Edible oil identification method based on GC-MS / GC-IMS combination

Abstract

The invention relates to the technical field of edible oil detection, in particular to an edible oil identification method based on GC-MS / GC-IMS combination. Comprising the following steps: putting edible oil into a headspace bottle, sealing, oscillating and incubating, injecting headspace air into a cold trap, heating the cold trap after 3-4 seconds, and then injecting gas into a GC-IMS system for analysis; edible oil is taken and placed in a headspace bottle, sealing and oscillation incubation are performed, then the headspace bottle is connected to a sampling pump, headspace air is blown to pass through a heat adsorption tube, temperature programming desorption is performed, the headspace air and carrier gas are focused through a cold trap, the cold trap is heated after 3-4 seconds, and then the gas is injected into a GC-MS system for analysis. According to the edible oil identification method based on GC-MS / GC-IMS combination, provided by the invention, the edible oil can be rapidly, highly sensitively and more comprehensively identified.

Description

Technical Field

[0001] This application relates to the field of edible oil detection technology, specifically to an edible oil identification method based on GC-MS / GC-IMS coupling. Background Technology

[0002] Edible oils possess unique flavors due to their raw materials and processing methods, allowing for rapid differentiation between different vegetable oils. In fact, most flavor components are part of the volatile components of vegetable oils, carrying unique information about them. Analyzing these volatile components reveals differences in volatile substances among different edible oils. Therefore, rapid and accurate identification of edible oils is crucial for ensuring food safety, maintaining market order, combating counterfeiting, and tracing the origin of oils. However, the chemical composition of edible oils is complex, and differences in authenticity, type, and quality often manifest in trace amounts of characteristic volatile organic compounds. These markers are diverse, with wide-ranging physicochemical properties, including highly volatile primary oxidation products such as acetaldehyde and hexanal, as well as semi-volatile secondary oxidation or process-related compounds such as nonanal, long-chain alkanes, and sterol derivatives. Therefore, developing a technology capable of comprehensively and sensitively capturing and analyzing this complex information is a core challenge currently facing the field of edible oil identification. Summary of the Invention

[0003] To address the aforementioned issues, the purpose of this application is to provide a method for identifying edible oils based on GC-MS / GC-IMS, which can provide rapid, highly sensitive, and more comprehensive identification of edible oils.

[0004] To achieve the above objectives, this application provides a method for identifying edible oils based on GC-MS / GC-IMS coupling, comprising the following steps: S1. Take edible oil into a headspace bottle, seal it, shake and incubate it, inject headspace air into the cold trap, heat the cold trap after 3-4 seconds, and then inject the gas into the GC-IMS system for analysis. S2. Take edible oil into a headspace bottle, seal it, shake and incubate it, then connect it to the sampling pump, purge the headspace air through the thermal adsorption tube, desorb it by programmed temperature rise, focus it with the carrier gas through the cold trap, heat the cold trap after 3-4 seconds, and then inject the gas into the GC-MS system for analysis.

[0005] Furthermore, the edible oil is rapeseed oil, peanut oil, sesame oil, and corn oil.

[0006] Furthermore, the oscillation incubation is carried out at an oscillation rate of 450-550 rpm for 15-20 minutes.

[0007] Furthermore, the cold trap described in step S1 has a temperature of -40 to -50°C.

[0008] Furthermore, in step S1, the heating cold trap is heated at a rate of 60-65°C / second, and heated to 200-250°C and maintained for 2-3 seconds.

[0009] Furthermore, the GC-IMS system has the following GC conditions: the chromatographic column is an FS-SE-54-CB-1 capillary column (15m×0.53mm, 0.5μm, 5% phenyl-95% polymethylsiloxane, weakly polar); the injection port temperature is 75-85℃; the injection mode is splitless injection; the column temperature is 75-85℃; the carrier gas is high-purity nitrogen (purity ≥99.999%); the flow rate is 1.5-2.5mL / min, held for 2-3 minutes, then increased to 10-11mL / min at 10 minutes, 100-110mL / min at 20 minutes, and 150-160mL / min at 30 minutes.

[0010] Furthermore, the GC-IMS system has the following IMS conditions: migration tube length of 95-100 mm, temperature of 40-50℃, migration voltage of 480-520 V / cm, drift gas of nitrogen (purity ≥99.999%), and drift gas flow rate of 145-155 mL / min.

[0011] Furthermore, the purging involves blowing headspace gas through the thermal adsorption tube at a flow rate of 40-60 mL / min for 10-20 minutes.

[0012] Furthermore, the adsorption tube contains an adsorbent composed of Tenax TA and Carbopack B, with a packing length ratio of 3:2-3.

[0013] Furthermore, the programmed temperature-induced desorption involves heating at a rate of 55-60°C / second to 250-300°C and holding for 3-5 minutes.

[0014] Furthermore, the cold trap described in step S2 has a temperature of -30 to -40°C.

[0015] Furthermore, in step S2, the heating cold trap is heated at a rate of 60-65°C / second, and heated to 250-300°C and maintained for 2-3 seconds.

[0016] Furthermore, the GC-MS system has the following GC conditions: chromatographic column: DB5-ms capillary column (30m×0.25mm, 0.25μm, 5% phenyl-95% polymethylsiloxane, weakly polar); injection port temperature: 245-255℃; injection mode: split injection, split ratio 5-6:1; column oven temperature program: 40-45℃ for 4-5 minutes, ramp to 80-85℃ at 5-6℃ / min, hold for 6-7 minutes, ramp to 230-235℃ at 10℃ / min, hold for 7-8 minutes; carrier gas: helium (purity ≥99.999%), flow rate: 0.5-1.5mL / min; transfer line temperature: 275-285℃.

[0017] Furthermore, the GC-MS system has the following MS conditions: an electron impact source (EI) is used, with no solvent delay; full scan mode is used, with a scan quality of 30-300; the ion source temperature is 225-235℃, and the quadrupole temperature is 145-155℃.

[0018] In summary, this application has the following beneficial effects: The edible oil identification method of this application combines GC-MS and GC-IMS for identification. GC-IMS is responsible for rapid screening, while GC-MS is responsible for accurate verification. A parallel dual-channel enrichment method is employed, with the two channels complementing each other to fully cover the volatile spectrum of edible oils. Channel 1 is a static headspace, cryogenic cold trap focusing method. A fixed volume of equilibrium headspace gas is drawn using an airtight syringe and injected into the cold trap. The injected gas is condensed in the low-temperature cold trap. Utilizing the principle of cryogenic condensation, the organic volatiles in the gas stream solidify in the cold trap, while most of the carrier gas, due to its extremely low boiling point, is not condensed and is released into the air. This achieves volumetric enrichment of the target analyte, concentrating trace components in the gas to almost zero physical space. Inside, rapid thermal desorption injection is then performed, instantly heating the cold trap to 200-250°C and maintaining this temperature for a short time before injecting it into the GC-IMS system for analysis. The rapid heating provides a large amount of thermal energy, causing all condensed components to vaporize almost simultaneously. According to chromatographic kinetics, the initial band width directly determines the peak width. The rapid heating of the cold trap causes all frozen components to vaporize almost simultaneously, forming an extremely narrow initial band. This provides a sharp starting point for chromatographic separation, resulting in sharper, higher peaks and better resolution in subsequent chromatographic separations. This is crucial for fingerprinting complex volatile components in edible oils, effectively separating more compounds co-eluting in GC-IMS and detecting... More substances; Channel 2 employs a dynamic headspace, adsorbent trapping, and thermal desorption method. High-purity nitrogen is continuously purged at a constant flow rate into the headspace. The gas flow passes through a sampling tube containing adsorbent. This is a dynamic, non-equilibrium, continuous extraction process. Continuous purging constantly disrupts the gas-liquid equilibrium, forcing high-boiling-point compounds to continuously volatilize from the oil phase. These volatiles are trapped by the adsorbent, accumulating a large amount of gas for cumulative adsorption of trace components. The absolute capture amount far exceeds that of static headspace, broadening the detection range. The gas is then rapidly heated to 250-300°C, utilizing the energy provided by the high temperature to overcome the adsorption force and achieve complete desorption. After desorption, the gas is focused again through a low-temperature cold trap, which is then rapidly heated again and maintained for a short period. The sample is then injected into the GC-MS system for analysis, achieving ultra-trace enrichment and full-volume injection. These are two independent and simultaneous routes, rather than sequential steps, maximizing time utilization and avoiding sample loss or contamination that may occur due to tandem operations. GC-IMS is simple, fast, and intuitive to operate, and the constructed identification model is more robust and has better predictive performance. GC-MS's powerful qualitative capabilities can identify specific compound types. The combination of the two has successfully established a set of objective edible oil identification methods based on volatile fingerprints, with high accuracy and the ability to sensitively detect adulteration in vegetable oils. It has great application potential in combating adulteration of edible oils that are of inferior quality or do not match the label. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 Scatter plot of the principal component analysis results for four types of oils: rapeseed oil (cz) in Example 1, peanut oil (hs) in Example 2, sesame oil (zm) in Example 3, and corn oil (ym) in Example 4. Figure 2 The fingerprint patterns are from Examples 4-11; Figure 3 The graph shows the correlation coefficient changes between blended oils in different proportions and sesame oil and corn oil; the solid blue line in the graph represents the correlation coefficient change curve between blended oils and sesame oil, and the dashed orange line represents the correlation coefficient change curve between blended oils and corn oil. Detailed Implementation

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

[0022] In the specific embodiments of this application, the particle size of the adsorbent is 60 mesh; the GC-IMS model is FlavorSpec. The manufacturer is GAS; the GC model in the GC-MS is 7890A, manufactured by Agilent, and the MS model is 5975C, also manufactured by Agilent; the edible oils are rapeseed oil, peanut oil, sesame oil, and corn oil. There are 29 types of rapeseed oil, some brands include: Daodaoquan, Caiziwang, Chuancaiwang, Henry Morgan, Jinlongyu, Haishi, Xinxing Grain & Oil, Duoli, Haishi, Luhua, COFCO, Haitian, Longxiang, Chang'anhua, Tianfu, Qihang, Cangmangyao, Jinchengfu, and Shanrun; there are 29 types of peanut oil, some brands include: Jinlongyu, Hujihua, Jinsheng Fresh Oil Mill, Changshouhua, Luhua, Shiqiu, Longda, Daomai, Yuhuang, Wuyang, Munong, Duoli, and Lv. Di, Pinpinhao, COFCO, Dunke, Xiyan; 31 types of sesame oil, some brands: Laozhafang, Cuizipai, Taitaile, Jiudouwan, Haitian, Xiangmanyuan, Jinlongyu, Yanzhuang, Duoli, Huzhenxing, Jideli, Lee Kum Kee, Luhua, Chuanlaohui, COFCO, Dunke; 29 types of corn oil, some brands: Beidahuang, Beizhiyou, Duoli, Gengqinyoufang, Haitian, Jianhua, Jinlongyu, Jinsheng, Jiusan, Luhua, Pinpinhao, Qiandaoyuan, Nissin, Tmall, Siegel, Xiwang, Yuhuang, Changshouhua, COFCO; GC-IMS GC conditions: chromatographic column was FS-SE-54-CB-1 capillary column (15m×0.53mm, 0.5μm, 5% phenyl-95) % polymethylsiloxane, weakly polar); injection port temperature: 80℃; injection mode: splitless injection; column temperature: 80℃; carrier gas: high-purity nitrogen (purity ≥99.999%); flow rate: 2 mL / min, hold for 2 minutes, increase to 10 mL / min at 10 minutes, increase to 100 mL / min at 20 minutes, and increase to 150 mL / min at 30 minutes; IMS conditions: migration tube length: 98 mm, temperature: 45℃; migration voltage: 500 V / cm; drift gas: high-purity nitrogen (purity ≥99.999%); drift gas flow rate: 150 mL / min; GC-MS conditions: column: DB5-ms A thin column (30m × 0.25mm, 0.25μm, 5% phenyl-95% polymethylsiloxane, weakly polar) was used; the injection port temperature was 250℃; the injection mode was split, with a split ratio of 5:1; the column oven temperature program was 40℃ for 4 minutes, ramped up to 80℃ at 6℃ / min, held for 6 minutes, ramped up to 230℃ at 10℃ / min, and held for 7 minutes; the carrier gas was high-purity helium (purity ≥99.999%), with a flow rate of 1mL / min; the transfer line temperature was 280℃; MS conditions: electron impact source (EI) was used, with no solvent delay; full scan mode, scan quality 30-300; ion source temperature was 230℃, and quadrupole temperature was 150℃.

[0023] Example 1 A method for identifying edible oils based on GC-MS / GC-IMS coupling includes the following steps: S1. Accurately weigh 3.0 g of rapeseed oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate with shaking (450 rpm) for 15 minutes. Using an autosampler, extract 500 μL of headspace gas and inject it into the cold trap (temperature -50 °C). After 3 seconds, heat the cold trap (heating rate 60 °C / second, heat to 250 °C and hold for 3 seconds), and then inject it into the GC-IMS system for analysis. S2. Accurately weigh 3.0 g of rapeseed oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate with shaking (450 rpm) for 15 minutes. Then connect it to the sampling pump and purge the headspace gas through the thermal adsorption tube at a flow rate of 40 mL / min for 10 minutes. Then desorb the sample using a thermal desorption instrument (heating rate 55 °C / s, heating to 250 °C, holding time 3 minutes). All desorbed components are carried out synchronously by the carrier gas (carrier gas flow rate 30 mL / min), focused in a cold trap (temperature -30 °C), and rapidly heated in the cold trap after 3 seconds (heating rate 60 °C / s, heating to 250 °C). The sample is then injected into the GC-MS system for analysis.

[0024] Example 2 A method for identifying edible oils based on GC-MS / GC-IMS coupling includes the following steps: S1. Accurately weigh 3.0 g of peanut oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate with shaking (450 rpm) for 15 minutes. Using an autosampler, extract 500 μL of headspace gas and inject it into the cold trap (temperature -50 °C). After 3 seconds, heat the cold trap (heating rate 60 °C / second, heat to 250 °C and hold for 3 seconds), and then inject it into the GC-IMS system for analysis. S2. Accurately weigh 3.0 g of rapeseed oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate with shaking (450 rpm) for 15 minutes. Then connect it to the sampling pump and purge the headspace gas through the thermal adsorption tube at a flow rate of 40 mL / min for 10 minutes. Then desorb the sample using a thermal desorption instrument (heating rate 55 °C / s, heating to 250 °C, holding time 3 minutes). All desorbed components are carried out synchronously by the carrier gas (carrier gas flow rate 30 mL / min), focused in a cold trap (temperature -30 °C), and rapidly heated in the cold trap after 3 seconds (heating rate 60 °C / s, heating to 250 °C). The sample is then injected into the GC-MS system for analysis.

[0025] Example 3 A method for identifying edible oils based on GC-MS / GC-IMS coupling includes the following steps: S1. Accurately weigh 3.0 g of sesame oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate it with shaking (450 rpm) for 15 minutes. Using an autosampler, extract 500 μL of headspace gas and inject it into the cold trap (temperature -50 °C). After 3 seconds, heat the cold trap (heating rate 60 °C / second, heat to 250 °C and hold for 3 seconds), and then inject it into the GC-IMS system for analysis. S2. Accurately weigh 3.0 g of rapeseed oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate with shaking (450 rpm) for 15 minutes. Then connect it to the sampling pump and purge the headspace gas through the thermal adsorption tube at a flow rate of 40 mL / min for 10 minutes. Then desorb the sample using a thermal desorption instrument (heating rate 55 °C / s, heating to 250 °C, holding time 3 minutes). All desorbed components are carried out synchronously by the carrier gas (carrier gas flow rate 30 mL / min), focused in a cold trap (temperature -30 °C), and rapidly heated in the cold trap after 3 seconds (heating rate 60 °C / s, heating to 250 °C). The sample is then injected into the GC-MS system for analysis.

[0026] Example 4 A method for identifying edible oils based on GC-MS / GC-IMS coupling includes the following steps: S1. Accurately weigh 3.0 g of corn oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate with shaking (450 rpm) for 15 minutes. Using an autosampler, extract 500 μL of headspace gas and inject it into the cold trap (temperature -50 °C). After 3 seconds, heat the cold trap (heating rate 60 °C / second, heat to 250 °C and hold for 3 seconds), and then inject it into the GC-IMS system for analysis. S2. Accurately weigh 3.0 g of rapeseed oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate with shaking (450 rpm) for 15 minutes. Then connect it to the sampling pump and purge the headspace gas through the thermal adsorption tube at a flow rate of 40 mL / min for 10 minutes. Then desorb the sample using a thermal desorption instrument (heating rate 55 °C / s, heating to 250 °C, holding time 3 minutes). All desorbed components are carried out synchronously by the carrier gas (carrier gas flow rate 30 mL / min), focused in a cold trap (temperature -30 °C), and rapidly heated in the cold trap after 3 seconds (heating rate 60 °C / s, heating to 250 °C). The sample is then injected into the GC-MS system for analysis.

[0027] Example 5 The difference between this embodiment and embodiment 4 is that the edible oil in this embodiment is a blended oil, consisting of 5% sesame oil and 95% corn oil.

[0028] Example 6 The difference between this embodiment and embodiment 4 is that the edible oil in this embodiment is a blended oil, consisting of 10% sesame oil and 90% corn oil.

[0029] Example 7 The difference between this embodiment and embodiment 4 is that the edible oil in this embodiment is a blended oil, consisting of 30% sesame oil and 70% corn oil.

[0030] Example 8 The difference between this embodiment and embodiment 4 is that the edible oil in this embodiment is a blended oil, consisting of 50% sesame oil and 50% corn oil.

[0031] Example 9 The difference between this embodiment and embodiment 4 is that the edible oil in this embodiment is a blended oil, consisting of 70% sesame oil and 30% corn oil.

[0032] Example 10 The difference between this embodiment and embodiment 4 is that the edible oil in this embodiment is a blended oil, consisting of 90% sesame oil and 10% corn oil.

[0033] Example 11 The difference between this embodiment and embodiment 4 is that the edible oil in this embodiment is a blended oil, consisting of 95% sesame oil and 5% corn oil.

[0034] Compare with Example 1 The difference between this comparative example and Example 1 is that this comparative example provides a method for identifying edible oils based on GC-MS / GC-IMS, which includes the following steps: S1. Accurately weigh 3.0 g of rapeseed oil sample into a 20 mL headspace vial, seal it, place the headspace vial on a sample tray at 75 °C, and incubate it with shaking (450 rpm) for 15 minutes. Using an autosampler, extract 500 μL of headspace gas and inject it into the cold trap (temperature -50 °C). After 3 seconds, heat the cold trap (heating rate 60 °C / second, heat to 200-250 °C and hold for 3 seconds), and then inject it into the GC-IMS system for analysis. S2. Connect the same headspace vial of oil sample incubated in step S1 to the sampling pump, purge the headspace gas through the cold trap (temperature -30℃) at a flow rate of 40 mL / min for focusing, and rapidly heat the cold trap after 3 seconds (heating rate 60℃ / second, temperature up to 250℃) and inject it into the GC-MS system for analysis.

[0035] Performance testing The edible oil composition analysis of Examples 1-4 and Control Example 1 is shown in Table 1; Table 1: Composition of four types of oils after analysis

[0036] As shown in the table, the rapeseed oil in Example 1 contained 49 qualitatively identified substances, mainly furans, pyrazines, pyridines, nitriles, ketones, alcohols, aldehydes, and acids. Among them, aldehydes were the most numerous with 13 types, followed by furans with 3 types, pyrazines with 3 types, pyridines with 1 type, nitriles with 6 types, ketones with 2 types, alcohols with 1 type, and acids with 1 type. The peanut oil in Example 2 contained 41 qualitatively identified substances, mainly furans, pyrazines, pyrroles, ketones, alcohols, aldehydes, acids, and esters. Among the main categories, there were 8 aldehydes, 7 esters, 4 pyrazines, and 4 alcohols. Example 3 identified 39 substances in sesame oil, mainly furans, pyrazines, pyridines, pyrroles, ketones, alcohols, esters, aldehydes, acids, amines, and thiazoles; including 5 furans, 5 pyrazines, 4 alcohols, and 2 esters. Example 4 identified 28 substances in corn oil, fewer than the previous three, including 6 aldehydes, 2 furans, 2 acids, and 4 alkenes. Comparative Example 1 and... The difference in Example 1 is the removal of the adsorption tube. The adsorbent in Example 1 continuously captures and stores trace molecules during long-term purging, achieving accumulation over time and high enrichment efficiency. In contrast, the cold trap retained in Comparative Example 1 can only condense components in the currently flowing gas, which is instantaneous and non-cumulative, resulting in a very low loss of enrichment ability for ultra-trace components. Compared with Example 1, one-third of the compounds were not detected, indicating that the identification method of this application has good substance detection effect and detects more compounds.

[0037] From the above qualitative analysis, we can preliminarily identify the different components. Nitriles in rapeseed oil are not detected in the other three types of vegetable oils, while esters in peanut oil are more abundant than in the other three. The total number of pyrazines detected in rapeseed oil, peanut oil, and sesame oil is greater than that in corn oil. Sesame oil has the most types of pyrazines, followed by peanut oil, then rapeseed oil, while corn oil has the fewest. Two pinene compounds in corn oil have not been qualitatively identified in other oils. Additionally, rapeseed oil, peanut oil, and sesame oil share nine common components: 2-pentyl-furan, pyrazine, 3-ethyl-2,5-dimethyl-pyrazine, methylpyrazine, methanol, acetaldehyde, furfural, heptanal, and acetic acid. Figure 1 It can be seen that the four types of edible oils are clearly separated. The separation mainly occurs in three directions: rapeseed oil and peanut oil samples tend to cluster at the top of the graph, corn oil samples cluster at the bottom left, and sesame oil samples cluster at the bottom right.

[0038] Table 2: Correlation coefficients between blended oils of different proportions and pure sesame oil and corn oil

[0039] Examples 5-11 are analyses of blended oils. Figure 2The fingerprint spectra are for 8 ratios of Examples 4-11. The proportion of sesame oil increases from bottom to top in the figure. When the proportion of sesame oil in the blended oil is less than 30%, there is a visually noticeable difference. The specific blending ratio is marked on the right side of the corresponding image. Table 2 shows the correlation coefficients between blended oils with different proportions and pure sesame oil and corn oil. Figure 3 This is a graph showing the changes in the correlation coefficients between blended oils of different proportions and sesame oil and corn oil. Figure 3 As the proportion of sesame oil in the blend increases, the correlation coefficient between the blended oil and sesame oil continuously increases, stabilizing at around 0.8 after the sesame oil content reaches 30%. Simultaneously, the correlation coefficient between the blended oil and corn oil first increases and then decreases, with the decrease slowing down after the sesame oil content exceeds 50%, reaching its lowest value at 0.23. At this point, the blended oil is 95% sesame oil. A 30% sesame oil content is the dividing point for the change in the correlation coefficient between the blended oil and sesame oil; before this point, the correlation coefficient increases with the increase in the sesame oil content, and then tends to remain constant. Based on the above analysis, using the identification method of this application for correlation analysis on blended oils containing sesame oil and corn oil as the object, the effective range is when the sesame oil content is 30% or less.

[0040] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. A method for identifying edible oils based on GC-MS / GC-IMS coupling, characterized in that, Includes the following steps: S1. Take edible oil into a headspace bottle, seal it, shake and incubate it, inject headspace air into the cold trap, heat the cold trap after 3-4 seconds, and then inject the gas into the GC-IMS system for analysis. S2. Take edible oil into a headspace bottle, seal it, shake and incubate it, then connect it to the sampling pump, purge the headspace air through the thermal adsorption tube, desorb it by programmed temperature rise, focus it with the carrier gas through the cold trap, heat the cold trap after 3-4 seconds, and then inject the gas into the GC-MS system for analysis.

2. The method for identifying edible oils based on GC-MS / GC-IMS coupling according to claim 1, characterized in that, The oscillation incubation is carried out at an oscillation rate of 450-550 rpm for 15-20 minutes.

3. The method for identifying edible oils based on GC-MS / GC-IMS coupling according to claim 1, characterized in that, The cold trap described in step S1 has a temperature of -40 to -50°C.

4. The method for identifying edible oils based on GC-MS / GC-IMS coupling according to claim 1, characterized in that, The heating cold trap described in step S1 has a heating rate of 60-65℃ / second, and is heated to 200-250℃ and maintained for 2-3 seconds.

5. The method for identifying edible oils based on GC-MS / GC-IMS coupling according to claim 1, characterized in that, The purging process involves blowing headspace gas through the thermal adsorption tube at a flow rate of 40-60 mL / min for 10-20 minutes.

6. The method for identifying edible oils based on GC-MS / GC-IMS coupling according to claim 1, characterized in that, The adsorption tube contains an adsorbent composed of Tenax TA and Carbopack B, with a packing length ratio of 3:2-3.

7. The method for identifying edible oils based on GC-MS / GC-IMS coupling according to claim 1, characterized in that, The programmed temperature rise desorption involves raising the temperature to 250-300°C at a rate of 55-60°C / second, and holding the temperature for 3-5 minutes.

8. The method for identifying edible oils based on GC-MS / GC-IMS coupling according to claim 1, characterized in that, The cold trap described in step S2 has a temperature of -30 to -40°C.

9. The method for identifying edible oils based on GC-MS / GC-IMS coupling according to claim 1, characterized in that, The heating cold trap described in step S2 has a heating rate of 60-65°C / second, and is heated to 250-300°C and maintained for 2-3 seconds.

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