Analysis system

Abstract

To provide an analysis system in which the ratio of a composition after oxidative decomposition is unlikely to change depending on the heating temperature of a reaction tube.SOLUTION: An analysis system (1) includes oxidative decomposition apparatus(6). The oxidative decomposition apparatus(6) includes: a reaction tube (30) for carrying out oxidative decomposition of a sample therein; a heating furnace (28) for accommodating the reaction tube (30) therein and heating the reaction tube (30); an oxidation gas supply unit (36) for supplying an oxidation gas for oxidizing the sample; a makeup gas supply unit (38) for supplying a makeup gas which is an inert gas that does not affect the oxidative decomposition of the sample; and an interface portion (32) having a structure for introducing the sample introduced from an inlet (33) and the oxidizing gas supplied from the oxidizing gas supply unit (36), and the makeup gas supplied from the makeup gas supply unit (38) into the inside of the reaction tube (30).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an analytical system including an oxidative decomposition device that performs oxidative decomposition of a sample. [Background technology]

[0002] Oxygen components (e.g. 16 A method for detecting and quantifying oxygen components in a sample containing oxygen isotopes (e.g., O) has been proposed (see Patent Document 1). In this method, oxygen isotopes (e.g., 18 The sample is oxidatively decomposed using an oxidizing gas containing O, and the oxidatively decomposed composition is analyzed by a mass spectrometer or the like. As a result, the oxygen component in the composition analyzed by the mass spectrometer or the like is 16 If O, it is from the sample. 18 If it is O, it can be identified as being derived from an oxidizing gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-508711 A Summary of the Invention [Problem to be solved by the invention]

[0004] To carry out the above method, it is necessary to pass the sample and oxidizing gas through a reaction tube heated to a high temperature (for example, about 600 to 1000°C) to completely oxidize and decompose the sample, so the reaction tube must be made of a material with high heat resistance. A ceramic material such as alumina is considered to be a material with high heat resistance. However, it has been found through experiments that when oxidative decomposition is carried out using an alumina reaction tube, the ratio of the composition after oxidative decomposition changes as the heating temperature of the reaction tube increases. For example, in the case of C 18 O 16 C for O (m / z=46) 16The ratio of O2 (m / z=44) was detected while changing the heating temperature of the reaction tube. 16 It was found that the proportion of O2 increased (see Figure 5). This is because 18 C produced by oxidative decomposition using an oxidizing gas containing O 18 O 16 O, for some reason, C 16 Under such circumstances, if the analysis described in the Background Art is performed, it becomes impossible to accurately distinguish whether the oxygen component in the composition detected by a mass spectrometer or the like is derived from the sample or the oxidizing gas.

[0005] Therefore, the present invention aims to provide an analytical system that improves the accuracy of detection and quantification in a method for detecting and quantifying oxygen components in a sample by oxidatively decomposing the sample using an oxidizing gas containing oxygen isotopes whose composition and distribution differ from those in nature, and detecting the composition obtained by oxidative decomposition. [Means for solving the problem]

[0006] The above mentioned C 18 O 16 O to C 16 After extensive research into the cause of the change to O2, C 18 O 16 As O passes through the reaction tube, it is absorbed into the alumina (Al2O3) that is the material of the reaction tube. 16 O and C 18 O 16 O 18 It was found that this is due to the substitution with O. Based on this finding, the following analytical system was invented.

[0007] That is, the analytical system according to the present invention is an analytical system for detecting and / or quantifying a compound containing a specific oxygen component in the sample, comprising: an oxidative decomposition device having an inlet and an outlet, which oxidatively decomposes a sample introduced from the inlet and then causes the sample to flow out from the outlet; and a detector for detecting an oxidation reaction product oxidatively decomposed in the oxidative decomposition device, The oxidative decomposition device includes: a reaction tube having one end and the other end, the one end being disposed on the inlet side and the other end being disposed on the outlet side, for carrying out oxidative decomposition of a sample therein; a heating furnace for accommodating the reaction tube therein and heating the reaction tube; an oxidation gas supply unit for supplying an oxidation gas for oxidizing the sample, the oxidation gas including an oxygen component having an isotope different from that of the specific oxygen component; a makeup gas supply unit that supplies a makeup gas that is an inert gas that does not affect the oxidative decomposition of the sample; and an interface portion having a structure for introducing the oxidizing gas supplied from the oxidizing gas supply portion and the makeup gas supplied from the makeup gas supply portion together with the sample introduced from the inlet into the inside of the reaction tube. Effect of the Invention

[0008] According to the analytical system of the present invention, the interface section of the oxidative decomposition apparatus has a structure that allows the oxidizing gas and the make-up gas to be introduced into the inside of the reaction tube together with the sample introduced from the inlet. This limits the chance of contact between the composition after oxidative decomposition in the reaction tube and the inner surface of the reaction tube, and prevents the oxidizing gas contained in the material in the reaction tube from coming into contact with the inner surface of the reaction tube. 16 O and the oxygen isotopes in the composition after oxidative decomposition ( 18 O and 17 O) is suppressed. This improves the accuracy of detection and quantification when a method is carried out in which a sample is oxidatively decomposed using an oxidizing gas containing oxygen isotopes whose composition and distribution differ from those in nature, and the composition obtained by the oxidative decomposition is detected to detect and quantify oxygen components in the sample. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram showing the flow path configuration in a GC-COMB-MS mode in one embodiment of the analysis system. [Diagram 2] FIG. 2 is a diagram showing the flow path configuration in a GC-MS mode in the same embodiment. [Diagram 3] FIG. 2 is a cross-sectional view showing an example of the structure of the oxidative decomposition apparatus according to the embodiment. [Figure 4] 13 is a graph showing the verification results of the relationship between the 44 / 46 ratio of 18-methanol and the heating furnace temperature in GC-Comb-MS mode in the same embodiment. [Diagram 5] 1 is a graph showing the results of verifying the relationship between the 44 / 46 ratio of 18-methanol and the heating furnace temperature in GC-Comb-MS mode when no make-up gas is used in the oxidative decomposition apparatus. [Figure 6] 13 is a graph showing the relationship between the change in outlet pressure of the reaction tube and the length of the resistance tube when switching from the GC-MS mode to the GC-Comb-MS mode in the same Example. [Figure 7] 13 is a graph showing the relationship between the baseline fluctuation of the detector signal of the mass spectrometer and the length of the resistance tube when switching from the GC-MS mode to the GC-Comb-MS mode in the same embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of an analysis system according to the present invention will be described with reference to the drawings.

[0011] 1 and 2, an analysis system 1 mainly comprises a sample vaporization chamber 2, a separation column 4, an oxidative decomposition device 6, a mass spectrometer 8, and a switching valve 10. The sample vaporization chamber 2 and the separation column 4 constitute a gas chromatograph, in which an injected sample is vaporized in the sample vaporization chamber 2 and introduced into the separation column 4 together with a carrier gas, and components in the sample are separated from one another in the separation column 4. The gas chromatograph consisting of the sample vaporization chamber 2 and the separation column 4 constitutes a sample supplying device that supplies a sample to the oxidative decomposition device 6.

[0012] The switching valve 10 has ports numbered 1 to 6, and is a two-position valve that can take two positions: a position that provides fluid communication between port 1 and port 6, between port 2 and port 3, and between port 4 and port 5 (position in FIG. 1), and a position that provides fluid communication between port 1 and port 2, between port 3 and port 4, and between port 5 and port 6 (position in FIG. 2).

[0013] Port No. 1 of the switching valve 10 is fluidly connected to a flow path 16 leading to the inlet of the mass spectrometer 8, port No. 2 is fluidly connected to the downstream end of the separation column 4, port No. 3 is fluidly connected to an inlet flow path 12 leading to the oxidative decomposition device 6, port No. 4 is closed, port No. 5 is fluidly connected to a pressure reduction flow path 22, and port No. 6 is fluidly connected to an outlet flow path 14 leading to the outlet of the oxidative decomposition device 6.

[0014] The switching valve 10 is a switching mechanism for switching between a GC-MS mode (first state) in which the gas chromatograph consisting of the sample vaporization chamber 2 and the separation column 4 is fluidly connected to the mass spectrometer 8 without the oxidative decomposition device 6 therebetween, and a GC-Comb-MS mode (second state) in which the gas chromatograph and the mass spectrometer 8 are fluidly connected to each other with the oxidative decomposition device 6 therebetween. Figure 1 shows the flow path configuration in the GC-Comb-MS mode, and Figure 2 shows the flow path configuration in the GC-MS mode.

[0015] The oxidative decomposition device 6 includes a heating furnace 28, a reaction tube 30, an interface section 32, an outlet adapter 34, an oxidizing gas supply section 36, and a make-up gas supply section 38.

[0016] At least the inner surface of the reaction tube 30 is made of alumina or the like. 16 It is a cylindrical member having high heat resistance and formed of an oxide containing O. The reaction tube 30 is housed inside the heating furnace 28 so as to penetrate the heating furnace 28, and is intended to perform oxidative decomposition of a sample inside. The heating furnace 28 heats the reaction tube 30 housed inside to a set temperature.

[0017] The interface section 32 is provided on one end side (the left side in the figure) of the reaction tube 30. The interface section 32 has an inlet 33, and the downstream end of the inlet flow channel 12 is fluidly connected to the inlet 33.

[0018] The outlet side adapter 34 is provided on the other end side (the right side in the figure) of the reaction tube 30 and serves to fluidly connect the other end of the reaction tube 30 to the upstream end of the outlet flow path 14 .

[0019] The oxidizing gas supply unit 36 ​​is a cylinder that supplies, as an oxidizing gas, a gas containing an oxygen isotope different from the specific oxygen compound contained in the oxygen-containing compound to be detected and / or quantified. For example, 16 When compounds containing O are to be detected and / or quantified, oxygen gas is used. 17 O or 18 A gas containing O can be used as the oxidizing gas. The oxidizing gas can also contain an inert gas such as helium gas or argon gas, and the ratio of oxygen gas to the inert gas in the oxidizing gas is, for example, 1:99. The oxidizing gas supplied from the oxidizing gas supply unit 36 ​​is introduced into the interface unit 32.

[0020] The makeup gas supply unit 38 is a cylinder separate from the oxidizing gas supply unit 36, which supplies an inert gas that does not affect the oxidative decomposition of the sample in the reaction tube 30. An example of the makeup gas is helium gas. The makeup gas supplied from the makeup gas supply unit 38 is introduced into the interface 32 and the outlet adapter 34.

[0021] 1, an inlet flow path 12 is connected downstream of the separation column 4, and the sample flowing out from the separation column 4 is introduced into an interface section 32 of the oxidative decomposition device 6 through the inlet flow path 12. The sample introduced into the interface section 32 is introduced into the reaction tube 30 together with an oxidizing gas supplied from an oxidizing gas supply section 36 and a make-up gas supplied from a make-up gas supply section 38, and is oxidatively decomposed in the reaction tube 30, and then introduced into the mass spectrometer 8.

[0022] Here, an example of a specific structure of the oxidative decomposition device 6 will be described with reference to FIG.

[0023] A hollow cylindrical outer jacket tube 40 is provided so as to surround the outer periphery of the reaction tube 30 of the oxidative decomposition device 6. The heating furnace 28 is in contact with the outer periphery of the outer jacket tube 40, and the outer jacket tube 40 is heated by the heating furnace 28, and the reaction tube 30 passing inside the outer jacket tube 40 is heated. The reaction tube 30 and the outer jacket tube 40 are not in contact with each other, and a gap 64 exists between the outer periphery of the reaction tube 30 and the inner periphery of the outer jacket tube 40. The main part of the outer jacket tube 40 housed in the heating furnace 28 is made of a heat-resistant material such as alumina, while at least the end part held by the interface part 32 may be made of a metal.

[0024] Inside the interface section 32, a space 42 is provided for fluidly connecting the pipe (hereinafter also referred to as the pipe 12) forming the inlet flow path 12 and the reaction tube 30. Although not shown in the figure, a thread is provided on the outer peripheral surface of one end side (left side in the figure) of the mantle tube 40. An opening is provided on the surface of the interface section 32 on the heating furnace 28 side, and a thread is provided on the inside of the opening to screw with the thread on the outer peripheral surface of the mantle tube 40 on the one end side. The mantle tube 40 is held by the mantle tube 40 by screwing the thread on the outer peripheral surface on the one end side with the thread on the inside of the opening of the interface section 32. Inside the opening of the interface section 32, a holder 40 and a packing 54 are provided so as to be sandwiched between the inner surface of the opening and the end of the mantle tube 40. The holder 48 is for fixing the position of one end of the reaction tube 30 in the interface section 32. The packing 54 is intended to prevent the gas in the internal space 42 from leaking out of the interface portion 32 through the outside of the outer tube 40 .

[0025] A hole for passing the piping constituting the inlet flow passage 12 is provided as an inlet 33 on the surface of the interface section 32 opposite to the heating furnace 28. The piping 12 is inserted from the inlet 33 into the internal space 42 of the interface section 32 while maintaining airtightness, and extends toward one end of the reaction tube 30. The interface section 32 is provided with a makeup gas introduction flow passage 50 for introducing the makeup gas supplied from the makeup gas supply section 38 into the internal space 42, and an oxidation gas introduction flow passage 52 for introducing the oxidation gas supplied from the oxidation gas supply section 36 into the internal space 42. The makeup gas introduced from the makeup gas introduction flow passage 50 is introduced into the gap between the inner surface of the interface section 32 and the outer peripheral surface of the piping 12, and the oxidation gas introduced from the oxidation gas introduction flow passage 52 is introduced between the downstream end of the piping 12 and one end of the reaction tube 30. The makeup gas introduced from the makeup gas introduction channel 50 prevents the sample introduced into the internal space 42 through the piping 12 from flowing back toward the inlet 33 .

[0026] The outlet adaptor 34 has a structure in which the outer peripheral surface of the other end side (right side in the figure) of the mantle tube 40 is held airtight by O-rings 60 and 62, and the outer peripheral surface of the other end side (right side in the figure) of the reaction tube 30 is held airtight by an O-ring 58. A pipe forming the outlet flow path 14 (hereinafter also referred to as the pipe 14) is inserted airtight from the surface of the outlet adaptor 34 opposite to the heating furnace 28, and the other end of the reaction tube 30 and the pipe 14 are fluidly connected airtight inside the outlet adaptor 34. The outlet adaptor 34 is provided with a make-up gas introduction flow path 56 for introducing make-up gas supplied from the make-up gas supply unit 38 into the inside. The make-up gas introduced from the make-up gas introduction flow path 56 flows into the internal space 42 of the interface unit 32 through a gap 64 between the outer peripheral surface of the reaction tube 30 and the inner peripheral surface of the mantle tube 40. This prevents the sample introduced into the internal space 42 of the interface section 32 through the piping 12 from flowing outside the reaction tube 30 toward the outlet adapter 34 .

[0027] The sample introduced into the internal space 32 of the interface 32 through the piping 12 flows through the reaction tube 30 together with the oxidizing gas and the make-up gas, is oxidatively decomposed in the reaction tube 30, and then is introduced into the mass spectrometer 8 through the piping 14.

[0028] Figures 4 and 5 show the results in GC-Comb-MS mode. 16 O and inert gas ( 16 A mixed gas of O gas and inert gas (1:99) was supplied. 18 The oxygen-containing compound 18-ethanol (CH3 18 The mass spectrometry data when 1,2-dichlorophenyl 1,2-dichlorophenyl 1,2-trifluoro ... 16 O2 (mass number = 44) and C 16 O 18 The data shows the abundance ratio (44 / 46 ratio) of O (mass number = 46). Figure 4 shows the data measured while flowing helium gas as makeup gas, and Figure 5 shows the data measured without flowing makeup gas.

[0029] As shown by the data in FIG. 5, when no make-up gas is used, the 44 / 46 ratio increases significantly as the temperature of the heating furnace 28 increases. This is because the 44 / 46 ratio increases when the temperature of the reaction tube 30 increases. 16 O and C produced by oxidative decomposition 16 O 18 O 18 O and exchange become active, and C 16 O 18 O is C 16 It is considered that the oxygen contained in the material of the reaction tube 30 was converted to O2. 16 If O is exchanged with the oxygen isotope contained in the composition after oxidative decomposition, the ratio of the composition material after oxidative decomposition changes, and the accuracy of detection and quantification of oxygen-containing compounds contained in the sample decreases. Note that the oxidizing gas contains an inert gas, and an inert gas is also supplied as a carrier gas. However, it is clear from the data in FIG. 5 that the inert gas contained in the oxidizing gas and the inert gas used as a carrier gas are not able to suppress the exchange of oxygen between the material of the reaction tube 30 and the composition after oxidative decomposition.

[0030] On the other hand, as shown by the data in Figure 4, when makeup gas is introduced into the inside of the reaction tube 30 together with the sample, the 44 / 46 ratio increases slightly when the heating furnace temperature exceeds 900°C, but does not change significantly. In this way, when the sample is oxidatively decomposed while supplying an inert gas as makeup gas to the inlet of the reaction tube 30 separately from the oxidizing gas and carrier gas, the contact opportunity between the material of the reaction tube 30 and the composition after oxidative decomposition is reduced, and the amount of the oxidative decomposition product contained in the material of the reaction tube 30 is reduced. 16 It can be seen that the exchange of O with the oxygen isotopes contained in the composition after oxidative decomposition is suppressed, and the effect of suppressing changes in the ratio of the constituent substances in the sample after oxidative decomposition can also be obtained.

[0031] Returning to FIG. 1 and FIG. 2, the description of the analysis system 1 will continue.

[0032] An aspiration pump 18 is connected to the mass spectrometer 8 via a flow path 20, so that the pressure inside the mass spectrometer 8 can be reduced. In addition, a pressure reduction flow path 22 is fluidly connected to the aspiration pump 18. A stop valve 24 and a flow path resistance adjuster 26 are provided on the pressure reduction flow path 22. As shown in Fig. 2, in the GC-MS mode, the pressure reduction flow path 22 is fluidly connected to the outlet flow path 14, so that the pressure inside the reaction tube 30 and the outlet flow path 14 are reduced by the aspiration pump 18.

[0033] In this analysis system 1, for example, the GC-MS mode is set until the target component is eluted from the separation column 4, and at the timing when the target component is eluted from the separation column 4, the GC-Comb-MS mode is switched to oxidatively decompose the target component, and mass spectrometry data of the composition after oxidative decomposition is obtained.

[0034] However, if the pressure in the reaction tube 30 in the GC-MS mode is significantly different from the pressure in the reaction tube 30 in the GC-Comb-MS mode, the pressure in the reaction tube 30 will fluctuate significantly when switching from the GC-MS mode to the GC-Comb-MS mode, and the time until the pressure in the reaction tube 30 stabilizes will be long. If the target component is introduced into the reaction tube during that time, the efficiency of oxidative decomposition of the target component may decrease. It has also been found that if the pressure in the reaction tube 30 fluctuates significantly, the baseline of the output signal of the mass spectrometer 8 will also fluctuate significantly, and the time required for the baseline to stabilize will also be long. If the time required for the baseline of the output signal of the mass spectrometer 8 to stabilize is long, the target component may be introduced into the mass spectrometer 8 before the baseline stabilizes, which may decrease the detection accuracy of the target component.

[0035] Therefore, in this analysis system 1, the difference between the pressure in the reaction tube 30 in the GC-MS mode and the pressure in the reaction tube 30 in the GC-Comb-MS mode is designed to be within an allowable range (for example, within 10% of the pressure in the reaction tube 30 in the GC-Comb-MS mode, but it is preferable that it is as small as possible) set in consideration of the pressure fluctuation in the reaction tube 30 when switching from the GC-MS mode to the GC-Comb-MS mode. In this analysis system 1, by inserting a flow resistance adjuster 26 in the pressure reduction flow path 22, the pressure reduction efficiency in the system from the oxidative decomposition device 6 to the suction pump 18 in the GC-MS mode is made to be close to the pressure reduction efficiency in the system from the oxidative decomposition device 6 to the suction pump 18 in the GC-Comb-MS mode, so that the difference between the pressure in the reaction tube 30 in the GC-MS mode and the pressure in the reaction tube 30 in the GC-Comb-MS mode is kept within an allowable range. The flow resistance adjuster 26 may be a resistance tube having a fixed flow resistance value, or may be a needle valve or a proportional solenoid valve whose flow resistance is variably adjustable.

[0036] FIG. 6 shows data indicating the results of a verification as to how the length of the resistance tube as the flow path resistance adjuster 26 affects the fluctuation in the outlet pressure of the reaction tube 30 when switching from the GC-MS mode to the GC-Comb-MS mode, and FIG. 7 shows data indicating the results of a verification as to how the length of the resistance tube as the flow path resistance adjuster 26 affects the fluctuation in the baseline of the output signal of the mass spectrometer 8 when switching from the GC-MS mode to the GC-Comb-MS mode.

[0037] According to the data of Figures 6 and 7, when no resistance tube is provided on the reduced pressure flow path 22, the outlet pressure of the reaction tube 30 in the GC-MS mode is extremely low, and when the mode is switched to the GC-Comb-MS mode, the outlet pressure of the reaction tube 30 fluctuates greatly, and the baseline of the output signal (detector signal) of the mass spectrometer 8 also fluctuates greatly, and it takes a long time for the baseline to stabilize. When the resistance tube is provided on the reduced pressure flow path 22 to increase the flow resistance of the reduced pressure flow path 22, the pressure inside the reaction tube 30 in the GC-MS mode also increases, and when a resistance tube with a length of 30 mm is provided, the fluctuation of the outlet pressure of the reaction tube 30 is the smallest, and the fluctuation of the baseline of the detector signal is also the smallest. On the other hand, when the length of the resistance tube is 50 mm or more, the pressure inside the reaction tube 30 in the GC-MS mode becomes higher than that in the GC-Comb-MS mode, and the pressure fluctuation when the mode is switched to the GC-Comb-MS mode also becomes large.

[0038] From the above verification results, it is found that by appropriately adjusting the flow path resistance of the pressure reduction flow path 22 installed between the oxidative decomposition device 6 and the suction pump 18 by the flow path resistance adjuster 26 in the GC-MS mode, it is possible to reduce the pressure fluctuation in the reaction tube 30 when switching from the GC-MS mode to the GC-Comb-MS mode.

[0039] The embodiment described above is merely one example of an embodiment of the analysis system according to the present invention. One embodiment of the analysis system according to the present invention is as follows.

[0040] One embodiment of the analytical system according to the present invention is an analytical system for detecting and / or quantifying a compound containing a specific oxygen component in the sample, comprising: an oxidative decomposition device having an inlet and an outlet, which oxidatively decomposes a sample introduced from the inlet and then causes the sample to flow out from the outlet; and a detector for detecting an oxidation reactant oxidatively decomposed by the oxidative decomposition device, the analytical system comprising: The oxidative decomposition device includes: a reaction tube having one end and the other end, the one end being disposed on the inlet side and the other end being disposed on the outlet side, for carrying out oxidative decomposition of a sample therein; a heating furnace for accommodating the reaction tube therein and heating the reaction tube; an oxidation gas supply unit for supplying an oxidation gas for oxidizing the sample, the oxidation gas including an oxygen component having an isotope different from the specific oxygen component; a makeup gas supply unit that supplies a makeup gas that is an inert gas that does not affect the oxidative decomposition of the sample; and an interface portion having a structure for introducing the oxidizing gas supplied from the oxidizing gas supply portion and the makeup gas supplied from the makeup gas supply portion together with the sample introduced from the inlet into the inside of the reaction tube.

[0041] In the aspect [1] of the above embodiment, the oxidizing gas supplied from the oxidizing gas supply unit and the makeup gas supplied from the makeup gas supply unit are supplied to the interface unit through separate flow paths.

[0042] In the above aspect [1], it is preferable that the interface unit has an internal space for allowing the oxidizing gas and the makeup gas to merge with the sample introduced from the inlet into the reaction tube, an oxidizing gas introduction flow path for introducing the oxidizing gas supplied from the oxidizing gas supply unit into the internal space, and a makeup gas introduction flow path for introducing the makeup gas supplied from the makeup gas supply unit into the internal space, and has a structure for introducing the sample, the oxidizing gas, and the makeup gas merged in the internal space into the reaction tube from the one end of the reaction tube.

[0043] In the aspect [2] of the above embodiment, at least the inner surface of the reaction tube is made of a heat-resistant material made of an oxide. This aspect [2] can be combined with the above aspect [1].

[0044] In the above aspect [2], the heat-resistant material may be alumina.

[0045] In the above embodiment, A sample supply device (2, 4) configured to supply a sample downstream by a carrier gas; A mass spectrometer as the detector; A switching mechanism for switching the flow path connection; a suction pump for reducing the pressure inside the reaction tube of the oxidative decomposition apparatus, The switching mechanism is configured to establish either a first state in which the mass spectrometer is fluidly connected downstream of the sample supply device without the oxidative decomposition device being interposed between the sample supply device and the mass spectrometer, or a second state in which the inlet of the oxidative decomposition device is fluidly connected downstream of the sample supply device and the mass spectrometer is fluidly connected downstream of the outlet of the oxidative decomposition device, The suction pump is fluidly connected downstream of the oxidative decomposition apparatus in the first state, and is configured so that a difference between a pressure in the reaction tube in the first state and a pressure in the reaction tube in the second state falls within an allowable range that is set in consideration of a magnitude of a pressure fluctuation in the reaction tube when the switching mechanism switches from the first state to the second state. This aspect [3] can be combined with the above aspect [1] and / or aspect [2].

[0046] In the above aspect [3], in the first state, the suction pump may be configured to be fluidly connected downstream of the oxidative decomposition device and simultaneously fluidly connected to the mass spectrometer, and in the second state, the suction pump may be configured to be fluidly connected to the mass spectrometer.In this case, the flow resistance of the flow path incorporated between the oxidative decomposition device and the suction pump in the first state may be set so that the pressure reduction efficiency in the system from the oxidative decomposition device to the suction pump in the first state is substantially the same as the pressure reduction efficiency in the system from the oxidative decomposition device to the suction pump in the second state.

[0047] In the above aspect [3], the allowable range may be within 10% of the pressure in the reaction tube in the second state.

[0048] In the above aspect [3], the sample supplying device may be a gas chromatograph. [Explanation of symbols]

[0049] 1. Analysis system 2. Sample vaporizer 4. Separation column 6. Oxidative Decomposition Equipment 10. Switching valve 12,14,16,20,22 Channel 18 Suction pump 24 Stop valve 26 Flow resistance regulator 28 Furnace 30 Reaction tube 32 Interface section 33 Entrance 34 Outlet adapter 35 Exit 36 Oxidizing gas supply section 38 Make-up gas supply unit 40 Mantle tube 42 Interior Space 48 Holder 50,56 Make-up gas inlet channel 52 Oxidizing gas introduction channel 54 Gasket 58,60,62 O-ring

Claims

1. An analytical system for detecting and / or quantifying a compound containing a specific oxygen component in a sample, comprising: an oxidative decomposition device having an inlet and an outlet, which oxidatively decomposes a sample introduced from the inlet and then discharges the sample from the outlet; and a detector for detecting an oxidation reactant oxidatively decomposed by the oxidative decomposition device, the system comprising: The oxidative decomposition device includes: a reaction tube having one end and the other end, the one end being disposed on the inlet side and the other end being disposed on the outlet side, for carrying out oxidative decomposition of a sample therein; a heating furnace for accommodating the reaction tube therein and heating the reaction tube; an oxidation gas supply unit for supplying an oxidation gas for oxidizing the sample, the oxidation gas including an oxygen component having an isotope different from that of the specific oxygen component; a makeup gas supply unit that supplies a makeup gas that is an inert gas that does not affect the oxidative decomposition of the sample; an interface unit having a structure for introducing the oxidizing gas supplied from the oxidizing gas supply unit and the makeup gas supplied from the makeup gas supply unit into the inside of the reaction tube together with the sample introduced from the inlet.

2. 2. The analytical system according to claim 1, wherein the oxidizing gas supplied from the oxidizing gas supply unit and the makeup gas supplied from the makeup gas supply unit are supplied to the interface unit through flow paths separate from each other.

3. 3. The analysis system according to claim 2, wherein the interface unit includes an internal space for allowing the oxidizing gas and the makeup gas to join the sample introduced from the inlet into the reaction tube, an oxidizing gas introduction flow path for introducing the oxidizing gas supplied from the oxidizing gas supply unit into the internal space, and a makeup gas introduction flow path for introducing the makeup gas supplied from the makeup gas supply unit into the internal space, and has a structure for introducing the sample, the oxidizing gas, and the makeup gas joined in the internal space into the reaction tube from the one end of the reaction tube.

4. 2. The analytical system according to claim 1, wherein at least an inner surface of the reaction tube is formed of a heat-resistant material made of an oxide.

5. The analytical system of claim 4 , wherein the heat-resistant material is alumina.

6. A sample supplying device configured to supply a sample downstream by a carrier gas; A mass spectrometer as the detector; A switching mechanism for switching the flow path connection; a suction pump for reducing the pressure inside the reaction tube of the oxidative decomposition apparatus, The switching mechanism is configured to establish either a first state in which the mass spectrometer is fluidly connected downstream of the sample supply device without the oxidative decomposition device being interposed between the sample supply device and the mass spectrometer, or a second state in which the inlet of the oxidative decomposition device is fluidly connected downstream of the sample supply device and the mass spectrometer is fluidly connected downstream of the outlet of the oxidative decomposition device, 2. The analytical system according to claim 1, wherein the suction pump is fluidly connected downstream of the oxidative decomposition device in the first state, and a difference between a pressure in the reaction tube in the first state and a pressure in the reaction tube in the second state is configured to be within an allowable range that is set taking into consideration a magnitude of a pressure fluctuation in the reaction tube when the reaction tube is switched from the first state to the second state by the switching mechanism.

7. In the first state, the suction pump is fluidly connected to the downstream of the oxidative decomposition device and is also fluidly connected to the mass spectrometer, and in the second state, the suction pump is fluidly connected to the mass spectrometer; The analytical system described in claim 6, wherein a flow path resistance of a flow path incorporated between the oxidative decomposition device and the suction pump in the first state is set so that a pressure reduction efficiency in the system from the oxidative decomposition device to the suction pump in the first state is substantially the same as a pressure reduction efficiency in the system from the oxidative decomposition device to the suction pump in the second state.

8. 7. The analytical system according to claim 6, wherein the tolerance is within 10% of the pressure in the reaction tube in the second state.

9. The analytical system of claim 6 , wherein the sample presentation device is a gas chromatograph.

Images