Quantitative analysis method of decomposable gas

Abstract

To provide a quantitative analysis method of decomposable gas which is excellent in operability and accuracy for quantitatively analysing the decomposable gas.SOLUTION: There is provided a method of quantitatively analysing decomposable gas contained in sample with gas chromatograph including a pulse discharge ionization detector. Before the sample is introduced into a gas chromatograph, alternate gas is used as reference gas to calibrate the pulse discharge ionization detector. The alternate gas satisfies a condition that a difference between ΔIE1 and ΔIE2 is -1 eV of higher and 1 eV or lower, where ΔIE1 denotes energy difference between photon energy obtained by light emission of discharge gas used in the pulse discharge ionization detector and ionization energy of the decomposable gas, and ΔIE2 denotes energy difference between photon energy obtained by light emission of discharge gas used in the pulse discharge ionization detector and ionization energy of the alternate gas.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for quantitatively analyzing decomposition gases. [Background technology]

[0002] Gas chromatography is a well-known analytical technique used to separate and analyze specific gas compounds contained in a sample, and is particularly useful as a method for quantitatively analyzing specific gas compounds (e.g., Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-057371 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when quantitatively analyzing the gas compound to be measured in a sample using a gas chromatograph, the detector is usually calibrated using the gas compound of known concentration as a standard gas (standard substance), and the concentration of the gas compound in the sample can be calculated using the calibrated detector.

[0005] However, when the measurement target is an unstable decomposable gas, the concentration of the decomposable gas changes over time, and it is difficult to obtain a decomposable gas with a known concentration, so it is usually difficult to use the decomposable gas itself as a standard gas. Therefore, when quantitatively analyzing the decomposable gas in a sample, a detector is calibrated using a highly stable alternative gas as a standard gas instead of the decomposable gas, but it is not easy to select the alternative gas, and there is a problem that the measurement accuracy is low.

[0006] On the other hand, a method for quantitatively analyzing decomposition gases using a gas chromatograph with an ICP mass spectrometer as a detector (so-called "GC-ICP-MS") is known. However, the measurement procedure is complicated and difficult to handle, and there is a problem that quantitative analysis is time-consuming when there are a large number of samples to be measured, for example.

[0007] Therefore, an object of the present invention is to provide a method for quantitatively analyzing decomposable gases that is excellent in operability and accuracy of the quantitative analysis of decomposable gases. [Means for solving the problem]

[0008] The present inventors have conducted extensive research with the aim of solving the above problems, and have newly discovered that the above problems can be solved by a method for quantitatively analyzing a decomposable gas contained in a sample using a gas chromatograph equipped with a pulse discharge ionization detector, in which the pulse discharge ionization detector is calibrated using a predetermined alternative gas as a standard gas before the sample is introduced into the gas chromatograph, and have completed the present invention.

[0009] That is, the present invention aims to advantageously solve the above-mentioned problems, and is a method for quantitatively analyzing a decomposable gas contained in a sample by using a gas chromatograph equipped with a pulse discharge ionization detector, in which, before the sample is introduced into the gas chromatograph, the pulse discharge ionization detector is calibrated using an alternative gas as a standard gas such that the difference between ΔIE1 and ΔIE2 is -1 eV or more and 1 eV or less, where ΔIE1 is the energy difference between the photon energy obtained by the emission of light from a discharge gas used in the pulse discharge ionization detector and the ionization energy of the decomposable gas, and ΔIE2 is the energy difference between the photon energy obtained by the emission of light from a discharge gas used in the pulse discharge ionization detector and the ionization energy of an alternative gas. In this specification, the elements or compounds constituting the decomposable gas and the alternative gas are not particularly limited as long as they are gases when analyzed by gas chromatography, and may be gases, liquids, or solids at room temperature (approximately 25°C). In this specification, the element or compound constituting the alternative gas is usually an element or compound that is more stable than the element or compound constituting the decomposable gas. In this specification, the photon energy obtained by the emission of light from a discharge gas was calculated by a quantum mechanical calculation method using "B3LYP" as a density functional method and "cc-pVDZ" as a basis function. In this specification, the ionization energies of the decomposable gases and alternative gases are calculated by a quantum mechanical calculation method using "B3LYP" as the density functional method and "cc-pVDZ" as the basis function to obtain the enthalpy of the ground state structure of the decomposable gases and alternative gases (enthalpy when the charge is 0) and the enthalpy of the positive charge structure (enthalpy when the charge is +1), and are the values ​​obtained by subtracting the enthalpy of the ground state structure from the enthalpy of the positive charge structure.

[0010] [2] In the quantitative analysis method for decomposable gases according to [1] above, it is preferable that the decomposable gases have a concentration change rate of 100 ppm / 30 days or more in a temperature environment of 5° C. or more and 300° C. or less.

[0011] [3] In the quantitative analysis method for decomposition gases according to the above [1] or [2], the discharge gas is preferably at least one gas selected from the group consisting of helium, neon, argon, krypton, xenon and nitrogen molecules.

[0012] [4] In any one of the above methods for quantitatively analyzing a decomposition gas [1] to [3], the alternative gas is preferably a hydrocarbon. Effect of the Invention

[0013] According to the present invention, a method for quantitatively analyzing decomposition gases that is easy to operate and has excellent accuracy can be provided. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a flow diagram showing an example of a method for quantitatively analyzing decomposable gases according to the present invention. [Diagram 2] 1 is a schematic diagram showing an example of a gas chromatograph used in the quantitative analysis method for decomposition gases of the present invention. [Diagram 3] 1 is a graph showing the time course of the rate of change in C concentration in Example 1 and Comparative Example 1. [Figure 4] 1 is a graph showing the time course of the rate of change in N concentration in Example 2 and Comparative Example 2. [Diagram 5] 1 is a graph showing the time course of the rate of change in P concentration in Example 3 and Comparative Example 3. [Figure 6] 1 is a graph showing the time course of the rate of change of Ge concentration in Example 4 and Comparative Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (Quantitative analysis method for decomposition gases) The quantitative analysis method for decomposable gases of the present invention (hereinafter, sometimes simply referred to as the "quantitative analysis method") is a method for quantitatively analyzing decomposable gases contained in a sample using a gas chromatograph equipped with a pulse discharge ionization detector (PPD). In the quantitative analysis method for decomposable gases of the present invention, before the sample is introduced into the gas chromatograph, the pulse discharge ionization detector is calibrated using, as a standard gas, an alternative gas (hereinafter, sometimes simply referred to as the "alternative gas") in which the difference between ΔIE1 and ΔIE2 is -1 eV or more and 1 eV or less, where ΔIE1 is the energy difference between the photon energy obtained by the emission of the discharge gas used in the pulse discharge ionization detector (hereinafter, sometimes referred to as the "emission energy") and the ionization energy of the decomposable gas, and ΔIE2 is the energy difference between the emission energy and the ionization energy of the alternative gas. The quantitative analysis method of decomposition gas as described above is excellent in operability and accuracy of quantitative analysis of decomposition gas. The reason is presumably that, since the correlation between the peak area and ΔIE is high in a gas chromatograph equipped with a pulse discharge ionization detector, a good calibration curve can be created even when the pulse discharge ionization detector is calibrated using an alternative gas.

[0016] <Gas chromatograph> The gas chromatograph used in the quantitative analysis method of the present invention is not particularly limited as long as it is equipped with a pulse discharge ionization detector, and any conventionally known gas chromatograph can be used, for example, GC7890B (G3440B) manufactured by Agilent Technologies.

[0017] Here, the pulse discharge ionization detector equipped in the gas chromatograph is a detector that uses light quantum (photon energy) obtained by pulse discharging a discharge gas such as helium as an ionization energy source. To explain more specifically, taking the case where the discharge gas is helium as an example, first, when a pulse high voltage is applied to the discharge gas introduced from the discharge gas inlet of the pulse discharge ionization detector, the helium is excited and dimerized by the pulse discharge energy. Here, the dimerized helium releases photon energy when returning to the original stable helium, and this photon energy becomes the ionization energy source. Then, the photon energy generated by the pulse discharge ionizes the outflow components (alternative gas, decomposition gas, etc.) from the column of the gas chromatograph, and the electrons generated by the ionization are collected by a bias electrode to a collecting electrode, and the current is amplified by an amplifier and can be observed as a peak.

[0018] <Alternative gas> In the quantitative analysis method of the present invention, it is necessary to use an alternative gas in which the difference between ΔIE1 and ΔIE2 ("ΔIE1" - "ΔIE2") is -1 eV or more and 1 eV or less. By using such an alternative gas, the quantitative analysis method of the present invention can provide excellent accuracy in quantitative analysis of decomposition gases. As the alternative gas, it is preferable to use one in which the difference between ΔIE1 and ΔIE2 is -0.5 eV or more and 0.5 eV or less, more preferably -0.3 eV or more and 0.3 eV or less, and even more preferably -0.1 eV or more and 0.1 eV or less.

[0019] Here, from the viewpoint of improving the accuracy of quantitative analysis of the decomposable gas, it is preferable to use an alternative gas in which the energy difference between the ionization energy of the decomposable gas and the ionization energy of the alternative gas is -1 eV or more and 1 eV or less, it is more preferable to use an alternative gas in which the energy difference is -0.5 eV or more and 0.5 eV or less, it is even more preferable to use an alternative gas in which the energy difference is -0.3 eV or more and 0.3 eV or less, and it is even more preferable to use an alternative gas in which the energy difference is -0.1 eV or more and 0.1 eV or less.

[0020] In one embodiment, the alternative gas is not particularly limited, but preferably has a fragmentation rate of 50% or less, more preferably 40% or less, and even more preferably 30% or less. If the fragmentation rate of the alternative gas is equal to or lower than the upper limit, the accuracy of the quantitative analysis of the decomposition gas can be improved. In this specification, "fragmentation" means that the compounds constituting the alternative gas are decomposed to have a lower molecular weight. In addition, in this specification, the "fragmentation rate" means the ratio of the fragmented compounds to the entire compounds before fragmentation, which can be measured using a gas chromatograph (so-called "GC-MS") equipped with a mass spectrometer with an ionization energy set to 17 eV.

[0021] The alternative gas is not particularly limited as long as the difference between ΔIE1 and ΔIE2 falls within the above-mentioned predetermined range, and examples of the alternative gas include simple substances such as nitrogen molecules, oxygen molecules, and hydrogen molecules; compounds such as hydrocarbons; etc. Among these, hydrocarbons are preferred from the viewpoints of ease of handling and improving the operability of quantitative analysis of decomposable gases, and of high correlation between ΔIE2 and the peak area in a pulse discharge ionization detector and improving the accuracy of quantitative analysis of decomposable gases.

[0022] In the present specification, a hydrocarbon is a compound consisting of carbon and hydrogen atoms, and usually does not contain any atoms other than carbon and hydrogen atoms. As such a hydrocarbon, for example, a hydrocarbon having 1 to 8 carbon atoms can be suitably used. An example of a hydrocarbon with one carbon atom is methane. Examples of hydrocarbons having two carbon atoms include ethane, ethylene, and acetylene. Examples of hydrocarbons having three carbon atoms include propane, propylene, and cyclopropane. Examples of hydrocarbons having four carbon atoms include n-butane, iso-butane, 1-butene, 2-butene, 2-butene, and 1,3-butadiene. Examples of hydrocarbons having 5 carbon atoms include n-pentane, iso-pentane, and neo-pentane. The six carbon hydrocarbons are: Hydrocarbons with five carbon atoms; n-hexane, 2-methylpentane, cyclohexane, 1-hexene, benzene, etc. Examples of hydrocarbons having seven carbon atoms include n-heptane, 2-methylhexane, 1-heptene, and toluene. Examples of hydrocarbons having 8 carbon atoms include n-octane, 3,4-dimethylhexane, 2,2,4-trimethylpentane, 1-octene, o-xylene, m-xylene, p-xylene, and styrene. Among the above-mentioned hydrocarbons, n-butane, n-pentane, benzene, toluene, and styrene are preferred from the viewpoint of further improving the operability of the quantitative analysis of the decomposable gas, and from the viewpoint of further improving the accuracy of the quantitative analysis of the decomposable gas by having a higher correlation between ΔIE2 and the peak area in a pulse discharge ionization detector. That is, it is preferable to use at least one compound selected from the group consisting of n-butane, n-pentane, benzene, toluene, and styrene as the alternative gas.

[0023] <Discharge gas> The discharge gas is not particularly limited as long as it is excited by pulse discharge energy to emit photon energy, but since it can easily emit photon energy, it is preferably at least one gas selected from the group consisting of helium, neon, argon, krypton, xenon, and nitrogen, and more preferably at least one gas of helium and argon.

[0024] In one embodiment, when the discharge gas is composed of one kind of gas, the discharge gas is preferably helium. Since helium has high photon energy (about 17.7 eV), if the discharge gas is helium, the obtained peak area can be increased, and as a result, the accuracy of quantitative analysis of decomposition gas can be improved.

[0025] In one embodiment, when the discharge gas is composed of two kinds of gases, the discharge gas is preferably a mixture gas of helium and argon. Since argon has a moderately low photon energy compared to helium, by using argon together with helium, the fragmentation of alternative gases and decomposable gases can be effectively suppressed, and as a result, the accuracy of quantitative analysis of decomposable gases can be improved. When the discharge gas is a mixed gas of helium and argon, the photon energy is, for example, 10.8 eV or more, and may be 11.3 eV or more, or may be, for example, 12.3 eV or less, and may be 12.8 eV or less.

[0026] <Decomposable gas> The decomposable gas is not particularly limited as long as it has a higher decomposability than the above-mentioned alternative gas. Specific examples of the decomposable gas include fluorocarbons such as C2F4, C4F8, and cyclo-C5F8; B2H6, B4H 10 , B5H9, B5H 11 boron hydrides (so-called borane) such as NH3, N2H4, N3N6, etc.; nitrogen hydrides such as NH3, N2H4, N3N6, etc.; germanium hydrides such as Ge2H6, etc.; phosphorus hydrides such as PH3, P2H4, etc.; however, since the quantitative analysis method of the decomposition gas of the present invention can more effectively exhibit its effect, the decomposition gas is preferably C2F4, B4H 10 , B5H9, B5H11 , N2H4, Ge2H6, and P2H4. In this specification, the decomposable gas may also include a reaction intermediate produced by decomposition or polymerization reaction of the decomposable gas.

[0027] In order for the quantitative analysis method of the present invention to be effective, the decomposition gas preferably has a concentration change rate of 100 [ppm / 30 days] or more in a temperature environment of 5° C. to 300° C. In addition, the concentration change rate is more preferably 1000 [ppm / 30 days] or more, and even more preferably 5000 [ppm / 30 days] or more. The concentration change rate is, for example, 20,000 [ppm / 30 days] or less, may be 15,000 [ppm / 30 days] or less, or may be 10,000 [ppm / 30 days] or less.

[0028] In one embodiment, the decomposition gas is not particularly limited, but the fragmentation rate is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. If the fragmentation rate of the decomposable gas is equal to or lower than the upper limit, the accuracy of the quantitative analysis of the decomposable gas can be improved.

[0029] Hereinafter, the method for quantitatively analyzing decomposable gases of the present invention will be described with reference to Figs. 1 and 2, but the method for quantitatively analyzing decomposable gases of the present invention is not limited thereto.

[0030] Fig. 1 is a flow diagram showing an example of the quantitative analysis method of the present invention for decomposable gases. As shown in Fig. 1, the quantitative analysis method 10 includes a calibration step 11 for calibrating a pulse discharge ionization detector using the above-mentioned predetermined alternative gas as a standard gas, an introduction step 12 for introducing a sample containing a decomposable gas into a gas chromatograph, a separation and detection step 13 for separating and detecting the decomposable gas in the sample, and an analysis step 14 for analyzing the quantitative value of the detected decomposable gas. The quantitative analysis method 10 may further include any step other than the calibration step 11, the introduction step 12, the separation and detection step 13, and the analysis step 14.

[0031] Here, Fig. 2 is a schematic diagram showing an example of a gas chromatograph used in the quantitative analysis method of decomposition gas of the present invention. The gas chromatograph 20 shown in Fig. 2 includes a separation column 21, an oven 22 for heating the separation column 21, and a pulse discharge ionization detector 23 connected to the separation column 21. A carrier gas is supplied from path A, an alternative gas or a sample is supplied from path B, and a discharge gas is supplied from path C. The various gases supplied are exhausted from exhaust section D as exhaust gas.

[0032] <Calibration process> In the calibration process, the pulse discharge ionization detector is calibrated using an alternative gas as a standard gas such that the difference between ΔIE1 and ΔIE2 is between -1 eV and 1 eV. Specifically, a calibration curve showing the relationship between the concentration of the alternative gas and the peak area is created using the alternative gas.

[0033] <Introduction process> In the introducing step, the sample containing the decomposable gas is introduced into a gas chromatograph. More specifically, the sample containing the decomposable gas is introduced into a column of the gas chromatograph.

[0034] In the introduction step, the amount of sample introduced into the gas chromatograph is not particularly limited and can be appropriately adjusted depending on the diameter and length of the gas chromatograph column, and is, for example, 0.1 mL or more and 5 mL or less.

[0035] <Separation and detection process> In the separation and detection step, the decomposable gas in the sample is separated and detected. More specifically, the sample is passed through a column together with a carrier gas to separate the decomposable gas, and the separated decomposable gas is detected by a pulse discharge ionization detector.

[0036] In the separation and detection step, the carrier gas is not particularly limited, and an inert gas such as helium can be used.

[0037] In the separation and detection step, the carrier flow rate is not particularly limited and is, for example, 1 mL / min or more and 20 mL / min or less.

[0038] In the separation and detection step, the column temperature is not particularly limited and can be appropriately adjusted depending on the physical properties of the decomposition gas and the alternative gas, but is, for example, 20°C or higher and 100°C or lower.

[0039] In the separation and detection step, the temperature of the pulse discharge ionization detector is not particularly limited and can be appropriately adjusted depending on the physical properties of the decomposable gas and the alternative gas, but is, for example, 100° C. or higher and 200° C. or lower.

[0040] <Analysis process> In the analysis step, the quantitative value of the detected decomposition gas is analyzed. The analysis of the quantitative values ​​is not particularly limited, and can be carried out using conventionally known analysis software, etc. EXAMPLES

[0041] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples in any way.

[0042] <Gas chromatograph equipped with a pulsed discharge ionization detector> In the following Examples and Comparative Examples, a 7890B (G3440B) manufactured by Agilent Technologies was used as a gas chromatograph equipped with a pulse discharge ionization detector (PDD-GC). The measurement conditions were as follows. <Measurement conditions> ·Column: Restek Rtx-Volatiles 30m×0.32mm×1.5μm Oven temperature: 40℃ Detector temperature: 150℃ Carrier gas: He (photon energy = approx. 17.7 eV) Carrier flow rate: 5mL / min Detector: PDD Calibration tube: 0.25mL

[0043] <Ionization energy of decomposition gases and alternative gases> In the following examples and comparative examples, the ionization energies of the decomposable gases and alternative gases were calculated using quantum mechanical calculations using "B3LYP" as the density functional method and "cc-pVDZ" as the basis function to calculate the enthalpy of the ground state structure of the decomposable gases and alternative gases (enthalpy when the charge is 0) and the enthalpy of the positive charge structure (enthalpy when the charge is +1), and were then calculated by subtracting the enthalpy of the ground state structure from the enthalpy of the positive charge structure.

[0044] <Fragmentation rate of decomposition gases and alternative gases> In the following Examples and Comparative Examples, the fragmentation rates of decomposition gases and alternative gases were measured under the following conditions using a gas chromatograph equipped with a mass spectrometer. <Measurement conditions> Analytical equipment: JEOL gas chromatograph mass spectrometer JMS-Q1500GC (GC part is Agilent Technologies 8890 GC system) ·Column: Restek Rtx-Volatiles 30m×0.32mm×1.5μm Carrier gas: He Carrier gas flow rate: 10 ccm Oven temperature: 40℃ Ionization current: 20μA Ionization energy: 17eV Ion source temperature: 120℃ ·Q-pole temperature: 70℃ Sample flow rate: 100ccm

[0045] <Fourier Transform Infrared Spectroscopy(FT-IR)> In the following Examples and Comparative Examples, FT-IR measurements were performed using an FT / IR6600 manufactured by JASCO Corp. The measurement conditions were as follows: <Measurement conditions> Gas flow rate: 100sccm Window material: KBr Cell path length: 1cm Detector: TGS (no attenuator, aperture diameter 7.1 mm) Cell pressure: 120kPaA Measurement wave number range: 1000~3000cm -1 ·Resolution: 4cm -1 Cell temperature: 35℃ - Number of integrations (background): 256 - Number of samples: 128 (2 min 34 s) Measurement interval: 26s Measurement time: 30 min

[0046] Example 1 <Sample preparation> First, a sample made of C4F8 was prepared. In the following, quantitative analysis was performed using C2F4 (ionization energy: 9.57 eV, ΔIE1: 8.13 eV, fragmentation rate: 25%) as the decomposition gas.

[0047] <Calibration process> Benzene (ionization energy: 9.01 eV, ΔIE2: 8.69 eV, fragmentation rate: 23%) was prepared as an alternative gas, and the pulse discharge ionization detector was calibrated using benzene as the standard gas. Specifically, a calibration curve showing the relationship between the benzene concentration and the peak area was created. The difference between ΔIE1 and ΔIE2 (8.13 eV-8.69 eV) for C2F4 (decomposition gas) and benzene (alternative gas) is -0.56 eV.

[0048] <Introduction process> Next, the above sample was stored under conditions of about 290° C., and the samples on the 0th day, 30th day, 65th day, 92nd day, 128th day, and 154th day were introduced into the PDD-GC.

[0049] <Separation and detection process> The sample was then passed through a column together with a carrier gas to separate the C2F4, which was then detected by a pulse discharge ionization detector.

[0050] <Analysis process> Next, the detected quantitative value of C2F4 was analyzed. Using the obtained analysis results, the carbon (C) concentration derived from C2F4 (hereinafter, sometimes referred to as "C concentration") was calculated, and the change in the C concentration derived from C2F4 at each elapsed day was calculated based on the C concentration derived from C2F4 on day 0 (0 ppm). The results are shown in Table 1.

[0051] <Confirmation of measurement accuracy> The above samples were measured by FT-IR on days 0, 30, 65, 92, 128, and 154 to calculate the C concentration derived from C4F8. The C concentration derived from C4F8 on day 0 was set as the standard (0 ppm) to calculate the change in the C concentration derived from C4F8 at each elapsed day. The results are shown in Table 1. Then, the change in C concentration derived from C2F4 and the change in C concentration derived from C4F8 were used to calculate the change rate of C concentration according to the following formula (1) to confirm the measurement accuracy. The closer the calculation result of formula (1) is to 100%, the higher the measurement accuracy is. The results are shown in Table 1. (1000000 + ("Change in C concentration derived from C2F4" + "Change in C concentration derived from C4F8") / 1000000 × 100 [mass%] (1)

[0052] [Table 1]

[0053] Comparative Example 1 Except for using C2F6 (ionization energy: 12.04 eV, ΔIE2: 5.66 eV, fragmentation rate: 15%) as an alternative gas, various operations, measurements, calculations and confirmations were performed in the same manner as in Example 1. The results are shown in Table 2. The difference between ΔIE1 and ΔIE2 in C2F4 and C2F6 (8.13 eV-5.66 eV) is 2.47 eV.

[0054] [Table 2]

[0055] FIG. 3 shows a graph of the change over time in the rate of change of the C concentration in Example 1 and Comparative Example 1.

[0056] As is clear from Tables 1 and 2 and Fig. 3, the quantitative analysis method of decomposition gas in Example 1 has excellent measurement accuracy because the rate of change in C concentration is close to 100 mass %. In addition, the quantitative analysis method of decomposition gas in Example 1 is easy to operate because it uses PDD-GC.

[0057] Example 2 <Sample preparation> First, a sample consisting of 10 mass% N2H4 and 90 mass% He was prepared. In the following, quantitative analysis was performed using N2H4 (ionization energy: 7.52 eV, ΔIE1: 10.18 eV, fragmentation rate: 45%) as the decomposition gas.

[0058] <Calibration process> Styrene (ionization energy: 8.03 eV, ΔIE2: 9.67 eV, fragmentation rate: 35%) was prepared as an alternative gas, and the pulse discharge ionization detector was calibrated using styrene as the standard gas. Specifically, a calibration curve showing the relationship between the concentration of styrene and the peak area was created. The difference between ΔIE1 and ΔIE2 (10.18 eV-9.67 eV) for N2H4 (decomposable gas) and styrene (alternative gas) is 0.51 eV.

[0059] <Introduction process> Next, the above samples were stored under conditions of about 60° C., and the samples on days 0, 30, 65, 92, 128, and 154 were introduced into a PDD-GC.

[0060] <Separation and detection process> The sample was then passed through a column together with a carrier gas to separate N2H4, which was then detected by a pulsed discharge ionization detector.

[0061] <Analysis process> Next, the quantitative values ​​of the detected N2H4 were analyzed. The obtained analysis results were used to calculate the N2H4-derived carbon (N) concentration (hereinafter, sometimes referred to as "N concentration"), and the change in the N2H4-derived N concentration at each elapsed day was calculated, with the N2H4-derived N concentration on day 0 set as the reference (0 ppm). The results are shown in Table 3.

[0062] <Confirmation of measurement accuracy> The above samples were measured by FT-IR on days 0, 30, 65, 92, 128, and 154 to calculate the N concentration derived from NH3. The N concentration derived from NH3 on day 0 was set as the standard (0 ppm) to calculate the change in the N concentration derived from NH3 at each elapsed day. The results are shown in Table 3. Then, the change in N concentration derived from N2H4 and the change in N concentration derived from NH3 were used to calculate the change rate of N concentration according to the following formula (2), and the measurement accuracy was confirmed. The closer the calculation result of formula (2) is to 100 mass%, the higher the measurement accuracy. The results are shown in Table 3. (100000 + ("Change in N concentration derived from N2H4" + "Change in N concentration derived from NH3") / 100000 × 100 [mass%] (2)

[0063] [Table 3]

[0064] Comparative Example 2 Except for using NH3 (ionization energy: 9.86 eV, ΔIE2: 7.84 eV, fragmentation rate: 55%) as an alternative gas, various operations, measurements, calculations and confirmations were performed in the same manner as in Example 2. The results are shown in Table 4. The difference between ΔIE1 and ΔIE2 in N2H4 and NH3 (10.18 eV-7.84 eV) is 2.34 eV.

[0065] [Table 4]

[0066] A graph showing the time course of the rate of change in N concentration in Example 2 and Comparative Example 2 is shown in FIG.

[0067] As is clear from Tables 3 and 4 and Fig. 4, the quantitative analysis method of decomposition gas in Example 2 has excellent measurement accuracy because the rate of change in N concentration is close to 100 mass %. In addition, the quantitative analysis method of decomposition gas in Example 2 has excellent operability because it uses PDD-GC.

[0068] Example 3 <Sample preparation> First, a sample consisting of 20 mass% PH3 and 80 mass% He was prepared. In the following, quantitative analysis was performed using P2H4 (ionization energy: 8.64 eV, ΔIE1: 9.06 eV, fragmentation rate: 27%) as the decomposition gas.

[0069] <Calibration process> Toluene (ionization energy: 8.53 eV, ΔIE2: 9.17 eV, fragmentation rate: 11%) was prepared as an alternative gas, and the pulse discharge ionization detector was calibrated using toluene as a standard gas. Specifically, a calibration curve showing the relationship between the toluene concentration and the peak area was created. The difference between ΔIE1 and ΔIE2 (9.06 eV-9.17 eV) for P2H4 (decomposition gas) and toluene (alternative gas) is -0.11 eV.

[0070] <Introduction process> Next, the above samples were stored under conditions of about 50° C., and the samples on days 0, 30, 65, 92, 128, and 154 were introduced into a PDD-GC.

[0071] <Separation and detection process> The sample was then passed through a column together with a carrier gas to separate P2H4, which was then detected by a pulsed discharge ionization detector.

[0072] <Analysis process> Next, the quantitative values ​​of the detected P2H4 were analyzed. Using the obtained analysis results, the P2H4-derived carbon (P) concentration (hereinafter, sometimes referred to as "P concentration") was calculated, and the P concentration derived from P2H4 on day 0 was set as the reference (0 ppm) to calculate the change in the P concentration derived from P2H4 at each elapsed day. The results are shown in Table 5.

[0073] <Confirmation of measurement accuracy> The above samples were measured by FT-IR on days 0, 30, 65, 92, 128, and 154 to calculate the P concentration derived from PH3. The P concentration derived from PH3 on day 0 was set as the standard (0 ppm) to calculate the change in the P concentration derived from PH3 at each elapsed day. The results are shown in Table 5. Then, the change in the P concentration derived from P2H4 and the change in the N concentration derived from PH3 were used to calculate the change rate of the P concentration according to the following formula (3), and the measurement accuracy was confirmed. The closer the calculation result of formula (3) is to 100 mass%, the higher the measurement accuracy is. The results are shown in Table 3. (200000 + ("Change in P concentration derived from P2H4" + "Change in P concentration derived from PH3") / 200000 × 100 [mass%] (3)

[0074] [Table 5]

[0075] Comparative Example 3 Except for using PH3 (ionization energy: 9.77 eV, ΔIE2: 7.93 eV, fragmentation rate: 35%) as an alternative gas, various operations, measurements, calculations and confirmations were performed in the same manner as in Example 3. The results are shown in Table 6. The difference between ΔIE1 and ΔIE2 in P2H4 and PH3 (9.06 eV-7.93 eV) is 1.13 eV.

[0076] [Table 6]

[0077] A graph showing the time course of the rate of change in P concentration in Example 3 and Comparative Example 3 is shown in FIG.

[0078] As is clear from Tables 5 and 6 and Fig. 5, the quantitative analysis method of decomposition gas in Example 3 has excellent measurement accuracy because the rate of change in P concentration is close to 100 mass %. In addition, the quantitative analysis method of decomposition gas in Example 3 is easy to operate because it uses PDD-GC.

[0079] Example 4 <Sample preparation> First, a sample made of Ge2H6 was prepared. In the following, quantitative analysis was performed using Ge2H6 (ionization energy: 9.26 eV, ΔIE1: 8.44 eV, fragmentation rate: 21%) as the decomposition gas.

[0080] <Calibration process> Benzene (ionization energy: 9.01 eV, ΔIE2: 8.69 eV, fragmentation rate: 23%) was prepared as an alternative gas, and the pulse discharge ionization detector was calibrated using benzene as the standard gas. Specifically, a calibration curve showing the relationship between the benzene concentration and the peak area was created. The difference between ΔIE1 and ΔIE2 (8.44 eV-8.69 eV) in Ge2H6 (decomposition gas) and benzene (alternative gas) is -0.25 eV.

[0081] <Introduction process> Next, the above samples were stored under conditions of about 40° C., and the samples on days 0, 30, 65, 92, 128, and 154 were introduced into PDD-GC.

[0082] <Separation and detection process> The sample was then passed through a column together with a carrier gas to separate Ge2H6, which was then detected by a pulsed discharge ionization detector.

[0083] <Analysis process> Next, the quantitative value of the detected Ge2H6 was analyzed. The obtained analysis results were used to calculate the carbon (Ge) concentration derived from Ge2H6 (hereinafter, sometimes referred to as "Ge concentration"), and the change in the Ge concentration derived from Ge2H6 at each elapsed day was calculated, with the Ge concentration derived from Ge2H6 on day 0 being set as the reference (0 ppm). The results are shown in Table 7.

[0084] <Confirmation of measurement accuracy> The above samples were measured by FT-IR on days 0, 30, 65, 92, 128, and 154 to calculate the Ge concentration derived from GeH4. The Ge concentration derived from GeH4 on day 0 was set as the standard (0 ppm) to calculate the change in the Ge concentration derived from GeH4 at each elapsed day. These results are shown in Table 7. Then, the change rate of Ge concentration was calculated by the following formula (4) using the change amount of Ge concentration originating from Ge2H6 and the change amount of Ge concentration originating from GeH4, and the measurement accuracy was confirmed. The closer the calculation result of formula (4) is to 100 mass%, the higher the measurement accuracy is. The results are shown in Table 7. (1000000 + ("Change in Ge concentration from Ge2H6" + "Change in Ge concentration from GeH4") / 1000000 × 100 [mass%] (4)

[0085] [Table 7]

[0086] Comparative Example 4 Except for using GeH4 (ionization energy: 11.16 eV, ΔIE2: 6.54 eV, fragmentation rate: 60%) as an alternative gas, various operations, measurements, calculations and confirmations were performed in the same manner as in Example 2. The results are shown in Table 8. The difference between ΔIE1 and ΔIE2 in Ge2H6 and GeH4 (8.44 eV-6.54 eV) is 1.90 eV.

[0087] [Table 8]

[0088] FIG. 6 is a graph showing the time course of the rate of change of Ge concentration in Example 4 and Comparative Example 4.

[0089] As is clear from Tables 7 and 8 and Fig. 6, the quantitative analysis method of decomposition gas in Example 4 has excellent measurement accuracy because the rate of change in Ge concentration is close to 100 mass %. In addition, the quantitative analysis method of decomposition gas in Example 4 has excellent operability because it uses PDD-GC. [Industrial Applicability]

[0090] According to the present invention, a method for quantitatively analyzing decomposition gases that is easy to operate and has excellent accuracy can be provided. [Explanation of symbols]

[0091] 10: Quantitative analysis method 11: Calibration process 12:Introduction process 13: Separation and detection process 14: Analysis process 20: Gas chromatograph 21: Separation column 22: Oven 23: Pulsed discharge ionization detector

Claims

1. A method for quantitatively analyzing a decomposition gas contained in a sample using a gas chromatograph equipped with a pulse discharge ionization detector, comprising the steps of: Before the sample is introduced into the gas chromatograph, the energy difference between the photon energy obtained by the emission of the discharge gas used in the pulse discharge ionization detector and the ionization energy of the decomposition gas is defined as ΔIE １ The energy difference between the photon energy obtained by the emission of the discharge gas used in the pulse discharge ionization detector and the ionization energy of the alternative gas is defined as ΔIE ２ In this case, ΔIE １ and ΔIE ２ a substitute gas having a difference of -1 eV or more and 1 eV or less from the standard gas, and the pulse discharge ionization detector is calibrated using the substitute gas as a standard gas.

2. 2. The method for quantitatively analyzing a decomposable gas according to claim 1, wherein the decomposable gas has a concentration change rate of 100 ppm / 30 days or more in a temperature environment of 5° C. or more and 300° C. or less.

3. 3. The method for quantitatively analyzing decomposable gases according to claim 1, wherein the discharge gas is at least one gas selected from the group consisting of helium, neon, argon, krypton, xenon and nitrogen molecules.

4. 3. The method for quantitatively analyzing decomposition gases according to claim 1, wherein the alternative gas is a hydrocarbon.

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