CN108072713B - The method of hydrogen isotope in on-line analysis fluid inclusion water - Google Patents

Abstract

The invention relates to the technical field of stable isotope analysis, and discloses a method for online analysis of hydrogen isotopes in fluid inclusion water, which is characterized in that the method comprises the following steps: (1) making the water in fluid inclusion Release and carry out reduction reaction to produce the mixed gas containing hydrogen; (II) adopt the enrichment device to enrich the mixed gas containing hydrogen produced in step (I); (III) utilize the gas chromatography column to enrich the hydrogen from step (II) (IV) The hydrogen separated in step (III) is introduced into the ion source of the isotope ratio mass spectrometer through the open split flow interface to analyze the hydrogen isotope in the fluid inclusion water and obtain the hydrogen isotope ratio. The method can not only meet the gas flow requirement of the ion source of the mass spectrometer, but also can introduce the generated sample gas into the isotope ratio mass spectrometer to the greatest extent, with low detection limit, small analysis error and high accuracy.

Description

Method for On-line Analysis of Hydrogen Isotope in Fluid Inclusion Water

technical field

The invention relates to the technical field of stable isotope analysis, in particular to a method for online analysis of hydrogen isotopes in fluid inclusion water.

Background technique

Fluid inclusions in diagenetic minerals are the inclusions of diagenetic ore-forming fluids due to factors such as crystal growth mechanism, growth rate, changes in the concentration of certain (some) components, or multi-phase interface interactions during the mineral crystal growth process. The rock-forming and ore-forming fluids in the mineral lattice defects or caves, which are still sealed in the main minerals and have a phase boundary with the main minerals, are the original samples of rock-forming and mineralization preserved so far. The study of hydrogen isotopes in fluid inclusions in ore deposits and dike rocks is of great significance for exploring the properties, sources, evolution and genesis of ore-forming fluids.

At present, the analysis method and means of hydrogen isotope composition in fluid inclusions in the world is mainly the high-frequency heating U/Zn/Cr conversion method. The quartz tube furnace thermal explosion method is a classic method to obtain water in fluid inclusions. It heats the sample through a quartz tube heating furnace, so that the gas-liquid phase in the fluid inclusions forms a greater pressure and is released from the rock. the process of. When analyzing the hydrogen isotope in the fluid inclusion water, firstly, the water in the fluid inclusion sample is released by heating at high temperature under vacuum conditions, then the H ₂ O is converted into H ₂ through the redox reaction, and finally through the double-channel injection The static analysis method analyzes the hydrogen isotope composition on a gas isotope ratio mass spectrometer. The traditional analysis method of hydrogen isotope ratio in fluid inclusion water is an off-line analysis method. In the off-line analysis system, the sample burst device, water sample collection device and high-temperature reaction tube are set independently. An accurate hydrogen isotope analysis by the traditional analysis method requires the amount of H in the sample to reach 10 ^-4 ~ 10 ^-6 moles. Therefore, for trace amounts of water samples and solid samples with very low water content, the traditional method has a large error and requires Lots of samples. For the analysis of hydrogen isotope in fluid inclusions, more than 2g of sample is required, which makes the traditional method unable to complete the analysis of hydrogen isotope in trace fluid inclusion water.

Recently, a new pyrolysis/element and isotope online continuous flow analysis method (TC/EA-MS) has emerged, which successfully analyzes trace amounts of water and alcohol samples, trace organic samples, and H in hydrous minerals. isotopic composition. This continuous flow analysis method can analyze the hydrogen isotope composition of samples containing about 10 ^-9 moles of H, and the external precision of the analysis is ±1‰～±10‰(1σ). Compared with the traditional method, it not only reduces the analysis error, It also reduces the amount of sample required for analysis. The schematic diagram of the device structure used to realize the method is shown in Figure 1. First, the sample is sent into the high-temperature cracking furnace through the automatic sampling device, where it is cracked and a mixed gas containing hydrogen is generated, purified by a chromatographic column, and then purified to obtain The hydrogen gas is introduced into the ion source of the stable isotope ratio mass spectrometer, and the neutral hydrogen atoms are ionized into charged particles with different mass-to-charge ratios, which are accelerated by the mass of the electromagnet, and the ions of different masses are separated into ion flows with different deflection amounts, and finally The Faraday cup receives and records the separated beams of ions and their intensities, and compares the analysis results of the sample gas with the analysis results of the reference gas through online processing to obtain the hydrogen isotope ratio in the fluid inclusion water. Due to the complexity of fluid inclusions compared to other substances, there is no international report on the analysis of hydrogen isotopes in trace fluid inclusions by this method. When the above-mentioned pyrolysis/element and isotope online continuous flow analysis method is used to analyze organic samples, it is usually first necessary to use glassy carbon in the reduction furnace to reduce the functional groups such as hydroxyl groups of organic samples to produce hydrogen, and the fluid inclusions are high-temperature Pyrolysis will produce some other gases (such as hydrocarbon gases), which may not be able to react with the glassy carbon in the reduction furnace, and then enter the gas isotope mass spectrometer, which will eventually affect the service life and data quality of the ion source.

In the process of pyrolysis/element and isotope online continuous flow analysis and testing, the flow rate of the carrier gas of the general element analyzer is controlled at about 80-100mL/min. If it directly enters the ion source of the mass spectrometer, the vacuum of the instrument will be greatly reduced. , it is difficult to achieve high-precision determination of isotopes, and at the same time, excessive gas flow impact will also affect the life of the filament in the ion source, so the common practice is to only allow a certain amount of gas to enter the ion source through a specific interface technology. In this method, the elemental analyzer (EA) is connected with the gas isotope mass spectrometer (IRMS) through a specific interface ConFlo, and the principle is illustrated as follows: as shown in Figure 2, when 80mL/min of gas flows to the gas isotope mass spectrometer, there is 72mL/min of gas is shunted away, and only the remaining 8mL/min of gas enters the open split of ConFlo, where it is mixed with another helium gas (this helium gas is mainly used to exclude the open split) The air in the capillary), and then a capillary guides the sample gas into the ion source through the pressure difference inside and outside the ion source. At this time, the gas flow in the capillary is only 0.5mL/min, which can greatly reduce the gas flow, thereby avoiding the impact on the ion source. interference. The disadvantage of this design is that not all the gas generated by the sample is sent to the ion source, and only a small part of the gas is used. Therefore, in order to meet the detection limit of the isotope mass spectrometer (the ion current intensity is above 2V), a large number of samples must be required. Therefore, it is necessary to choose one that can meet the gas flow requirements of the ion source of the mass spectrometer, and can also send the generated sample gas to the isotope ratio mass spectrometer to the maximum extent, greatly reducing the detection limit of the instrument, thereby realizing the hydrogen concentration of trace samples. High-precision online analysis of isotope ratio is an urgent problem in the field of hydrogen isotope analysis in fluid inclusion water.

Contents of the invention

The purpose of the present invention is to overcome the large analysis errors, high sample consumption, cumbersome experimental process and low efficiency of the existing off-line analysis technology of hydrogen isotope in fluid inclusion water, as well as the existing high-temperature cracking/on-line continuous flow of elements and isotopes. The analysis method is not suitable for the on-line analysis of hydrogen isotopes in fluid inclusion water, and the analysis method of pyrolysis/on-line continuous flow of elements and isotopes cannot maximize the use of sample gas, high instrument detection limit, low precision and other defects. Provide A method for on-line analysis of hydrogen isotopes in fluid inclusion water, which can realize rapid analysis of hydrogen isotopes in trace amounts of fluid inclusion water, solves the problem that it is difficult to analyze when the water content of fluid inclusions is low, and the analysis process is simple and controllable, easy operation, the sample gas can be used to the maximum extent, the detection limit of the instrument is low, the sensitivity is high, the analysis error is small, and the accuracy is high.

In order to achieve the above object, the present invention provides a method for online analysis of hydrogen isotopes in fluid inclusion water, the method comprising the following steps:

(1) in the reaction tube that is filled with chromium powder, utilize dynamic flash method to make the water in the fluid inclusion release and carry out redox reaction to produce the mixed gas that contains hydrogen;

(II) enriching the mixed gas containing hydrogen produced in step (I) by means of an enrichment device;

(III) Utilize gas chromatographic column i to separate hydrogen from the mixed gas containing hydrogen enriched in step (II);

(IV) The hydrogen gas separated in step (III) is introduced into the ion source of the isotope ratio mass spectrometer through the open shunt type interface j to analyze the hydrogen isotope in the fluid inclusion water and obtain the hydrogen isotope ratio,

Wherein, the enrichment device includes an eight-way valve d, a sample tube g and a cooling trap, and the eight-way valve d is provided with an interface for receiving the mixed gas containing hydrogen generated in the step (1), for converting the step ( II) The enriched mixed gas containing hydrogen is output to the interface of the gas chromatographic column i and the interface used to communicate with the two ends of the sample tube g, and the eight-way valve d is also provided with a switching knob for switching The eight-way valve d has two connection modes of sampling and injection. The sample tube g is provided with a spiral sample ring h, and the sample ring h is filled with porous materials. The sample ring h can be freely The way of putting in or taking out is arranged in the cooling well, and a press-fit connector k is arranged in the opening shunt type interface j.

This method optimizes the packing design of the high-temperature cracking tube of the elemental analyzer and combines it with the gas isotope mass spectrometer to reduce the isotope fractionation effect converted to hydrogen molecules, improve the quality of hydrogen isotope testing of solid samples, and make it suitable for microfluid inclusions The analysis of hydrogen isotopes in water can not only meet the gas flow requirements of the ion source of the mass spectrometer, but also send the generated sample gas to the isotope ratio mass spectrometer to the maximum extent, greatly reducing the detection limit of the instrument and improving the sensitivity of the instrument .

Description of drawings

Fig. 1 is a structural schematic diagram of an elemental analyzer-ConFlo-isotope ratio mass spectrometer coupled device for analyzing trace amounts of water samples, organic samples and hydrogen isotope compositions in hydrous minerals;

Fig. 2 is a schematic diagram of gas splitting in the ConFlo opening shunt type interface in the elemental analyzer-ConFlo-isotope ratio mass spectrometer coupling device;

Fig. 3 is a structural schematic diagram of the combined device for online analysis of hydrogen isotopes in fluid inclusion water used in the present invention;

Fig. 4 is the schematic diagram of the material flow path during the sampling communication mode and the sampling communication mode of the eight-way valve d used in the present invention;

Fig. 5 is a schematic structural view of the press-fit connector used in the present invention.

Explanation of reference signs

a. Isotope ratio mass spectrometer a1. Ion source

a2, electromagnet a3, Faraday cup

b. ConFlo type interface b1. Open shunt type interface

c. Elemental analyzer c1. High temperature cracking furnace

c2. Gas chromatographic column d. Eight-way valve

e. Reaction tube f. Solid autosampler

g. Sample tube h. Sample loop

i. Gas chromatographic column j. Open split flow interface

k. Press-fit connector 1. The first interface

2. The second interface 3. The third interface

4. The fourth interface 5. The fifth interface

6. The sixth interface 7. The seventh interface

8. The eighth interface 1#, the first capillary

2#, the second capillary 3#, the third capillary

Detailed ways

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

In the present invention, unless stated otherwise, the used orientation words such as "upper and lower" generally refer to the structure schematic diagram of the device for online analysis of hydrogen isotopes in fluid inclusion water according to the present invention position. "Inner and outer" are defined relative to the actual structure of the device for online analysis of hydrogen isotopes in fluid inclusion water according to the present invention.

As mentioned above, the present invention provides a method for online analysis of hydrogen isotopes in fluid inclusion water, the method comprising the following steps:

(1) in the reaction tube that is filled with chromium powder, utilize dynamic flash method to make the water in the fluid inclusion release and carry out redox reaction to produce the mixed gas that contains hydrogen;

(II) enriching the mixed gas containing hydrogen produced in step (I) by means of an enrichment device;

(III) Utilize gas chromatographic column i to separate hydrogen from the mixed gas containing hydrogen enriched in step (II);

(IV) The hydrogen gas separated in step (III) is introduced into the ion source of the isotope ratio mass spectrometer through the open shunt type interface j to analyze the hydrogen isotope in the fluid inclusion water and obtain the hydrogen isotope ratio,

Wherein, the enrichment device includes an eight-way valve d, a sample tube g and a cooling trap, and the eight-way valve d is provided with an interface for receiving the mixed gas containing hydrogen generated in the step (1), for converting the step ( II) The enriched mixed gas containing hydrogen is output to the interface of the gas chromatographic column i and the interface used to communicate with the two ends of the sample tube g, and the eight-way valve d is also provided with a switching knob for switching There are two connection modes of sampling (LOAD MODE) and sampling (INJECT MODE) of the eight-way valve d, the sample tube g is provided with a spiral sample ring h, and the sample ring h is filled with porous materials, The sample loop h is set in the cooling well in such a way that it can be freely put in or taken out, and a press-fit connector k is set in the open shunt interface j.

According to the present invention, in step (I), the process of using the dynamic flash method to release the water in the fluid inclusions includes: using a tin cup or a silver cup to encapsulate the fluid inclusions, and then the encapsulated fluid inclusions Enter the reaction tube through the solid autosampler, control the temperature of the reaction tube to 900-1100 ° C, and perform flash combustion in the presence of the first carrier gas, so that the fluid inclusions are heated and burst, and the fluid inclusions are released of water.

According to the present invention, the components of the tin cup or the silver cup do not contain water and hydrogen elements, which will not affect the final hydrogen isotope ratio test results.

According to the present invention, the first carrier gas is used to carry the sample gas to the enrichment device, and the selection of the first carrier gas is not particularly limited, as long as it does not interfere with the dynamic flash combustion process and the It is sufficient that the reactants and reaction products in the reduction reaction process react without affecting the analysis of the hydrogen isotope composition in the fluid inclusion water by the final isotope ratio mass spectrometer. Preferably, the first carrier gas is helium.

According to the present invention, the process of the thermal explosion of the fluid inclusions is carried out in the reaction tube filled with chromium powder, and the water released after the dynamic flash combustion of the fluid inclusions is directly in contact with the chromium powder filled in the reaction tube .

According to the present invention, in order to further increase the temperature of the dynamic flashing process, which is more conducive to the full combustion and bursting of the fluid inclusions encapsulated with tin cups or silver cups, the dynamic flashing process is preferably performed under the condition of oxygen injection next.

According to the present invention, when the fluid inclusions packaged in tin cups or silver cups are dynamically flashed under the condition of oxygen injection, the flow rate of the oxygen can be selected according to the actual amount of the fluid inclusions that are dynamically flashed , preferably, the oxygen injection conditions include: the oxygen injection flow rate is 15-30mL/min, and the oxygen injection time is 20-60s. If the oxygen flow rate is lower than 15mL/min, it will cause insufficient bursting of the fluid inclusion sample, and the residual ash in the reaction tube will affect the test and analysis results of the next sample. If the oxygen flow rate is higher than 30mL/min, it will affect The extent to which the gas generated by the fluid inclusions undergoes dynamic flash combustion undergoes the next oxidation-reduction reaction to generate hydrogen gas will also affect the test and analysis results of the sample. When dynamic flashing is carried out under the condition of oxygen injection, the heat released by the reaction of the tin cup or silver cup with oxygen can further increase the temperature in the reaction tube. Preferably, the oxygen injection conditions meet the requirement that the flashing temperature reaches 1700-1800°C, This is more conducive to the sufficient bursting of the fluid inclusions sealed with the tin cup or silver cup and the release of water in the fluid inclusions.

According to the present invention, the redox reaction process includes: under heating conditions, the water released from the fluid inclusions is brought into contact with the chromium powder filled in the reaction tube. The reaction of the water released by the fluid inclusions and the chromium powder proceeds according to the following formula:

According to the present invention, the heating conditions need to reach the temperature required for the reaction between the chromium powder and the water released from the fluid inclusions. If the heating temperature is too high or too low, it will affect the final analysis of the hydrogen isotope analysis results in the fluid inclusions water. , and the heating time is sufficient for all the water samples to react, and the heating conditions preferably include: the heating temperature is 900-1100° C., and the heating time is 5-12 minutes. In the method provided by the present invention, the temperature required for dynamic flashing of the fluid inclusions and thermal explosion also satisfies the temperature required for redox reactions between the chromium powder and the water released from the fluid inclusions, and the fluid inclusions After dynamic flash combustion and thermal explosion, the temperature in the reaction tube can quickly drop back to the preset temperature, which will not adversely affect the reaction between the chromium powder and the water released from the fluid inclusions. Therefore, the fluid The process of thermally exploding the inclusions to release water and the process of reduction reaction can be carried out simultaneously in the reaction tube, so as to realize the purpose of parallel experiment.

According to the present invention, the solid autosampler adopts a unique turntable design, which can simultaneously store 40 samples of fluid inclusions to be analyzed, and can realize automatic continuous sampling according to a preset time interval. In order to provide sufficient reducing agent, the chromium powder filled in the reaction tube can satisfy the requirements of dynamic flash combustion and thermal explosion of all fluid inclusion samples to be analyzed that are continuously injected into the reaction tube by the solid autosampler. After all the released water is reduced to hydrogen, the amount of the chromium powder needs to be higher than the theoretical reaction amount. Preferably, the weight ratio of the filling amount of the chromium powder to the amount of the fluid inclusions is 500-1500: 1.

According to a specific embodiment of the present invention, when the amount of each fluid inclusion sample to be analyzed is 100 mg, and the filling amount of chromium powder in the reaction tube is 100 g, it is enough to convert hundreds of fluid inclusion samples to be analyzed The released water is all reduced to hydrogen.

According to the present invention, in order to prevent the chromium oxide and unreacted chromium powder generated after the redox reaction of the chromium powder from hindering the smoothness of the flow of the mixed gas containing hydrogen generated by the redox reaction between the water in the fluid inclusion and the chromium powder, the The bottom of the reaction tube is preferably also provided with a quartz membrane, the quartz membrane is made of quartz cellulose, has good heat resistance stability and gas permeability, and can guarantee the delivery of the mixed gas containing hydrogen in the first carrier gas. Flow smoothly to the enrichment device for the mixed gas containing hydrogen.

According to the present invention, in order to ensure that the water in the fluid inclusions undergoes oxidation-reduction reaction with the chromium powder to generate a mixed gas containing hydrogen that is completely introduced into the subsequent enrichment device, the first carrier gas is preferably injected into the reaction at a flow rate of 80-100mL/min Tube.

According to the present invention, in the step (II), the enrichment of the mixed gas containing hydrogen generated in the step (I) is performed by switching the two communication modes of sampling and injection of the eight-way valve d in the enrichment device.

According to the present invention, as shown in FIG. 4, the eight-way valve d is provided with a first interface 1 to an eighth interface 8, and each interface communicates with an adjacent interface, and the eight-way valve d uses sampling or When the sample injection mode is connected, the connection relationship of each interface of the eight-way valve d is respectively:

When the communication mode of the eight-way valve d is the sampling communication mode, as shown in Figure 4 (A), the second port 2 of the eight-way valve d communicates with the third port 3, and the fourth port 4 communicates with the fifth port. The interface 5 is connected, the sixth interface 6 is connected with the seventh interface 7, and the eighth interface 8 is connected with the first interface 1;

When the communication mode of the eight-way valve d is the sampling communication mode, as shown in Figure 4 (B), the second port 2 of the eight-way valve d communicates with the first port 1, and the fourth port 4 communicates with the first port 1. The three ports 3 are connected, the sixth port 6 is connected to the fifth port 5 , and the eighth port 8 is connected to the seventh port 7 .

According to the present invention, the sample tube g is provided with a helical sample ring h, and the sample ring h is filled with porous materials. The porous material is preferably a porous material having the function of absorbing hydrogen. For example, the porous material can be a porous carbon-based material and a porous silicon-based material. Preferably, the porous material is at least one of activated carbon, 5A molecular sieve and 13A molecular sieve. One, more preferably, the porous material is 5A molecular sieve. In this way, when the mixed gas containing hydrogen generated in step (I) passes through the sample loop h, it can be absorbed into the porous material in the sample loop h.

According to the present invention, in order to further promote the adsorption of the porous material to the mixed gas containing hydrogen generated in step (1), the enrichment device also includes a cooling trap, and the sample loop h can be freely placed or The removal means is set in the cooling trap. When the sample loop h was placed in the cooling trap, the pressure in the sample loop h placed in the cooling trap was reduced, so that the higher temperature generated in step (1) contained hydrogen When the mixed gas flows through the sample ring h in the cooling trap, it is fully absorbed into the pores of the porous material in the sample ring h.

According to the present invention, in order to facilitate the enrichment of the hydrogen-containing mixed gas produced in the step (I), simultaneously satisfying the pressure in the sample ring h can reach the The desired temperature of the adsorption pressure of the mixed gas containing hydrogen, the cooling trap is preferably a Dewar flask filled with a coolant, and the cooling trap is further preferably a Dewar flask filled with liquid nitrogen.

According to the present invention, in order to further control the gas flow of the mixed gas containing hydrogen from step (I), the inner diameter of the sample tube g is preferably 0.4-0.8mm, so that the sample tube g is from step (I) The mixed gas containing hydrogen generated in the gas can play a throttling role. In order to ensure the mechanical strength of the sample tube g, the wall thickness of the sample tube g is preferably 0.2-0.5 mm. In order to prolong the flow path length of the mixed gas containing hydrogen generated in step (1) in the sample tube g as much as possible, so that the mixed gas containing hydrogen is fully absorbed by the porous material, and at the same time it is convenient for the sample loop h can be set in the cooling trap in a free way of putting in or taking out. The sample ring h is located in the middle of the sample tube g, and the middle part of the sample tube g is wound 1-3 times to form a helical sample ring h with a diameter of 4-10 cm.

According to the present invention, in step (II), the carrier gas used to carry the mixed gas containing hydrogen generated in step (I) to the enrichment device is still the first carrier gas described in step (I). The process of enriching the mixed gas containing hydrogen generated in the step (1) may include: setting the communication mode of the eight-way valve d as a sampling communication mode, putting the sample loop h into the cooling trap, and making the step The mixed gas containing hydrogen produced in (I) is under the carrying of the first carrier gas, as shown in Figure 4 (A), along the second interface 2-the third interface 3-sample tube g-the sixth interface 6- The seventh interface 7 flows through the path and is adsorbed in the pores of the porous material filled in the sample ring h.

According to the present invention, the flow rate of the first carrier gas is consistent with the flow rate of the first carrier gas in step (1), which is still 80-100mL/min.

According to the present invention, in order to remove the impurity gas contained in the hydrogen-containing mixed gas enriched in step (II), and separate to obtain pure hydrogen, the hydrogen-containing mixed gas enriched from step (II) It also needs to be further separated and removed by gas chromatographic column i. Preferably, in step (III), the process of separating hydrogen from the hydrogen-containing mixed gas enriched in step (II) includes: waiting for all the fluid inclusion water in step (I) to react, no longer generating hydrogen-containing gas When mixing gas, turn the switching knob of the eight-way valve d to change the connection mode of the eight-way valve d into the sample connection mode, remove the cooling trap, and make the adsorption in the pores of the porous material filled in the sample ring h The mixed gas containing hydrogen is desorbed and carried by the second carrier gas, as shown in Figure 4(B), along the fifth interface 5-sixth interface 6-sample tube g-third interface 3-fourth The path of port 4 flows to the gas chromatographic column i, and the hydrogen gas is separated from the mixed gas through the adsorption and desorption of the stationary phase in the chromatographic column.

According to the present invention, as shown in FIG. 4 , the fifth port 5 of the eight-way valve d is the inlet port of the second carrier gas. When the communication mode of the eight-way valve d is set as the sampling communication mode, The second carrier gas flows directly to the gas chromatographic column i along the path from the fifth port 5 to the sixth port 6; when the connection mode of the eight-way valve d changes to the sample connection mode, the second carrier gas The mixed gas containing hydrogen obtained from the desorption of the porous material in the sample ring h flows to the gas chromatography column i along the path of the fifth interface 5 - the sixth interface 6 - the sample tube g - the third interface 3 - the fourth interface 4 .

According to the present invention, in order to reduce the flow of the hydrogen-containing mixed gas enriched in step (II) passing through the gas chromatographic column i and finally flowing to the isotope ratio mass spectrometer, the gas chromatographic column i of step (III) is separated to obtain The hydrogen gas enters the isotope ratio mass spectrometer as much as possible, while satisfying that the isotope ratio mass spectrometer has a relatively high degree of vacuum. Preferably, the flow rate of the second carrier gas is 1-3mL/min.

According to the present invention, the selection of the second carrier gas is not particularly limited, as long as it does not affect the adsorption and separation of the porous material in the sample loop h and the gas chromatographic column i to the mixed gas containing hydrogen enriched in step (II), It is sufficient that the final isotope ratio mass spectrometer does not interfere with the analysis of the hydrogen isotope composition in the fluid inclusion water. Preferably, the second carrier gas is helium.

According to the present invention, in order to further reduce the flow rate of the hydrogen gas separated by step (III) gas chromatographic column i into the ion source in the isotope ratio mass spectrometer to meet the requirements of the ion source on the gas flow rate, thereby avoiding the impact of the sample gas on the ion source Source interference, the gas chromatographic column i and the isotope ratio mass spectrometer are preferably connected through an open split type interface j, so that the hydrogen separated by the gas chromatographic column i is introduced into the isotope ratio mass spectrometer through the open split type interface j.

According to the present invention, in order to more finely adjust the hydrogen flow rate entering the isotope ratio mass spectrometer, while having a higher throttling function, the airtightness of the connection between the gas chromatographic column i and the isotope ratio mass spectrometer is ensured The open shunt type interface j is preferably provided with a press-fit connector k. As shown in Figure 5, the press-fit connector k is arranged at one end of the open shunt type interface j, and the other end of the open shunt type interface j is fixedly inserted side by side into the second capillary 2# and the third capillary 3# , the inlet end of the press-fit joint k is fixedly inserted into the outflow end of the gas chromatography column i (the first capillary 1#), and the inlets of the second capillary 2# and the third capillary 3# inserted side by side are connected with the The outlet of the first capillary 1# is set opposite to each other. The third capillary 3# bears a pressure drop of 0.1-0.2 MPa, matches the vacuum pump of the isotope ratio mass spectrometer, and introduces the hydrogen gas separated by the gas chromatography column i into the ions of the isotope ratio mass spectrometer. source. The second capillary 2# is used to feed helium gas into the open split flow interface j, and fill the open split flow interface j with helium. When the flow of hydrogen separated from the gas chromatographic column i is greater than the working flow of the ion source of the isotope ratio mass spectrometer, too much gas chromatographic column i flows out hydrogen and the second carrier gas flows in with the second capillary 2# The helium gas flowing out of the open split flow interface j; when the flow rate of the hydrogen gas separated from the gas chromatographic column i is less than the working flow rate of the ion source of the isotope ratio mass spectrometer, the helium in the open split flow interface j Supplement is provided, and the hydrogen gas separated by the gas chromatography column i is introduced into the ion source of the isotope ratio mass spectrometer.

According to the present invention, under the joint regulation of the open shunt type interface j and the press-fit connector k, the hydrogen gas separated in step (III) flows into the open shunt type interface j from the first capillary 1# The gas flow rate at the inlet of the press-fit joint k can be 1-3mL/min, and the hydrogen gas separated in step (III) flows from the third capillary 3# to the press-fit joint k in the open shunt type interface j. The gas flow rate of the ion source of the isotope ratio mass spectrometer can be 0.3-0.8mL/min, and the gas flow rate of passing helium into the open shunt type interface j from the second capillary 2# can be 2-5mL/min. min. This sampling method can not only meet the gas flow requirements of the ion source of the isotope ratio mass spectrometer, but also ensure that the sample gas enters the ion source of the isotope ratio mass spectrometer to the maximum extent, improve the utilization rate of the sample gas, and realize microfluid wrapping Analysis of hydrogen isotopes in body water.

According to the present invention, when all the sample gas enters the ion source of the isotope ratio mass spectrometer, when using an online computer to analyze the composition of hydrogen isotopes in fluid inclusion water, it can Compared the analysis results of the ratio of ¹ H ⁺ and ² H ⁺ in the hydrogen gas prepared by using these standard water samples, and the hydrogen calibrated steel cylinder hydrogen gas prepared by these standard water samples, and directly calculated the relative The δD value (‰) of the hydrogen isotope composition of the standard water sample is represented by its ratio to the corresponding isotope in the standard water sample. Specifically, it is calculated according to the following formula:

In the formula: SA represents the measured fluid inclusion water, ST represents the standard water sample.

The method for online analysis of hydrogen isotopes in fluid inclusion water provided by the present invention is simple and easy to operate, has high test efficiency and high analysis accuracy, and effectively reduces the time required for the analysis of hydrogen isotopes in fluid inclusion water under the premise of ensuring precision and accuracy. The amount of sample used, the entire analysis process of each sample can be completed within 5-10 minutes, realizing the rapid analysis of hydrogen isotopes in microfluid inclusion water.

The present invention will be described in detail below by way of examples.

In the following examples, the isotope ratio mass spectrometer is a model Delta S mass spectrometer produced by Thermo Fisher, and the _H2 prepared by the fluid inclusion water to be analyzed is introduced into the ion source of the isotope ratio mass spectrometer for detection. , Weigh 6 parts of the same fluid inclusions with the same weight and package them in tin cups or silver cups for sample preparation, repeat the analysis 6 times, and take the average value as the final analysis result.

In the following examples, the high-purity hydrogen gas in steel cylinders (δD value -134.1‰) is used as the standard gas, and the δD value (‰) of the hydrogen isotope in the measured fluid inclusion water represents the hydrogen isotope composition in the measured fluid inclusion water, and its The ratio of the corresponding isotopes in the standard gas (VSMOW) is expressed, specifically calculated according to the following formula:

In the formula, SA stands for fluid inclusion water, and VSMOW stands for Vienna Standard Mean Ocean Water.

Example 1

(1) Assemble the instruments and devices required for on-line analysis of hydrogen isotopes in fluid inclusion water

As shown in Figure 3, the elemental analyzer is sequentially connected with the enrichment device, the gas chromatographic column i and the isotope ratio mass spectrometer, wherein the enrichment device includes an eight-way valve d, a sample tube g and a Dewar filled with liquid nitrogen bottle, the gas outlet of the elemental analyzer and one end of the gas chromatographic column i are respectively connected to the two interfaces of the eight-way valve d, and the other end of the gas chromatographic column i is shunted with the isotope ratio mass spectrometer through an opening Type interface j connectivity settings.

As shown in Figure 4, the gas outlet of the elemental analyzer is connected to the second port 2 of the eight-way valve d in the enrichment device, and the fifth port 5 of the eight-way valve d is connected to another carrier gas (helium) sampling line is communicated and set, the fourth port 4 of the eight-way valve d is communicated with the sample port of the gas chromatographic column i, the third port 3 and the sixth port 6 of the eight-way valve d connected to the two ends of the sample tube g respectively. The inner diameter of the sample tube g is 0.6 mm, the wall thickness of the sample tube g is 0.3 mm, the sample ring h is located in the middle of the sample tube g, and is wound 2 turns by the middle of the sample tube g to form a spiral shape with a diameter of 8 cm. The sample loop h is filled with 5A molecular sieves.

As shown in Figure 5, the press-fit connector k is fixed to one end of the open shunt type interface j, and the other end of the open shunt type interface j is fixedly inserted into the second capillary 2# and the third capillary 3 #, the inlet end of the press-fit joint k is fixedly inserted into the outflow end of the gas chromatographic column i (the first capillary 1#), and the inlets of the second capillary 2# and the third capillary 3# inserted side by side are connected with The outlet of the first capillary 1# is arranged oppositely.

(2) On-line analysis of hydrogen isotopes in fluid inclusion water

First, the sample loop h is put into a Dewar bottle equipped with liquid nitrogen, and the communication mode of the eight-way valve d is set to a sampling communication mode. At this time, as shown in FIG. 4(A), the The second port 2 of the eight-way valve d communicates with the third port 3 , the fourth port 4 communicates with the fifth port 5 , the sixth port 6 communicates with the seventh port 7 , and the eighth port 8 communicates with the first port 1 .

Then, 100 mg of the fluid inclusion sample was weighed, sealed with a tin cup, and then the packaged fluid inclusion was placed in the solid autosampler f of the elemental analyzer. Feed the first carrier gas helium and oxygen into the reaction tube filled with 50g chromium powder, wherein the injection flow rate of the first carrier gas helium is 80mL/min, the injection flow rate of oxygen is 20mL/min, control the reaction tube program Heating up, when the temperature in the reaction tube rises to 1000°C, the aforementioned fluid inclusions sealed in a tin cup enter the reaction tube through the solid autosampler according to the procedure, and after injecting oxygen for 30 seconds, close the oxygen injection valve and stop the oxygen injection. During the process of oxygen injection, the fluid inclusions encapsulated in tin cups flashed at a high temperature, and the temperature reached 1800°C. The fluid inclusions fully burst and released the water in the fluid inclusions. Subsequently, the water released from the fluid inclusions contacts the chromium powder filled in the reaction tube at this temperature, and a reduction reaction occurs to generate a mixed gas containing hydrogen, which flows to eight Through valve d. And flow along the path of second interface 2-third interface 3-sample tube g-sixth interface 6-seventh interface 7, and be adsorbed in the pores of the porous material filled in the sample ring h.

When the water in the fluid inclusions has completely reacted and the mixed gas containing hydrogen is no longer generated, turn the switching knob of the eight-way valve d to change the connection mode of the eight-way valve d to the sample connection mode, and remove the Dewar bottle, the mixed gas that is adsorbed in the hole of the porous material filled in the sample ring h is desorbed, and under the carrying of the second carrier gas (the second carrier gas is helium, Injection flow rate is 2mL/min), as shown in Figure 4 (B), along the path of the fifth interface 5-the sixth interface 6-sample tube g-the third interface 3-the fourth interface 4 flows to the gas chromatography column i, through the chromatographic The stationary phase in the column adsorbs and desorbs to separate the hydrogen from the gas mixture. The hydrogen gas separated by the gas chromatography column i flows from the first capillary 1# to the press-fit joint k inlet provided in the open shunt type interface j. The gas flow at the inlet is 2mL/min. The press-fit connector k in the open shunt interface j flows from the third capillary 3# to the ion source of the isotope ratio mass spectrometer at a flow rate of 0.5mL/min, and from the second capillary 2# to the The gas flow rate of helium into the open shunt type interface j is 4mL/min.

Finally, the hydrogen gas prepared from the fluid inclusion water and separated by the gas chromatographic column i enters the ion source of the isotope ratio mass spectrometer through the aforementioned sampling method, and uses an online computer to analyze the composition of hydrogen isotopes in the fluid inclusion water to obtain The hydrogen isotope ratio in the hydrogen gas produced from the fluid inclusion water, thereby obtaining the hydrogen isotope ratio in the measured fluid inclusion water equivalent to the hydrogen isotope ratio in the hydrogen gas produced from the fluid inclusion water. The analysis results are shown in Table 1. The same fluid inclusions of the same weight were weighed, and the above analysis process was repeated 6 times, and the results of each analysis are shown in Table 2.

Example 2

According to the method of Example 1, the instruments and devices required for the on-line analysis of hydrogen isotopes in fluid inclusion water are assembled and the on-line analysis of hydrogen isotopes in fluid inclusion water is carried out. The material for encapsulating the body is a silver cup. The analysis results are shown in Table 1. The same fluid inclusions of the same weight were weighed, and the above analysis process was repeated 6 times, and the results of each analysis are shown in Table 2.

Example 3

According to the method of Example 1, the various instruments and devices required for online analysis of hydrogen isotopes in fluid inclusion water are assembled and the online analysis of hydrogen isotopes in fluid inclusion water is carried out. The difference is that the inner diameter of the sample tube g is 0.5mm , the wall thickness of the sample tube g is 0.2 mm, the sample ring h is located in the middle of the sample tube g, and the middle part of the sample tube g is wound 2 times to form a spiral sample ring h with a diameter of 5 cm. Filled with activated carbon. The analysis results are shown in Table 1. The same fluid inclusions of the same weight were weighed, and the above analysis process was repeated 6 times, and the results of each analysis are shown in Table 2.

Example 4

According to the method of Example 1, the instruments and devices required for online analysis of hydrogen isotopes in fluid inclusion water are assembled and online analysis of hydrogen isotopes in fluid inclusion water is carried out. The difference is that the injection flow rate of the first carrier gas helium is: 90mL/min, the injection flow rate of the second carrier gas helium is 3mL/min. The analysis results are shown in Table 1. The same fluid inclusions of the same weight were weighed, and the above analysis process was repeated 6 times, and the results of each analysis are shown in Table 2.

Example 5

According to the method of Example 1, the various instruments and devices required for the on-line analysis of hydrogen isotopes in fluid inclusion water are assembled and the on-line analysis of hydrogen isotopes in fluid inclusion water is carried out. The difference is that the hydrogen separated by gas chromatographic column i is obtained by The first capillary 1# flows to the gas flow at the inlet of the press-fit connector k provided in the open split-flow interface j is 3mL/min, and the hydrogen separated in step (III) is connected through the press-fit connection in the open split-flow interface j The gas flow rate of head k flowing from the third capillary 3# to the ion source of the isotope ratio mass spectrometer is 0.6mL/min, and helium gas is passed into the open split flow interface j from the second capillary 2# The gas flow rate is 3mL/min. The analysis results are shown in Table 1. The same fluid inclusions of the same weight were weighed, and the above analysis process was repeated 6 times, and the results of each analysis are shown in Table 2.

Comparative example 1

According to the method of Example 1, the instruments and devices required for online analysis of hydrogen isotopes in fluid inclusion water are assembled and online analysis of hydrogen isotopes in fluid inclusion water is carried out. The difference is that the gas chromatographic column i and the isotope ratio mass spectrometer pass Conflo-type interface connection, and no enrichment device is used to enrich the hydrogen-containing mixed gas obtained from the water released by the bursting of fluid inclusions and the reduction reaction. The schematic diagram of the analysis device is shown in Figure 2, which is separated by gas chromatography column i The hydrogen gas flows to the isotope ratio mass spectrometer at a flow rate of 80mL/min, of which 72mL/min hydrogen gas is shunted away, and only the remaining 8mL/min hydrogen gas enters the open split type interface j (open split) of ConFlo, where it is connected with another One path of helium gas is mixed, and then a capillary tube introduces the sample gas into the ion source through the pressure difference inside and outside the ion source. At this time, the gas flow rate in the capillary tube is 0.5mL/min. The amount of fluid inclusions and analysis results are shown in Table 1. The same fluid inclusions of the same weight were weighed, and the above analysis process was repeated 6 times, and the results of each analysis are shown in Table 2.

Comparative example 2

According to the method disclosed in the invention patent CN104181245B, the hydrogen isotope in the fluid inclusion water was analyzed, and the amount of fluid inclusion and the analysis results are shown in Table 1. The same fluid inclusions of the same weight were weighed, and the above analysis process was repeated 6 times, and the results of each analysis are shown in Table 2.

Table 1

Example number Fluid inclusion dosage δD _SA-VSMOW analysis time Example 1 100mg -66.1‰ 7min Example 2 100mg -66.2‰ 5min Example 3 100mg -66.7‰ 6min Example 4 100mg -65.8‰ 9min Example 5 100mg -65.9‰ 8min Comparative example 1 2g -60.3‰ 20min Comparative example 2 2.5g -70.2‰ 120min

Table 2

As can be seen from the results in Table 1 and Table 2, the method provided by the present invention can improve the quality of hydrogen isotope testing of solid samples, making it suitable for the analysis of hydrogen isotopes in trace fluid inclusion water, and can meet the requirements of mass spectrometer ion sources. The requirement of gas flow rate can also send the generated sample gas to the isotope ratio mass spectrometer to the maximum extent, greatly reducing the detection limit of the instrument, and effectively reducing the fluid inclusions under the premise of ensuring accuracy, accuracy and reproducibility. The amount of sample required for hydrogen isotope analysis in water, the entire analysis process can be completed within 5-10 minutes, realizing the rapid analysis of hydrogen isotope in micro fluid inclusion water.

The preferred embodiments of the present invention have been described in detail above, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims (15)

1. a kind of method of hydrogen isotope in on-line analysis fluid inclusion water, which is characterized in that the method includes following steps Suddenly：

(I) in the reaction tube for being filled with chromium powder, so that the water in fluid inclusion is discharged using dynamic flash burn method and aoxidized Reduction reaction generates the gaseous mixture containing hydrogen；

(II) enriching apparatus is used to be enriched with the gaseous mixture containing hydrogen generated in step (I)；

(III) gas chromatographic column (i) is utilized to isolate hydrogen in the gaseous mixture containing hydrogen of enrichment from step (II)；

(IV) hydrogen for isolating step (III) by open split type interface (j) import isotope-ratio mass spectrometer from Component carries out the analysis of hydrogen isotope in fluid inclusion water and obtains hydrogen isotope ratio,

Wherein, the enriching apparatus includes eight ways valve (d), sample cell (g) and cooling pit, and the eight ways valve (d), which is provided with, to be used for The interface of the gaseous mixture containing hydrogen generated in receiving step (I), the mixing containing hydrogen for step (II) to be enriched with Gas is exported to the interface of gas chromatographic column (i) and the interface for being connected to setting with the both ends of the sample cell (g), and described eight is logical Valve (d) is additionally provided with switch knob, two kinds of mode of communicating of sampling and sample introduction for switching the eight ways valve (d), the sample It is provided with helical form sample loop (h) on pipe (g), is filled with porous material in the sample loop (h), the sample loop (h) is with energy It is freely put into or removal method is arranged in cooling pit, press-fit connector is provided in the open split type interface (j) (k),

In step (I), the process for making the water in fluid inclusion discharge using dynamic flash burn method includes：Use tin can or silver Cup is packaged fluid inclusion, and then the packaged fluid inclusion enters reaction tube through solid autosampler In, the temperature of the reaction tube is controlled to 900-1100 DEG C, in the presence of the first carrier gas, is carried out flash burn, is made fluid inclusion By thermal spalling, and release the water in fluid inclusion.

2. according to the method described in claim 1, wherein, in step (I), first carrier gas is with the flow of 80-100mL/min Inject reaction tube.

3. according to the method described in claim 1, wherein, in step (I), the process of the dynamic flash burn is under conditions of noting oxygen It carries out.

4. according to the method described in claim 3, wherein, the condition of the note oxygen includes：Note oxygen flow is 15-30mL/min, The note oxygen time is 20-60s, and flash ignition temperature reaches 1700-1800 DEG C.

5. according to the method described in claim 1, wherein, in step (I), the process of the redox reaction includes：Adding Under conditions of heat, the water that fluid inclusion discharges is made to be contacted with the chromium powder loaded in reaction tube.

6. according to the method described in claim 5, wherein, the condition of the heating includes：Heating temperature is 900-1100 DEG C, is added The hot time is 5-12min.

7. according to the method described in claim 5, wherein, the weight of the amount of fill of the chromium powder and the dosage of the fluid inclusion Amount is than being 500-1500：1.

8. according to the method described in claim 1, wherein, the cooling pit is the Dewar bottle equipped with coolant.

9. according to the method described in claim 8, wherein, the coolant is liquid nitrogen.

10. according to the method described in claim 1, wherein, the internal diameter of the sample cell (g) is 0.4-0.8mm, wall thickness 0.2- 0.5mm, the sample loop (h) are located at the middle part of sample cell (g), are enclosed by winding 1-3 in the middle part of sample cell (g) and form a diameter of 4- The helical form sample loop (h) of 10cm.

11. according to the method described in claim 1, wherein, the eight ways valve (d) is provided with first interface (1)~the 8th interface (8), each interface interface adjacent thereto selects a connection, when the eight ways valve (d) is connected in a manner of sampling or sample introduction respectively, The connected relation of each interface of the eight ways valve (d) is respectively：

When the mode of communicating of the eight ways valve (d) is sampling mode of communicating, second interface (2) is connected to third interface (3), the Four interfaces (4) are connected to the 5th interface (5), and the 6th interface (6) is connected to the 7th interface (7), the 8th interface (8) and first interface (1) it is connected to；

When the mode of communicating of the eight ways valve (d) is sample introduction mode of communicating, second interface (2) is connected to first interface (1), the Four interfaces (4) are connected to third interface (3), and the 6th interface (6) is connected to the 5th interface (5), the 8th interface (8) and the 7th interface (7) it is connected to.

12. method according to claim 1 or claim 7, wherein in step (II), to what is generated in step (I) containing hydrogen The process that gaseous mixture is enriched with includes：The mode of communicating of the eight ways valve (d) is set to sampling mode of communicating, by the sample Product ring (h) is put into cooling pit, makes the gaseous mixture containing hydrogen generated in step (I) under the carrying of the first carrier gas, along the Two interfaces (2)-six interface of third interface (3)-sample cell (g)-the (6)-the seven interface (7) path flowing, and it is attracted to dress Have in the sample loop (h) of porous material.

13. method according to claim 1 or claim 7, wherein in step (III), contain hydrogen from what is be enriched in step (II) Gaseous mixture in isolate the process of hydrogen and include：When step (I) no longer generates the gaseous mixture containing hydrogen, eight ways valve is rotated (d) switch knob makes the mode of communicating of the eight ways valve (d) become sample introduction mode of communicating, removes cooling pit, makes to be adsorbed on dress There is the gaseous mixture desorption containing hydrogen in the sample loop (h) of porous material, and under the carrying of the second carrier gas, along the 5th interface (5)-the six interfaces (6)-sample cell (g)-third interface (3)-the four interface (4) path flows to gas chromatographic column, through gas phase color Stationary phase absorption and the desorption in column are composed, hydrogen is detached from gaseous mixture.

14. according to the method for claim 13, wherein the flow of second carrier gas is 1-3mL/min.

15. according to the method described in claim 1, wherein, in step (IV), the hydrogen that step (III) is isolated passes through opening During bypass type interface (j) imports the ion source of isotope-ratio mass spectrometer, the hydrogen that step (III) is isolated flows through out The flow of mouth inlet bypass type interface (j) is 1-3mL/min, and the hydrogen that step (III) is isolated is through open split type interface (j) flow that the press-fit connector (k) in flows to the ion source of the isotope-ratio mass spectrometer is 0.3-0.8mL/min.