A method and system for determining the stable isotope values ​​of hydrogen and oxygen

Abstract

This invention discloses a method and system for determining the stable isotope values ​​of hydrogen and oxygen, belonging to the field of isotope detection technology. The method includes: sealing the sample at low temperature in a vacuum; desorbing and releasing moisture under a gradient temperature rise in an inert gas atmosphere; generating a hydrogen-oxygen mixture through platinum-rhodium alloy catalytic cracking; and simultaneously acquiring the characteristic absorption spectral signals of hydrogen and oxygen isotopes using a multi-channel tunable diode laser absorption spectrometer, followed by baseline drift correction, pressure broadening compensation, and compensation for dynamic interference from ambient temperature, humidity, and atmospheric pressure. The system includes a sample pretreatment unit, a water vapor cracking unit, a multi-channel laser spectrometer, an environmental monitoring module, a control unit, and a data processing terminal. This invention achieves high-precision, low-bias, and efficient simultaneous determination of various types of water-containing samples, avoids isotope fractionation, and features a high degree of automation and intelligence, making it applicable to multiple fields such as climate environment and eco-hydrology.

Description

Technical Field

[0001] This invention relates to the field of isotope detection technology, and discloses a method and system for determining the stable isotope values ​​of hydrogen and oxygen. Background Technology

[0002] Stable isotopes of hydrogen and oxygen ( , The determination of isotopic ratios is a core research tool in many fields, including climate and environmental evolution, ecosystem water cycles, geological resource exploration, and biological metabolic mechanisms. Its numerical characteristics can directly reflect the source, migration pathways, and transformation processes of substances. For example, it can be used to reconstruct paleoclimate changes through the isotopic composition of ice cores and precipitation samples, trace water use strategies using plant tissue isotopes, and analyze groundwater recharge mechanisms using isotopic analysis. It holds irreplaceable importance in scientific research and practical applications.

[0003] Currently, the determination of stable isotope values ​​of hydrogen and oxygen mainly relies on traditional offline analysis techniques. The core process includes two main steps: sample pretreatment and isotope detection. Sample pretreatment primarily uses freeze-drying, which involves freezing the sample at low temperatures to solidify the water, followed by sublimation in a vacuum environment to remove the water. The collected water is then subjected to subsequent isotope analysis. The detection step mainly employs isotope mass spectrometry (IRMS), which calculates isotope ratios by measuring the mass differences of the target gases.

[0004] In traditional freeze-drying processes, light isotopes (such as...) 1 H, 16 O (oxygen) exhibits higher volatility and is prone to selective volatilization, leading to changes in the isotopic composition of water in the sample and introducing systematic bias. Simultaneously, freeze-drying has limited sublimation efficiency, making it difficult to completely remove some bound water, resulting in a high water loss rate and further affecting the accuracy of isotopic ratios. Oxygen is also sensitive to changes in environmental parameters such as temperature, humidity, and atmospheric pressure. Most detection systems lack effective dynamic compensation mechanisms; fluctuations in environmental parameters can cause baseline drift in the spectral signal and exacerbate pressure broadening effects, thereby affecting the accuracy of absorption peak integration and reducing the long-term stability of the measurement results. Summary of the Invention

[0005] To address the above problems, the present invention provides a method for determining the stable isotope values ​​of hydrogen and oxygen, characterized by comprising:

[0006] Acquire the sample to be tested and perform low-temperature vacuum sealing and encapsulation;

[0007] The encapsulated sample is introduced into a constant temperature desorption chamber, and gradient temperature desorption is performed in an inert gas atmosphere to release the moisture in the sample.

[0008] The released water vapor is catalytically cracked to produce a mixture of hydrogen and oxygen.

[0009] The mixed gas is introduced into a multi-channel tunable diode laser absorption spectrometer, and the characteristic absorption spectral signals corresponding to hydrogen isotopes and oxygen isotopes are acquired simultaneously.

[0010] Based on the preset standard material calibration curve, baseline drift correction and pressure broadening compensation are performed on the original spectral signal.

[0011] Extract the integral area of ​​the characteristic absorption peaks of each isotope and calculate their ratio;

[0012] Real-time monitoring data of ambient temperature, humidity and atmospheric pressure are introduced to dynamically compensate for environmental interference in isotope ratios;

[0013] The compensated isotope ratios were normalized to the international standard Vienna mean seawater to obtain stable hydrogen isotopes. Values ​​and stable isotopes value;

[0014] Generate containing the Value and Value determination report;

[0015] The measurement results are uploaded to the cloud analysis platform and the local calibration database is updated simultaneously.

[0016] Preferably, acquiring the sample to be tested and performing low-temperature vacuum sealing and encapsulation includes:

[0017] Soil, plant tissue, ice core, biological fluid, or precipitation samples are placed in stainless steel sample tubes pre-cooled to -80°C, the sample tubes being equipped with double-layer vacuum jackets and metal sealing valves.

[0018] The sealing is completed inside a high-purity nitrogen glove box with a dew point temperature below -70°C.

[0019] A unique radio frequency identification tag is attached to the outer wall of the packaged sample tube.

[0020] Preferably, the encapsulated sample is introduced into a constant-temperature desorption chamber, and gradient-temperature desorption is performed under an inert gas atmosphere to release moisture from the sample, including:

[0021] Evacuate the constant temperature desorption chamber to... After Pascal, high-purity helium was introduced as a carrier gas at a constant flow rate of 50 ml per minute.

[0022] The sample tube is delivered into the center of the cavity using an automated robotic arm.

[0023] Execute a gradient temperature program: start at 30°C and hold for 30 minutes, then increase to 120°C at a rate of 2°C per minute and hold for 60 minutes, then increase to 180°C and hold for 30 minutes.

[0024] Preferably, the released water vapor is catalytically cracked to generate a mixture of hydrogen and oxygen, including:

[0025] Water vapor and helium are mixed and flow through a quartz reaction tube filled with a platinum-rhodium alloy catalyst;

[0026] The quartz reaction tube was placed in a 400-degree constant temperature furnace to cause the water molecules to undergo a cracking reaction:

[0027] 2H₂O→2H₂+O₂;

[0028] A cold trap is placed at the outlet of the reaction tube to capture trace amounts of unreacted water vapor.

[0029] Preferably, the mixed gas is introduced into a multi-channel tunable diode laser absorption spectrometer to simultaneously acquire characteristic absorption spectral signals corresponding to hydrogen isotopes and oxygen isotopes, including:

[0030] A distributed feedback laser with a wavelength of 1.4 micrometers was used to detect the absorption characteristics near the P transition line of hydrogen molecules;

[0031] The absorption characteristics of the oxygen ν1+ν3 combined frequency band were detected using a quantum cascade laser with a wavelength of 2.7 micrometers; ν1 is a symmetric stretching vibration and ν3 is an antisymmetric stretching vibration.

[0032] Two laser beams are coupled through optical fibers and then passed through a 50-centimeter-long gas absorption cell with the same gold-plated inner wall.

[0033] The two laser channels are controlled by a synchronous triggering mechanism to collect transmitted light intensity signals within the same time window.

[0034] Preferably, based on a preset standard material calibration curve, baseline drift correction and pressure broadening compensation are performed on the original spectral signal, including:

[0035] Using three known and Establish absorption intensity-concentration response curves for internationally certified water samples;

[0036] Instrument baseline drift was subtracted by fitting third- to fifth-order polynomials.

[0037] Based on the measured chamber pressure and temperature, the absorption peak was corrected for pressure broadening using the Voigt line function.

[0038] Preferably, the integral area of ​​the characteristic absorption peaks of each isotope is extracted and their ratio is calculated, including:

[0039] Identification using peak detection algorithm 1 H2, 2 H 1 H,16 O 16 O and 16 O 18 The center position of the absorption peak of O;

[0040] The area of ​​the corresponding absorption peak was calculated using the trapezoidal numerical integration method. , , and ;

[0041] Calculate the hydrogen isotope ratio and oxygen isotope ratio .

[0042] Preferably, real-time monitoring data of ambient temperature, humidity, and atmospheric pressure are incorporated to dynamically compensate for environmental disturbances in the isotope ratio, including:

[0043] The measured temperature is collected once per second. air pressure With relative humidity ;

[0044] Application compensation model Make corrections, among which , , To calibrate the reference value, , , These are the compensation coefficients determined by fitting using the least squares method. It is the isotope ratio. The isotope ratio obtained after compensation.

[0045] Preferably, the compensated isotope ratios are normalized to the international standard Vienna mean seawater to obtain... Value and Values, including:

[0046] According to the formula Calculate δ 2 H value;

[0047] According to the formula Calculate δ 18 O value;

[0048] The hydrogen isotope ratio obtained after compensation, The oxygen isotope ratio obtained after compensation, This represents the standard ratio of hydrogen isotopes in the Vienna standard mean seawater. This represents the standard ratio of oxygen isotopes in the Vienna standard mean seawater.

[0049] The present invention also provides a system for determining the stable isotope values ​​of hydrogen and oxygen, comprising:

[0050] The sample pretreatment unit is used to acquire the sample to be tested and perform low-temperature vacuum sealing and encapsulation, and to introduce the encapsulated sample into the isothermal desorption chamber for gradient temperature desorption to release the sample moisture.

[0051] The water vapor cracking unit is used to catalytically crack the released water vapor to generate a mixture of hydrogen and oxygen.

[0052] A multi-channel tunable diode laser absorption spectrometer is used to simultaneously acquire characteristic absorption spectral signals corresponding to hydrogen isotopes and oxygen isotopes.

[0053] The environmental monitoring module is used to collect real-time data on ambient temperature, humidity, and atmospheric pressure.

[0054] The control unit is used to coordinate the operation of the sample pretreatment unit, the water vapor pyrolysis unit, the multi-channel tunable diode laser absorption spectrometer, and the environmental monitoring module.

[0055] The data processing terminal is used to perform baseline drift correction and pressure broadening compensation on the raw spectral signal based on the calibration curve of standard substances, extract the integral area of ​​isotope characteristic absorption peaks and calculate the ratio, perform dynamic environmental interference compensation in conjunction with environmental monitoring data, and normalize the compensated ratio with the VSMOW standard to obtain the final value. Value and The system generates a measurement report and uploads the measurement results to a cloud analysis platform to synchronously update the local calibration database.

[0056] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0057] 1. This invention employs a closed-loop processing scheme combining low-temperature vacuum sealing and gradient temperature desorption. This avoids localized boiling and selective volatilization of light isotopes caused by rapid heating, ensuring the integrity of water release and the originality of the isotopic composition. Combined with platinum-rhodium alloy catalytic cracking in a sealed environment, water molecules are completely converted into a mixture of H2 and O2 gases without secondary oxidation or isotope exchange reactions. This eliminates the core problems of isotope fractionation and sample loss in traditional technologies from the source. , The systematic bias of the measurement results was significantly reduced, and the data accuracy was greatly improved.

[0058] 2. This system enables simultaneous acquisition and analysis of two isotopes, shortening the single measurement cycle and improving detection efficiency. At the same time, it avoids environmental fluctuation errors caused by multiple measurements, significantly optimizing the intrinsic consistency of hydrogen and oxygen isotope data, and providing a reliable guarantee for subsequent quality control analysis such as global atmospheric water lines.

[0059] 3. The system has built-in high-precision temperature and humidity sensors and barometers to collect environmental parameters. Through a dynamic compensation model based on least squares fitting, it corrects the influence of temperature, humidity and atmospheric pressure fluctuations on the spectral signal in real time. Combined with a dual signal processing strategy of third- to fifth-order polynomial baseline correction and Voigt linear pressure broadening correction, it ensures that the integral area of ​​the absorption peak only reflects the isotope concentration and is not affected by instrument drift and physical environment fluctuations. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the overall technical architecture of the method and system for determining the stable isotope values ​​of hydrogen and oxygen proposed in this invention.

[0061] Figure 2 This is a schematic diagram of the core principle framework of the algorithm based on adaptive correction of spectral signals and analysis of isotope ratios in this invention;

[0062] Figure 3 This is a logical flow diagram of the sample pretreatment and water vapor conversion stages in this invention;

[0063] Figure 4 This is a logical flowchart of the laser absorption spectrum acquisition and multi-channel signal synchronous processing stage in this invention;

[0064] Figure 5 This is a logical flow diagram of the standard substance calibration and environmental interference compensation module in this invention;

[0065] Figure 6 This is a schematic diagram of the multi-level interaction relationship and data flow between the instrument terminal, control unit and cloud analysis platform in this invention. Detailed Implementation

[0066] Please refer to Figures 1 to 6 This invention provides a method and system for determining the stable isotope values ​​of hydrogen and oxygen, aiming to solve the technical problems of high sample moisture loss and systematic bias introduced by the selective volatilization of light isotopes during traditional freeze-drying pretreatment. This method achieves high-precision, low-bias determination of the stable isotope ratio of hydrogen and oxygen in liquid or solid aqueous samples by constructing an integrated, closed-loop controlled water vapor conversion and laser absorption spectroscopy analysis process. The specific embodiments of this invention will be described in detail below with reference to method steps S1 to S10.

[0067] The method includes the following steps:

[0068] S1, acquire the sample to be tested and perform low-temperature vacuum sealing and encapsulation;

[0069] S2, the packaged sample is introduced into the constant temperature desorption chamber, and the sample moisture is released by gradient heating desorption under an inert gas atmosphere;

[0070] S3 catalytically cracks the released water vapor to produce a mixture of hydrogen and oxygen.

[0071] S4. The mixed gas is introduced into a multi-channel tunable diode laser absorption spectrometer to simultaneously collect the characteristic absorption spectral signals corresponding to hydrogen isotopes and oxygen isotopes.

[0072] S5, based on the preset standard material calibration curve, performs baseline drift correction and pressure broadening compensation on the original spectral signal;

[0073] S6, extract the integral area of ​​the characteristic absorption peaks of each isotope and calculate their ratio;

[0074] S7 incorporates real-time monitoring data of ambient temperature, humidity and atmospheric pressure to dynamically compensate for environmental interference in isotope ratios.

[0075] S8, the compensated isotope ratios are normalized to the international standard Vienna standard mean seawater;

[0076] S9, generates a function containing Value and The measurement report is generated; S10, the measurement results are uploaded to the cloud analysis platform and the local calibration database is updated synchronously.

[0077] In step S1, the sample to be tested is acquired and subjected to low-temperature vacuum sealing. The sample is an aqueous medium such as soil, plant tissue, ice core, biological fluid, or precipitation. Immediately after collection, the sample is placed in a stainless steel sample tube pre-cooled to -80°C, equipped with a double-layer vacuum jacket and a metal sealing valve. The sealing process is completed in a glove box filled with high-purity nitrogen, with the dew point temperature controlled below -70°C to prevent the ingress of ambient moisture. After sealing, a unique RFID tag is affixed to the outer wall of the sample tube for end-to-end tracking. This step ensures that the moisture content and isotopic composition of the sample remain stable during transportation and storage, preventing isotopic fractionation caused by exposure to the atmosphere.

[0078] In step S2, the packaged sample is introduced into a constant-temperature desorption chamber, where gradient temperature desorption is performed under an inert gas atmosphere to release moisture from the sample. The constant-temperature desorption chamber is made of high-purity quartz and is equipped with a precision temperature-controlled heating belt and thermocouple array, with a temperature control accuracy of ±0.1°C. The chamber is pre-evacuated to... Pascal, and high-purity helium gas was introduced as a carrier gas at a constant flow rate of 50 ml per minute.

[0079] After the sample tube is fed into the center of the chamber by an automated robotic arm, a gradient heating program is initiated: the initial temperature is set at 30°C and held for 30 minutes to remove surface adsorbed water; then, the temperature is increased to 120°C at a rate of two degrees Celsius per minute and held for 60 minutes to release bound water; finally, the temperature is increased to 180°C and held for 30 minutes to ensure complete desorption. The entire desorption process lasts 120 minutes, and the released water vapor is carried by a helium flow into the downstream processing unit. This gradient heating strategy avoids localized boiling and isotope fractionation caused by rapid heating, ensuring the integrity and representativeness of water release.

[0080] In step S3, the released water vapor undergoes catalytic cracking to generate a mixture of hydrogen and oxygen. The water vapor and helium mixture flows through a quartz reaction tube filled with a platinum-rhodium alloy catalyst, and the reaction tube is placed in a 400°C constant-temperature furnace. Under this temperature and the action of the catalyst, water molecules undergo a cracking reaction:

[0081] 2H₂O→2H₂+O₂.

[0082] A cold trap is installed at the outlet of the reaction tube to capture trace amounts of unreacted water vapor and prevent it from entering the spectroscopic detection unit. The pyrolysis products are a ternary gas mixture of hydrogen, oxygen, and helium, wherein the hydrogen contains protium (…). 1 H) and deuterium ( 2 H), oxygen contains 16 O、 17 O and 18 O. The pyrolysis process is carried out in a closed, oxygen-free environment to avoid secondary oxidation or isotope exchange reactions, thus ensuring the chemical purity and isotope fidelity of the pyrolysis products.

[0083] In step S4, the mixed gas is introduced into a multi-channel tunable diode laser absorption spectrometer to simultaneously acquire the characteristic absorption spectral signals corresponding to hydrogen isotopes and oxygen isotopes. This spectrometer contains two independent but synchronously triggered laser channels: the first channel uses a 1.4-micrometer wavelength distributed feedback laser to detect the absorption characteristics of hydrogen molecules near the p-transition line, which corresponds to... 2 H / 1 The H ratio is sensitive; the second channel uses a 2.7-micron quantum cascade laser to detect the absorption characteristics of oxygen in the ν1+ν3 combination band, which is sensitive to... 18 O / 16O ratio sensitive. ν1 is a symmetric stretching vibration, and ν3 is an antisymmetric stretching vibration. Two laser beams are coupled via optical fibers and passed through the same 50 cm long gas absorption cell, with gold-plated inner walls to reduce adsorption. The laser wavelength is tuned by a combination of current and temperature, and the scanning range covers the complete outline of the target absorption line. A photodetector receives the transmitted light intensity signal, which is converted into a voltage signal by a transimpedance amplifier and then digitized by a 16-bit analog-to-digital converter at a sampling rate of 100,000 times per second. A synchronous triggering mechanism ensures that both channels acquire data under the same gas conditions and time window, eliminating errors introduced by timing drift.

[0084] In step S5, baseline drift correction and pressure broadening compensation are performed on the original spectral signal based on a preset standard material calibration curve. The standard materials include three known... and The internationally certified water samples are used, with values ​​covering low, medium, and high ranges. Before each measurement, the system automatically injects standard substances to perform a calibration procedure, generating absorption intensity-concentration response curves for the corresponding isotopes. The raw spectral signal is first fitted with a polynomial to subtract instrument baseline drift; the fitting order is dynamically selected based on the signal-to-noise ratio, typically third to fifth order. Subsequently, based on the measured chamber pressure and temperature, the absorption peaks are corrected for pressure broadening using the Voigt line shape function. The Voigt line shape is formed by the convolution of a Gaussian component (Doppler broadening) and a Lorentz component (collision broadening), and its mathematical expression is:

[0085] ;

[0086] in, This is the output of the Voigt linear function. It is a Gaussian function. For Lorentz function, For the target frequency, This is the integral variable. This correction ensures that the absorption peak area reflects only the isotope concentration and is not affected by fluctuations in the physical environment.

[0087] In step S6, the integrated areas of the characteristic absorption peaks of each isotope are extracted, and their ratios are calculated. The corrected spectral signal is used to identify the center position of the absorption peak through a peak detection algorithm, and then the area under the peak is calculated using the trapezoidal numerical integration method. For hydrogen isotopes, integration is performed separately. 1 H2 and 2 H 1 The characteristic absorption peak area of ​​H molecule and For oxygen isotopes, the integral 16 O 16 O and 16 O 18 absorption peak area of ​​O and Isotope ratios Defined as:

[0088] ;

[0089] This refers to the hydrogen isotope ratio. This is the oxygen isotope ratio. This ratio directly reflects the relative abundance of heavy and light isotopes in the sample.

[0090] In step S7, real-time monitoring data of ambient temperature, humidity, and atmospheric pressure are introduced to dynamically compensate for environmental interference in the isotope ratio. The system incorporates high-precision temperature and humidity sensors and a barometer, with a sampling frequency of once per second. Environmental parameters are corrected for residual systematic errors in the isotope ratio using empirical formulas. The compensation model is trained based on historical calibration data and takes the following form:

[0091] ;

[0092] in, The isotope ratio obtained after compensation, , , These are the measured temperature, air pressure, and relative humidity, respectively. , , To calibrate the reference value, , , The compensation coefficient was determined by least squares fitting. This compensation mechanism effectively suppresses the influence of environmental disturbances on the measurement results and improves long-term stability.

[0093] In step S8, the compensated isotope ratio is normalized to the international standard Vienna standard mean seawater. The isotope ratio R_VSMOW of VSMOW is a known constant. The value is calculated using the following formula:

[0094] ；

[0095] ;

[0096] Values ​​are expressed as per mille; positive values ​​indicate enrichment of heavy isotopes in the sample, while negative values ​​indicate depletion. The hydrogen isotope ratio obtained after compensation, The oxygen isotope ratio obtained after compensation, This represents the standard ratio of hydrogen isotopes in the Vienna standard mean seawater. This represents the standard ratio of oxygen isotopes in the Vienna standard mean seawater.

[0097] In step S9, a generator containing Value and The report includes the sample number, measurement time, raw spectrum, calibration curve, environmental parameters, compensation coefficient, and other relevant information. The value and its expanded uncertainty. The uncertainty is evaluated using Monte Carlo simulation, taking into account multiple factors such as calibration error, signal noise, and environmental fluctuations.

[0098] In step S10, the measurement results are uploaded to the cloud analysis platform, and the local calibration database is updated synchronously. After receiving the data, the cloud platform performs quality control checks, such as... and Does it conform to the global atmospheric water line relationship? If not, a retest command is triggered. Simultaneously, the newly measured standard material data is used to update the calibration curve online, enabling system self-learning and performance optimization.

[0099] The system comprises a sample pretreatment unit, a water vapor pyrolysis unit, a multi-channel laser absorption spectrometer, an environmental monitoring module, a control unit, and a data processing terminal. The sample pretreatment unit includes a low-temperature sample chamber, a constant-temperature desorption chamber, and an automated sample introduction robotic arm, enabling non-destructive desorption of the sample. The water vapor pyrolysis unit consists of a catalytic reaction tube and a cold trap, ensuring complete conversion of water into measurable gases. The multi-channel laser absorption spectrometer integrates a dual-wavelength laser source, a shared absorption cell, and a high-speed data acquisition card, supporting simultaneous multi-isotope detection. The environmental monitoring module acquires real-time temperature, humidity, and air pressure data. The control unit coordinates the actions of each unit and executes preset procedures. The data processing terminal runs the aforementioned algorithms to complete signal processing, calibration, compensation, and report generation. All units are interconnected via industrial Ethernet, with data streams encrypted throughout, ensuring traceability and security of the measurement process.

[0100] This method and system, through closed-loop control, gradient analysis, catalytic cracking, and multi-channel synchronous spectral analysis, completely avoids the isotope fractionation caused by traditional freeze-drying, and achieves high-precision and high-reliability determination of stable hydrogen and oxygen isotope values.

Claims

1. A method for determining the stable isotope values ​​of hydrogen and oxygen, characterized in that, include: Acquire the sample to be tested and perform low-temperature vacuum sealing and encapsulation; The packaged sample to be tested is introduced into a constant temperature desorption chamber, and the sample moisture is released by gradient temperature increase desorption under an inert gas atmosphere. The released water vapor is catalytically cracked to produce a mixture of hydrogen and oxygen. The mixed gas is introduced into a multi-channel tunable diode laser absorption spectrometer, and the characteristic absorption spectral signals corresponding to hydrogen isotopes and oxygen isotopes are acquired simultaneously. Based on the preset standard material calibration curve, baseline drift correction and pressure broadening compensation are performed on the original spectral signal. Extract the integral area of ​​the characteristic absorption peaks of each isotope and calculate their ratio; Real-time monitoring data of ambient temperature, humidity and atmospheric pressure are introduced to dynamically compensate for environmental interference in isotope ratios; The compensated isotope ratios were normalized to the Vienna standard mean seawater to obtain stable hydrogen isotopes. Values ​​and stable oxygen isotopes value; Generate a stable isotope containing the hydrogen Values ​​and stable oxygen isotopes Value determination report; The test report is uploaded to the cloud analysis platform, and the local calibration database is updated synchronously. Acquiring the sample to be tested and performing low-temperature vacuum sealing encapsulation includes: Soil, plant tissue, ice core, biological fluid, or precipitation samples are placed in stainless steel sample tubes pre-cooled to -80°C, the sample tubes being equipped with double-layer vacuum jackets and metal sealing valves. The sealing is completed inside a high-purity nitrogen glove box with a dew point temperature below -70°C. A unique radio frequency identification tag is attached to the outer wall of the packaged sample tube; The encapsulated sample is introduced into a constant-temperature desorption chamber, and gradient temperature desorption is performed under an inert gas atmosphere to release moisture from the sample, including: Evacuate the constant temperature desorption chamber to... After Pascal, high-purity helium was introduced as a carrier gas at a constant flow rate of 50 ml per minute. The sample tube is delivered into the center of the cavity using an automated robotic arm. Execute a gradient temperature program: Initial temperature 30℃, hold for 30 minutes, then increase to 120℃ at a rate of 2 degrees Celsius per minute, hold for 60 minutes, and then increase to 180℃, hold for 30 minutes. The released water vapor is catalytically cracked to produce a mixture of hydrogen and oxygen, including: Water vapor and helium are mixed and flow through a quartz reaction tube filled with a platinum-rhodium alloy catalyst; The quartz reaction tube was placed in a 400-degree constant temperature furnace to cause the water molecules to undergo a cracking reaction: 2H₂O→2H₂+O₂; A cold trap is placed at the outlet of the quartz reaction tube to capture trace amounts of unreacted water vapor.

2. The method for determining the stable isotope values ​​of hydrogen and oxygen according to claim 1, characterized in that, The mixed gas is introduced into a multi-channel tunable diode laser absorption spectrometer, and characteristic absorption spectral signals corresponding to hydrogen isotopes and oxygen isotopes are acquired simultaneously, including: A distributed feedback laser with a wavelength of 1.4 micrometers was used to detect the absorption characteristics near the P transition line of hydrogen molecules; The absorption characteristics of the oxygen ν1+ν3 combined frequency band were detected using a quantum cascade laser with a wavelength of 2.7 micrometers; ν1 is a symmetric stretching vibration and ν3 is an antisymmetric stretching vibration. Two laser beams are coupled through optical fibers and then passed through a 50-centimeter-long gas absorption cell with the same gold-plated inner wall. The two laser channels are controlled by a synchronous triggering mechanism to collect transmitted light intensity signals within the same time window.

3. The method for determining the stable isotope values ​​of hydrogen and oxygen according to claim 2, characterized in that, Based on a preset standard material calibration curve, baseline drift correction and pressure broadening compensation are performed on the original spectral signal, including: Using three known and Establish absorption intensity-concentration response curves for internationally certified water samples; Instrument baseline drift was subtracted by fitting third- to fifth-order polynomials. Based on the measured chamber pressure and temperature, the absorption peak is compensated for by pressure broadening using the Voigt line function.

4. The method for determining the stable isotope values ​​of hydrogen and oxygen according to claim 3, characterized in that, Extract the integrated area of ​​the characteristic absorption peaks of each isotope and calculate their ratios, including: Identification using peak detection algorithm 1 H2, 2 H 1 H, 16 O 16 O and 16 O 18 The center position of the absorption peak of O; Calculate using the trapezoidal numerical integration method 1 H2 and 2 H 1 The characteristic absorption peak area of ​​H molecule and , 16 O 16 O and 16 O 18 absorption peak area of ​​O and ; Calculate the hydrogen isotope ratio and oxygen isotope ratio .

5. The method for determining the stable isotope values ​​of hydrogen and oxygen according to claim 4, characterized in that, Real-time monitoring data of ambient temperature, humidity, and atmospheric pressure are incorporated to dynamically compensate for environmental disturbances in isotope ratios, including: The measured temperature is collected once per second. air pressure With relative humidity ; Application compensation model Make corrections, among which , , To calibrate the reference value, , , These are the compensation coefficients determined by fitting using the least squares method. It is the isotope ratio. The isotope ratio after compensation.

6. The method for determining the stable isotope values ​​of hydrogen and oxygen according to claim 5, characterized in that, The compensated isotope ratios were normalized to the international standard Vienna mean seawater to obtain stable hydrogen isotopes. Values ​​and stable oxygen isotopes Values, including: According to the formula Calculation of stable hydrogen isotopes value; According to the formula Calculation of stable oxygen isotopes value; The compensated hydrogen isotope ratio, This refers to the compensated oxygen isotope ratio. This represents the standard ratio of hydrogen isotopes in the Vienna standard mean seawater. This represents the standard ratio of oxygen isotopes in the Vienna standard mean seawater.

7. A system for determining the stable isotope values ​​of hydrogen and oxygen, characterized in that, Implementing the method as claimed in any one of claims 1 to 6, comprising: The sample pretreatment unit is used to acquire the sample to be tested and perform low-temperature vacuum sealing and encapsulation, and to introduce the encapsulated sample into the isothermal desorption chamber for gradient temperature desorption to release the sample moisture. The water vapor cracking unit is used to catalytically crack the released water vapor to generate a mixture of hydrogen and oxygen. A multi-channel tunable diode laser absorption spectrometer is used to simultaneously acquire characteristic absorption spectral signals corresponding to hydrogen isotopes and oxygen isotopes. The environmental monitoring module is used to collect real-time data on ambient temperature, humidity, and atmospheric pressure. The control unit is used to coordinate the operation of the sample pretreatment unit, the water vapor pyrolysis unit, the multi-channel tunable diode laser absorption spectrometer, and the environmental monitoring module. The data processing terminal is used to perform baseline drift correction and pressure broadening compensation on the original spectral signal based on the calibration curve of standard materials, extract the integral area of ​​isotope characteristic absorption peaks and calculate the ratio, perform dynamic environmental interference compensation in conjunction with environmental monitoring data, and normalize the compensated isotope ratios with the Vienna standard mean seawater to obtain hydrogen stable isotopes. Values ​​and stable oxygen isotopes The system generates a measurement report and uploads it to a cloud-based analysis platform to synchronize and update the local calibration database.

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