Gas chromatography device for detecting ppb-grade Ne in high-purity helium

Abstract

The invention provides a gas chromatography device for detecting ppb-grade Ne in high-purity helium, the gas chromatography device has the characteristics of high sensitivity, strong anti-interference performance and excellent stability, a plasma emission detector is combined with an Ne characteristic optical filter, an Ne characteristic spectrum can be selectively detected, interference of coexisting gas such as H2 or O2 is avoided, and the detection sensitivity is high. Meanwhile, by optimizing a chromatographic column combination and a carrier gas system, efficient separation of Ne and a ppb-level detection lower limit are achieved, the problems of signal quenching, narrow dynamic range and insufficient sensitivity in the prior art are effectively solved, and the method is particularly suitable for meeting the requirement for accurate analysis of trace Ne in high-end fields such as semiconductors and superconducting scientific research.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, in particular to a gas chromatograph for ppb-level Ne detection in high-purity helium, which is mainly used in the fields of semiconductor lithography process, superconducting and quantum scientific research, special gas industry, space propulsion system, etc. BACKGROUND

[0002] High-purity helium, as a key gas, is widely used in the fields of semiconductor lithography process, superconducting and quantum scientific research, special gas industry, and space propulsion system, etc. Among them, the detection of trace impurity Ne (neon) in helium is particularly important, because the presence of Ne may affect the process precision, scientific research data accuracy or system safety. With the development of technology, the requirement for Ne detection sensitivity has been improved from ppm level to ppb level, which puts high requirements on the analysis method and device.

[0003] Currently, the detection of Ne in high-purity helium mainly adopts gas chromatography combined with helium ionization detector (DID) for analysis. The existing technical scheme usually uses 7N grade ultra-pure helium as carrier gas, is equipped with a helium purifier to ensure the purity of the carrier gas, and adopts a chromatographic column system composed of Hayesep Q and molecular sieve column to realize the separation of Ne / He through ten-way valve center cutting technology. However, this scheme has significant problems: first, the coexisting gas interference is serious, when the concentration of H2 or O2 in the sample exceeds 1 ppm, the metastable helium (*He) in DID will be quenched, causing the Ne signal to decay by more than 30%, which seriously affects the detection accuracy; second, the dynamic range is bottlenecked, high concentration Ne (more than 100 ppb) and trace components (such as H2) cannot be analyzed in the same chromatogram, often requiring range switching or secondary sampling, increasing the operation complexity and time cost; finally, the sensitivity is insufficient, the detection lower limit of the existing DID detector is usually only in ppm level, which is difficult to meet the detection demand of ppb-level Ne, especially in high-end application scenarios.

[0004] Therefore, there is an urgent need in the art to develop a new type of gas chromatography detection scheme, which can effectively overcome the coexisting gas interference, expand the dynamic range, and significantly improve the detection sensitivity, to realize the accurate, rapid and stable detection of ppb-level Ne in high-purity helium. SUMMARY

[0005] The purpose of the present application is to provide a gas chromatograph for ppb-level Ne detection in high-purity helium to solve the problems existing in the prior art.

[0006] To achieve the above purpose, the present application provides the following scheme: The present application provides a gas chromatograph for ppb-level Ne detection in high-purity helium, comprising: A carrier gas system is provided to supply ultra-pure helium carrier gas; A sample injection system is provided to include a sample injection valve and a constant volume loop; A chromatographic separation system is provided to include a first chromatographic column and a second chromatographic column; A detection system is provided to be a plasma emission detector.

[0007] Preferably, the carrier gas system includes a 7N grade ultra-pure helium source and a helium purifier to provide and maintain the purity of the carrier gas.

[0008] Preferably, the sample injection valve is a ten-way valve to realize sample injection and flow path switching.

[0009] Preferably, the constant volume loop has a volume of 0.5-2mL.

[0010] Preferably, the first chromatographic column is a molecular sieve packed column with a length of 6 feet; and the second chromatographic column is a modified molecular sieve packed column with a length of 8 feet.

[0011] Preferably, the plasma emission detector includes a quartz flow cell, an electrode set, a light splitting device, and a photodetector; the electrode set is arranged on the upper and lower sides of the quartz flow cell in parallel to apply a high-frequency high-voltage alternating electric field to form a plasma.

[0012] Preferably, the light splitting device includes a Ne characteristic filter to selectively transmit light signals of Ne characteristic wavelengths.

[0013] Preferably, the plasma emission detector has a working frequency of 10-50kHz and a voltage of 1-5kV.

[0014] Preferably, a signal processing unit is further included to receive the output signals of the photodetector and perform data analysis and concentration calculation.

[0015] Preferably, the entire gas circuit of the device adopts stainless steel or inert material pipelines to reduce adsorption and pollution.

[0016] The present application has the following beneficial technical effects relative to the prior art: The gas chromatography device for ppb level Ne detection in high-purity helium provided by the present application has the characteristics of high sensitivity, strong anti-interference and excellent stability, wherein the plasma emission detector is combined with the Ne characteristic filter to selectively detect the Ne characteristic spectrum, avoiding the interference of coexisting gases such as H2 or O2, and through the optimization of the chromatographic column combination and the carrier gas system, the efficient separation of Ne and the ppb level detection lower limit are realized, effectively solving the problems of signal quenching, narrow dynamic range and insufficient sensitivity in the prior art, and the device is particularly suitable for the precise analysis of trace Ne in high-end fields such as semiconductor and superconducting research. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a gas chromatography apparatus for detecting ppb-level Ne in high-purity helium provided by the present invention. Detailed Implementation

[0019] The serial numbers assigned to components in this document, such as "first," "second," etc., are merely used to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0020] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The purpose of this invention is to provide a gas chromatography apparatus for the detection of ppb-level Ne in high-purity helium, in order to solve the problems existing in the prior art.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1: like Figure 1 As shown, the present invention provides a gas chromatography apparatus for the detection of ppb-level Ne in high-purity helium, which mainly includes a carrier gas system, an injection system, a chromatographic separation system, a detection system, and a signal processing unit.

[0025] Specifically, the carrier gas system provides ultrapure helium and includes a 7N-grade ultrapure helium source and a helium purifier to provide and maintain the purity of the carrier gas. The purity of the 7N-grade ultrapure helium is not less than 99.99999%. The helium purifier uses a highly efficient adsorbent or low-temperature purification technology to remove any trace amounts of impurities such as moisture, oxygen, and nitrogen that may remain in the carrier gas, ensuring minimal background interference. The carrier gas flow rate is typically controlled within the range of 10-50 mL / min and can be precisely adjusted according to analytical requirements, with flow rate stability better than ±1%.

[0026] Furthermore, the injection system 1 includes an injection valve and a quantitative loop. The injection valve is preferably a ten-way valve, driven electromagnetically or pneumatically, used for sample injection and flow path switching. The volume of the quantitative loop is 0.5-2 mL, selected based on detection sensitivity and sample concentration; typically, a 1 mL quantitative loop is used to ensure injection accuracy and repeatability. The sample enters the injection valve through the sample inlet. Driven by the carrier gas, the sample gas fills the quantitative loop, and then the sample in the quantitative loop is injected into the chromatographic separation system 2 via valve switching. The entire injection system is made of stainless steel or inert materials (such as polytetrafluoroethylene) to reduce sample adsorption and cross-contamination.

[0027] Furthermore, the chromatographic separation system 2 includes a first chromatographic column 21 and a second chromatographic column 22. The first chromatographic column 21 is a molecular sieve-packed column, 6 feet long and 1 / 8 inch in inner diameter, filled with 5A molecular sieve or a similar adsorbent, used for the initial separation of Ne from other gaseous components (such as H2, O2, etc.). The second chromatographic column 22 is a modified molecular sieve-packed column, 8 feet long and 1 / 8 inch in inner diameter, enhanced with surface modification or the addition of a specific stationary phase (such as metal oxides) to improve the selective separation and retention of Ne. The column material is stainless steel or inert material, and the column temperature is controlled between room temperature and 100°C. Depending on the separation requirements, isothermal or programmed temperature modes can be used, with temperature stability better than ±0.5°C. The columns are connected by a ten-port valve to achieve center-cutting technology, effectively separating Ne from the main component helium and other impurities.

[0028] Furthermore, detection system 3 is a plasma emission detector (PED), whose core components include a quartz flow cell, an electrode assembly, a spectrometer, and a photodetector. The quartz flow cell is cylindrical, internally polished to reduce light scattering, with a volume of approximately 100-200 μL and a pressure resistance of not less than 0.5 MPa. The electrode assembly is arranged parallel to the upper and lower sides of the quartz flow cell, made of platinum or other inert metals. An alternating electric field is applied by an external high-frequency power supply, with an operating frequency of 10-50 kHz and a voltage of 1-5 kV, to form a stable helium plasma within the flow cell. When the separated gas components enter the flow cell, they are excited and emit characteristic spectra under the influence of the electric field. The spectrometer includes a Ne characteristic filter with a center wavelength of 640.2 nm (the characteristic wavelength of Ne) and a half-width of less than 10 nm to selectively transmit the Ne characteristic light signal and avoid spectral interference from other gas components (such as H2 and O2). The photodetector is a photomultiplier tube or a semiconductor photodetector, with a response wavelength range covering 600-700nm. It converts optical signals into electrical signals and has a detection sensitivity better than 0.1pA.

[0029] Furthermore, the signal processing unit receives the output signal from the photodetector, amplifies, filters, and performs analog-to-digital conversion, and then calculates the Ne concentration using built-in algorithms (such as integration, peak identification, and calibration curve fitting). The signal processing unit may also include data display, storage, and communication functions, supporting real-time monitoring and remote operation.

[0030] Furthermore, the overall gas path of the device uses stainless steel or inert material tubing, and all connections use Swagelok or similar connectors to ensure airtightness and reduce sample adsorption and contamination. The gas path design employs a low dead volume structure to minimize peak broadening and memory effects.

[0031] The working process of this invention is as follows: First, the carrier gas system is turned on, the carrier gas flow rate is adjusted to the set value (e.g., 30 mL / min), and the chromatographic column and detector are preheated. After the system stabilizes (usually 30-60 minutes), a high-purity helium sample is introduced into the injection system through the sample inlet. After the sample fills the quantitative loop, the ten-way valve is switched, and the carrier gas carries the sample in the quantitative loop into the chromatographic separation system. The sample first passes through the first chromatographic column for preliminary separation, where Ne is separated from other impurities (e.g., H2, O2). Then, the gas enters the second chromatographic column for further separation, where Ne is selectively retained and subsequently desorbed. The separated Ne component is carried by the carrier gas into the plasma emission detector. Inside the detector, Ne is excited in the plasma and emits a characteristic spectrum, which is detected by the photodetector after passing through a Ne characteristic filter. The signal processing unit records the light intensity and calculates the Ne concentration according to a pre-established calibration curve. The detection limit can reach 1 ppb, and the linear dynamic range covers 1-1000 ppb.

[0032] In one specific embodiment, the column temperature was set to 50°C, the carrier gas flow rate to 30 mL / min, the plasma emission detector operating frequency to 30 kHz, and the voltage to 3 kV. Under these conditions, a high-purity helium sample containing 5 ppb Ne was detected, with a signal-to-noise ratio greater than 3 and a repeatability relative standard deviation of less than 5%. Furthermore, through selective detection using a Ne characteristic filter, even with the presence of up to 10 ppm of H2 and O2 in the sample, the detection signal attenuation of Ne remained less than 5%, significantly outperforming the performance of traditional DID detectors.

[0033] This invention effectively overcomes the problems of coexisting gas interference, narrow dynamic range, and insufficient sensitivity in existing technologies by optimizing the chromatographic column combination and using a plasma emission detector. It achieves accurate, rapid, and stable detection of ppb-level Ne in high-purity helium, and is particularly suitable for high-end fields such as semiconductor lithography, superconductivity, and quantum research.

[0034] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] It should be noted that the components mentioned in the above embodiments are all general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0036] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.

Claims

1. A gas chromatographic apparatus for the detection of ppb-level Ne in high-purity helium, characterized in that: include: A carrier gas system that provides ultrapure helium carrier gas; The injection system includes an injection valve and a metering loop; A chromatographic separation system, the chromatographic separation system comprising a first chromatographic column and a second chromatographic column; The detection system is a plasma emission detector.

2. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to claim 1, characterized in that: The carrier gas system includes a 7N-grade ultrapure helium source and a helium purifier, used to provide and maintain the purity of the carrier gas.

3. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to claim 1, characterized in that: The injection valve is a ten-way valve, used to realize sample injection and flow path switching.

4. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to claim 1, characterized in that: The volume of the metering ring is 0.5-2 mL.

5. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to claim 1, characterized in that: The first chromatographic column is a molecular sieve packed column with a length of 6 feet; the second chromatographic column is a modified molecular sieve packed column with a length of 8 feet.

6. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to claim 1, characterized in that: The plasma emission detector includes a quartz flow cell, an electrode assembly, a spectrometer, and a photodetector; the electrode assembly is arranged in parallel on the upper and lower sides of the quartz flow cell to apply a high-frequency, high-voltage alternating electric field to form plasma.

7. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to claim 6, characterized in that: The beam splitter includes a Ne characteristic filter for selectively transmitting light signals of the Ne characteristic wavelength.

8. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to claim 6, characterized in that: The plasma emission detector operates at a frequency of 10-50kHz and a voltage of 1-5kV.

9. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to claim 6, characterized in that: It also includes a signal processing unit for receiving the output signal of the photodetector and performing data analysis and concentration calculation.

10. The gas chromatographic apparatus for detecting ppb-level Ne in high-purity helium according to any one of claims 1-9, characterized in that: The entire gas path of the device uses stainless steel or inert material pipelines to reduce adsorption and contamination.

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