Sample injection system and method for stable isotope mass spectrometer

Abstract

The invention discloses a sampling system and method for a stable isotope mass spectrometer, and relates to the technical field of mass spectrometers. Comprising a sampling device, an atomization device, a sample introduction device and a mass spectrometer which are connected in sequence, the sampling device is used for sampling a to-be-detected sample and conveying the to-be-detected sample to the atomization device; the atomization device is used for generating an atomized sample required by mass spectrometer detection; the sample introduction device is used for introducing the atomized sample into the mass spectrometer; and the mass spectrometer is used for performing mass spectrometry on the atomized sample. According to the invention, by quantitatively introducing the produced gas into the mass spectrometer, the error of the test result is reduced, the accuracy of the test result is improved, continuous sample introduction is realized, the test continuity is ensured, and the accuracy of the test result is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mass spectrometers, and in particular to a sample injection system and method for a stable isotope mass spectrometer. Background Art

[0002] In 1910, Thomson of the Cavendish Laboratory in Cambridge, England, developed the first mass spectrometer in the modern sense. The birth of this mass spectrometer marked the creation of a new field of scientific research - mass spectrometry. The double-focusing mass spectrometer, which was born in 1934, was another milestone in the development of mass spectrometry. In 1943, the first commercial mass spectrometer appeared, and mass spectrometers have since entered the field of industrial and agricultural production. The 1950s was an era of rapid development of mass spectrometry technology. In terms of mass analyzers, the performance of high-resolution double-focusing instruments was further improved, and quadrupole mass filters and pulsed time-of-flight analyzers appeared. In the late 1960s, tandem mass spectrometers were developed, and the success of gas chromatography and mass spectrometry combined made mass spectrometry occupy a unique position in the analysis of complex organic mixtures. In the 1990s, matrix-assisted laser desorption ionization sources, electrospray ionization sources, atmospheric pressure chemical ionization sources, and atmospheric pressure chemical ionization sources opened up a new field of mass spectrometry technology for studying biomacromolecules. In 2002, American scientist John Fenn and Japanese scientist Koichi Tanaka shared the Nobel Prize in Chemistry for their invention of "electrospray ionization and matrix-assisted laser desorption ionization-mass spectrometry for biomacromolecules."

[0003] Mass spectrometry is the most common and accurate method for stable isotope analysis. It first ionizes the molecules or atoms in the sample to form similar ions of each isotope, and then separates the ion flows of different mass-to-charge ratios for detection under the action of electric and magnetic fields.

[0004] Isotopes refer to elements with the same atomic number (number of protons) but different mass numbers (number of neutrons). They can be divided into stable isotopes and radioactive isotopes. Stable isotopes are a type of naturally occurring isotopes that cannot be detected by technical means. Stable isotopes are present in low concentrations in nature, and it is difficult to express the difference between isotopes in absolute quantities. Therefore, relative measurement methods are used in practice, that is, the isotope ratio (i.e., δ value) of the sample is obtained based on the isotope ratio of the measured sample and the isotope ratio of the corresponding standard. Stable isotopes are widely used in soil, medicine, agriculture, biology, ecology, and the environment.

[0005] Stable isotope mass spectrometer refers to a mass spectrometer (IRMS) that specifically measures the ratio of stable isotopes such as C, H, O, N and S. When analyzing the stable isotopes of light elements, mass spectrometry is performed in the form of gas, so the sample to be analyzed must first be converted into gas. In the ion source, gas molecules are ionized into positively charged ions, and the ions are separated according to their mass-to-charge ratio by the action of electric and magnetic fields, and then the stable isotope ratio is determined according to the intensity of different ion beam currents; stable isotope mass spectrometry can be measured by a single channel or by a dual channel (sample channel and standard channel). The existing sample injection method requires first weighing the weight of the sample-wrapped tin foil, peeling and weighing the sample weight, wrapping the sample, and then injecting the sample on the machine, which is relatively cumbersome. Therefore, how to obtain an automatic injection system that is simple to operate and ensure the accuracy of the test results is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] In view of this, the present invention provides a sampling system and method for a stable isotope mass spectrometer, which reduces the error of the test result and improves the accuracy of the test result by quantitatively introducing the gas produced by the mass spectrometer, realizes continuous sampling, ensures the continuity of the test, and improves the accuracy of the test result.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A sample injection system for a stable isotope mass spectrometer, comprising a sampling device, an atomizing device, a sample injection device and a mass spectrometer connected in sequence;

[0009] A sampling device, used for taking the sample to be tested and conveying the sample to be tested to the atomization device;

[0010] A nebulizer, used to generate a nebulized sample required for detection by a mass spectrometer;

[0011] A sample injection device, used for injecting the atomized sample into the mass spectrometer;

[0012] Mass spectrometer, used for mass spectrometry analysis of nebulized samples.

[0013] The above system may optionally further include a sample tray connected to the input end of the sampling device for carrying a tin boat containing a sample to be tested.

[0014] In the above system, optionally, the atomization device includes a liquid storage block, a hollow capillary and a cavity, one end of the hollow capillary is connected to the bottom of the liquid storage block as a sample injection end, the other end of the hollow capillary extends into the cavity as a spray end, the injection device is connected to the cavity, and auxiliary atomization gas is input to act on the spray end of the hollow capillary.

[0015] The above system may optionally further include a vacuum device for providing a vacuum environment for the mass spectrometer. The vacuum device is pre-evacuated by a mechanical pump and then continuously operated by a diffusion pump to maintain a vacuum environment for the mass spectrometer.

[0016] In the above system, optionally, the sample injection device is provided with a plurality of filter membrane nets, the filter membrane nets are provided with holes, and the outlets of the plurality of filter membrane nets merge into one outlet.

[0017] The above system may optionally further include a data monitoring and processing device for collecting data and calculation results, analyzing and judging results, storing and calling data, and monitoring various parameters of the system.

[0018] The above system can optionally use a gas-tight syringe to inject the sample to be tested.

[0019] A sampling method for a stable isotope mass spectrometer, using any of the above-mentioned sampling systems for a stable isotope mass spectrometer, comprising: continuously introducing gas into a sampling device, injecting a sample to be tested into an atomizing device using a gas-tight syringe, atomizing the sample to be tested and sending it to a mass spectrometer, and the mass spectrometer analyzing the gas to be tested.

[0020] It can be seen from the above technical solution that, compared with the prior art, the present invention provides a sampling system and method for a stable isotope mass spectrometer, which has the following beneficial effects: by quantitatively introducing the gas produced into the mass spectrometer, the error of the test result is reduced, the accuracy of the test result is improved, continuous sampling is achieved, the continuity of the test is ensured, and the accuracy of the test result is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 A structural block diagram of a sample injection system for a stable isotope mass spectrometer provided by the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Reference Figure 1 As shown, the present invention discloses a sample injection system for a stable isotope mass spectrometer, comprising a sampling device, an atomizing device, a sample injection device and a mass spectrometer connected in sequence;

[0025] A sampling device, used for taking the sample to be tested and conveying the sample to be tested to the atomization device;

[0026] A nebulizer, used to generate a nebulized sample required for detection by a mass spectrometer;

[0027] A sample injection device, used for injecting the atomized sample into the mass spectrometer;

[0028] Mass spectrometer, used for mass spectrometry analysis of nebulized samples.

[0029] Specifically, the mass spectrometer used was a Flash EA 1112 mass spectrometer equipped with a continuous flow interface device Conflo III.

[0030] Specifically, the sample to be tested is N2, N2O, NO or CO2.

[0031] Furthermore, it also includes a sample tray connected to the input end of the sampling device and used for carrying a tin boat containing samples to be tested.

[0032] Furthermore, the atomization device includes a liquid storage block, a hollow capillary and a cavity. One end of the hollow capillary is connected to the bottom of the liquid storage block as a sample injection end, and the other end of the hollow capillary extends into the cavity as a spray end. The injection device is connected to the cavity, and auxiliary atomization gas is input to act on the spray end of the hollow capillary.

[0033] Furthermore, it also includes a vacuum device for providing a vacuum environment for the mass spectrometer. The vacuum device uses a mechanical pump to pre-evacuate the vacuum, and then uses a diffusion pump to continuously operate to maintain a vacuum environment for the mass spectrometer.

[0034] Specifically, the vacuum device is made of stainless steel and is detachably connected to other devices, so that all devices can be cleaned during pre-treatment cleaning and maintenance inspections.

[0035] Furthermore, the sample injection device is provided with a plurality of filter membrane nets, the filter membrane nets are provided with holes, and the outlets of the plurality of filter membrane nets merge into one outlet.

[0036] Specifically, the material of the filter membrane net is copper, nickel, and molybdenum.

[0037] Furthermore, it also includes a data monitoring and processing device for collecting data and calculating results, analyzing and judging results, storing and calling data, and monitoring various parameters of the system.

[0038] Specifically, the data monitoring and processing device includes a signal amplifier, a digital converter and a memory.

[0039] Furthermore, a gas-tight syringe is used to inject the sample to be tested.

[0040] In a specific embodiment, the Flash EA 1112 mass spectrometer system is turned on and the carrier-He gas is passed through for 2.5 hours and then the temperature is increased. The oxidation column temperature is set to 980°C, the reduction column temperature is set to 640°C, and the water absorption column temperature is set to 40°C.

[0041] The sample to be tested is tightly wrapped in a tin boat and sent into the EA oxidation column through the sampling system of the present invention. The sample to be tested is instantly decomposed at high temperature in an oxygen peroxide environment, and the formed mixed gas containing various components such as carbon, nitrogen, oxygen, and sulfur enters the continuous flow interface device Conflo III under the carrier of high-purity helium (99.999%); in this process, the carbon in the sample is finally converted into CO2, and is separated and purified from other gases through a chromatographic separation column; CO2 is rectified by the continuous flow interface device Conflo III and sent to the ion source of IRMS under the carrier of high-purity helium (99.999%); the ion source ionizes the atoms and molecules in the CO2 sample into ions, and the mass analyzer separates the ions according to the mass-to-charge ratio, and the ion flow intensity is measured and recorded by an ion detector, and high-purity carbon dioxide (99.995%) is used as a reference standard to obtain a mass spectrum; finally, the carbon isotope ratio of the sample is measured by calculation through a data processing system.

[0042] In another specific embodiment, a 1 mL gas-tight syringe is used to collect N2 gas, which is injected into the injection system of the stable isotope mass spectrometer of the present invention through a gas injection device. The N2 gas enters the stable isotope mass spectrometer to measure the nitrogen isotope ratio of N2.

[0043] and Figure 1 Corresponding to the system, an embodiment of the present invention also provides a sampling method for a stable isotope mass spectrometer, which specifically includes: continuously introducing gas into a sampling device, and using a gas-tight syringe to inject the sample to be tested into a nebulizer, atomizing the sample to be tested and sending it to a mass spectrometer, and the mass spectrometer analyzes the gas to be tested.

[0044] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0045] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sample injection system for a stable isotope mass spectrometer, characterized in that: It includes a sampling device, an atomizing device, a sample injection device and a mass spectrometer which are connected in sequence; A sampling device, used for taking the sample to be tested and conveying the sample to be tested to the atomization device; A nebulizer, used to generate a nebulized sample required for detection by a mass spectrometer; A sample injection device, used for injecting the atomized sample into the mass spectrometer; Mass spectrometer, used for mass spectrometry analysis of nebulized samples.

2. The sample injection system for a stable isotope mass spectrometer according to claim 1, characterized in that: Also included is a sample tray connected to the input end of the sampling device and used for carrying a tin boat containing a sample to be tested.

3. The sample injection system for a stable isotope mass spectrometer according to claim 1, characterized in that: The atomization device includes a liquid storage block, a hollow capillary and a cavity. One end of the hollow capillary is connected to the bottom of the liquid storage block as a sample injection end, and the other end of the hollow capillary extends into the cavity as a spray end. The injection device is connected to the cavity, and auxiliary atomization gas is input to act on the spray end of the hollow capillary.

4. The sample injection system for a stable isotope mass spectrometer according to claim 1, characterized in that: It also includes a vacuum device for providing a vacuum environment for the mass spectrometer. The vacuum device uses a mechanical pump to pre-evacuate the vacuum, and then uses a diffusion pump to continuously operate to maintain the vacuum environment for the mass spectrometer.

5. The sample injection system for a stable isotope mass spectrometer according to claim 1, characterized in that: The sample injection device is provided with a plurality of filter membrane nets, the filter membrane nets are provided with holes, and the outlets of the plurality of filter membrane nets are merged into one outlet.

6. The sample injection system for a stable isotope mass spectrometer according to claim 1, characterized in that: It also includes a data monitoring and processing device for collecting data and calculating results, analyzing and judging results, storing and calling data, and monitoring various parameters of the system.

7. The sample injection system for a stable isotope mass spectrometer according to claim 1, characterized in that: Use a gas-tight syringe to inject the sample to be tested.

8. A sampling method for a stable isotope mass spectrometer, characterized in that: A sample injection system for a stable isotope mass spectrometer according to any one of claims 1 to 7, comprising: Gas is continuously introduced into the sampling device, and the sample to be tested is injected into the atomization device using a gas-tight syringe. The sample to be tested is atomized and sent to the mass spectrometer, and the mass spectrometer analyzes the gas to be tested.

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