CN112629985A

CN112629985A - Isotope sample purification and collection preparation system and method and application thereof

Info

Publication number: CN112629985A
Application number: CN201910920116.XA
Authority: CN
Inventors: 孙维贞; 王肖波; 郭新磊; 田春桃; 余海棠; 王羿涵; 李传金; 赵雪茹
Original assignee: Cold and Arid Regions Environmental and Engineering Research Institute of CAS
Current assignee: Cold and Arid Regions Environmental and Engineering Research Institute of CAS
Priority date: 2019-09-24
Filing date: 2019-09-26
Publication date: 2021-04-09
Also published as: DE112020000037T5; WO2021056943A1

Abstract

The invention discloses a system and a method for purifying, collecting and preparing isotope samples, wherein the system for purifying, collecting and preparing isotope samples sequentially comprises a sample introduction unit, a VOC trap, an adsorption trap group, a liquid nitrogen cold trap, a liquid nitrogen enrichment trap, a chromatographic column, a purification re-enrichment trap and a sample collection pipe which are communicated through pipelines, and the method for purifying, collecting and preparing isotope samples comprises the following steps: the purification and enrichment process comprises the following steps: step 1, introducing a sample through a sample introduction unit, and sequentially introducing a gas sample into a VOC trap to remove water and VOC components; and 2, delivering the sample in the liquid nitrogen enrichment trap into the chromatographic column GC by the carrier gas introduced into the second carrier gas supply pipeline, and separating in the chromatographic column GC according to different retention times. Transferring, enriching and collecting processes: step 1, cutting off a pipeline for communicating the purification and re-enrichment trap with the chromatographic column, and discharging carrier gas introduced into the third carrier gas supply pipeline from the sample discharge pipeline after the carrier gas passes through the purification and re-enrichment trap and the communication pipeline thereof; vacuumizing a communicating pipeline of the purification re-enrichment trap and the sample collecting pipe through a vacuum pipeline so as to discharge impurity gas and carrier gas; and diffusing the target gas enriched in the purification and re-enrichment trap into the sample collection tube.

Description

Isotope sample purification and collection preparation system and method and application thereof

Technical Field

The invention relates to the technical field of isotope detection, in particular to an isotope sample purification, collection and preparation system, a method and application thereof.

Background

The development of isotope theory and mass spectrometer from one-dimensional to one-dimensional isotope measurement becomes a milestone in the method of single element stable isotope system, and is applied to exploring many subjects of celestial chemistry, geochemistry, geology, biology and the like. In the beginning of this century, a new visual angle of isotope research, namely cluster isotope geochemistry, was introduced, which researches the geochemistry behavior of an isotope body from the angle of isotope combination, can obtain information which cannot be provided by the traditional isotope for the research of the overall composition, and is a revolutionary technology with great potential after the traditional stable isotope. In particular, the advent of MAT 253-ultra (thermo Fisher) and Panoroma (Nu instruments) analytical equipment has advanced the isotope analysis techniques from the determination of simple molecules to molecular isotope analysis, such as the determination of the isotopic ratio of molecular clusters and specific sites in molecules.

However, advanced mass spectrometers must also prepare or convert the original sample (inorganic or complex organic) into a pure gas such as N by various methods₂、O₂、H₂、CO₂、SO₂、N₂O、CH₄And the corresponding isotope detection can be carried out in the mass spectrum, so that the pretreatment technology of the sample and a matched pretreatment device become the key for successful mass spectrum detection. The pure gas is obtained through a complicated impurity removal process, and trace gas is required to be enriched and separated, and target gas is required to be collected and converted.

The collection of samples from different sources and different target gases corresponds to different pretreatment methods, and the international collection of the methane cluster isotope (I) is¹³CH₃D and¹²CH₂D₂) Analytical techniques have become an important detection tool for natural gas research following carbonates. The detection technology of the methane binary isotope mainly aims at2 isotopologues (18) with mass-to-charge ratio in the isotopologues of methane¹³CH₃D and¹²CH₂D₂) The detection was carried out because these two isotopologues of methane have 2 heavy isotopic substitutions (also called cluster isotopes), and their relative abundance was very low (6.92 x 10, respectively)^-6And 1.44 x 10^-7) Firstly, a mass spectrometer is required to have extremely high sensitivity and extremely high precision in order to accurately obtain the abundance condition of the mass spectrometer; at the same time, the sample is required to have extremely high purity,to avoid any interference of other substances to achieve good mass spectrum separation.

At present, large-scale high-resolution double-focusing stable isotope mass spectra have high resolution, such as MAT253Ultra (Thermo Scientific) and Panorama (NU) mass spectra, the resolution of the mass spectra can reach-27000), and the mass spectra can be used for methane cluster isotopes¹³CH₃D and¹²CH₂D₂was tested for total concentration (expressed as Δ 18); the resolution of the latter can reach 40000, and the product can be used in methane binary isotope¹³CH₃D and¹²CH₂D₂the concentrations of (a) and (b) were measured separately. Due to very low natural abundance in methane¹³CH₃D and¹²CH₂D₂the whole molecular weight is 18amu, and after the methane sample enters the mass spectrometer and is ionized, atoms in the ion source are combined into corresponding ions with certain probability if water molecules, oxygen atoms (from oxygen and oxygen-containing compounds), nitrogen atoms (from nitrogen and nitrogen-containing compounds), hydrogen atoms (other than methane) and carbon atoms (other than carbon, nitrogen and oxygen atoms are combined to form interference ions), carbon atoms (other than methane) and argon atoms (isotopes) exist in the sample³⁶Doubly charged ions of Ar) and the like, which have a mass number of about 18amu, will seriously interfere with the binary isotope of methane¹³CH₃D and¹²CH₂D₂the gas purity was accurately tested.

Accurate determination is a very challenging task because of the low relative abundance of the isotopic molecules of the methane cluster and the high interference of other substances. At present, the empire academy of science and engineering and the Protium company develop a set of automatic purification system (IBEX), which mainly works according to the following principle: removal of H from methane in a liquid helium environment at a temperature range of 10K to 320K using ultra-low temperature helium refrigeration pumps₂，He，CO₂，O₂，N₂And (3) waiting for impurity gases, then heating and releasing the frozen methane, transferring the methane into a sample tube filled with a 5A molecular sieve by using liquid nitrogen, sealing by burning, and then heating and releasing the methane to finish measurement on a mass spectrum. The liquid helium refrigeration pump used in the system is expensive to maintain; and the system has not yetThe commercial production is realized; in addition, the system only gives an index after methane purification: the inner precision of the delta 18 is 0.4 per mill.

In addition, the sample injection and collection process of different amounts of samples have different requirements, and for a large amount of samples (such as petroleum and natural gas) and a small amount of samples (such as rare samples collected in cold regions (south poles or north poles)), the sample injection mode and the collection mode need to be distinguished, and the existing purification and collection preparation system cannot meet the requirements of the two modes at the same time.

Therefore, a set of sample purification and collection preparation system for binary isotope detection needs to be established to ensure that all possibly existing interference item ions are removed before sample gas enters mass spectrometry, and a rare sample is enriched to realize accurate detection of an isotope compound, and meanwhile, the system can be applied to methane binary isotope detection¹³CH₃D and¹²CH₂D₂and (4) during detection.

Disclosure of Invention

The invention aims to solve the problem that isotope samples in the prior art need high purity in mass spectrum detection, and provides an isotope sample purification, collection and preparation system, wherein a corresponding isotope purification and enrichment device and an isotope mass spectrometer are in online connection, for small samples, a sample can be injected through an injector sample injection unit, and then enriched after GC, and enters the mass spectrometer for analysis after being enriched in a sample bottle, and the samples can be detected in batches after enrichment.

Another object of the present invention is to provide the use of the isotope sample purification and collection preparation system in isotope detection, which can accomplish methane detection¹³C-D(¹³CH₃D、¹³CH₂D₂、¹³CHD₃、¹³CD₄) Isotope detection provides technical support for oil exploration, deep land resource exploration, global climate change and water resource evaluation, and can also be applied to the isotope detectionIn the purification and collection of the isotope, the technique is used for expanding cluster isotope monitoring of various greenhouse gases in tripolar regions (south pole, north pole and Qinghai-Tibet plateau).

The invention also aims to provide a preparation method for purifying and collecting isotope samples, and the method for purifying methane can achieve the following main technical indexes: the inner precision of delta 18 is 0.3 per thousand, the inner precision of delta 13CH3D is 0.4 per thousand, and the outer precision of methane is as follows: Δ 18 is 2% o, and Δ 13CH3D is 2.5% o.

The technical scheme adopted for realizing the purpose of the invention is as follows:

the utility model provides an isotope sample purification and collection preparation system, includes sample introduction unit, VOC trap, adsorption trap group, liquid nitrogen cold trap, liquid nitrogen enrichment trap, chromatographic column, purification enrichment trap and the sample collection pipe that loop through the pipeline and are linked together, wherein:

the inlet of the VOC trap is connected with a first carrier gas supply pipeline, and the outlet of the VOC trap is connected with a discharge pipeline to discharge the frozen water and the VOC components in the VOC trap;

a carrier gas purging pipeline is arranged on a pipeline connecting the adsorption trap group and the liquid nitrogen cold trap, wherein the carrier gas purging pipeline comprises a zeroth carrier gas supply pipeline for supplying carrier gas to an inlet of the adsorption trap group and an impurity gas discharge pipeline connected to an outlet of the liquid nitrogen cold trap;

the outlet of the liquid nitrogen enrichment trap is connected with a permanent gas discharge pipe so as to discharge permanent gas (such as gas components of nitrogen, oxygen, hydrogen, argon and the like) which cannot be condensed in the liquid nitrogen enrichment trap;

the inlet of the liquid nitrogen enrichment trap is connected with a second carrier gas supply pipeline, during sampling, carrier gas introduced by the second carrier gas supply pipeline sends the sample enriched in the liquid nitrogen enrichment trap into the inlet of the chromatographic column, the outlet of the chromatographic column is respectively connected with a heavy gas discharge pipeline and a purification and re-enrichment trap, the heavy gas discharge pipeline is used for discharging impurity gas with retention time after the target gas, for example, after methane is purified, ethane and ethylene which may be doped in methane have retention time after the methane, and after methane extraction is completed, other impurities are discharged through the heavy gas discharge pipeline;

the inlet of the purification and re-enrichment trap is connected with a third carrier gas supply pipeline, the outlet of the purification and re-enrichment trap is respectively communicated with a sample collecting pipe and a sample discharge pipeline, the sample collecting pipe is positioned in the sample collecting trap, and the outlet of the sample collecting pipe is connected with a vacuum pipeline for removing impurity gas and carrier gas.

In the above technical scheme, the zeroth carrier gas supply pipeline is connected to the inlet of the adsorption trap group, or the zeroth carrier gas supply pipeline is connected to the sample introduction unit, and the sample introduction unit is communicated with the inlet of the adsorption trap group through a pipeline.

In the above technical scheme, the sample injection unit is an injector sample injection unit and/or a steel cylinder sample injection unit.

In the technical scheme, the injector sample injection unit comprises an injection sample injector communicated with the VOC trap through a pipeline, and the zeroth carrier gas supply pipeline is connected to the injection sample injector; the steel bottle advance kind unit include through the connecting tube with the natural gas sample steel bottle that the VOC trap is linked together, be equipped with the steel bottle manometer of reducing pressure on the connecting tube.

In the above technical solution, the adsorption trap group at least includes a CO oxidation trap and an acid gas adsorption trap.

In the technical scheme, a verification enrichment trap is arranged on a pipeline between the liquid nitrogen enrichment trap and the chromatographic column to verify whether a sample in the liquid nitrogen enrichment trap is completely enriched, particularly for an unknown sample to be detected, the lengths of pipelines connected with the liquid nitrogen cold trap and the liquid nitrogen enrichment trap in the early stage and the flow rate of a carrier gas can be verified to be matched through the verification enrichment trap, and the adjustment is carried out in time until no methane target gas is released in the verification enrichment trap, so that the set parameters of the liquid nitrogen cold trap and the liquid nitrogen enrichment trap are reasonable.

In the above technical scheme, the vacuum pipeline comprises a primary vacuum pipeline communicated with the dry pump and a secondary vacuum pipeline communicated with the molecular pump.

In another aspect of the invention, the isotope sample purification and collection preparation system is in methane¹³C-D(¹³CH₃D、¹³CH₂D₂、¹³CHD₃、¹³CD₄) Use in isotope detection.

In another aspect of the present invention, the purification and collection method of the isotope sample purification and collection preparation system includes the steps of:

the purification and enrichment process comprises the following steps:

step 1, introducing a sample through a sample introduction unit, sequentially introducing a gas sample into a VOC trap to remove water and VOC components, introducing the gas sample into an adsorption trap group to remove impurity gas, introducing the gas sample into a liquid nitrogen cold trap to remove impurities with boiling points higher than that of target gas, and finally introducing the gas sample into a liquid nitrogen enrichment trap to be enriched, wherein other non-condensable impurity gases are discharged through a permanent gas discharge pipe;

and 2, the carrier gas introduced into the second carrier gas supply pipeline sends the sample in the liquid nitrogen enrichment trap into the chromatographic column GC, the sample is separated in the chromatographic column GC according to different retention times, the separated target gas is enriched in the purification and re-enrichment trap, and impurities except the target gas are discharged through a heavy gas discharge pipeline.

Transferring, enriching and collecting processes:

step 1, cutting off a pipeline for communicating the purification and re-enrichment trap with the chromatographic column, and discharging carrier gas introduced into the third carrier gas supply pipeline from the sample discharge pipeline for pipeline purging after the carrier gas passes through the purification and re-enrichment trap and the communication pipeline thereof;

step 2, vacuumizing a communicating pipeline of the purification re-enrichment trap and the sample collecting pipe through a vacuum pipeline so as to discharge impurity gas and carrier gas;

and 3, diffusing the target gas enriched in the purification and re-enrichment trap into the sample collection tube.

In the above technical solution, in step 1 of the transfer re-enrichment collection process, the third carrier gas completely transfers and enriches the target gas while purging the pipeline, and is stored in the purification re-enrichment trap.

In the technical scheme, when the communicating pipeline of the purification re-enrichment trap and the sample collecting pipe is vacuumized, the dry pump is firstly used for vacuumizing to discharge impurity gas, and then the molecular pump is used for vacuumizing to discharge carrier gas.

In the above technical solution, during or after the transfer and re-enrichment collection process, the cleaning of the front pipeline of the chromatographic column may be performed, including:

(1) and (3) recovering the function of the VOC trap: raising the temperature of the VOC trap T1, introducing carrier gas into a first carrier gas supply pipeline, and discharging water and VOC components remained in the VOC trap through a discharge pipeline;

(2) purging an adsorption trap group and a liquid nitrogen cold trap: introducing carrier gas into the zeroth carrier gas supply pipeline, and discharging the carrier gas from the impurity gas discharge pipeline after passing through the adsorption trap group and the liquid nitrogen cold trap;

an isotope sample purification and collection preparation system, comprising a sample introduction unit, a first switching valve (valcoB), a VOC trap, an adsorption trap group, a liquid nitrogen cold trap, a second switching valve (valcoC), a chromatographic column, a third switching valve (valcoD) and a purification re-enrichment trap, wherein:

a zeroth carrier gas supply pipeline is connected to the sample injection unit;

the port of the first conversion valve is respectively connected with a sample introduction pipeline, a sample introduction port of a VOC trap, a sample outlet of the VOC trap, a sample introduction port of an adsorption trap group, a first carrier gas supply pipeline and a discharge pipeline through pipelines, the sample introduction pipeline is communicated with a sample introduction unit, when the first conversion valve is in a sampling state (load), the sample introduction ports of the sample introduction pipeline, the VOC trap and the adsorption trap group are sequentially communicated, the first carrier gas supply pipeline is communicated with the discharge pipeline, when the first conversion valve is in a sample introduction state (inject), the sample introduction pipeline is communicated with the adsorption trap group, the first carrier gas supply pipeline, the VOC trap and the discharge pipeline are sequentially communicated, the first carrier gas supply pipeline is communicated with the sample introduction port of the VOC trap, and the sample outlet of the VOC trap is communicated with the discharge pipeline;

the appearance mouth that goes out of absorption trap group pass through the pipeline with the inlet port of liquid nitrogen cold-trap is linked together, the port of second change-over valve respectively the pipeline with the appearance mouth of liquid nitrogen cold-trap, the inlet port and the appearance mouth of liquid nitrogen enrichment trap, the second carrier gas supply tube way, the inlet port and the foreign gas discharge pipeline of chromatographic column are linked together, wherein: when the second switching valve is in a sampling state (load), the liquid nitrogen cold trap and the liquid nitrogen enrichment trap are sequentially communicated with an impurity gas discharge pipeline, a sample inlet of the liquid nitrogen cold trap is communicated with a sample outlet of the adsorption trap group, the sample outlet of the liquid nitrogen cold trap is communicated with the sample inlet of the liquid nitrogen enrichment trap, the sample outlet of the liquid nitrogen enrichment trap is communicated with the impurity gas discharge pipe, the second carrier gas supply pipeline is communicated with a sample inlet of the chromatographic column, when the second switching valve is in a sample inlet state (inject), the sample outlet of the liquid nitrogen cold trap is communicated with the impurity gas discharge pipeline, the second carrier gas supply pipeline is sequentially communicated with the liquid nitrogen enrichment trap and the sample inlet of the chromatographic column, the second carrier gas supply pipeline is communicated with the sample inlet of the liquid nitrogen enrichment trap, and the sample outlet of the liquid nitrogen enrichment trap is communicated with the sample inlet of the chromatographic column;

the port of the third conversion valve is respectively communicated with the sample outlet of the chromatographic column, the sample inlet of the purification re-enrichment trap, the third carrier gas supply pipeline and the heavy gas discharge pipeline through pipelines, wherein: when the third switching valve is in a sampling state, the sample outlet of the chromatographic column is communicated with the sample inlet of the purification and re-enrichment trap, the third gas-carrying supply pipeline is communicated with the heavy gas discharge pipeline, when the third switching valve is in a sample inlet state, the sample outlet of the chromatographic column is communicated with the heavy gas discharge pipeline, and the third gas-carrying supply pipeline is communicated with the sample inlet of the purification and re-enrichment trap;

the sample outlet of the purification and re-enrichment trap is respectively communicated with a sample discharge pipeline and a sample collecting pipe through pipelines, wherein the sample collecting pipe is positioned in the sample collecting trap providing a low-temperature environment, and the sample collecting pipe is connected with a vacuum pipeline used for removing carrier gas and miscellaneous gas.

In the above technical solution, the sample injection unit comprises an injection sample injector, a natural gas sample steel cylinder and a change-over valve (ValcoA), wherein the port of the conversion valve is respectively communicated with the sample outlet of the injection sample injector, the sample outlet of the natural gas sample steel cylinder, the exhaust pipeline and the inlet of the first conversion valve through pipelines, when the switching valve is in a sampling state (when the sample amount is small (load)), the sample outlet of the injection sample injector is communicated with the inlet of the sample introduction pipeline (first switching valve), the sample outlet of the natural gas sample steel cylinder is communicated with the exhaust pipeline, when the change-over valve is in a sample introduction state (when the sample amount is larger (inject)), the outlet of the natural gas sample steel cylinder is communicated with the inlet of the sample injection pipeline (a first conversion valve), and the outlet of the injection sample injector is communicated with the exhaust pipeline. In the above technical solution, the adsorption trap group at least includes a CO adsorption trap and an acid gas adsorption trap.

In the technical scheme, a verification enrichment trap is arranged on a pipeline between the liquid nitrogen enrichment trap and the chromatographic column to verify whether the sample in the liquid nitrogen enrichment trap is completely enriched, a sample outlet of the liquid nitrogen enrichment trap is connected with a sample inlet of the verification enrichment trap, and a sample outlet of the verification enrichment trap is connected with a sample inlet of the liquid nitrogen enrichment trap.

In the above technical scheme, the vacuum pipeline comprises a primary vacuum pipeline communicated with the dry pump and a secondary vacuum pipeline communicated with the molecular pump so as to remove miscellaneous gases and carrier gases in the pipeline.

In another aspect of the present invention, the purification and collection method further comprising the isotope sample purification and collection preparation system comprises the steps of:

the purification and enrichment process comprises the following steps:

step 1, a first conversion valve and a second conversion valve are in a sampling state, and gas samples sequentially enter a VOC trap to remove water and VOC components; the gas enters an adsorption trap group to remove impurity gas, enters a liquid nitrogen cold trap to remove impurities with boiling points higher than that of target gas, finally enters a liquid nitrogen enrichment trap to be enriched, and other non-condensable impurity gases are discharged through a permanent gas discharge pipeline;

and 2, the second switching valve is in a sample introduction state, the carrier gas introduced into the second carrier gas supply pipeline sends the sample in the liquid nitrogen enrichment trap into the chromatographic column GC, the sample is separated in the chromatographic column GC according to different retention times of different component gases, the third switching valve is in a sampling state when the target gas flows out, the separated target gas is enriched in the purification and enrichment trap, and the third switching valve is in a sample introduction state and is discharged through a heavy gas discharge pipeline when the heavy gas with the retention time behind the target gas flows out.

Transferring, enriching and collecting processes:

the third conversion valve is in a sample injection state:

step 1, the carrier gas introduced into the third carrier gas supply pipeline passes through the purification and re-enrichment trap and the communication pipeline thereof, and is discharged from the sample discharge pipeline, and the purification and re-enrichment trap and the communication pipeline thereof are purged;

In the technical scheme, when the purification re-enrichment trap and the sample collection pipe are vacuumized, the dry pump is firstly used for vacuumizing to discharge impurity gas, and then the molecular pump is used for vacuumizing to discharge the impurity gas and carrier gas.

In the above technical solution, the method further comprises:

(1) the first conversion valve is in a sample injection state: a carrier gas is introduced into the first carrier gas supply pipeline, and water and VOC components remained in the VOC trap T1 are discharged through a discharge pipeline;

(2) the first switching valve is in a sampling state: introducing carrier gas into the zeroth carrier gas supply pipeline, and discharging impurities remained in the adsorption trap group, the liquid nitrogen cold trap and the liquid nitrogen enrichment trap from the impurity gas discharge pipeline;

an isotope sample purification and collection preparation system comprises a two-position four-way valve A, a two-position six-way valve B, a two-position six-way valve C, a two-position four-way valve D, VOC trap T1, an adsorption trap T2, an adsorption trap T3, a chemical trap T4, a liquid nitrogen cold trap T5, a liquid nitrogen enrichment trap T6, a verification enrichment trap T7, a purification re-enrichment trap T8 and a sample collection trap T9, wherein:

the two-position four-way valve A is provided with four hole sites of a1, a2, a3 and a4, the a2 is communicated with a natural gas sample steel bottle through a connecting pipeline, the a4 is communicated with an injection sample injector through a pipeline, the injection sample injector is provided with a GC sample inlet, the injection sample injector is provided with a zero carrier gas input pipeline, and the a1 is communicated with an exhaust pipeline;

the two-position six-way valve B is provided with six hole sites B1, B2, B3, B4, B5 and B6, the B2 is communicated with the a3 through a pipeline, the B3 is communicated with an inlet of a VOC trap T1 through a pipeline, an outlet of the VOC trap T1 is communicated with B6 through a pipeline, the B1 is communicated with an inlet of a liquid nitrogen cold trap T5 through an impurity removing pipeline, the impurity removing pipeline is sequentially connected with an adsorption trap T2, an adsorption trap T3 and a chemical trap T4, the B4 is connected with a first load gas input pipeline, and the B5 is connected with a discharge pipeline;

the two-position six-way valve C is provided with six hole sites of C1, C2, C3, C4, C5 and C6, the outlet of the liquid nitrogen cold trap T5 is communicated with the C2 through a pipeline, the C3 is communicated with the inlet of the liquid nitrogen enrichment trap T6 through a pipeline, the outlet of the liquid nitrogen enrichment trap T6 is communicated with the inlet of the verification enrichment trap T7 through a pipeline, the outlet of the verification enrichment trap T7 is communicated with the C6 through a pipeline, the C1 is connected with an impurity gas discharge pipeline, the C4 is communicated with a second load gas input pipeline, and the C5 is communicated with the inlet of a chromatographic column GC8 through a pipeline;

the two-position four-way valve D is provided with four hole sites of D1, D2, D3 and D4, the D1 is communicated with the outlet of a chromatographic column GC through a pipeline, the D2 is communicated with the inlet of a purification re-enrichment trap T8 through an enrichment pipeline, the D3 is communicated with a third load gas input pipeline, the D4 is communicated with a heavy gas discharge pipe, a switch valve V1 is arranged on the enrichment pipeline, the outlet of the purification re-enrichment trap T8 is communicated with the inlet of a sample collection trap T9 through a pipeline, the sample collection trap T9 is respectively communicated with a sample discharge pipeline and a collection pipeline through a communication pipeline, a switch valve V2 is arranged on the communication pipeline, a switch valve V3 is arranged on the sample discharge pipeline, a switch valve V4 is arranged on the collection pipeline, the collection pipeline is respectively communicated with a vacuum branch pipe and a collection branch pipe, the vacuum branch pipe is connected with a vacuum source, a switch valve V5 and a switch valve V10 are arranged on, the tail ends of the collecting branch pipes are connected with sample collecting pipes, and the sample collecting pipes are positioned in the sample collecting traps.

In the above technical scheme, low vacuum gauge P1 is connected on vacuum branch pipe through first connecting tube, be equipped with ooff valve V8 on the first connecting tube, the dry pump passes through the second connecting tube to be connected on the vacuum branch pipe, be equipped with ooff valve V6 on the second connecting tube, high vacuum gauge P2 is connected through the third connecting tube on the vacuum branch pipe, be equipped with ooff valve V9 on the third connecting tube, the molecular pump passes through the fourth connecting tube to be connected on the vacuum branch pipe, be equipped with ooff valve V7 on the fourth connecting tube.

In the technical scheme, the connecting pipeline is provided with a steel cylinder decompression meter.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention completes the sample purification, collection and preparation of the methane binary isotope detection by the functions of impurity removal, enrichment, purification, transfer, carrier gas release, collection and the like of the collected gas sample. Each component in the system is reasonable in design and convenient to operate, and the sample gas is purified and collected together by aggregation.

2. The invention can simultaneously accommodate the sample introduction modes of two source samples, namely injection type sample introduction and steel cylinder type sample introduction, and the two modes are freely switched through the valve body, so that the taking and the use are convenient and the applicability is strong.

3. The collected methane gas can be in a manual sample injection mode or an online automatic sample injection mode and is butted with a double-path sample injection system of an isotope mass spectrometer, so that the binary isotope of methane is realized¹³CH₃D and¹²CH₂D₂Δ 18 and Δ 13CH₃D, analyzing and detecting.

4. The invention has simple principle, integrates the functions of sampling, adsorption, separation, enrichment, purification, transfer, collection and the like on the structural design, ensures that the test flow of the sample is simple and convenient, has convenient operation, can effectively improve the accuracy of the test value, and is a set of sample preparation system with scientific research significance and strong pertinence. Has good use and popularization value.

Drawings

Fig. 1 is a system block diagram of embodiment 1 of the present invention.

FIG. 2 is a piping connection diagram in example 1 of the present invention.

FIG. 3 is a diagram showing the state of enrichment of a methane sample in example 2 of the present invention.

FIG. 4 is a diagram showing a state of purification transfer collection of a methane sample according to example 2 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

An isotope sample purification and collection preparation system comprises a sample introduction unit, a VOC trap T1, an adsorption trap T2, an adsorption trap T3, a chemical trap T4, a liquid nitrogen cold trap T5, a liquid nitrogen enrichment trap T6, a verification enrichment trap T7, a chromatographic column GC, a purification re-enrichment trap T8 and a sample collection trap T9 which are sequentially communicated through pipelines, wherein:

the inlet of the sample introduction unit is connected with a GC sample introduction port 1 and a zeroth carrier gas supply pipeline, the GC sample introduction port 1 is provided with a switch valve V24, and the zeroth carrier gas supply pipeline is provided with a switch valve V23;

the outlet of the sample introduction unit is communicated with the inlet of the VOC trap T1 through a first pipeline, a switch valve V11 is arranged on the first pipeline, the outlet of the sample introduction unit is communicated with the inlet of the adsorption trap T2 through a second pipeline, and a switch valve V12 is arranged on the second pipeline;

the inlet of the VOC trap T1 is connected with a first carrier gas supply pipeline, and the outlet is connected with a discharge pipeline to discharge the frozen water and the VOC components in the VOC trap; a switch valve V13 is arranged on the first carrier gas supply pipeline, and a V14 is arranged on the discharge pipeline;

a carrier gas purging pipeline is arranged on a pipeline connected with the adsorption trap T2, the adsorption trap T3, the chemical trap T4 and the liquid nitrogen cold trap T5, wherein the carrier gas purging pipeline comprises a zeroth carrier gas supply pipeline and an impurity gas discharge pipeline connected to an outlet of the liquid nitrogen cold trap T5, and a switch valve V15 is arranged on the impurity gas discharge pipeline;

a switching valve V16 is arranged on a pipeline between the liquid nitrogen cold trap T5 and the liquid nitrogen enrichment trap T6, a second carrier gas supply pipeline is connected to an inlet of the liquid nitrogen enrichment trap T6, a switching valve V17 is arranged on the second carrier gas supply pipeline, the second carrier gas supply pipeline is connected with an inlet of the chromatographic column GC through a third pipeline, and a switching valve V18 is arranged on the third pipeline;

the outlet of the verification enrichment trap T7 is connected with a permanent gas discharge pipe to discharge non-condensable gases such as nitrogen, oxygen, hydrogen, argon and the like in the liquid nitrogen cold trap and the liquid nitrogen enrichment trap, and the permanent gas discharge pipe is provided with a switch valve V19;

the inlet of the purification and re-enrichment trap T8 is connected with a third carrier gas supply pipeline, the third carrier gas supply pipeline is provided with a switch valve V20, a pipeline between the chromatographic column GC and the purification and re-enrichment trap T8 is provided with a valve V1, the outlet of the purification and re-enrichment trap is respectively communicated with a heavy gas discharge pipeline, a sample collection pipe and a sample discharge pipeline, the heavy gas discharge pipeline is provided with a switch valve V22, the sample collection pipe is positioned in the sample collection trap, and the outlet of the sample collection pipe is connected with a vacuum pipeline for removing carrier gas. When sampling, the carrier gas introduced by the second carrier gas supply pipeline sends the sample enriched in the liquid nitrogen enrichment trap into the inlet of the chromatographic column; and a heavy gas discharge pipeline is connected to an outlet of the chromatographic column to discharge impurity gas with retention time after the target gas, for example, when methane is purified, ethane doped in a sample has retention time after the methane, and when the methane is extracted, the ethane is discharged through the heavy gas discharge pipeline.

Preferably, the sample injection unit is a syringe sample injection unit and/or a steel cylinder sample injection unit. The injector sample injection unit comprises an injector sample injector communicated with the VOC trap through a pipeline; the steel bottle advance kind unit include through the connecting tube with the natural gas sample steel bottle that the VOC trap is linked together, be equipped with the steel bottle manometer of reducing pressure on the connecting tube.

The pipeline between the liquid nitrogen enrichment trap and the chromatographic column is provided with a verification enrichment trap to verify whether the sample in the liquid nitrogen enrichment trap is completely enriched, and particularly when a sample to be detected is newly sent, whether the lengths of the cooling pipelines in the liquid nitrogen cold trap and the liquid nitrogen enrichment trap in the early stage are proper and the cooling temperature is proper can be verified through the verification enrichment trap, and the adjustment is carried out in time until the sample is not enriched in the verification enrichment trap, so that the set parameters of the liquid nitrogen cold trap and the liquid nitrogen enrichment trap are reasonable.

Preferably, the vacuum pipeline comprises a primary vacuum pipeline communicated with the dry pump and a secondary vacuum pipeline communicated with the molecular pump. Concretely, low vacuum gauge P1 connects on vacuum branch pipe through first connecting tube, be equipped with ooff valve V8 on the first connecting tube, dry pump 6 connects through the second connecting tube on the vacuum branch pipe, be equipped with ooff valve V6 on the second connecting tube, high vacuum gauge P2 connects through the third connecting tube on the vacuum branch pipe, be equipped with ooff valve V9 on the third connecting tube, molecular pump 7 connects through the fourth connecting tube on the vacuum branch pipe, be equipped with ooff valve V7 on the fourth connecting tube.

Example 2

The purification and collection method of the isotope sample purification and collection preparation system described in example 1 includes the steps of:

the enrichment process comprises the following steps:

step 1, introducing a sample through a sample introduction unit, opening switch valves V24, V11, V16, V18 and V19, other switch valves are closed, the gas sample enters the VOC trap T1 to remove water and VOC components (the temperature control range of the VOC trap T1 is between-24 ℃ and-0 ℃, HayeSep D or PoraPLOT Q resin or molecular sieve packing is arranged in the gas sample to remove a large amount of VOC components in the sample), then the sample enters an adsorption trap T2 (filled with diiodo pentaoxide to oxidize CO into carbon dioxide), an adsorption trap T3 (filled with soda lime or sodium hydroxide to remove acid gas carbon dioxide and the like), a chemical trap T4 (a standby trap is used for removing other impurities in a targeted manner), a liquid nitrogen cold trap T5 (a liquid nitrogen cold trap without a filler to remove sulfur dioxide and volatile gases), a liquid nitrogen enrichment trap T6 and a verification enrichment trap T7, the final sample is enriched in the liquid nitrogen enrichment trap T6, and other impurity gases are discharged through a permanent gas discharge pipe;

and 2, opening switching valves V17, V21, V1 and V3, closing other switching valves, sending the sample in the liquid nitrogen enrichment trap T6 into the chromatographic column GC by the carrier gas introduced into the second carrier gas supply pipeline, separating in the chromatographic column GC according to different retention times, opening V1 when target gas flows out, enriching the target gas in the purification re-enrichment trap T8, closing V1 and opening V22 when heavy gas (gas with retention time after the target gas) flows out, and discharging the heavy gas through a heavy gas discharge pipeline.

Transferring, enriching and collecting processes:

step 1, opening the switch valves V20, V1, V2 and V3, closing other switch valves, and discharging the carrier gas introduced into the third carrier gas supply pipeline from the sample discharge pipeline after passing through the purification and re-enrichment trap T8.

Step 2, closing V1, V2 and V5, opening V2, V4, V6 and V8, evacuating miscellaneous gases in a passage by the operation of a dry pump 6, closing a vacuum valve V6 when a vacuum gauge P1 shows a value of 0.1mbar, opening vacuum valves V7 and V9, continuously evacuating carrier gases in the passage by a molecular pump unit 7, closing V7 and opening V10 when a vacuum gauge P2 shows that the requirements are met, releasing and diffusing methane samples in a purification re-enrichment trap T8 into a pre-pumped sample collection pipe 5, and placing the sample collection pipe 5 in a sample collection trap T9.

During or after the transfer and re-enrichment collection process, cleaning of the front pipeline can be performed, specifically:

(1) recovery of VOC trap T1 function: opening V13 and V14, closing other valves, raising the temperature (100 ℃) of the VOC trap T1, introducing carrier gas into the first carrier gas supply pipeline, and discharging water and VOC components remained in the VOC trap T1 through a discharge pipeline;

(2) purging an adsorption trap group, a chemical trap and a liquid nitrogen cold trap: opening V23, V12, V16 and V19, closing other switch valves, introducing carrier gas into a zeroth carrier gas supply pipeline, passing through an adsorption trap T2, an adsorption trap T3, a chemical trap T4 and a liquid nitrogen cold trap T5, and then discharging the carrier gas from an impurity gas discharge pipeline;

example 3

the two-position four-way valve A is provided with four hole sites of a1, a2, a3 and a4, the a2 is communicated with a natural gas sample steel bottle 3 through a connecting pipeline, a steel bottle decompression meter 4 is installed on the connecting pipeline, the a4 is communicated with an injection sample injector 2 through a pipeline, a GC sample inlet 1 is formed in the injection sample injector 2, and a zero carrier gas input pipeline is formed in the injection sample injector 2;

the two-position four-way valve D is provided with four hole sites of D1, D2, D3 and D4, the D1 is communicated with an outlet of a chromatographic column GC8 through a pipeline, the D2 is communicated with an inlet of a purification re-enrichment trap T8 through an enrichment pipeline, the D3 is communicated with a third load gas input pipeline, the D4 is communicated with a permanent gas discharge pipe, the enrichment pipeline is provided with a switch valve V1, an outlet of the purification re-enrichment trap T8 is communicated with an inlet of a sample collection trap T9 through a pipeline, the sample collection trap T9 is respectively communicated with a sample discharge pipeline and a collection pipeline through a communication pipeline, the communication pipeline is provided with a switch valve V2, the sample discharge pipeline is provided with a switch valve V3, the collection pipeline is provided with a switch valve V4, the collection pipeline is respectively communicated with a vacuum branch pipe and a collection branch pipe, the collection pipe is provided with a switch valve V5 and a switch valve V10, the end-to-end connection who collects the branch pipe has sample collection pipe 5, sample collection pipe 5 is located sample collection trap T9, and low vacuum gauge P1 connects on vacuum branch pipe through first connecting tube, be equipped with ooff valve V8 on the first connecting tube, dry pump 6 connects through the second connecting tube on the vacuum branch pipe, be equipped with ooff valve V6 on the second connecting tube, high vacuum gauge P2 connects through the third connecting tube on the vacuum branch pipe, be equipped with ooff valve V9 on the third connecting tube, molecular pump 7 connects through the fourth connecting tube on the vacuum branch pipe, be equipped with ooff valve V7 on the fourth connecting tube.

In the vacuum control unit, in order to reduce the gas diffusion volume and avoid the possible air bleeding influence of the low vacuum gauge P1 and the influence caused by the safety protection of the high vacuum gauge P2 and the ionization of the high vacuum gauge P2, the low vacuum gauge P1 and the high vacuum gauge P2 in the system are respectively connected to the vacuum system through vacuum valves V8 and V9.

The temperature control range of the VOC trap T1 in the embodiment is between-24 ℃ and-0 ℃. HayeSep D or PoraPLOT Q resin or molecular sieve packing is arranged in the sample, so that a large amount of VOC components in the sample are removed; adsorption trap T2 was filled with diiodo pentaoxide (oxidizing CO to carbon dioxide); the adsorption trap T3 is filled with soda lime or sodium hydroxide (acid gas carbon dioxide and the like are removed); chemical trap T4 is a spare trap (targeted to remove other impurities); the liquid nitrogen cold trap T5 is a liquid nitrogen cold trap without filler (shorter than a cooling pipeline in the liquid nitrogen enrichment trap T6, and used for removing sulfur dioxide and some volatile impurity gases); the liquid nitrogen enrichment trap T6 and the verification enrichment trap T7 are two completely identical liquid nitrogen cold traps which are connected in series, are internally provided with molecular sieve type or resin type fillers and are connected in series. The switch valves V1, V2, V3, V4, V5, V6, V7, V8, V9 and V10 are vacuum manual valves and are distributed in all the pipelines to complete the collection of target gases.

Two positions of the four rotary valves are respectively in a sample injection (Inject) state when the four rotary valves rotate clockwise and a sampling (load) state when the four rotary valves rotate anticlockwise, and the functions of removing impurities, enriching, purifying, separating, transferring and the like of the sample gas are realized through switching and combining hole sites among the two-position four-way valve (A), the two-position six-way valve (B), the two-position six-way valve (C) and the two-position four-way valve (D); the vacuum switch valves V1, V2, V3, V4, V5, V6, V7, V8, V9 and V10 are matched for use to realize the functions of re-enrichment, transfer, collection, online sample injection analysis and the like of target gas. The valve body is combined for use.

I) a sample injection mode, namely, communicating a relatively concentrated gas sample with an injection sample injector 2, two-position four-way valves A sampling (load) state hole sites a4 and a3 and two-position six-way valves B sampling (load) state hole sites B2 and B3, introducing He0 carrier gas from a GC sample injection port 1, and introducing the sample in the injection sample injector 2 into a system; secondly, communicating the low-concentration sample gas in the natural gas sample steel cylinder 3 with the low-concentration steel cylinder gas, the hole sites a2 and a3 in the state of two-position four-way valve A sampling (Inject) and the hole sites B2 and B3 in the state of two-position six-way valve B sampling (load), and introducing He0 carrier gas into the system from a GC sample inlet 1;

II) removing impurity gas: after the sample gas enters the system, He0 carrier gas sequentially passes through a VOC trap T1 to remove water and VOC components; the two-position six-way valve B (load) hole sites b6 and b1 are communicated with an adsorption trap T2, an adsorption trap T3, a chemical trap T4, a liquid nitrogen cold trap T5, a two-position six-way valve C (load) hole sites c2, c3 and a liquid nitrogen enrichment trap T6, and a chemical trap combination is arranged to remove impurity gas components; purifying and enriching a sample in a liquid nitrogen enrichment trap T6 for storage, and then verifying the enrichment effect of the enrichment target gas in a verification enrichment trap T7 (so as to adjust the length of a connecting pipeline of a liquid nitrogen cold trap T5 and the liquid nitrogen enrichment trap T6 and the flow rate of carrier gas, so that the sample is completely enriched in the liquid nitrogen enrichment trap T6); other impurity gases in the sample gas are discharged to the outside through the two-position six-way valve C (load) hole sites c6, c1 and an impurity gas discharge pipeline.

III) chromatographic separation and methane gas re-enrichment: and removing the carrier gas to collect methane, and completing the transfer and collection of methane gas. The method comprises the steps of communicating hole sites C4 and C3 of a two-position six-way valve C (Inject), a liquid nitrogen enrichment trap T6, a verification enrichment trap T7, hole sites C6 and C5 of the two-position six-way valve C (Inject), a chromatographic column 8, a two-position four-way valve D (load) hole sites d1 and d2, a vacuum valve V1 and a purification re-enrichment trap T8, introducing carrier gas of He2 from the hole site C4 of the two-position six-way valve C, introducing purified methane gas stored in the liquid nitrogen enrichment trap T6 into the chromatographic column 8, separating methane by using a separation chromatographic column or a capillary column, switching the separated methane gas through a valve body, finishing methane enrichment, storing in the purification re-enrichment trap T8, and waiting for next transfer and collection.

IV) carrier gas removal and methane collection: closing vacuum valves V1, V3 and V5, opening vacuum valves V2, V4, V6 and V8, evacuating the impure gas in the channel by the operation of the dry pump 6, closing the vacuum valve V6 when the vacuum gauge P1 shows a value of 0.1mbar, opening the vacuum valves V5, V7 and V9, continuously evacuating the carrier gas in the molecular pump unit 7, and reaching the requirement when the vacuum gauge P2 shows that the value is not inferior to 1 × 10 (the value is not inferior to 1 × 10)^- ⁶mbar), V7 was closed, V5, V10 were opened, and the methane sample in the purge recollection trap T8 was released to diffuse into the pre-evacuated sample collection tube 5, which sample collection tube 5 was placed in sample collection trap T9.

V) gas stable isotope mass spectrometry: the sample collection pipe 5 is directly connected with a two-way sample injection system of a gas stable isotope mass spectrometer (MAT253Ultra Thermo Scientific), or is opened to be directly diffused into a two-way sample injection storage tank of the isotope mass spectrometer in an equilibrium mode by V5, and is matched with a gas isotope mass spectrometer MAT253Ultra (Thermo Scientific) to jointly complete the analytical measurement of binary isotopes 13CH3D and 12CH2D2 in a methane sample, and complete the analytical detection of delta 18 and delta 13CH3D of the methane binary isotopes 13CH3D and 12CH2D 2.

Besides, the system also has the following functions:

i) functional recovery of VOC trap T1: the temperature of the VOC trap T1 is adjusted to 100 ℃, the carrier gas of the hole sites B4 and B3 of the two-position six-way valve B (Inject), the VOC trap T1, the hole sites B6 and B5 of the two-position six-way valve B are communicated, the He1 carrier gas is introduced from the hole site B4 of the two-position six-way valve B, and the frozen water and other VOC components in the system are discharged for reuse;

II) chemical trap purging mode: communicating two-position four-way valve A (load) hole sites a4 and a3, two-position six-way valve B (project) hole sites b2 and b1, adsorption trap T2, adsorption trap T3, chemical trap T4, liquid nitrogen cold trap T5, two-position six-way valve C hole sites C2 and C1, introducing He0 carrier gas from GC sample inlet 1, exhausting and discharging after passing through a pipeline, and maintaining the gas path system clean;

III) permanent gas evacuation mode: the liquid nitrogen cold trap T5 and the two-position six-way valve C (load) hole sites c2 and c3, the liquid nitrogen enrichment trap T6, the verification enrichment trap T7 and the two-position six-way valve C (load) hole sites c6 and c1 are communicated, He0 carrier gas is introduced from the two-position six-way valve A (load) and the two-position six-way valve B (load) in a sequentially connected mode, permanent gas reserved in a connecting pipeline is discharged in an empty mode, and the system is maintained to be clean.

IV) purification and re-enrichment mode: and carrier gases of hole positions D3 and D2 of the two-position four-way valve D (inject), a vacuum valve V1, a purification re-enrichment trap T8, a vacuum valve V2, a vacuum valve V3 and He3 are led in by the hole positions D3 and D2 of the two-position four-way valve D and are discharged out of the system by a vacuum valve V3, so that the purification and re-enrichment of the methane sample are completed.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The isotope sample purification, collection and preparation system is characterized by comprising a two-position four-way valve A, a two-position six-way valve B, a two-position six-way valve C, a two-position four-way valve D, VOC trap T1, an adsorption trap T2, an adsorption trap T3, a chemical trap T4, a liquid nitrogen cold trap T5, a liquid nitrogen enrichment trap T6, a verification enrichment trap T7, a purification re-enrichment trap T8 and a sample collection trap T9, wherein:

2. The isotope sample purification and collection preparation system in accordance with claim 1 wherein low vacuum gauge P1 is connected to a vacuum branch pipe through a first connecting pipe, said first connecting pipe being provided with a switch valve V8, the dry pump being connected to said vacuum branch pipe through a second connecting pipe, said second connecting pipe being provided with a switch valve V6, high vacuum gauge P2 being connected to said vacuum branch pipe through a third connecting pipe, said third connecting pipe being provided with a switch valve V9, the molecular pump being connected to said vacuum branch pipe through a fourth connecting pipe, said fourth connecting pipe being provided with a switch valve V7.

3. The isotope sample purification and collection preparation process of the isotope sample purification and collection preparation system claimed in any one of claims 1 to 2 including the steps of:

i) sample injection, namely, communicating a relatively concentrated gas sample with an injection sample injector, two-position four-way valve A sampling state hole sites a4 and a3, and two-position six-way valve B sampling state hole sites B2 and B3, introducing He0 carrier gas from a GC sample injection port, and introducing the sample in the injection sample injector into a system; secondly, communicating the low-concentration sample gas in the natural gas sample steel cylinder with the low-concentration steel cylinder gas, sample state hole sites a2 and a3 of a two-position four-way valve A and sample state hole sites B2 and B3 of a two-position six-way valve B, and introducing He0 carrier gas into the system from a GC sample inlet 1;

II) removing impurity gas: after the sample gas enters the system, He0 carrier gas sequentially passes through a VOC trap T1 to remove water and VOC components; the two-position six-way valve B hole sites B6 and B1 are communicated with an adsorption trap T2, an adsorption trap T3, a chemical trap T4, a liquid nitrogen cold trap T5, two-position six-way valve C hole sites C2 and C3 and a liquid nitrogen enrichment trap T6, and a chemical trap combination is arranged to remove impurity gas components; purifying and enriching the sample in a liquid nitrogen enrichment trap T6 for storage, and then verifying the enrichment effect of the enriched target gas in a verification enrichment trap T7; other impurity gases in the sample gas are discharged to discharge permanent gases through the two-position six-way valve C hole sites C6 and C1 and an impurity gas discharge pipeline;

III) chromatographic separation and methane gas re-enrichment: removing carrier gas to collect methane, completing the transfer and collection of methane gas, communicating hole sites C4 and C3 of the two-position six-way valve C, a liquid nitrogen enrichment trap T6, a verification enrichment trap T7, hole sites C6 and C5 of the two-position six-way valve C, a chromatographic column 8, a hole site D1 and D2 of the two-position four-way valve D, a vacuum valve V1 and a purification re-enrichment trap T8, introducing the carrier gas of He2 from the hole site C4 of the two-position six-way valve C, introducing the purified methane gas stored in the liquid nitrogen enrichment trap T6 into the chromatographic column 8, completing the separation of methane by using a separation chromatographic column or a capillary column, switching the separated methane gas through a valve body, completing the accumulation of methane in the purification re-enrichment trap T8, and waiting for the next transfer and collection;

IV) carrier gas removal and methane collection: closing vacuum valves V1, V3 and V5, opening vacuum valves V2, V4, V6 and V8, evacuating miscellaneous gases in a passage by dry pump operation, closing vacuum valve V6 when a vacuum gauge P1 shows a value of 0.1mbar, opening vacuum valves V5, V7 and V9, continuously evacuating carrier gases in the passage by a molecular pump set, closing V7 when the vacuum gauge P2 shows that the requirements are met, opening V5 and V10, releasing and diffusing a methane sample in a purification re-enrichment trap T8 into a pre-extracted sample collection pipe, and placing the sample collection pipe in a sample collection trap T9;

v) gas stable isotope mass spectrometry: the sample collecting pipe is directly connected with a gas stable isotope mass spectrometer double-path sample injection system, or the V5 is opened to directly and evenly diffuse into a double-path sample injection storage tank of the isotope mass spectrometer, and the isotope analysis and detection are completed together with the gas isotope mass spectrometer.

4. The utility model provides an isotope sample purification and collection preparation system which characterized in that, includes appearance unit, first change-over valve, VOC trap, adsorption trap group, liquid nitrogen cold trap, second change-over valve, chromatographic column, third change-over valve and purification enrichment trap again, wherein:

a zeroth carrier gas supply pipeline is connected to the sample injection unit;

the port of the first conversion valve is respectively connected with a sample introduction pipeline, a sample introduction port of a VOC trap, a sample outlet of the VOC trap, a sample introduction port of an adsorption trap group, a first carrier gas supply pipeline and a discharge pipeline through pipelines, the sample introduction pipeline is communicated with the sample introduction unit, when the first conversion valve is in a sampling state, the sample introduction pipeline, the VOC trap and the adsorption trap group are sequentially communicated, the first carrier gas supply pipeline is communicated with the discharge pipeline, when the first conversion valve is in a sample introduction state, the sample introduction pipeline is communicated with the adsorption trap group, and the first carrier gas supply pipeline, the VOC trap and the discharge pipeline are sequentially communicated;

the appearance mouth that goes out of absorption trap group pass through the pipeline with the introduction port of liquid nitrogen cold-trap is linked together, be connected with respectively through the pipeline on the port of second change-over valve the appearance mouth that goes out of liquid nitrogen cold-trap, the introduction port and the appearance mouth of liquid nitrogen enrichment trap, second carrier gas supply tube way, the introduction port and the foreign gas discharge pipeline of chromatographic column, wherein: when the second switching valve is in a sampling state, the liquid nitrogen cold trap and the liquid nitrogen enrichment trap are sequentially communicated with the impurity gas discharge pipeline, the second carrier gas supply pipeline is communicated with the sample inlet of the chromatographic column, when the second switching valve is in the sample inlet state, the sample outlet of the liquid nitrogen cold trap is communicated with the impurity gas discharge pipeline, and the second carrier gas supply pipeline is sequentially communicated with the liquid nitrogen enrichment trap and the sample inlet of the chromatographic column;

5. The isotope sample purification and collection preparation system in accordance with claim 4, wherein said sample introduction unit comprises an injection sample injector, a natural gas sample cylinder, and a change-over valve, wherein said change-over valve is connected to a sample outlet of said injection sample injector, a sample outlet of said natural gas sample cylinder, an exhaust line, and an inlet of a first change-over valve, respectively, said sample outlet of said injection sample injector is communicated with said sample introduction line when the sample amount is small, said sample outlet of said natural gas sample cylinder is communicated with said exhaust line, said sample outlet of said natural gas sample cylinder is communicated with said sample introduction line when the sample amount is large, and said sample outlet of said injection sample injector is communicated with said exhaust line.

6. The isotope sample purification and collection preparation system in accordance with claim 4, wherein said set of adsorption traps includes at least a CO adsorption trap and an acid gas adsorption trap.

7. The isotope sample purification and collection preparation system in accordance with claim 4 wherein a validation enrichment trap is provided on the line between said liquid nitrogen enrichment trap and said chromatography column to validate complete enrichment of the sample in said liquid nitrogen enrichment trap.

8. The isotope sample purification and collection preparation system in accordance with claim 4 wherein said vacuum line comprises a primary vacuum line in communication with a dry pump and a secondary vacuum line in communication with a molecular pump to remove miscellaneous and carrier gases from the lines.

9. The purification and collection preparation method of an isotope sample purification and collection preparation system in accordance with claim 4 includes the steps of:

the purification and enrichment process comprises the following steps:

step 2, the second switching valve is in a sample injection state, the carrier gas introduced into the second carrier gas supply pipeline sends the sample in the liquid nitrogen enrichment trap into the chromatographic column GC, separation is carried out in the chromatographic column GC according to different retention times of different component gases, when the target gas flows out, the third switching valve is in a sampling state, the separated target gas is enriched in the purification and enrichment trap, when the heavy gas after the retention time of the target gas flows out, the third switching valve is in a sample injection state and is discharged through a heavy gas discharge pipeline;

transferring, enriching and collecting processes:

the third conversion valve is in a sample injection state:

10. The isotope sample purification and collection preparation method in accordance with claim 9 wherein in step 1 of said transfer re-enrichment collection process, the third carrier gas completes complete transfer enrichment of the target gas while purging the line and is stored in the purification re-enrichment trap.

11. The method for purifying, collecting and preparing an isotope sample according to claim 9 wherein when the connecting line between the purification recollection trap and the sample collection tube is evacuated, the impurity gas is evacuated by a dry pump and then the impurity gas and the carrier gas are evacuated by a molecular pump.

12. The isotope sample purification and collection preparation method of claim 9, further comprising a line purging method:

(2) the first switching valve is in a sampling state: and introducing carrier gas into the zeroth carrier gas supply pipeline, and discharging impurities remained in the adsorption trap group, the liquid nitrogen cold trap and the liquid nitrogen enrichment trap from the impurity gas discharge pipeline.

13. The utility model provides an isotope sample purification and collection preparation system which characterized in that, includes sample introduction unit, VOC trap, adsorption trap group, liquid nitrogen cold trap, liquid nitrogen enrichment trap, chromatographic column, purification enrichment trap and the sample collecting pipe that loops through the pipeline and is linked together, wherein:

the inlet of the liquid nitrogen enrichment trap is connected with a second carrier gas supply pipeline, during sampling, the carrier gas introduced by the second carrier gas supply pipeline sends the sample enriched in the liquid nitrogen enrichment trap into the inlet of the chromatographic column, the outlet of the chromatographic column is respectively connected with a heavy gas discharge pipeline and a purification re-enrichment trap, and the heavy gas discharge pipeline is used for discharging impurity gas with retention time after target gas;

14. The isotope sample purification and collection preparation system in accordance with claim 13 wherein said zeroth carrier gas supply line is connected to an inlet of said adsorption trap array or said zeroth carrier gas supply line is connected to said sample introduction unit which is in turn connected to an inlet of said adsorption trap array through a pipe.

15. The isotope sample purification and collection preparation system in accordance with claim 13, wherein said sample introduction unit is a syringe sample introduction unit and/or a cylinder sample introduction unit;

the injector sample injection unit comprises an injection sample injector communicated with the VOC trap through a pipeline, and the zeroth carrier gas supply pipeline is connected to the injection sample injector; the steel bottle advance kind unit include through the connecting tube with the natural gas sample steel bottle that the VOC trap is linked together, be equipped with the steel bottle manometer of reducing pressure on the connecting tube.

16. The isotope sample purification and collection preparation system in accordance with claim 13, wherein said set of adsorption traps includes at least a CO oxidation trap and an acid gas adsorption trap.

17. The isotope sample purification and collection preparation system in accordance with claim 13 wherein a verification enrichment trap is provided on a conduit between said liquid nitrogen enrichment trap and said chromatographic column to verify whether the enrichment of the sample in said liquid nitrogen enrichment trap is complete.

18. The isotope sample purification and collection preparation system in accordance with claim 13, wherein said vacuum line comprises a primary vacuum line in communication with a dry pump and a secondary vacuum line in communication with a molecular pump.

19. The isotope sample purification and collection preparation system in accordance with claim 1 or 4 or 13, wherein said isotope sample purification and collection preparation system is in methane¹³Application in C-D isotope detection.

20. The isotope sample purification and collection preparation method is characterized by comprising the following steps:

the purification and enrichment process comprises the following steps:

step 2, the carrier gas introduced into the second carrier gas supply pipeline sends the sample in the liquid nitrogen enrichment trap into a chromatographic column GC, the sample is separated in the chromatographic column GC according to different retention times, the separated target gas is enriched in a purification and re-enrichment trap, and impurities except the target gas are discharged through a heavy gas discharge pipeline;

transferring, enriching and collecting processes:

21. The purification and collection preparation method of claim 20, wherein in step 1 of the transfer-reenrichment collection process, the third carrier gas completes complete transfer-enrichment of the target gas while purging the line and is stored in the purification-reenrichment trap.

22. The purification and collection preparation process of claim 20, wherein when the purge recollection trap and the sample collection tube are evacuated, the purge trap is evacuated by a dry pump to remove the impurity gas, and the purge trap is evacuated by a molecular pump to remove the carrier gas.

23. The purification and collection preparation process of claim 20, wherein cleaning of the pre-column tubing during or after transfer of the re-enrichment collection is performed, comprising:

(2) purging an adsorption trap group and a liquid nitrogen cold trap: and carrier gas is introduced into the zeroth carrier gas supply pipeline, passes through the adsorption trap group and the liquid nitrogen cold trap and is discharged from the impurity gas discharge pipeline.