Screening method of novel p-phenylenediamine compounds in atmosphere and application
By combining fragment analysis and precursor ion scanning of known p-phenylenediamine compounds with high-resolution mass spectrometry, novel p-phenylenediamine compounds in the atmosphere were screened out, solving the problem of screening difficulties in existing technologies. A detailed compound information database was established, providing precise targets for the identification of unknown compounds.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2026-01-26
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies are unable to effectively screen for novel p-phenylenediamine compounds, especially in the atmosphere where targeted screening is not possible. Furthermore, non-targeted analysis techniques present significant challenges in compound identification, and there is a lack of specific screening methods for novel p-phenylenediamine compounds.
By performing fragment analysis on known p-phenylenediamine compounds, characteristic fragment ions are screened. Combined with precursor ion scanning and multiple reaction monitoring modes, high-resolution mass spectrometry is used to establish fracture fingerprints, identify compounds with common core structures, and deduce their structural differences through neutral loss analysis. This establishes an information database and provides targets for unknown compounds.
It has achieved efficient screening of novel p-phenylenediamine compounds in the atmosphere, rapidly and accurately screened out structurally similar unknown compounds from complex matrices, provided precise targets for subsequent confirmation, and established a detailed compound database.
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Figure CN122016985A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of screening for novel pollutants in the atmosphere, and in particular to a method and application for screening novel p-phenylenediamine compounds in the atmosphere. Background Technology
[0002] p-Phenylenediamines (PPDs) are a class of para-phenylene ring compounds containing two amino substituents. They have wide applications in industrial and consumer products, such as dyeing wool, fur, and hair, photographic contrast agents, and rubber antioxidants (especially 6PPD and IPPD). However, PPDs (such as p-phenylenediamine and m-phenylenediamine) are chemicals with potential health risks. PPDs and their degradation products are diverse, with many unknown compounds and potentially more toxic degradation products. Given their serious ecological hazards and potential health risks, as well as the current lack of understanding of potential PPD analogues, establishing a comprehensive analytical database by screening novel PPD compounds in the environment is crucial.
[0003] Currently, novel phenylenediamine compounds (such as their degradation products) cannot be specifically screened using commercially available standard materials. Untargeted analysis aims to comprehensively detect and collect data on small molecule compounds in samples without bias, offering the advantage of broad compound coverage; however, subsequent compound identification often faces significant challenges. In contrast, precursor ion scanning is a targeted screening strategy based on specific structural features. This technique, by monitoring a characteristic product ion (such as a fragment of a common functional group in a class of compounds), can efficiently and specifically identify all precursor ions that can produce that fragment from complex mass spectrometry data, thereby enabling rapid classification and identification of metabolites with a common structural core (such as a class of lipids or specifically modified metabolites). However, combining untargeted analysis techniques with precursor ion scanning to improve the specificity of target substances is crucial. Furthermore, there are no reports on specific screening methods for novel phenylenediamine compounds, resulting in a limited understanding of the types of novel phenylenediamine compounds. Summary of the Invention
[0004] In view of this, the present invention proposes a novel screening method for p-phenylenediamine compounds in the atmosphere, and also proposes the application of this screening method.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention proposes a novel method for screening p-phenylenediamine compounds in the atmosphere, including... The first step is to perform fragment analysis on known p-phenylenediamine compounds, screen out at least one set of structurally distinctive fragment ions, and determine the chemical formulas corresponding to the distinctive fragment ions; among them, known p-phenylenediamine compounds include IPPD, CPPD, DPPD, DNPD, 6PPD, and 6PPD-Q; The second step is to determine the liquid chromatography-mass spectrometry (LC-MS) conditions for the p-phenylenediamine compounds known in the first step. The third step involves using the characteristic fragment ions identified in the first step to perform targeted screening of atmospheric samples under precursor ion scanning mode and the chromatographic conditions and mass spectrometry parameters determined in the second step. The goal is to retain fragments with a mass-to-charge ratio below 500 Da and a signal intensity above 5 × 10⁻⁶. 4 The precursor ion of cps; The fourth step involves performing neutral loss analysis based on the candidate precursor ions obtained in the third step and the characteristic fragment ions screened in the first step. Candidate precursor ions that are simultaneously pointed to by two or more different characteristic fragment ions are retained, and the neutral loss mass difference must at least match the theoretical mass number of a neutral small molecule. In the fifth step, the atmospheric sample is targeted for identification under the chromatographic conditions and mass spectrometry parameters determined in the second step in the multiple reaction monitoring mode. The chromatographic peak of each candidate precursor ion in the fourth step is obtained, and the type of candidate precursor ion is determined based on the neutral loss mass difference, the mass number of the precursor ion and the retention time, and the molecular formula is deduced.
[0006] The beneficial effects are as follows: This invention is based on the principle that p-phenylenediamine compounds, due to their common core structure (i.e., phenylenediamine), will produce fragments in mass spectrometry that reflect the characteristics of the diphenylamine core. By accurately measuring the fragments of these known substances through high-resolution mass spectrometry, their "fracture fingerprint spectrum" is established. By using precursor ion scanning, all compounds that can produce fragments with the same characteristics are captured. For the screened candidates, by performing neutral loss analysis on their secondary mass spectrometry, the differences between them and the known core structure (i.e., substituents) can be deduced in reverse. Thus, unknown compounds that are structurally highly similar to known p-phenylenediamine substances can be efficiently screened from the complex PM2.5 matrix, providing a precise target for subsequent absolute confirmation using high-resolution mass spectrometry or standards.
[0007] Furthermore, in the first step, fragment ion mass spectrometry analysis of known p-phenylenediamine compounds is performed using HR-MS, with the collision energy starting at 5V and increasing sequentially in 5V increments.
[0008] Furthermore, the chromatographic conditions for the liquid chromatography-mass spectrometry (LC-MS) in the second step are as follows: mobile phase A: 0.1% formic acid in water; mobile phase B: acetonitrile; flow rate: 0.3 ml / min; injection volume: 10 μL; gradient elution of mobile phase: 0-2 min, 10% B; 2-25 min, 10-90% B; 25-28 min, 90% B; 28-30 min, 10% B. The mass spectrometry parameters were as follows: ion source temperature 500 °C, ion spraying voltage 5500 V, Gas 1, Gas 2 and Curtaingas 50, 50 and 35 psi respectively, and injection rate 3.0 μL / min.
[0009] Furthermore, in the third step, the atmospheric samples are obtained using PM2.5. 2.5 PM was obtained by sampling membrane sampling, and PM was then processed. 2.5 The sampled membrane strips were placed in centrifuge tubes and extracted sequentially with hexane, acetone, and hexane / acetone by ultrasonication. The extracts were centrifuged to remove impurities, and the supernatant was dried with a nitrogen blower. The extracts were then redissolved in acetonitrile, concentrated, and filtered through a membrane.
[0010] Furthermore, in the third step, when performing targeted screening in precursor ion scanning mode, the mass-to-charge ratio of the substance is set in the range of 150-1000 Da; the collision energy starts at 5V and increases in increments of 5V until it reaches 50V; the scanning rate is 1000 Da / s.
[0011] This invention also proposes the application of a screening method for novel p-phenylenediamine compounds in the atmosphere in establishing a database of novel p-phenylenediamine compounds. The database includes characteristic fragment ions, parent ion mass-to-charge ratios, retention times, and inferred molecular formulas of the novel p-phenylenediamine compounds. This information provides precise targets for the absolute identification of novel p-phenylenediamine analogs.
[0012] Compared with the prior art, the advantages of the present invention are as follows: This invention is based on the principle that p-phenylenediamine compounds, due to their shared core structure (i.e., phenylenediamine), exhibit fragmentation in mass spectrometry that reflects the characteristic features of the diphenylamine core. High-resolution mass spectrometry is used to accurately determine the fragments of these known substances, establishing their "fracture fingerprint." Precursor ion scanning is employed to capture all compounds that produce the same characteristic fragments. For screened candidates, neutral loss analysis of their secondary mass spectrometry allows for the reverse deduction of the differences (i.e., substituents) from the known core structure, thereby revealing the complex PM... 2.5 The matrix can be rapidly and accurately narrowed down to efficiently screen unknown compounds that are structurally highly similar to known p-phenylenediamine analogs, providing precise targets for the absolute confirmation of novel p-phenylenediamine analogs. Attached Figure Description
[0013] Figure 1 These are the secondary mass spectra of six known p-phenylenediamine compounds in this invention.
[0014] Figure 2 This is the XIC diagram of the IPPD, 6PPD analogue of the present invention.
[0015] Figure 3 This is the XIC diagram of CPPD and DPPD analogues in this invention.
[0016] Figure 4 This is the XIC diagram of the DNPD analogue in this invention.
[0017] Figure 5 This is the XIC diagram of the 6PPD-Q analogue in this invention.
[0018] Figure 6 This is a seasonal distribution map of p-phenylenediamine compounds and their analogues in Example 2 of the present invention. Detailed Implementation
[0019] The present invention will now be described in more detail with reference to specific embodiments. The IPPD, CPPD, DPPD, DNPD, 6PPD, 6PPD-Q, cyclohexane, acetone, and mobile phase used in this invention are commercially available reagents.
[0020] Example 1 This invention proposes a novel method for screening p-phenylenediamine compounds in the atmosphere, including... The first step involved fragment ion mass spectrometry analysis of six known p-phenylenediamine compounds using HR-MS (high-resolution mass spectrometry). Collision energies were increased sequentially in 5V increments, starting at 5V. All fragment ions produced at each collision energy were recorded. For each known compound, at least one set of structurally characteristic fragment ions was identified, and the corresponding chemical formulas were determined. See details below. Figure 1 and Table 1; Among them, the known p-phenylenediamine compounds include IPPD, CPPD, DPPD, DNPD, 6PPD, and 6PPD-Q, and MS2 mode was used for fragmentation analysis.
[0021] Table 1. Characteristic fragment ions of known p-phenylenediamine compounds The second step involves determining the liquid chromatography-mass spectrometry (LC / MS-MS) conditions for the known p-phenylenediamine compounds from the first step. The optimized LC conditions for analyzing these compounds are as follows: Mobile phase A: 0.1% formic acid in water; Mobile phase B: acetonitrile; Flow rate: 0.3 ml / min; Injection volume: 10 μL; Gradient elution: 0–2 min, 10% B; 2–25 min, 10–90% B; 25–28 min, 90% B; 28–30 min, 10% B; Mass spectrometry parameters: Ion source temperature: 500 ℃; Ion spray voltage: 5500 V; Gas1, Gas2, and Curtain gas: 50, 50, and 35 psi, respectively; Injection rate: 3.0 μL / min. The third step involves preprocessing the atmospheric samples and performing targeted screening on the preprocessed samples using LC / MS-MS. The mass spectrometry mode is precursor ion scanning mode, and other mass spectrometry parameters and chromatographic conditions are the same as in the second step. Specifically, during targeted screening, the mass-to-charge ratio is set within the range of 150-1000 Da; the collision energy starts at 5 V and increases in 5 V increments up to 50 V; the scan rate is 1000 Da / s; and retention is performed when the mass-to-charge ratio is ≤500 Da and the signal intensity is higher than 5 × 10⁻⁶. 4 The precursor ion of cps is used as a candidate precursor ion; The pretreatment of atmospheric samples is as follows: using PM2.5... 2.5 Sampling membrane sampling, PM after sampling 2.5 The sampled membrane strips were placed in centrifuge tubes and extracted first with 6 mL of n-hexane by sonication, then with 6 mL of acetone by sonication, and finally with 5 mL of n-hexane / acetone (v:v=1:1) by sonication. The three extracts were then combined and centrifuged at 3000 rpm. -1 Centrifuge for 20 min to remove impurities, blow the supernatant dry with a nitrogen blower, then redissolve with 1 mL of acetonitrile, concentrate to 250 μL, filter the concentrate through a 0.22 μm membrane, and then load the sample for analysis. Fourth, perform neutral loss analysis on the candidate precursor ions obtained in the third step and the characteristic fragment ions in the first step, and retain the candidate precursor ions that are simultaneously pointed to by two or more different characteristic fragment ions, as shown in Table 2; when performing neutral analysis, the difference in neutral loss mass between the retained candidate precursor ions and characteristic fragment ions should at least match the theoretical mass number of a neutral small molecule. Step 5: Target identification of the pretreated atmospheric sample from Step 3 was performed using UPLC-MS / MS. The mass spectrometry mode was multiple reaction monitoring (MRM), and the other parameters were the same as in Step 2. This confirmed the actual presence of the candidate precursor ions retained in Step 4 in the atmospheric sample, and obtained the corresponding chromatographic peaks and retention times (see...). Figure 2-5Based on candidate precursor ions, characteristic fragment ions, and neutral analysis, and combined with retention time, the specific type and corresponding molecular formula of each candidate precursor ion were inferred, as shown in Table 2. Table 2 Characteristic fragment ions, parent ions, retention times, and molecular formulas of novel phenylenediamine compounds The detailed derivation process of the molecular formulas corresponding to the above candidate parent ions is as follows: (1) When the parent ion m / z = 227 Da, it is simultaneously affected by C 12 H 12 N2⁺ (m / z = 184.1 Da) and C 14 H 16 Two characteristic fragment ions of N2⁺ (m / z = 212.1 Da) were captured by precursor ion scanning. Multiple reaction monitoring (MRM) mode validation showed clear chromatographic peaks with consistent retention times in both channels. The mass differences between this precursor ion and the two common characteristic fragment ions were 43 Da and 15 Da, respectively. The corresponding neutral losses are likely the neutral loss of propyl (C3H7•) and methyl (CH3•), respectively. The inferred molecular formula is likely C... 15 H 18 N2; the substance was identified as IPPD based on its retention time and neutral loss. The results demonstrate the correctness of the screening method of this invention.
[0022] (2) The characteristic fragment ion C corresponding to the parent ion m / z = 255 Da 12 H 12 N2⁺ (m / z = 184.1 Da) and C 14 H 16 N2⁺ (m / z = 212.1 Da). This parent ion reacts with C 12 H 12 The mass difference of N2⁺ (m / z = 184.1 Da) is 71 Da, corresponding to the neutral loss of pentyl (C5H) groups. 11 •); The parent ion and C 14 H 16 The mass difference of N2⁺ (m / z = 212.1 Da) is 43 Da, corresponding to the neutral loss of isopropyl groups (C3H7•). Therefore, the molecular formula of this substance is determined to be C... 17 H 22 N2, this substance is an analogue of IPPD or 6PPD.
[0023] (3) When the parent ion m / z = 259 Da, its corresponding characteristic fragment ion is C. 12 H 12 N2⁺ (m / z = 184.1 Da) and C 14 H16 N2⁺ (m / z = 212.1 Da), the parent ion and C 12 H 12 The mass difference between N2⁺ (m / z = 184.1 Da) and C is 75 Da, corresponding to the neutral loss of propylthio (C3H6S•); this parent ion and C 14 H 16 The mass difference of N2⁺ (m / z = 212.1 Da) is 47 Da, corresponding to the neutral loss of the methylthio group (CH3S•). Therefore, the molecular formula of this substance is determined to be C. 15 H 18 N2S is an analogue of IPPD or 6PPD.
[0024] (4) Fragment ion C corresponding to parent ion m / z = 320 Da 12 H 12 N2⁺ (m / z = 184.1) and C 14 H 16 N2⁺ (m / z = 212.1 Da). The mass differences between the parent ion and the two characteristic fragment ions are 136 Da and 108 Da, respectively. C 14 H 16 N2⁺ corresponds to the neutral loss of pyridinyl (C5H4N•) and methoxy (CH3O•), C 12 H 12 N2⁺ corresponds to the loss of pyridinyl (C5H4N•), methoxy (CH3O•), and ethylene (C2H4) groups, thus determining the molecular formula of this substance to be C. 20 H 21 N3O is an analogue of IPPD or 6PPD.
[0025] (5) The fragment ion corresponding to the parent ion m / z = 334 Da is C. 12 H 12 N2⁺ (m / z = 184.1 Da) and C 14 H 16 N2⁺ (m / z = 212.1 Da), the parent ion and C 12 H 12 The neutral loss mass difference of N2⁺ (m / z = 184.1 Da) is 150 Da, corresponding to the neutral loss of N-methylaminobenzoic acid (C8H8NO2•). This parent ion is related to C 14 H 16 The mass difference of N2⁺ (m / z = 212.1 Da) is 122 Da, corresponding to the neutral loss of nitrophenyl (C6H4NO2•). Therefore, the molecular formula of this substance is determined to be C6H4NO2•. 20 H 19N3O2 is an analogue of IPPD or 6PPD.
[0026] (6) The fragment ion corresponding to the parent ion m / z = 226 Da is C. 12 H 10 N + (m / z = 168.1 Da) and C 12 H 12 N2 + (m / z = 184.1 Da), the parent ion and C 12 H 12 N2 + The mass difference of (m / z = 184.1 Da) is 42 Da, corresponding to the neutral loss of N-methylimino group (C2H5N•); this parent ion and C 12 H 10 N + The mass difference (m / z = 168.1 Da) is 58 Da, corresponding to the neutral loss of the N-methylimino group (C2H5N•) and the amino group (NH2•). Therefore, the molecular formula of this substance can be determined to be C. 14 H 15 N3 is an analogue of CPPD or DPPD.
[0027] (7) The fragment ion corresponding to the parent ion m / z = 241 Da is C. 12 H 10 N + (m / z = 168.1 Da) and C 12 H 12 N2 + (m / z = 184.1 Da), the parent ion and C 12 H 10 N + The neutral mass difference of (m / z = 168.1 Da) is 73 Da, corresponding to the loss of neutral groups: tert-butyl (C4H9•) and amino (NH2•); this parent ion is related to C 12 H 12 N2 + The mass difference (m / z = 184.1 Da) is 57 Da, corresponding to the loss of a neutral group, tert-butyl (C4H9•). Therefore, the molecular formula of this substance can be determined to be C. 16 H 20 N2 is an analogue of CPPD or DPPD.
[0028] (8) The fragment ion corresponding to the parent ion m / z = 262 Da is C. 16 H 12 N + (m / z = 218.3 Da) and C 16H 14 N2 + (m / z = 234.1 Da), the parent ion and C 16 H 12 N + The mass difference (m / z = 218.3 Da) is 44 Da, corresponding to the loss of neutrality in ammonium cyanide (CH4N2•); this parent ion and C 16 H 14 N2 + The mass difference (m / z = 234.1 Da) is 28 Da, corresponding to the loss of a methylene amino group (CH2N•). Therefore, the molecular formula of this substance can be determined to be C. 17 H 15 N3 is an analogue of DNPD.
[0029] (9) The fragment ion corresponding to the parent ion m / z = 278 Da is C. 16 H 12 N + (m / z = 218.3) and C 16 H 14 N2 + (m / z = 234.1), the parent ion and C 16 H 12 N + The mass difference is 60 Da, corresponding to the loss of amino (NH2•) and ethylamino (C2H6N•) groups in neutral groups; this parent ion and C 16 H 14 N2 + The corresponding mass difference is 44 Da, corresponding to the loss of an ethylamino group (C2H6N•). Therefore, the molecular formula of this substance can be determined to be C. 18 H 19 N3 is an analogue of DNPD.
[0030] (10) The fragment ion corresponding to the parent ion m / z = 297 Da is C. 14 H 13 N2O2 + (m / z = 240.7 Da) and C 11 H 11 N2O + (m / z = 187.1 Da), the parent ion and C 14 H 13 N2O2 + The mass difference (m / z = 240.7 Da) is 56 Da, corresponding to the neutral loss of butene (C4H8); this parent ion and C 11 H 11 N2O +The mass difference (m / z = 187.1 Da) is 110 Da, corresponding to a neutral loss of 2,4-heptadienal (C7H 10 O). Therefore, the molecular formula of this substance can be determined to be C. 18 H 20 N2O2 has the same molecular formula as the previously reported CPPD-Q.
[0031] (11) The fragment ion corresponding to the parent ion m / z = 259 Da is C. 14 H 13 N2O2 + (m / z = 240.7) and C 11 H 11 N2O + (m / z = 187.1 Da), the parent ion and C 14 H 13 N2O2 + The mass difference (m / z = 240.7) is 18 Da, corresponding to the loss of neutral water (H2O); this parent ion and C 11 H 11 N2O + The mass difference (m / z = 187.1 Da) is 72 Da, corresponding to the neutral loss of acrylic acid (C3H4O2). Therefore, the molecular formula of this substance can be determined to be C... 14 H 14 N2O3, which is an analogue of 6PPD-Q.
[0032] As can be seen from the above, the screening method established in this invention can rapidly screen out various atmospheric PM2.5 concentrations. 2.5 The present invention addresses the technical challenge of rapidly and accurately narrowing down the scope of research from massive amounts of environmental data to identify worthy targets for study by screening p-phenylenediamine analogs (i.e., novel p-phenylenediamine compounds). Furthermore, the invention identifies multiple precursor ions targeted by two or more different characteristic fragment ions during the screening process. Based on these screened precursor ions and their corresponding characteristic fragment ions and retention times, a database of novel p-phenylenediamine compounds can be established, providing precise targets for the absolute confirmation of novel p-phenylenediamine analogs.
[0033] Example 2: Application of the Information Database of the Present Invention Example 1 of this invention establishes an information database containing the parent ion, its corresponding characteristic fragment ions, retention time, and inferred molecular formula. To this end, this invention performs mass spectrometry analysis on atmospheric samples from four seasons (spring, summer, autumn, and winter) at a certain location under multiple reaction monitoring (MRM) mode and the same liquid chromatography-mass spectrometry (LC-MS) conditions as in the second step of Example 1. The results are shown in [Figure 1]. Figure 6 .Depend on Figure 6It can be seen that the paraphenylenediamine compounds in the atmospheric environment of this region in spring, summer, autumn and winter are mainly IPPD and 6PPD analogs, followed by DNPD analogs, then 6PPD-Q analogs, and CPPD and DPPD analogs are the least.
[0034] In summary, this invention is based on the principle that p-phenylenediamine compounds, due to their shared core structure (i.e., phenylenediamine), will exhibit fragmentation in mass spectrometry that reflects the core characteristics of diphenylamine. High-resolution mass spectrometry is used to accurately determine the fragments of these known substances, establishing their "fracture fingerprint spectrum." Precursor ion scanning is employed to capture all compounds that produce the same characteristic fragments. For the screened candidates, neutral loss analysis of their secondary mass spectrometry allows for the reverse deduction of the differences (i.e., substituents) between them and the known core structure. This enables rapid and accurate narrowing of the range from the complex PM2.5 matrix, efficiently screening out unknown compounds that are structurally highly similar to known p-phenylenediamines, providing precise targets for the absolute confirmation of phenylenediamine analogs.
Claims
1. A method for screening novel p-phenylenediamine compounds in the atmosphere, characterized in that: include The first step is to perform fragment analysis on known p-phenylenediamine compounds, screen out at least one set of structurally distinctive fragment ions, and determine the chemical formulas corresponding to the distinctive fragment ions; among them, known p-phenylenediamine compounds include IPPD, CPPD, DPPD, DNPD, 6PPD, and 6PPD-Q; The second step is to determine the liquid chromatography-mass spectrometry (LC-MS) conditions for the p-phenylenediamine compounds known in the first step. The third step involves using the characteristic fragment ions identified in the first step to perform targeted screening of atmospheric samples under precursor ion scanning mode and the chromatographic conditions and mass spectrometry parameters determined in the second step. The goal is to retain fragments with a mass-to-charge ratio below 500 Da and a signal intensity above 5 × 10⁻⁶. 4 The precursor ion of cps; The fourth step involves performing neutral loss analysis based on the candidate precursor ions obtained in the third step and the characteristic fragment ions screened in the first step. Candidate precursor ions that are simultaneously pointed to by two or more different characteristic fragment ions are retained, and the neutral loss mass difference must at least match the theoretical mass number of a neutral small molecule. In the fifth step, the atmospheric sample is targeted for identification under the chromatographic conditions and mass spectrometry parameters determined in the second step in the multiple reaction monitoring mode. The chromatographic peak of each candidate precursor ion in the fourth step is obtained, and the type of candidate precursor ion is determined based on the neutral loss mass difference, the mass number of the precursor ion and the retention time, and the molecular formula is deduced.
2. The method for screening novel p-phenylenediamine compounds in the atmosphere according to claim 1, characterized in that: In the first step, fragment ion mass spectrometry analysis of known p-phenylenediamine compounds is performed using HR-MS, with the collision energy starting at 5V and increasing in 5V increments.
3. The method for screening novel p-phenylenediamine compounds in the atmosphere according to claim 1, characterized in that: The chromatographic conditions for the second step of liquid chromatography-mass spectrometry are as follows: mobile phase A: 0.1% formic acid in water; mobile phase B: acetonitrile; flow rate: 0.3 ml / min; injection volume: 10 μL; gradient elution of mobile phase: 0-2 min, 10% B; 2-25 min, 10-90% B; 25-28 min, 90% B; 28-30 min, 10% B; The mass spectrometry parameters were as follows: ion source temperature 500 °C, ion spraying voltage 5500 V, Gas 1, Gas 2 and Curtaingas 50, 50 and 35 psi respectively, and injection rate 3.0 μL / min.
4. The method for screening novel p-phenylenediamine compounds in the atmosphere according to claim 1, characterized in that: In the third step, the atmospheric sample is obtained using PM2.
5. 2.5 PM was obtained by sampling membrane sampling, and PM was then processed. 2.5 The sampled membrane strips were placed in centrifuge tubes and extracted sequentially with hexane, acetone, and hexane / acetone by ultrasonication. The extracts were centrifuged to remove impurities, and the supernatant was dried with a nitrogen blower. The extracts were then redissolved in acetonitrile, concentrated, and filtered through a membrane.
5. The method for screening novel p-phenylenediamine compounds in the atmosphere according to claim 1, characterized in that: In the third step, when performing targeted screening in precursor ion scanning mode, the mass-to-charge ratio of the material is set in the range of 150-1000 Da; the collision energy starts at 5V and increases in increments of 5V until it reaches 50V; the scanning rate is 1000 Da / s.
6. The application of the screening method according to any one of claims 1-5 in constructing a novel p-phenylenediamine compound database, wherein, The database includes characteristic fragment ions, parent ion mass-to-charge ratios, retention times, and inferred molecular formulas of novel p-phenylenediamine compounds.