat generation gas mass spectrometry is hereinafter sometimes referred to as TPD-MS. TPD-MS is a technique in which the generated gas is measured by mass spectrometry (hereinafter sometimes referred to as MS) when the temperature of a substance is changed isothermally or non-isothermally (by heating or cooling) according to a controlled program, and the mass spectrometer intensity (hereinafter sometimes referred to as MS intensity) corresponding to the molecular weight of each gas species is measured as a function of temperature or time (Non-Patent Document 1). The results obtained from TPD-MS measurement are an MS intensity-temperature curve or an MS intensity-time curve (hereinafter sometimes referred to as a TPD-MS curve).

[0003] In conventional TPD-MS measurements, the time lag between when the gas generated from the sample is detected by the mass spectrometer and when the generated gas remains in the device, resulting in the signal being detected by the mass spectrometer with a time distribution (hereinafter, sometimes referred to as broadening), is not corrected. In particular, the effect of broadening becomes more serious as the heating rate increases. For example, if a pulse-injected gas broadens at 300 s when detected, in a measurement with a heating rate of 10 °C / min, the behavior of the generated gas will have an apparent temperature distribution of 50 °C, and the behavior of the generated gas cannot be accurately understood. Furthermore, in reaction kinetics analysis in which the behavior of the generated gas is analyzed by changing the heating rate, this is the main cause of serious analysis errors. There is also the issue that the time lag and the broadening time vary depending on the configured device system.

[0004] In analytical techniques, deconvolution (Non-Patent Document 2), which is one of the signal analyses, is generally used for peak separation in spectra, X-ray diffraction, liquid chromatography mass spectrometry (hereinafter sometimes referred to as LC-MS), gas chromatography mass spectrometry (hereinafter sometimes referred to as GC-MS), and gel permeation chromatography (hereinafter sometimes referred to as GPC). In LC-MS and GC-MS, the MS intensity measured is a single component peak overlapped, and the mass spectrum of each component obtained by deconvolution can be searched from a mass spectrum library, so it is possible to determine whether or not it is the same peak based on the difference in the retention time of the peak top and the peak shape (Non-Patent Document 3). In addition, examples of the application of deconvolution in analysis to investigate the inflow and outflow of heat from a sample when the temperature of a substance is changed to isothermal or non-isothermal (heating or cooling) according to a regulated program include impulse thermal response analysis of a calorimeter at isothermal temperature (Non-Patent Documents 4 and 5) and analysis of the melting rate of a polymer using high-speed calorimetry (Non-Patent Document 6). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Hitoshi Asahina, Kinji Yaguchi, Application of Temperature Programmed Desorption or Decomposition Mass-Spectrometry (TPD-MS) in Materials Research, J. Mass Spectrum. Soc. Jpn., Vol.46, No.4(1998)357-360. [Non-Patent Document 2] Arend den Harder, Leo De Galan, Evaluation of a method for real-time deconvolution, Analytical Chemistry Vol.46, No.11 (1974) 1464-1470. [Non-Patent Document 3] Takaya Sato, Kentaro Takahara, Tomoaki Kondo, Ryo Ogasawara, Tomoka Nogami, Analysis Techniques in Mass Spectrometry, Journal of the Pesticide Science Society of Japan 42(1), (2017) 203-215. [Non-Patent Document 4] Satohiro Tanaka, Linear theory applied to a calorimeter during quasi-isothermal operation, Thermochimica Acta 115 (1987) 303-316. [Non-Patent Document 5] T. Yamane, S. Katayama, M. Todoki, Application of a deconvolution method to kinetic studies with conduction type microcalorimeters, Thermochimica Acta 183 (1991) 329-338. [Non-Patent Document 6] Y. Furushima, M. Nakada, M. Murakami, T. Yamane, A. Toda, C. Schick, Method for Calculation of the Lamellar Thickness Distribution of Not-Reorganized Linear Polyethylene Using Fast Scanning Calorimetry in Heating, Macromolecules 48 (2015) 8831-8837. Summary of the Invention [Problem to be solved by the invention]

[0006] The objective of the present invention is to apply deconvolution to TPD-MS curves to remove the signal broadening that occurs when gas evolved from a sample is detected by a mass spectrometer in conventional TPD-MS measurements, thereby enabling us to understand the actual behavior of the evolved gas. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention comprises the following configuration.

[0008] In other words, this is a mass spectrometry method that performs deconvolution analysis on an intensity curve as a function of time or an intensity curve as a function of temperature in mass spectrometry, and an analysis method that uses the above mass spectrometry method to correct for temperature changes or time changes in gas generated when a sample is heated. Effect of the Invention

[0009] By applying the data correction method (deconvolution) of the present invention to the TPD-MS curve, it becomes possible to obtain the actual behavior of the gas evolved from the sample. [Brief description of the drawings]

[0010] [Figure 1] This is an example of the configuration of a general TPD-MS measurement device. [Diagram 2] This is a TPD-MS curve under isothermal maintenance using the apparatus of Figure 1. [Diagram 3] This shows the TPD-MS curve under isothermal maintenance using the apparatus in Figure 1 and the results after deconvolution. [Figure 4] This shows the TPD-MS curve and the results after deconvolution when the zeolite absorbed moisture using the apparatus in Figure 1 was heated at 10°C / min. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] FIG. 1 shows an example of a typical TPD-MS apparatus. The temperature inside the furnace in which the sample is placed is controlled, and the gas generated by heating the sample is introduced into the mass spectrometer through piping and capillaries together with the carrier gas. In this apparatus, the piping and capillaries through which the gas flows downstream of the furnace are preferably maintained in the range of 100 to 400°C, for example, at 250°C. The temperature rise rate set in this apparatus is preferably in the range of 0.1 to 90°C / min, for example, 10°C / min. In the present invention, examples of low molecular weight gases include 1-butene (concentration 7.99%) (hereinafter sometimes referred to as 1-Bu), carbon dioxide (hereinafter CO 2 Nitrogen (hereafter, N 2 When a microsyringe is used to inject pulses (preferably 1 μL to 10 μL in this device) from a check valve installed directly above the sample introduction part shown in FIG. 1 under a carrier gas flow (helium flow of 50 mL / min in this device), it is possible to generate the same time lag (12 seconds in this device, for example) from the injection of the pulsed gas until it is detected by the mass spectrometer, regardless of the temperature of the sample introduction part (preferably 25°C to 500°C in this device). This time lag changes in proportion to the flow rate of the carrier gas and the distance from the sample introduction part to the detector of the mass spectrometer.

[0012] Next, the results of investigating the change over time of the MS intensity, with the start time of the gas component detected by the mass spectrometer set to zero seconds, are shown in Figure 2. It can be confirmed that the shape of the change over time of the MS intensity is consistent regardless of the gas type. In addition, when the same equipment is used, it can be confirmed that the repeatability of the measurement is good regardless of the gas injection amount (preferably in the range of 1 μL to 10 μL). From this, the change over time of the MS intensity shown in Figure 2 (hereinafter, the change over time of the measured MS intensity may be written as θ(t) as a function of time t)) can be regarded as the response function of the device when gas is injected in a pulsed form (hereinafter, sometimes referred to as impulse response function g(t)). Therefore, when a linear relationship is established between θ(t) and g(t), the following relational equation (1) is established. Note that g(t) may also be acquired by injecting the same molecule as the gas component acquired at θ(t) in a pulse.

[0013]

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[0014] Here, ν(η) is the change over time of MS intensity without response delay, and represents the actual behavior of the evolved gas. g(t-η) is an impulse response function, a delay function that specifies the broadening of the evolved gas until it is detected by the device. Here, by using deconvolution analysis, ν(η) can be derived from θ(t) and g(t). For the method of deconvolution analysis, Non-Patent Documents 2, 4, and 5 can be referred to. Note that g(t) can be obtained by investigating the signal intensity of the MS when a pulsed gas is injected in advance, as shown in FIG. 2. θ(t) is the change over time of the actually measured MS intensity when the evolved gas from the sample to be evaluated is measured by TPD-MS.

[0015] The present invention is a mass spectrometry method that performs deconvolution analysis on an intensity curve as a function of time or an intensity curve as a function of temperature in mass spectrometry, and this deconvolution analysis method for mass spectrometry intensity curves is the first to apply deconvolution to a TPD-MS curve. The basic equations for the deconvolution are the following equations (2) to (4).

[0016]

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[0017]

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[0018]

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[0019] Here, i is the imaginary unit and ω is the frequency. Equations (2) and (3) represent the Fourier transforms of θ(t) and g(t), respectively, and equation (4) is based on equations (2) and (3), and can derive ν(η) by taking the quotient of the function obtained by performing a Fourier transform and then performing an inverse Fourier transform.

[0020] Examples of objects of analysis include porous materials, inorganic substances, organic substances, pharmaceuticals, biomolecules, catalysts, and polymeric materials (e.g., thermosetting resins, thermoplastic resins). Among them, zeolite, which is a porous material capable of adsorbing gases and liquids, is a preferred example. EXAMPLES

[0021] The present invention will now be described with reference to examples.

[0022] The MS measurements were performed using a Shimadzu mass spectrometer, GCMS-QP2010. The measurement was performed with a helium flow of 50 mL / min as the carrier gas.

[0023] At room temperature, 5 μL of 1-Bu was injected twice in a pulsed manner at 1-min intervals through the check valve shown in FIG. 1 using a microsyringe.

[0024] The TPD-MS curve obtained by a single injection of 5 μL of 1-Bu is shown in Figure 2. 2 , and CO 2The TPD-MS curve obtained from a single injection is also shown in Figure 2.

[0025] The measured TPD-MS curve (corresponding to θ(t)) plotted with the time when the MS signal originating from 1-Bu was detected by the mass spectrometer set as 0 s is shown by the dotted line in Figure 3. Two peaks are seen corresponding to the two gas injections, and it takes about 300 s for the signal to be detected, confirming that the pulsed gas injection broadens the signal (not deconvoluted).

[0026] The TPD-MS curve obtained by injecting 5 μL of 1-Bu twice as shown in Figure 2 is denoted as g(t), and ν(η) calculated using equations (2) to (4) is shown by the solid line in Figure 3. As a result of deconvolution, two peaks appear at positions corresponding to the injection times, and it can be confirmed that the peak shapes are sharper than those of the actually measured TPD-MS curve. It can also be confirmed that the actual injection time and the peak positions after deconvolution are closer to each other.

[0027] Figure 4 shows the TPD-MS curve of water molecules when zeolite (4A type, Fujifilm Wako Pure Chemical Corporation) that had absorbed moisture for three days under saturated vapor pressure at room temperature was heated at 10°C / min. Compared to the measured TPD-MS curve shown by the dotted line, the deconvolution curve shows a peak on the low temperature side, and the peak width is narrower, indicating that correction has been applied to remove signal broadening. The peak temperature changed by about 10°C before and after deconvolution, indicating that the broadening of about 60 s in time has been corrected. [Explanation of symbols]

[0028] 1: Helium gas (carrier gas) 2: Check valve 3: Sample introduction section (gas generation source) 4: Temperature controlled furnace 5: Release valve 6: Gas introduction 7: Mass spectrometer 8: Capillary tube 9: Detector 10:1- Bu was injected at 5 μL (first injection) 11:1- Bu 5μL injected (second injection) 12: Deconvolution curve ν(t) 13: Actual TPD-MS curve θ(t) 14: Deconvolution curve ν(t) of zeolite with moisture control 15: Measured TPD-MS curve θ(t) of zeolite with moisture control

Claims

1. A mass spectrometry method in which a deconvolution analysis is performed in which a quotient of a function obtained by Fourier transforming an intensity curve as a function of time or an intensity curve as a function of temperature is obtained, and then an inverse Fourier transform is performed to derive the desired function.

2. 2. An analytical method using the mass spectrometry method according to claim 1, which corrects for temperature changes or time changes of gas generated when a sample is heated.

3. 2. An analytical method using the mass spectrometry method according to claim 1, comprising correcting for a time change in a gas generated when a sample is kept isothermal.

4. 4. The analytical method for correcting for temperature or time change of evolved gas according to claim 2 or 3, wherein the heating rate, set temperature and set time are arbitrarily determined during heating or isothermal holding of the sample.

5. 5. The analytical method for correcting for temperature changes or time changes in generated gas according to claim 2, wherein the change in intensity of a mass spectrometer after a pulsed gas is injected into a sample heating furnace is used as an impulse response function.

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