Method for identifying dracocephalum heterophyllum in different drying modes

Abstract

The invention discloses a method for identifying dracocephalum heterophyllum benth in different drying modes, which comprises the following steps: S1, drying dracocephalum heterophyllum benth, including natural drying in the shade, hot air drying and vacuum freeze drying; s2, feeding the dried sample in a headspace mode; s3, a GC-IMS instrument is used for analysis; and S4, carrying out qualitative and quantitative analysis on the detected volatile components through VOCal software, and constructing a GC-IMS spectrogram and a fingerprint spectrum of the volatile components. Through GC-IMS technology and VOCal software analysis, dracocephalum heterophyllum benth subjected to natural shade drying, hot air drying and vacuum freeze drying treatment can be distinguished precisely with high sensitivity, and a reliable technical means is provided for quality control of medicinal materials.

Description

Technical Field

[0001] The invention relates to the field of analysis and detection, in particular to a method for identifying cyanus heterophylla with different drying methods. Background Art

[0002] Dracocephalum heterophyllum Benth, scientifically known as "white flower branch flower", is a perennial herbaceous plant of the genus Dracocephalum (L.) of the family Labiatae. It is widely distributed in northwest my country and is a commonly used Tibetan medicinal material in ethnic areas. It is mainly used to treat oral ulcers, jaundice-type fever, liver heat, bronchitis, hypertension and other symptoms. It is rich in volatile oils, polysaccharides, flavonoids, terpenes and lignans and other active ingredients. The "Chinese Medicine Dictionary" records that heterophyllum Benth has the effects of calming the liver and clearing away heat. It can be used to treat jaundice hepatitis, gingival swelling and pain caused by rising liver fire, oral ulcers and other diseases.

[0003] Freshly collected Orchidaceae plants have high water content. If they are not processed in time, they will wither and rot, which will limit the storage and utilization of Orchidaceae and cause waste of Orchidaceae resources. Post-harvest drying is one of the main methods for processing Orchidaceae plants. In addition to the traditional drying methods of shade drying and sun drying, with the development of modern science and technology, effective drying methods such as hot air drying and vacuum freeze drying have been gradually developed. Different drying methods have different volatile components. In the traditional quality evaluation system of medicinal materials, smell is one of the evaluation criteria for judging the quality of medicinal materials. The smell of Orchidaceae is sweet and refreshing, which is due to the volatile components it contains, which gives it a unique smell. It can be seen that the volatile components of Orchidaceae are also one of the key factors for judging its quality. Therefore, a method for identifying Orchidaceae with different drying methods is needed. Summary of the invention

[0004] In order to overcome the shortcomings of the existing analytical technology, the purpose of the present invention is to provide a rapid and effective identification method for Cymbidium heterophyllum with different drying methods.

[0005] The present invention provides a method for identifying different drying methods of Cymbidium heterophyllum, characterized in that it comprises the following steps:

[0006] S1. Take the dried product of Cymbidium heterophyllum to be tested;

[0007] S2, crush the dried product and inject it by headspace method;

[0008] S3, analysis using GC-IMS instrument;

[0009] S4. Qualitatively and / or quantitatively analyze the detected volatile components through VOCal software, and construct the GC-IMS spectra and / or fingerprint spectra of the volatile components;

[0010] Detect the contents of aromatic alcohol, 3-octanone (D), γ-terpinene (D), limonene (D), benzaldehyde (D), benzaldehyde (M), 2-furaldehyde (D), ethyl 2-methylbutyrate, propyl butyrate, butyrolactone (D), butyrolactone (M), (E),(E)-2,4-heptadienal (M), ethyl acetate (M), ethyl hexanoate, 2-acetylfuran, valeraldehyde (D), so as to determine the drying method of Dracocephalum heterophyllum Benth.

[0011] In the present invention, "M" and "D" in the compound respectively represent the monomer and dimer of the compound. For example, 3-octanone (D) is the dimer 3-octanone compound, butyrolactone (D) is the dimer butyrolactone, butyrolactone (M) is the monomer butyrolactone, and so on.

[0012] In the invention, the volatile components of three drying methods, namely natural air drying, hot air drying, and vacuum freeze drying, are studied. It is found that: a total of 72 volatile substances are qualitatively detected in the samples treated by 3 different drying methods, including: carvone, isopulegol, linalool, benzaldehyde, propyl butyrate, 1-octen-3-ol, 3-octanone, (E)-2-heptenal, β-pinene, pinene, butyrolactone, n-hexanol, (E)-2-hexenal, hexanal, 1-pentanol, isoamyl alcohol, isopropyl butyrate, 2-furaldehyde, (E)-2-pentenal, 3-hydroxy-2-butanone, 2-butanone-3-hydroxy, longifolene, γ-terpinene, limonene, heptanal, (E),(E)-2,4-heptadienal, nonanal, ethyl acetate, 3-methyl-2-butenal, ethyl hexanoate, benzyl butyrate, 2-methyl-1-butanol, 2-acetylfuran, 3-carene, cyclohexanone, methyl 3-methylbutyrate, valeraldehyde, 2-methylbutyraldehyde, ethyl 2-methylbutyrate, methyl valerate, 2-butanone, 2-pentanone, 1-propanol, 1-octen-3-one; among them, there are 17 aldehyde compounds, accounting for about 36.2%, 14 alkene compounds, accounting for about 29.8%, 13 ketone and alcohol compounds each, accounting for about 27.7%, 11 ester compounds, accounting for about 23.4%, and in addition, there are other types of components such as furan compounds.

[0013] In some specific embodiments of the present invention, the drying method includes natural drying, heat drying, and vacuum freeze drying.

[0014] In some specific embodiments of the present invention, if the relative percentage content of aromatic alcohol in the volatile components after drying treatment is not less than 0.6%; and / or, the relative percentage content of 3-octanone (D) is not less than 1%; and / or, the relative percentage content of γ-terpinene (D) is not less than 2.5%; and / or, the relative percentage content of limonene (D) is not less than 1%, then the drying method is natural air drying;

[0015] If the relative percentage content of benzaldehyde (D) in the volatile components after drying treatment is not less than 2%; and / or, the relative percentage content of benzaldehyde (M) is not less than 2%; and / or, the relative percentage content of 2-furaldehyde (D) is not less than 0.1%; and / or, the relative percentage content of ethyl 2-methylbutyrate is not less than 0.1%, then the drying method is vacuum freeze-drying;

[0016] If the relative percentage content of propyl butyrate in the volatile components after drying treatment is not less than 0.2%; and / or, the relative percentage content of butyrolactone (D) is not less than 0.1%; and / or, the relative percentage content of butyrolactone (M) is not less than 0.5%; and / or, the relative percentage content of (E),(E)-2,4-heptadienal (M) is not less than 0.2%; and / or, the relative percentage content of ethyl acetate (M) is not less than 0.1%; and / or, the relative percentage content of ethyl hexanoate is not less than 0.2%; and / or, the relative percentage content of 2-acetylfuran is not less than 0.1%; and / or, the relative percentage content of valeraldehyde (D) is not less than 1.5%, then the drying method is hot air drying.

[0017] In some specific embodiments of the present invention, if the relative percentage content of aromatic alcohol in the volatile components after drying treatment is not less than 0.8%; and / or, the relative percentage content of 3-octanone (D) is not less than 2%; and / or, the relative percentage content of γ-terpinene (D) is not less than 3%; and / or, the relative percentage content of limonene (D) is not less than 1.5%, then the drying method is natural air drying;

[0018] If the relative percentage content of benzaldehyde (D) in the volatile components after drying treatment is not less than 6%; and / or, the relative percentage content of benzaldehyde (M) is not less than 2%; and / or, the relative percentage content of 2-furaldehyde (D) is not less than 0.2%; and / or, the relative percentage content of ethyl 2-methylbutyrate is not less than 0.4%, then the drying method is vacuum freeze-drying;

[0019] If the relative percentage content of propyl butyrate in the volatile components after drying treatment is not less than 0.3%; and / or, the relative percentage content of butyrolactone (D) is not less than 0.2%; and / or, the relative percentage content of butyrolactone (M) is not less than 0.9%; and / or, the relative percentage content of (E),(E)-2,4-heptadienal (M) is not less than 0.5%; and / or, the relative percentage content of ethyl acetate (M) is not less than 0.2%; and / or, the relative percentage content of ethyl hexanoate is not less than 0.3%; and / or, the relative percentage content of 2-acetylfuran is not less than 0.2%; and / or, the relative percentage content of pentanal (D) is not less than 2%, then the drying method is hot air drying.

[0020] In some specific embodiments of the present invention, in step S2, the headspace analysis conditions include one of the following conditions:

[0021] Incubation temperature: 30 - 50 °C;

[0022] Incubation time: 10 - 20 min;

[0023] Sample injection volume: 500 - 1500 μL;

[0024] Sample injection needle temperature: 60 - 100 °C.

[0025] In some specific embodiments of the present invention, in step S2, the headspace analysis conditions are: incubation temperature 40 °C, incubation time 15 min, sample injection volume 1000 μL, sample injection needle temperature 85 °C.

[0026] In some specific embodiments of the present invention, in step S3, the analysis conditions of gas chromatography - ion mobility spectrometry include at least one of the following conditions:

[0027] Carrier gas: nitrogen or hydrogen;

[0028] Drift gas: nitrogen or hydrogen;

[0029] Initial carrier gas flow rate: 1 - 3 mL / min;

[0030] Drift gas flow rate: 60 - 80 mL / min;

[0031] IMS migration tube temperature: 40 - 50 °C;

[0032] Analysis time: 50 - 70 min.

[0033] In some specific embodiments of the present invention, both the carrier gas and the drift gas are high-purity nitrogen, the initial carrier gas flow rate: 2.0 mL / min, the drift gas flow rate is 75 mL / min, the IMS migration tube temperature is 45 °C, and the analysis time is 59 min.

[0034] The present invention also provides a method for identifying different drying methods of Dracocephalum heterophyllum Benth., comprising the following steps:

[0035] S1. Take the dried product of Dracocephalum heterophyllum Benth. to be tested;

[0036] S2. Prepare the dried product into a test sample and inject it;

[0037] S3. Detect the test sample;

[0038] If the relative percentage content of aromatic alcohol in the volatile components after drying treatment is not less than 0.6%; and / or, the relative percentage content of 3-octanone (D) is not less than 1%; and / or, the relative percentage content of γ-terpinene (D) is not less than 2.5%; and / or, the relative percentage content of limonene (D) is not less than 1%, then the drying method is natural shade drying;

[0039] If the relative percentage content of benzaldehyde (D) in the volatile components after drying treatment is not less than 2%; and / or, the relative percentage content of benzaldehyde (M) is not less than 2%; and / or, the relative percentage content of 2-furaldehyde (D) is not less than 0.1%; and / or, the relative percentage content of ethyl 2-methylbutyrate is not less than 0.1%, then the drying method is vacuum freeze-drying;

[0040] If the relative percentage content of propyl butyrate in the volatile components after drying treatment is not less than 0.2%; and / or, the relative percentage content of butyrolactone (D) is not less than 0.1%; and / or, the relative percentage content of butyrolactone (M) is not less than 0.5%; and / or, the relative percentage content of (E),(E)-2,4-heptadienal (M) is not less than 0.2%; and / or, the relative percentage content of ethyl acetate (M) is not less than 0.1%; and / or, the relative percentage content of ethyl hexanoate is not less than 0.2%; and / or, the relative percentage content of 2-acetylfuran is not less than 0.1%; and / or, the relative percentage content of valeraldehyde (D) is not less than 1.5%, then the drying method is hot air drying.

[0041] In the present invention, the detection method of the components includes all detectable methods, such as gas chromatography, etc.

[0042] The beneficial effects of the present invention are:

[0043] (1) Through GC-IMS technology and VOCal software analysis, the present invention can highly sensitively and accurately distinguish Dracocephalum heterophyllum Benth. treated by natural shade drying, hot air drying and vacuum freeze-drying, providing a reliable technical means for the quality control of medicinal materials.

[0044] (2) By constructing the GC-IMS spectrogram and fingerprint of the volatile components of Dracocephalum heterophyllum Bge., this method helps to evaluate the effects of different drying methods on the quality of medicinal materials, so as to optimize the drying process and ensure the best retention of active ingredients in the medicinal materials.

[0045] (3) The method of the present invention can not only detect and quantitatively analyze the volatile components in Dracocephalum heterophyllum Bge., but also intuitively compare the differences between different dried samples by means of principal component analysis (PCA), etc., providing a scientific basis for the quality evaluation and standardized production of medicinal materials. Description of the Drawings

[0046] Figure 1 GC-IMS spectrogram of volatile organic compounds in Dracocephalum heterophyllum Bge. treated by different drying methods (A. Natural air drying; B. Vacuum freeze drying; C. Hot air drying; D. Fresh sample);

[0047] Figure 2 Qualitative analysis of volatile organic compounds in Dracocephalum heterophyllum Bge. treated by natural air drying;

[0048] Figure 3 Qualitative analysis of volatile organic compounds in Dracocephalum heterophyllum Bge. treated by vacuum freeze drying;

[0049] Figure 4 Qualitative analysis of volatile organic compounds in Dracocephalum heterophyllum Bge. treated by hot air drying;

[0050] Figure 5 Qualitative analysis of volatile organic compounds in fresh Dracocephalum heterophyllum Bge. samples;

[0051] Figure 6 Fingerprint of volatile organic compounds in Dracocephalum heterophyllum Bge. treated by different drying methods (YYQL-YG for natural air drying; YYQL-DG for freeze drying; YYQL-HG for hot air drying; YYQL-HZ for fresh sample);

[0052] Figure 7 Principal component analysis diagram and PCA three-dimensional score diagram of Dracocephalum heterophyllum Bge. samples treated by different drying methods. Detailed Embodiments

[0053] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] Example 1

[0055] 1 Experimental Method

[0056] 1.1 Materials

[0057] Type gas-phase ion mobility spectrometry coupled instrument, (G.A.S. Company, Germany), DGH-9140A electrothermal blast drying oven (Shanghai Yiheng Scientific Instrument Co., Ltd.); LGJ-10B vacuum freeze dryer (Beijing Sihuan Scientific Instrument Factory); FW-200 high-speed universal crusher (Beijing Zhongxing Weiye Century Instrument Co., Ltd.); PL303 electronic balance (Shanghai Mettler-Toledo Instrument Co., Ltd.).

[0058] Dracocephalum heterophyllum was collected from Tongren City, Huangnan Tibetan Autonomous Prefecture, Qinghai Province in late July 2024. After being dug up, it was identified by Researcher Gao Qingbo of the Northwest Institute of Plateau Biology, Chinese Academy of Sciences as the whole plant of Dracocephalum heterophyllum Benth. Samples with consistent maturity, uniform size and color, free from pests and diseases and mechanical damage were selected as experimental materials. The sediment on the root surface was washed, and after being dried with absorbent paper, it was reserved for use.

[0059] 1.2 Drying treatment of Dracocephalum heterophyllum

[0060] Select Dracocephalum heterophyllum plants with relatively consistent lengths. After weighing to determine the mass, they were evenly divided into 3 groups, 100 g for each group. After being marked for different drying methods, they were evenly spread on metal trays and subjected to different drying treatments respectively. Drying was terminated when the mass difference obtained from two consecutive measurements was <0.1 g. Among them, natural air drying was to place the plants in a cool place indoors and let them dry naturally at room temperature, which took 165 h; hot air drying was carried out in a drying oven, with the temperature set at 60 °C, which took 72 h; vacuum freeze drying was set at a temperature of -40 °C and an absolute pressure of 10 Pa, which took 48 h.

[0061] 1.3 GC-IMS analysis

[0062] The dried Dracocephalum heterophyllum and fresh Dracocephalum heterophyllum plants were pulverized and passed through a 40-mesh sieve. 2 g of the sample was accurately weighed and placed in a 20 mL headspace vial. The injection volume was 1000 μL, the incubation temperature was set at 40 °C, and it was incubated at 500 r·min -1 for 15 min. The injection needle temperature was 85 °C. Both the carrier gas and the drift gas were high-purity nitrogen (purity ≥99.999%). The initial carrier gas flow rate was 2.0 mL·min -1 and the drift gas flow rate was 75 mL·min -1 . The IMS migration tube temperature was 45 °C, and the analysis time was 59 min.

[0063] 1.4 Software analysis

[0064] Using the VOCal software provided with the instrument, the migration time and retention time of the detected volatile organic substances are retrieved and compared with the built-in National Institute of Standards and Technology (NIST) gas-phase retention index database and ion mobility time database (IMS) of the system to qualitatively analyze the target substances. Using plugins such as Reporter, GalleryPlot, and Dynamic PCA in the software, three-dimensional spectra, two-dimensional spectra, difference spectra, fingerprint spectra, and PCA graphs of volatile components are generated respectively to analyze the volatile organic compounds in Dracocephalum heterophyllum Benth.

[0065] 2 Results and Analysis

[0066] 2.1 GC-IMS Analysis of Samples

[0067] The volatile substances in Dracocephalum heterophyllum Benth. treated by different drying methods were identified and analyzed by GC-IMS technology, and its gas-phase ion mobility spectrum was obtained by the differential comparison mode, as Figure 1 , where the horizontal axis represents the relative ion mobility time and the vertical axis represents the retention time of gas chromatography. The reaction ion peak (RIP) after normalization is on the far left. Each point on both sides of each RIP peak represents a volatile organic compound. The concentration of the substance is reflected by the color. Blue indicates a lower concentration, and red indicates a higher concentration. The darker the color, the greater the concentration. The results show that the vacuum freeze-dried sample of Dracocephalum heterophyllum Benth. has the fewest volatile components and the lowest content; the oven-dried sample comes second, with fewer types of volatile components. The main volatile organic substances in Dracocephalum heterophyllum Benth. are in the range of migration time 1.0 - 1.7 ms and retention time 100 - 1000 ms. There are multiple reaction ion peaks in each sample, indicating that Dracocephalum heterophyllum Benth. treated by different drying methods contains a variety of volatile substances, and the concentration of each substance is different. The components in region A in the figure are relatively abundant in the samples of natural air-drying and hot-air drying. The components in region B are the most in the vacuum freeze-dried sample. The richness of the components in region C is only high in natural air-drying. The components in region D are more significant in hot-air drying and can be used as specific components. The components in region E only show a high content in fresh plants.

[0068] 2.2 Qualitative Analysis of Volatile Components in Dracocephalum heterophyllum Benth.

[0069] Using the built-in gas-phase retention index database and IMS database in the software, the volatile components of Dracocephalum heterophyllum Benth. were qualitatively analyzed. The qualitative results of the volatile substances in the samples of Dracocephalum heterophyllum Benth. treated by different drying methods are as Figures 2 to 5As shown in Table 1, a total of 72 volatile substances were qualitatively detected in the samples treated by 4 different drying methods according to different retention indices and migration times. Among them, there were 17 aldehyde compounds, accounting for about 36.2%, 14 alkene compounds, accounting for about 29.8%, 13 ketone and alcohol compounds each, accounting for about 27.7%, 11 ester compounds, accounting for about 23.4%. In addition, there were also other compounds such as furans. In Dracocephalum heterophyllum Benth. samples, aldehyde and alkene compounds were the main components of their volatile components. During the detection process, it was observed that some compounds showed multiple signals in the IMS. This was because some volatile components had monomers and their dimers detected simultaneously. High-concentration substances promoted the combination of protonated molecules and neutral molecules in the ionization region to form dimers. And when the proton affinity of the compound exceeded the proton affinity of water, the proton of the reactant would transfer to such compounds with high proton affinity, ultimately forming dimers or polymers. The retention times of the dimer and monomer of the same substance were relatively close. However, since the mass of the dimer was greater than that of the monomer, there would be a certain difference in their migration times.

[0070] Table 1 GC-IMS Qualitative Analysis of Volatile Components in Dracocephalum heterophyllum Benth.

[0071]

[0072]

[0073]

[0074] 2.3 Fingerprint of Volatile Components in Dracocephalum heterophyllum Benth.

[0075] The fingerprint of volatile components in Dracocephalum heterophyllum Benth. after being treated by different drying methods is as Figure 6 shown. Each row represents all the signal peaks selected from a Dracocephalum heterophyllum Benth. sample, and each column represents the signal peaks of the same volatile organic compound in different samples. As Figure 6 can be seen, the volatile components in region A were common to the Dracocephalum heterophyllum Benth. samples treated by 3 different drying methods and the fresh plants, and the contents of these components were all relatively high, including carvone and isopulegol. Different drying methods had little effect on these 2 compounds. The compounds in region C had higher contents after hot air drying than other drying methods, including ethyl acetate, butyrolactone, propyl butyrate, valeraldehyde, etc. It was speculated that this was due to the continuously higher temperature.

[0076] Figure 6The compounds in region B have a relatively high content after natural air-drying and are the characteristic volatile substances of natural air-drying, including γ-terpinene, linalool, limonene, etc.; region F contains volatile components with high content in fresh plants, including hexanol and 2-pentanone; region D contains unique volatile components after vacuum freeze-drying, including benzaldehyde, ethyl 2-methylbutyrate, nonanal, and furfural; the compounds in region E have a lower content after vacuum freeze-drying than other drying methods and are close to fresh plants, including hexanal, 2-pentenal, isopentanol, pentanol, acetoin, and 2-heptenal.

[0077] Table 2 Relative contents of volatile components after different drying methods

[0078]

[0079]

[0080]

[0081] 2.4 PCA

[0082] Principal component analysis (PCA) is a multivariate statistical method used to examine the correlation between multiple variables. It can more intuitively compare the differences between different dried samples of Dracocephalum heterophyllum. The results are as Figure 7 shown. Taking PC-1 as the abscissa and PC-2 as the ordinate to plot a graph, visually showing the differences between samples and the three-dimensional score map of samples. The cumulative contribution rate of the principal components is 65%, where the contribution rate of the first principal component (PC1) is 45% and the contribution rate of the second principal component (PC2) is 20%. It can be intuitively observed from the graph that the differences in the volatile components contained in Dracocephalum heterophyllum plants treated by different drying methods can be clearly distinguished. The volatile components of the vacuum freeze-dried samples are similar to those of fresh Dracocephalum heterophyllum plants and are quite different from those of hot air drying and natural air-drying. Through comprehensive analysis, the vacuum freeze-drying method has a greater impact on the volatile components of Dracocephalum heterophyllum, and the natural air-drying method is more suitable as a method for retaining volatile components.

[0083] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for identifying different drying methods of Cymbidium heterophyllum, characterized in that: The steps include: S1. Take the dried product of Cymbidium heterophyllum to be tested; S2, crush the dried product and inject it by headspace method; S3, analysis using GC-IMS instrument; S4. Perform qualitative and / or quantitative analysis on the detected volatile components through VOCal software, and construct GC-IMS spectra and / or fingerprints of the volatile components; The contents of aromatic alcohol, 3-octanone (D), γ-terpinene (D), limonene (D), benzaldehyde (D), benzaldehyde (M), 2-furfural (D), ethyl 2-methylbutyrate, propyl butyrate, butyrolactone (D), butyrolactone (M), (E), (E)-2,4-heptadienal (M), ethyl acetate (M), ethyl hexanoate, 2-acetylfuran, and valeraldehyde (D) were tested to determine the drying method of the heterophylla.

2. The method according to claim 1, characterized in that The drying methods include natural drying, heating drying and vacuum freeze drying.

3. The method according to claim 1, characterized in that If the relative percentage content of aromatic alcohol in the volatile components after drying is not less than 0.6%; and / or the relative percentage content of 3-octanone (D) is not less than 1%; and / or the relative percentage content of γ-terpinene (D) is not less than 2.5%; and / or the relative percentage content of limonene (D) is not less than 1%, then the drying method is natural shade drying; If the relative percentage content of benzaldehyde (D) in the volatile components after drying is not less than 2%; and / or, the relative percentage content of benzaldehyde (M) is not less than 2%; and / or, the relative percentage content of 2-furfural (D) is not less than 0.1%; and / or, the relative percentage content of ethyl 2-methylbutyrate is not less than 0.1%, then the drying method is vacuum freeze drying; If the relative percentage content of propyl butyrate in the volatile components after drying treatment is not less than 0.2%; and / or, the relative percentage content of butyrolactone (D) is not less than 0.1%; and / or, the relative percentage content of butyrolactone (M) is not less than 0.5%; and / or, the relative percentage content of (E), (E)-2,4-heptadienal (M) is not less than 0.2%; and / or, the relative percentage content of ethyl acetate (M) is not less than 0.1%; and / or, the relative percentage content of ethyl hexanoate is not less than 0.2%; and / or, the relative percentage content of 2-acetylfuran is not less than 0.1%; and / or, the relative percentage content of valeraldehyde (D) is not less than 1.5%, then the drying method is hot air drying.

4. The method according to claim 3, characterized in that If the relative percentage content of aromatic alcohol in the volatile components after drying is not less than 0.8%; and / or the relative percentage content of 3-octanone (D) is not less than 2%; and / or the relative percentage content of γ-terpinene (D) is not less than 3%; and / or the relative percentage content of limonene (D) is not less than 1.5%, then the drying method is natural shade drying; If the relative percentage content of benzaldehyde (D) in the volatile components after drying is not less than 6%; and / or, the relative percentage content of benzaldehyde (M) is not less than 2%; and / or, the relative percentage content of 2-furfural (D) is not less than 0.2%; and / or, the relative percentage content of ethyl 2-methylbutyrate is not less than 0.4%, then the drying method is vacuum freeze drying; If the relative percentage content of propyl butyrate in the volatile components after drying treatment is not less than 0.3%; and / or the relative percentage content of glycine (D) is not less than 0.2%; and / or the relative percentage content of glycine (M) is not less than 0.9%; and / or the relative percentage content of (E), (E)-2,4-heptadienal (M) is not less than 0.5%; and / or the relative percentage content of ethyl acetate (M) is not less than 0.2%; and / or the relative percentage content of ethyl hexanoate is not less than 0.3%; and / or the relative percentage content of 2-acetylfuran is not less than 0.2%; and / or the relative percentage content of valeraldehyde (D) is not less than 2%, then the drying method is hot air drying.

5. The method according to claim 1, characterized in that: In step S2, the headspace analysis conditions include one of the following conditions: Incubation temperature: 30-50°C; Incubation time: 10-20 min; Injection volume: 500~1500μL; Injection needle temperature: 60~100℃.

6. The method according to claim 5, characterized in that In step S2, the headspace analysis conditions are: incubation temperature 40°C, incubation time 15 min, injection volume 1000 μL, injection needle temperature 85°C.

7. The method according to claim 1, characterized in that In step S3, the analysis conditions of gas chromatography-ion mobility spectrometry include at least one of the following conditions: Carrier gas: nitrogen or hydrogen; Drift gas: nitrogen or hydrogen; Initial carrier gas flow rate: 1-3 mL / min; Drift gas flow rate: 60-80 mL / min; IMS migration tube temperature: 40-50°C; Analysis time: 50 to 70 minutes.

8. The method according to claim 7, characterized in that Both the carrier gas and the drift gas were high-purity nitrogen, the initial carrier gas flow rate was 2.0 mL / min, the drift gas flow rate was 75 mL / min, the IMS migration tube temperature was 45°C, and the analysis time was 59 min.

9. A method for identifying different drying methods of Cymbidium heterophyllum, characterized in that: The steps include: S1. Take the dried product of Cymbidium heterophyllum to be tested; S2, prepare the dried product into a test sample and inject the sample; S3. Test the test product; If the relative percentage content of aromatic alcohol in the volatile components after drying is not less than 0.6%; and / or the relative percentage content of 3-octanone (D) is not less than 1%; and / or the relative percentage content of γ-terpinene (D) is not less than 2.5%; and / or the relative percentage content of limonene (D) is not less than 1%, then the drying method is natural shade drying; If the relative percentage content of benzaldehyde (D) in the volatile components after drying is not less than 2%; and / or, the relative percentage content of benzaldehyde (M) is not less than 2%; and / or, the relative percentage content of 2-furfural (D) is not less than 0.1%; and / or, the relative percentage content of ethyl 2-methylbutyrate is not less than 0.1%, then the drying method is vacuum freeze drying; If the relative percentage content of propyl butyrate in the volatile components after drying treatment is not less than 0.2%; and / or, the relative percentage content of butyrolactone (D) is not less than 0.1%; and / or, the relative percentage content of butyrolactone (M) is not less than 0.5%; and / or, the relative percentage content of (E), (E)-2,4-heptadienal (M) is not less than 0.2%; and / or, the relative percentage content of ethyl acetate (M) is not less than 0.1%; and / or, the relative percentage content of ethyl hexanoate is not less than 0.2%; and / or, the relative percentage content of 2-acetylfuran is not less than 0.1%; and / or, the relative percentage content of valeraldehyde (D) is not less than 1.5%, then the drying method is hot air drying.

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