Method for identifying oil stain pollution source based on nuclear magnetic hydrogen spectrum and mass spectrometry

Abstract

The invention discloses a method for identifying an oil stain pollution source based on nuclear magnetic hydrogen spectrum and mass spectrometry, and relates to the field of tobacco and cigarette products, and the method comprises the following steps: respectively extracting spot-forming substances in an oil stain sample and a pollution source simulation spot sample by using an organic solvent to prepare an extract liquid sample; testing the 1H NMR spectrum of the extract sample, comparing and analyzing the spectrogram characteristics, preliminarily screening to obtain pollution source simulation spots similar to the spectrogram characteristics of the oil stain sample, calculating the characteristic ratios B1 and B2, comparing the conformity, and grading to obtain pollution sources with high and medium conformity; then negative ion mode mass spectrum testing is conducted, the mass spectrum similarity value S is calculated, and the pollution source with the maximum mass spectrum similarity is obtained.

Description

Technical Field

[0001] This invention relates to the field of tobacco and cigarette products, and particularly to the field of manufacturing process control and quality inspection of tobacco and cigarette products, specifically a method for identifying the source of oil stains based on nuclear magnetic resonance hydrogen spectroscopy and mass spectrometry. Background Technology

[0002] The national standard GB5606.3-2005, "Cigarettes Part 3: Packaging, Rolling Technical Requirements and Storage and Transportation," stipulates that the surface of cigarettes should be clean and free of oil stains or spots longer than 2.0 mm. Oil stains are considered a relatively serious quality defect. They are mainly caused by the leakage of lubricating oil or grease from production machinery during the cigarette production process, which contaminates the tobacco or cigarette paper.

[0003] Tracing the source of oil stains has always been a key task for cigarette manufacturers, as the accuracy of this tracing is crucial for defining quality responsibilities and formulating quality control measures. In recent years, numerous research papers and patents have been published on methods for tracing the source of cigarette contaminants; however, existing detection techniques and experimental strategies have the following shortcomings: Single detection methods are insufficient for accurate source tracing of oil stains. For example, patent application CN112345654A, "A Method for Identifying Oil Stain Sources Based on Chromatographic Fingerprint," discloses a method for identifying oil stain sources based on gas chromatography fingerprinting. This method is suitable for light components but difficult to apply to identifying heavy components in pollutants such as lubricating greases. While technologies combining multiple methods still have limitations, CN112014395A, "A Method for Identifying Insect Spots on Cigarette Surfaces Based on Characteristic Fingerprint," and CN113686805A, "Characteristic Fingerprint Spectrum of Oil Products and its Establishment Method and its Application in Identifying Oil Stains on Cigarettes," both propose combining infrared spectroscopy and gas chromatography-mass spectrometry to trace pollutants. However, both methods suffer from incomplete coverage and insufficient accuracy. Inaccurate source tracing of oil stains leads to difficulties in defining quality responsibility and affects the formulation of quality control measures. Summary of the Invention

[0004] To address the limitations of existing detection technologies in tracing the source of oil stains (especially heavy components), where single methods are insufficient for accurate source tracing and combined methods still suffer from insufficient accuracy leading to unreliable identification, this invention provides a method for identifying the source of oil stains based on 1H NMR spectroscopy and mass spectrometry.

[0005] This invention is achieved using the following techniques: A method for identifying the source of oil stains based on proton nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry includes the following steps: a. Extraction of oil stains and contaminants Organic solvents were used to extract the staining substances from oil stain samples and pollution source simulated spots to prepare oil stain extract samples and pollution source simulated spot extract samples. Specifically, one or more oil stain samples from the same cigarette or batch of cigarettes are immersed in 0.5-1 mL of deuterated chloroform or deuterated toluene solvent for 4 hours. The extract is collected into a clean sample bottle. During solvent extraction, the solvent can be shaken to encourage the staining substances to be extracted into the solvent. The extraction is repeated once. The extracts are combined and mixed well to obtain the oil stain extract sample. The same method was used to process the lubricant-impregnated simulated spot samples to obtain the pollution source simulated spot extract samples.

[0006] b. Comparative analysis of proton NMR spectral data Test extract sample 1 H NMR spectroscopy, focusing on the chemical shift region δ=0.50-1.50 ppm, compared and analyzed the spectral characteristics of oil stain extract samples and pollution source simulated stain extract samples, and carried out preliminary screening to screen out pollution source simulated stains with high consistency with the staining substances in oil stains and soot stains. If the NMR characteristic peak set of the pollution source simulated spot extract sample is reproducible in the oil stain soot spot extract sample, it is considered that the chemical structure characteristics of the two are consistent. Based on this, pollution source simulated spots with high consistency with the spot-forming substances in oil stain soot spots can be preliminarily screened.

[0007] c. Calculate the characteristic ratios B1 and B2 Based on the spectrum obtained in step b, calculate the characteristic ratios B1 and B2 of the simulated pollution source spots after the initial screening in step b. B1= I 1.35-1.20 / I 0.95-0.70 In the formula: I 1.35-1.20 δ 1,CH2 The integral area of ​​the spectral lines in the region of 1.35-1.20 ppm. I 0.95-0.70 δ 1,CH3 =0.95-0.70 ppm region of spectral line integral area; B2 = I 1.50-1.00 / I 1.00-0.50 In the formula: I 1.50-1.00 δ 2,CH2 =1.50-1.00 ppm region spectral line integral area I 1.00-0.50 δ 2,CH3 =Integrated area of ​​spectral lines in the 1.00-0.50 ppm region; The characteristic ratios B1 and B2 of the oil stain samples were compared with those of the simulated pollution source stains, and the samples were divided into three levels: high, medium, and low, based on the degree of agreement. The screening criteria were as follows: If the characteristic ratios B1 and B2 of oil stains and soot spots are both greater than the characteristic ratios B1 and B2 of simulated pollution source spots, then the consistency is high. If the characteristic ratio B1 of oil stains and soot is greater than the characteristic ratio B1 of simulated pollution source spots, while the characteristic ratio B2 of oil stains and soot is less than or equal to the characteristic ratio B2 of simulated pollution source spots, then the degree of conformity is considered moderate. If the characteristic ratios B1 and B2 of oil stains and soot spots are both less than or equal to the characteristic ratios B1 and B2 of simulated pollution source spots, then the consistency is low.

[0008] d, Mass spectrometry analysis Extract samples of pollution source simulation spots with high and medium compliance in step c were subjected to negative ion mode liquid chromatography-mass spectrometry (LC-MS). Electrospray source mass spectrometry (ESI-MS) or direct real-time analysis source mass spectrometry (DART-MS) were used for the test, with a mass-to-charge ratio range of m / z = 80-1400. The mass spectrometry similarity value S between the oil stain sample and the simulated pollution source sample was calculated using the cosine similarity method.

[0009]

[0010] In the formula: S represents the cosine similarity of the included angle. x i and y i These represent the two mass spectra at the [missing information] th ... i Characteristic peaks (m / z) i The relative abundance, The pollution source is determined based on the S value. If S ≥ 80%, it is judged as a highly similar pollution source. The larger the S value, the higher the similarity. If the condition is met, the result is output.

[0011] By combining statistical information from NMR and mass spectrometry databases (which summarize and record historical test data and identification results) of oil stains and grease spots (characteristic peaks, B1 values, B2 values, and S values ​​of various brands of cigarettes and various types of grease spots), the source of pollution is identified. The consistency of the source identification results is further analyzed. The correctness of the source identification results is verified by checking and improving the cigarette production line.

[0012] Compared with the prior art, the present invention has the following beneficial effects: This invention presents a method for identifying the source of oil stains based on 1H NMR spectroscopy and mass spectrometry. The method utilizes 1H NMR spectroscopy (NMR spectroscopy) to... 1Combining 1H NMR and liquid chromatography-mass spectrometry (MS), 1H NMR quantitatively characterizes saturated hydrocarbons (typically accounting for 80-95% of the lubricating oil / lipid content) and nonpolar structures (such as alkyl chains) in additive molecules in lubricating oils (greases). Liquid chromatography-mass spectrometry characterizes lubricating oil (grease) additive molecules (such as carboxylates, accounting for approximately 5-15% of the lubricating grease mass), accurately tracing the source of oil stain contaminants and improving the accuracy of oil stain contaminant tracing to over 90%, allowing for the location of lubricant leaks in specific production equipment. In application... 1 When identifying substances using H NMR and MS spectroscopic data, characteristic indicators (B1 and B2 values, S value) that can quantitatively characterize the overall distribution of spectral data are proposed. By combining the characteristic peak comparison method and the characteristic indicator comparison method, the material structure characteristics of oil stains and lubricating greases can be extracted more comprehensively, ensuring the reliability of the derived conclusions. Attached Figure Description

[0013] Figure 1 This is a flowchart illustrating the source tracing and detection of contaminants in oil stains.

[0014] Figure 2 This refers to the extract samples of oil stain #1 and simulated stains from pollution sources. 1 H NMR spectrum.

[0015] Figure 3 express Figure 2 A partial view.

[0016] Figure 4 This indicates oil stain #1, grease 1 immersion stain, and grease 3 immersion stain. 1 H NMR spectral morphology and characteristic ratios B1 and B2.

[0017] Figure 5 This shows the negative ion mass spectrum of the extract of oil stain #1.

[0018] Figure 6 This shows the negative ion mass spectrum of the extract of the grease 1 impregnation spot.

[0019] Figure 7 This shows the negative ion mass spectrum of the extract of the grease 3 impregnation spot.

[0020] Figure 8 A radar chart representing the relative abundance of characteristic negative ions in mass spectrometry. Detailed Implementation

[0021] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0022] A method for identifying the source of oil stains based on proton nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry, such as Figure 1 As shown, it includes the following steps: a. Extraction of oil stains and contaminants The oil stain #1 sample was immersed in 0.5-1 mL of deuterated chloroform or deuterated toluene solvent for 4 hours. The extract was collected into a clean sample bottle. During the solvent extraction process, the solvent was shaken to promote the extraction of the staining substances into the solvent. The extraction was repeated once. The extracts were combined and mixed well to obtain the oil stain #1 extract sample. The same method was used to process the simulated spot samples impregnated with six kinds of lubricants to prepare the pollution source simulated spot extract samples. The six lubricants included three kinds of grease and three kinds of lubricating oil, which were respectively denoted as grease 1 impregnation spot, grease 2 impregnation spot, grease 3 impregnation spot, lubricating oil 1 impregnation spot, lubricating oil 2 impregnation spot, and lubricating oil 3 impregnation spot.

[0023] b. Comparative analysis of proton NMR spectral data The above seven extract samples were collected using a Bruker Avance III 600 MHz high-resolution liquid nuclear magnetic resonance spectrometer (Bruker Corporation, USA). 1 1H NMR spectroscopy; Test conditions: ZG30 pulse, temperature 25℃, spectral width 20.0276, center frequency 6 ppm, number of sampling points 32 k, number of samplings 8, sampling time 1.36 s, relaxation delay time 1 s; Data processing was performed using TopSpin 3.7 software, and the measured spectrum is shown below. Figure 2 , 3 , Focusing on the chemical shift δ=0.50-1.50 ppm region, and through comparison of characteristic peak morphology, preliminary screening was conducted based on the reproduction of characteristic peaks of the simulated pollution source spots in the oil stain spot spectrum. Simulated pollution source spots with high consistency with the spot-forming substances in oil stains and soot spots were selected. Figure 3 As shown, the samples with the most similar spectral peak morphology to oil stain 1# in the δ=0.50-1.50 ppm range are grease 1 immersion stain and grease 3 immersion stain. The pollution source simulated stains with high consistency with the staining substances in oil stains and soot stains were initially screened out.

[0024] c. Calculate the characteristic ratios B1 and B2 Based on the spectrum measured in step b, calculate the characteristic ratios B1 and B2 of the oil stain sample from step b and the simulated pollution source spots after initial screening, respectively. B1= I 1.35-1.20 / I 0.95-0.70 In the formula: I 1.35-1.20 δ 1,CH2 The integral area of ​​the spectral lines in the region of 1.35-1.20 ppm. I 0.95-0.70 δ 1,CH3=0.95-0.70 ppm region of spectral line integral area; B2 = I 1.50-1.00 / I 1.00-0.50 In the formula: I 1.50-1.00 δ 2,CH2 =1.50-1.00 ppm region spectral line integral area I 1.00-0.50 δ 2,CH3 =Integrated area of ​​spectral lines in the 1.00-0.50 ppm region; like Figure 4 As shown, the consistency of the characteristic ratios B1 and B2 between the oil stain sample and the simulated pollution source stain is compared. The measured characteristic ratios B1 and B2 are: B 1（油渍斑1#） =1.58, B 1（润滑脂1浸渍斑） =1.39, B 1（润滑脂3浸渍斑） =1.63, B 2（油渍斑1#） =2.24, B 2（润滑脂1浸渍斑） =2.08, B 2（润滑脂3浸渍斑） =2.26, Comparing the B1 and B2 values, both show the following pattern: Grease 3 impregnation spot > Oil stain 1# > Grease 1 impregnation spot. This indicates that the alkyl chain structure of the contaminant causing oil stain 1# has a high degree of consistency with the material structure characteristics of grease 1 impregnation spot, but a low degree of consistency with grease 3 impregnation spot.

[0025] d, Mass spectrometry analysis Extracts from oil stain #1, grease 1 impregnation stain, and grease 3 impregnation stain were analyzed using a DART-MS mass spectrometer. DART source parameters: helium ionization gas, temperature 300 °C, sample introduction via glass rod and liquid film. Mass spectrometer (OrbitrapExploris, Thermo Fisher Scientific, USA) coupled with the following conditions: negative ion mode, gas transfer tube temperature 320 °C, mass range m / z 80~1500, resolution 45000. Figures 7-8 As shown, data processing was performed using the instrument's built-in software, and six characteristic negative ions were selected for comparison, such as... Figure 5 , 6 As shown, it can be determined that the polar components of the contaminants causing oil stain #1 have a high degree of consistency with the polar components of grease 1, while the consistency with grease 3 is relatively low. The cosine similarity S between the mass spectra of the oil stain sample and the grease 1 and grease 3 impregnation stains was calculated using the relative abundance of ions with a relative abundance greater than 5%.

[0026] In the formula: S represents the cosine similarity of the included angle. x i and y i These represent the two mass spectra at the [missing information] th ... i Characteristic peaks (m / z) i The relative abundance, The calculated mass spectrometry similarity between grease 1 and oil stain 1# is 84% ​​(>80% threshold), while the mass spectrometry similarity between grease 3 and oil stain 1# is 10% (<<80% threshold).

[0027] Based on the combined results of 1H NMR and mass spectrometry data, it can be determined that the contaminants in oil stain #1 are highly consistent with the material structure characteristics of grease #1, indicating that grease #1 is the source of contamination for oil stain #1. Process investigation revealed a leak in grease #1, and the generation of oil fumes was eliminated after mechanical repairs.

[0028] For example, in step d, the mass spectrometry similarity (S-value) between oil stains and simulated contaminant spots is compared. Besides using the cosine similarity method to calculate the S-value, methods such as Euclidean distance and Mahalanobis distance can also be used. The criteria for judging the degree of mass spectrometry similarity differ depending on the method used. In step d, for some samples, gas chromatography-mass spectrometry can also be used instead of liquid chromatography-mass spectrometry.

[0029] The scope of protection claimed by this invention is not limited to the specific embodiments described above. Moreover, for those skilled in the art, this invention can have various modifications and alterations. Any modifications, improvements, and equivalent substitutions made within the concept and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for identifying the source of oil stains based on proton nuclear magnetic resonance spectroscopy and mass spectrometry, characterized in that: Includes the following steps: a. Extraction of oil stains and contaminants Organic solvents were used to extract the staining substances from oil stain samples and pollution source simulated spots to prepare oil stain extract samples and pollution source simulated spot extract samples. b. Comparative analysis of proton NMR spectral data Test extract sample 1 H NMR spectroscopy, focusing on the chemical shift region δ=0.50-1.50 ppm, compared and analyzed the spectral characteristics of oil stain extract samples and pollution source simulated stain extract samples, and carried out preliminary screening to screen out pollution source simulated stains with high consistency with the staining substances in oil stains and soot stains. c. Calculate the characteristic ratios B1 and B2 Based on the spectrum obtained in step b, calculate the characteristic ratios B1 and B2 of the simulated pollution source spots after the initial screening in step b. B1= I 1.35-1.20 / AND 0.95-0.70 In the formula: I 1.35-1.20 δ 1,CH2 The integral area of ​​the spectral lines in the region of 1.35-1.20 ppm. I 0.95-0.70 δ 1,CH3 =0.95-0.70 ppm region of spectral line integral area; B2= I 1.50-1.00 / I 1.00-0.50 In the formula: I 1.50-1.00 δ 2,CH2 =1.50-1.00 ppm region spectral line integral area I 1.00-0.50 δ 2,CH3 =Integrated area of ​​spectral lines in the 1.00-0.50 ppm region; The characteristic ratios B1 and B2 of the oil stain samples and the simulated pollution source stains were compared and divided into three levels: high, medium and low according to the degree of conformity. d, Mass spectrometry analysis Extract samples of pollution source simulation spots with high and medium compliance in step c were subjected to negative ion mode liquid chromatography-mass spectrometry, with a mass-to-charge ratio range of m / z = 80-1400. The mass spectrometry similarity value S between the oil stain sample and the simulated pollution source sample is calculated. The mass spectrometry similarity value S is calculated using the cosine similarity method of the included angle, and the pollution source is determined based on the S value.

2. The method for identifying the source of oil stains based on 1H NMR and mass spectrometry according to claim 1, characterized in that: In step a, one or more oil stain samples from the same cigarette or batch of cigarettes are immersed in 0.5-1 mL of deuterated chloroform or deuterated toluene solvent for 4 hours. The extract is collected into a clean sample bottle, and the extraction is repeated once. The extracts are combined and mixed to obtain the oil stain extract sample. The same method is used to treat the lubricant-impregnated simulated stain samples to obtain the pollution source simulated stain extract sample.

3. The method for identifying the source of oil stains based on 1H NMR and mass spectrometry according to claim 1, characterized in that: In step b, if the NMR characteristic peak set of the pollution source simulated spot extract sample is reproducible in the oil stain soot spot extract sample, it is considered that the chemical structure characteristics of the two are consistent. Based on this, pollution source simulated spots with high consistency with the spot-forming substances in oil stain soot spots are initially screened.

4. The method for identifying the source of oil stains based on 1H NMR and mass spectrometry according to claim 1, characterized in that: In step b, If the characteristic ratios B1 and B2 of oil stains and soot spots are both greater than the characteristic ratios B1 and B2 of simulated pollution source spots, then the consistency is high. If the characteristic ratio B1 of oil stains and soot is greater than the characteristic ratio B2 of simulated pollution source spots, while the characteristic ratio B2 of oil stains and soot is less than or equal to the characteristic ratio B2 of simulated pollution source spots, then the degree of conformity is considered moderate. If the characteristic ratios B1 and B2 of oil stains and soot spots are both less than or equal to the characteristic ratios B1 and B2 of simulated pollution source spots, then the consistency is low.

5. The method for identifying the source of oil stains based on 1H NMR and mass spectrometry according to claim 1, characterized in that: In step d, ， In the formula: S represents the cosine similarity of the mass spectrometry angle. x i and y i These represent the two mass spectra at the [missing information] th ... i Characteristic peaks (m / z) i The relative abundance, If S≥80%, it is judged as a high similarity pollution source. The larger S is, the higher the similarity. If it meets the criteria, the result is output and imported into the database. If it does not meet the criteria, an anomaly is reported.

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