A method and system for analyzing carbon isotope abundance in perfluorohexane

Abstract

The present invention discloses a method for analyzing the carbon isotope abundance in perfluorohexane, comprising the following steps: S1: establishing seven molecular weight C6F 14 Molecular abundance calculation model; S2: The molar abundance of C-12 isotope in CF3 group is measured by mass spectrometry system m ; S3: C measured by S2 m Substitute seven molecular weights of C6F 14 Molecular abundance calculation model, seven molecular weights of C6F 14 Molar abundance of molecules. This analytical method obtains the carbon isotope abundance in CF3 ions through existing mass spectrometry system analysis, and uses classical profile theory to obtain the relationship between the carbon isotope abundance in CF3 ions and the carbon isotope abundance in perfluorohexane. Then, using binomial distribution theory, the molecular abundance of perfluorohexane allotropes is calculated.

Description

Technical Field

[0001] The present invention relates to the technical field of mass spectrometry analysis, and in particular to a method and system for analyzing carbon isotope abundance in perfluorohexane. Background Art

[0002] At present, isotope abundance analysis mass spectrometers have specific requirements for the molecular weight of ion fragments after ionization. A mass spectrometer can only meet the collection and abundance analysis of ion fragments within a certain molecular weight range. For perfluorohexane, the existing mass spectrometer can only collect and analyze the CF3 ion fragments after ionization, and CF2 ions cannot be collected and analyzed. Therefore, the existing mass spectrometer directly analyzes and measures the abundance of carbon isotopes in CF3 ions, but the actual analysis and measurement requirements are to obtain the abundance of carbon isotopes in perfluorohexane and the abundance of perfluorohexane allotrope molecules.

[0003] On the other hand, the molecular weights of CF3 ions and CF2 ions are quite different. Collecting and analyzing the two ions using the same mass spectrometer system requires the modification and upgrading of the Faraday cage of the mass spectrometer, which places very high demands on the Faraday cage. This will significantly increase the cost of the mass spectrometer system and make the analysis expensive. Summary of the invention

[0004] The purpose of the present invention is to provide a method for analyzing the abundance of carbon isotopes in perfluorohexane in view of the technical defect that the abundance of carbon isotopes in perfluorohexane and the abundance of allotrope molecules of perfluorohexane cannot be accurately measured in the prior art.

[0005] Another object of the present invention is to provide a system for analyzing carbon isotope abundance in perfluorohexane.

[0006] The technical solution adopted to achieve the purpose of the present invention is:

[0007] A method for analyzing carbon isotope abundance in perfluorohexane comprises the following steps:

[0008] S1: Establish seven molecular weight C6F 14 The calculation model of the molecular molar abundance is shown in formula (1);

[0009]

[0010] In the formula, C i (i=1,2,3,4,5,6,7) represent C6F with molecular weights of 338, 339, 340, 341, 342, 343 and 344 respectively 14 The molar abundance of the molecule;

[0011] C m represents the molar abundance of C-12 isotope in CF3 group detected by mass spectrometry;

[0012] S2: The molar abundance of C-12 isotope in CF3 group was measured by mass spectrometry system. m ;

[0013] S3: C measured by S2 m Substituting into formula (1), we can obtain seven molecular weights of C6F 14 Molar abundance of the molecule C i .

[0014] In the above technical solution, the formula (1) is derived based on the binomial distribution theory.

[0015] In the above technical solution, the formula (1) is based on the fact that the molar abundance of the C-12 isotope in the CF3 group detected by mass spectrometry is equal to that of the C6F 14 The molar abundance of C-12 isotope atoms in a molecule is given by formula (2):

[0016] C m =C (2)

[0017] This theory was obtained.

[0018] In the above technical solution, formula (2) is derived by the following method:

[0019] S1.1: Calculate seven molecular weights of C6F 14 Molecules that can be detected by mass spectrometry 12 CF 3+ The number of ions N i (i=1,2,3,4,5,6,7);

[0020] S1.2: Consider all n C6F 14 The molecule is ionized according to formula (3) to obtain CF 3+ Total number of ions;

[0021] N m =(2x2+3x3+4x4)n (3)

[0022] S1.3: Based on the definition of molar abundance, calculate the molar abundance of C-12 isotope atoms in the CF3 group measured by the existing mass spectrometry system according to formula (4);

[0023]

[0024] S1.4: Consider C6F 14 For all C atoms in the sample, the molar abundance of C-12 isotope atoms is calculated according to the definition of molar abundance using formula (5);

[0025]

[0026] S1.5: By comparing equation (4) and equation (5), we can get

[0027] C m =C (2).

[0028] In the above technical solution, in S1.1, seven molecular weights C6F are calculated based on the classical prototypical theory and the classification theory in permutations and combinations. 14 Molecules that can be detected by mass spectrometry 12 CF 3+ The number of ions N i .

[0029] In the above technical solution, it is characterized in that:

[0030] C6F with a molecular weight of 338 14 Molecules, ionized 12 CF 3+ The number of ions is:

[0031]

[0032] C6F with a molecular weight of 339 14 Molecules, ionized 12 CF 3+ The number of ions is:

[0033]

[0034] In the above technical solution, C6F with a molecular weight of 340 14 Molecules, ionized 12 CF 3+ The number of ions is:

[0035]

[0036] In the above technical solution, C6F with a molecular weight of 341 14 Molecules, ionized 12 CF 3+ The number of ions is:

[0037]

[0038] In the above technical solution, C6F with a molecular weight of 342 14 Molecules, ionized 12 CF 3+ The number of ions is:

[0039]

[0040] In the above technical solution, C6F with a molecular weight of 343 14 Molecules, ionized 12 CF 3+ The number of ions is:

[0041]

[0042] C6F with a molecular weight of 343 14 Molecules, after ionization, do not produce 12 CF3 + Ions, i.e.

[0043] N7=0 (12).

[0044] In another aspect of the present invention, the above-mentioned carbon isotope abundance analysis system in perfluorohexane comprises:

[0045] Mass spectrometer, used to detect the molar abundance of C-12 isotope in CF3 group m ;

[0046] Calculation module, including seven molecular weight C6F 14 Calculate the model of the molar abundance of molecules and perform calculations;

[0047] The seven molecular weight C6F 14 The calculation model of the molecular molar abundance is shown in formula (1);

[0048]

[0049] Output module for displaying seven molecular weight C6F 14 Molar abundance of the molecule C i (i=1,2,3,4,5,6,7).

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. The method for analyzing carbon isotope abundance in perfluorohexane provided by the present invention saves manpower and time costs.

[0052] 2. The method for analyzing carbon isotope abundance in perfluorohexane provided by the present invention can realize the analysis of carbon isotope abundance in perfluorohexane without any modification to the existing mass spectrometer system, thereby reducing the analysis cost.

[0053] 3. The method for analyzing carbon isotope abundance in perfluorohexane provided by the present invention provides an evaluation method for the carbon isotope separation effect of perfluorohexane, and lays a foundation for the application of perfluorohexane in carbon isotope separation. DETAILED DESCRIPTION

[0054] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] Example 1

[0056] A method for analyzing carbon isotope abundance in perfluorohexane comprises the following steps:

[0057] S1: Establish seven molecular weight C6F 14 The calculation model of the molecular molar abundance is shown in formula (1);

[0058]

[0059] In the formula, C i (i=1,2,3,4,5,6,7) represent C6F with molecular weights of 338, 339, 340, 341, 342, 343 and 344 respectively 14 The molar abundance of the molecule;

[0060] C m represents the molar abundance of C-12 isotope in CF3 group detected by mass spectrometry;

[0061] S2: The molar abundance of C-12 isotopes in the CF3 group was measured using a mass spectrometry system

[0062] C m =98.90%;

[0063] S3: C measured by S2 m Substituting into formula (1), we can obtain seven molecular weights of C6F 14 The molar abundance of the molecule is

[0064]

[0065] Example 2

[0066] This example is based on Example 1 and introduces seven molecular weight C6F 14 The process of establishing a molecular molar abundance calculation model.

[0067] In nature, carbon has three isotopes, namely C-12, C-13 and C-14. However, the natural abundance of C-14 isotope is trace, and in most cases, its abundance does not need to be considered. Therefore, for perfluorohexane (hereinafter referred to as C6F 14 When only the C-12 and C-13 isotopes are considered, a total of seven molecular weights can be formed, with molecular weights of 338, 339, 340, 341, 342, 343 and 344 respectively. The molar abundances of the seven molecular weights satisfy formula (13):

[0068]

[0069] The number of CF3 groups in C6F 14 The isomers can be classified into three categories, with the number of CF3 groups being 2, 3 and 4 respectively. The molar contents of the three isomers satisfy formula (14):

[0070] x2+x3+x4=1 (14).

[0071] In the formula, x2 represents C6F with two CF3 groups. 14 Isomer molar content; x3 represents C6F with 3 CF3 groups 14 Isomer molar content; x4 represents C6F with 4 CF3 groups 14 Molar content of isomers.

[0072] Since C6F 14 The CC bonds in the molecule are all single bonds with small bond energy. All CC single bonds can be broken in the mass spectrometer ionization chamber to form CF2 + and CF3 + ions. Existing mass spectrometry systems can only analyze CF3 + The ions are collected and analyzed for their C-12 isotope abundance.

[0073] Under natural conditions, the properties of C-12 and C-13 isotopes are almost identical, so the two isotope atoms form C6F 14 molecules, that is, the C-12 and C-13 isotopes are completely randomly distributed in the C6F 14 Therefore, the molecular weight of each C6F can be calculated using classical prototypical theory and classification theory in permutations and combinations. 14 Isomers can produce 12 CF3 + The number of ions. The following is a classification discussion of molecules of seven molecular weights.

[0074] For C6F with a molecular weight of 338 14 The carbon atoms that make up the molecule are all C-12 isotope atoms, so each CF3 produced by ionization + The ions are 12 CF3 + Ions, i.e.

[0075]

[0076] For C6F with a molecular weight of 339 14molecules, one of which is a C-13 isotope atom, which may or may not be present in the CF3 group, so the ionization produces 12 CF3 + The number of ions is

[0077]

[0078] For C6F with a molecular weight of 340 14 In the molecule, two carbon atoms are C-13 isotope atoms, which may all appear in the CF3 group, or none of them, or some of them may appear in the CF3 group. Therefore, the ionization produces 12 CF3 + The number of ions is

[0079]

[0080] For C6F with a molecular weight of 341 14 In the case of a molecule, 3 carbon atoms are C-13 isotopes: for isomers with 4 CF3 groups, at least 1 C-13 isotope atom appears in the CF3 group; for isomers with 3 CF3 groups, there may be 0, 1, 2, or 3 C-13 isotopes appearing in the CF3 group; for isomers with 2 CF3 groups, there may be 0, 1, or 2 C-13 isotopes appearing in the CF3 group. 12 CF3 + The number of ions is

[0081]

[0082] For C6F with a molecular weight of 342 14 In the case of a molecule, 4 carbon atoms are C-13 isotope atoms: for the isomer with 4 CF3 groups, at least 2 C-13 isotope atoms appear in the CF3 group; for the isomer with 3 CF3 groups, at least 1 C-13 isotope atom appears in the CF3 group; for the isomer with 2 CF3 groups, there may be 0, 1, or 2 C-13 isotope atoms appearing in the CF3 group. 12 CF3 + The number of ions is

[0083]

[0084] For C6F with a molecular weight of 343 14In the molecule, 5 carbon atoms are C-13 isotope atoms: for the isomer with 4 CF3 groups, at least 3 C-13 isotope atoms appear in the CF3 group; for the isomer with 3 CF3 groups, at least 2 C-13 isotope atoms appear in the CF3 group; for the isomer with 2 CF3 groups, at least 1 C-13 isotope atom appears in the CF3 group. Therefore, the ionization produces 12 CF3 + The number of ions is

[0085]

[0086] For C6F with a molecular weight of 344 14 The carbon atoms that make up the molecule are all C-13 isotope atoms, so after ionization, no 12 CF3 + Ions, i.e.

[0087] N7=0 (12).

[0088] Consider all n C6F 14 The total number of CF3+ ions obtained after ionization is;

[0089] N m =(2x2+3x3+4x4)n (3)

[0090] According to the definition of molar abundance, the molar abundance of C-12 isotope atoms in the CF3 group measured by the existing mass spectrometry system is calculated according to formula (3) and formula (6)-(12):

[0091]

[0092] Consider C6F 14 For all C atoms in the , calculate the molar abundance of C-12 isotope atoms according to the definition of molar abundance;

[0093]

[0094] By comparing equation (4) and equation (5), we can get

[0095] C m =C (2).

[0096] Formula (2) shows that the molar abundance of the C-12 isotope in the CF3 group detected by the existing mass spectrometry system is equal to that of the C6F 14 The molar abundance of C-12 isotope atoms in a molecule.

[0097] Thus, the present invention proves that the molar abundance of C-12 isotope atoms in the CF3 group measured by the mass spectrometry system is C6F 14 The molar abundance of C-12 isotope atoms in a molecule. In practical carbon isotope separation applications, the seven molecular weights C6F 14 The molar abundance of molecules is calculated using binomial distribution theory for seven molecular weights C6F 14 The molar abundance of the molecule gives seven molecular weights C6F 14 Model for calculating the molar abundance of molecules.

[0098] Example 3

[0099] A carbon isotope abundance analysis system in perfluorohexane, comprising:

[0100] Mass spectrometer, used to detect the molar abundance of C-12 isotope in CF3 group m ;

[0101] Calculation module, including seven molecular weight C6F 14 Calculate the model of the molar abundance of molecules and perform calculations;

[0102] Output module for displaying seven molecular weight C6F 14 The molar abundance of a molecule.

[0103] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for analyzing carbon isotope abundance in perfluorohexane, characterized in that: The following steps are involved: S1: Establish seven molecular weight C6F 14 The calculation model of the molecular molar abundance is shown in formula (1); In the formula, C i (i=1,2,3,4,5,6,7) represent C6F with molecular weights of 338, 339, 340, 341, 342, 343 and 344 respectively 14 The molar abundance of the molecule; C m represents the molar abundance of C-12 isotope in CF3 group detected by mass spectrometry; S2: The molar abundance of C-12 isotope in CF3 group was measured by mass spectrometry system. m ; S3: C measured by S2 m Substituting into formula (1), we can obtain seven molecular weights of C6F 14 Molar abundance of the molecule C i .

2. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 1, characterized in that: The formula (1) is derived based on the binomial distribution theory.

3. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 2, characterized in that: The formula (1) is based on the fact that the molar abundance of the C-12 isotope in the CF3 group detected by mass spectrometry is equal to that of the C6F 14 The molar abundance of C-12 isotope atoms in a molecule is given by formula (2): C m =C (2) This theory was obtained.

4. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 3, characterized in that: Formula (2) is derived by the following method: S1.1: Calculate seven molecular weights of C6F 14 Molecules that can be detected by mass spectrometry 12 CF 3+ The number of ions N i (i=1,2,3,4,5,6,7); S1.2: Consider all n C6F 14 The molecule is ionized according to formula (3) to obtain CF 3+ Total number of ions; N m =(2x2+3x3+4x4)n (3) S1.3: Based on the definition of molar abundance, calculate the molar abundance of C-12 isotope atoms in the CF3 group measured by the existing mass spectrometry system according to formula (4); S1.4: Consider C6F 14 For all C atoms in the sample, the molar abundance of C-12 isotope atoms is calculated according to the definition of molar abundance using formula (5); S1.5: By comparing equation (4) and equation (5), we get C m =C (2)。 5. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 4, characterized in that: In S1.1, seven molecular weights of C6F are calculated based on classical prototypical theory and classification theory in permutations and combinations. 14 Molecules that can be detected by mass spectrometry 12 CF 3+ The number of ions N i .

6. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 5, characterized in that: C6F with a molecular weight of 338 14 Molecules, ionized 12 CF 3+ The number of ions is: C6F with a molecular weight of 339 14 Molecules, ionized 12 CF 3+ The number of ions is:

7. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 5, characterized in that: C6F with a molecular weight of 340 14 Molecules, ionized 12 CF 3+ The number of ions is:

8. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 5, characterized in that: C6F with a molecular weight of 341 14 Molecules, ionized 12 CF 3+ The number of ions is:

9. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 5, characterized in that: C6F with a molecular weight of 342 14 Molecules, ionized 12 CF 3+ The number of ions is:

10. The method for analyzing carbon isotope abundance in perfluorohexane according to claim 5, characterized in that: C6F with a molecular weight of 343 14 Molecules, ionized 12 CF 3+ The number of ions is: C6F with a molecular weight of 343 14 Molecules, after ionization, do not produce 12 CF3 + Ions, i.e. N7＝0 (12)。 11. A carbon isotope abundance analysis system in perfluorohexane, characterized in that: include: Mass spectrometer, used to detect the molar abundance of C-12 isotope in CF3 group m ; Calculation module, including seven molecular weight C6F 14 Calculate the molar abundance of molecules using a model and perform calculations; The seven molecular weight C6F 14 The calculation model of the molecular molar abundance is shown in formula (1); Output module for displaying seven molecular weight C6F 14 Molar abundance of the molecule C i (i=1,2,3,4,5,6,7).

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