Thin-layer chromatography method for identifying lignum dalbergiae odoriferae and adulterants thereof

Abstract

The invention provides a thin-layer chromatography method for identifying lignum dalbergiae odoriferae and adulterants thereof, and belongs to the technical field of thin-layer chromatography analysis. By improving a developing system, the volatile oil and the flavone in the dalbergia wood can be simultaneously identified by only one developing solvent, so that the operation steps are simplified, and the identification time is shortened; according to the method, common and non-toxic cyclohexane, ethyl acetate and acetic acid are adopted as developing solvents, toxic and harmful reagents such as methylbenzene, trichloromethane and diethyl ether are prevented from being used, volatile oil and flavone are effectively separated, and meanwhile use of the toxic reagents is reduced; the invention also provides a novel volatile oil detection method, which comprises the following steps: spraying a mixed solution composed of a vanillin sulfuric acid solution and absolute ethyl alcohol, heating, and placing under a 365nm ultraviolet lamp for detection to display fluorescent spots with different colors, thereby overcoming the problem of weak identification capability caused by the color intensity in the existing method.

Description

Technical Field

[0001] The invention relates to the technical field of thin layer chromatography analysis, in particular to a thin layer chromatography method for identifying dalbergia woodii and its mixed and counterfeited products. Background Art

[0002] Dalbergia is the dried heartwood of the trunk and root of the leguminous plant Dalbergiae odoriferae T.Chen. Dalbergia has the effects of removing blood stasis and stopping bleeding, regulating qi and relieving pain. It has the effects of promoting qi and blood circulation, relieving pain and stopping bleeding. In ancient times, Dalbergia was mainly used to treat traumatic injuries, bleeding from metal wounds, rheumatism and pain. At present, Dalbergia is mainly used for cardiovascular and cerebrovascular diseases, with an annual demand of about 300 tons. Dalbergia is not only a traditional Chinese medicine, but also a raw material for high-quality mahogany furniture and handicrafts. Under natural conditions, the formation cycle of Dalbergia heartwood is long, and wild Dalbergia resources are endangered, resulting in Dalbergia medicinal materials mainly coming from the scraps of the mahogany market, and a variety of mahogany are seriously mixed. A large number of counterfeit products such as Indian Dalbergia, Indian Rosewood, Hainan Dalbergia, Vietnamese incense sticks, etc. have replaced Dalbergia as medicine, resulting in the quality of Dalbergia being affected, the efficacy of the medicine being significantly reduced, and the safety of the medicine being threatened.

[0003] Thin layer chromatography is one of the effective methods to identify the authenticity of traditional Chinese medicine. The main components of Dalbergia odorifera are volatile oils and flavonoids. The current "Chinese Pharmacopoeia" (2020 edition) uses two steps of thin layer chromatography identification of Dalbergia odorifera medicinal materials, using two development systems and two inspection methods to identify volatile oils and flavonoids, respectively. Specifically: methanol is used as a solvent to prepare the test solution and the control medicinal material solution, and then the thin layer chromatography method (General Rule 0502) is used to test toluene-ether-chloroform (7:2:1) as the developing agent to identify the volatile oil components; then the thin layer chromatography method (General Rule 0502) is used to test toluene-ethyl acetate (2:1) as the developing agent to identify the flavonoid components. The above two development systems are used for separation and inspection, and the operation process is relatively cumbersome. In addition, harmful reagents such as toluene, chloroform, and ether are also used in the developing agent. The inspection method of volatile oil is to spray a mixed solution of 1% vanillin sulfuric acid solution and anhydrous ethanol (1:9), and heat it at 105°C until the spots are clearly colored. In actual operation, the operator conducts qualitative analysis based on the intensity of the same color, which is prone to deviation and weak identification ability. Therefore, it is of great significance to provide a new Dalbergia odorifera thin layer chromatography identification method that can solve the technical problems of complex operation, high toxicity of the development reagent, long time consumption and weak color identification ability of the existing identification method. Summary of the invention

[0004] The purpose of the present invention is to provide a thin layer chromatography method for identifying Dalbergia odorifera and its mixed and counterfeit products. The method provided by the present invention.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a thin layer chromatography method for identifying dalbergia woodii and its mixed and counterfeited products, comprising the following steps:

[0007] (1) After mixing the sample powder and methanol, ultrasonic treatment is performed. After standing, the supernatant is filtered through a microporous filter membrane to obtain a test solution;

[0008] Take Dalbergia odorifera as a control medicinal material, and prepare a control medicinal material solution according to the same method as above;

[0009] (2) 2 μL of the sample solution and the test solution obtained in step (1) are respectively spotted at different positions at the same height on the same silica gel GF254 thin layer plate to form a spotting origin, thereby obtaining a GF254 thin layer plate after spotting;

[0010] (3) using cyclohexane-ethyl acetate-acetic acid as a developing agent, placing it in a developing cylinder, then sealing the developing cylinder, performing a pre-saturation treatment, and then opening the developing cylinder, placing the spotted GF254 thin layer plate obtained in step (2) into the developing cylinder, sequentially developing, taking out and drying, and then placing it under a 365 nm ultraviolet lamp for a first inspection, and observing the chromatogram of the test sample and the chromatogram of the control medicinal material;

[0011] Wherein, when the sample powder to be tested is Dalbergia aromatica, the chromatogram of the test sample shows a main fluorescent spot of the same color at the corresponding position of the chromatogram of the control medicinal material;

[0012] Then spray a mixed solution consisting of vanillin sulfuric acid solution and anhydrous ethanol onto the surface of the thin layer plate, heat it, and then place it under a 365nm ultraviolet lamp for a second inspection;

[0013] When the sample powder to be tested is Dalbergia aromatica, the test sample chromatogram shows a main fluorescent spot of the same color at a position corresponding to the control medicinal material chromatogram, thereby achieving the identification of Dalbergia aromatica and its mixed and counterfeit products.

[0014] Preferably, in step (1), the ratio of the mass of the sample powder to be tested to the volume of methanol is 1 g: (7-13) mL.

[0015] Preferably, in step (1), the power of ultrasound is (300-500) W, and the time of ultrasound is 28-48 min.

[0016] Preferably, in the step (2), the volume ratio of cyclohexane, ethyl acetate and acetic acid in the developing solvent is (5-7): (3-5): (0.05-0.15).

[0017] Preferably, in the step (2), the volume ratio of cyclohexane, ethyl acetate and acetic acid in the developing solvent is (5.5-6.5):(3.5-4.3):(0.08-0.12).

[0018] Preferably, the pre-saturation treatment time in step (3) is 15 to 25 minutes.

[0019] Preferably, in step (3), when the front edge of the developing agent moves upward to a distance of 6 cm to 10 cm from the sample spot origin, the developing is completed and the GF254 thin layer plate is taken out.

[0020] Preferably, the mass concentration of vanillin in the vanillin sulfuric acid solution in step (3) is 0.5-1.5%.

[0021] Preferably, in step (3), the volume ratio of the vanillin sulfuric acid solution to anhydrous ethanol is 1:(8-10).

[0022] Preferably, the heating temperature in step (3) is 105° C. and the heating time is 2 to 3 minutes.

[0023] The invention provides a thin layer chromatography method for identifying agarwood and its counterfeits. By improving the development system, only one developing agent is needed to meet the simultaneous identification of volatile oil and flavonoids in agarwood. Compared with the Chinese Pharmacopoeia which adopts two development systems to identify volatile oil and flavonoids respectively, the method of the invention simplifies the operation steps and shortens the identification time. The invention adopts common and non-toxic cyclohexane, ethyl acetate and acetic acid as developing agents, avoids the use of toxic and harmful reagents such as toluene, chloroform and ether, realizes effective separation of volatile oil and flavonoids, and reduces the use of toxic reagents. The invention also provides a new volatile oil detection method, which sprays a mixed solution composed of vanillin sulfuric acid solution and anhydrous ethanol, and places the mixed solution under a 365nm ultraviolet lamp for detection after heating, so as to display fluorescent spots of different colors, thereby overcoming the problem that the original pharmacopoeia method (fluorescent spots with similar colors) relies on the strength of color to cause weak identification ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention adopts the method of Example 1 to identify the test sample chromatogram of samples 1 to 4, wherein: Figure 1 a in the middle is the first inspection (identification of flavonoids), Figure 1 b in the middle is the second inspection (identification of volatile oils);

[0025] Figure 2 The present invention adopts the method of comparative example 1 to identify the test sample chromatogram of samples 1 to 4, wherein: Figure 2 a in the middle is the first inspection (identification of flavonoids), Figure 2 b in the middle is the second inspection (identification of volatile oils);

[0026] Figure 3 The chromatograms of the samples 1 to 3 and the fake Dalbergia aromatica mixed products i, ii, iii and iv are shown in the figure using the method of Example 1 of the present invention, wherein: Figure 3 a in the middle is the first inspection (identification of flavonoids), Figure 3 Middle b is the second inspection (identification of volatile oils). DETAILED DESCRIPTION

[0027] The present invention provides a thin layer chromatography method for identifying dalbergia woodii and its mixed and counterfeited products, comprising the following steps:

[0028] (1) After mixing the sample powder and methanol, ultrasonic treatment is performed. After standing, the supernatant is filtered through a microporous filter membrane to obtain a test solution;

[0029] Take Dalbergia odorifera as a control medicinal material, and prepare a control medicinal material solution according to the same method as above;

[0030] (2) 2 μL of the sample solution and the test solution obtained in step (1) are respectively spotted at different positions at the same height on the same silica gel GF254 thin layer plate to form a spotting origin, thereby obtaining a GF254 thin layer plate after spotting;

[0031] (3) using cyclohexane-ethyl acetate-acetic acid as a developing agent, placing it in a developing cylinder, then sealing the developing cylinder, performing a pre-saturation treatment, and then opening the developing cylinder, placing the spotted GF254 thin layer plate obtained in step (2) into the developing cylinder, sequentially developing, taking out and drying, and then placing it under a 365 nm ultraviolet lamp for a first inspection, and observing the chromatogram of the test sample and the chromatogram of the control medicinal material;

[0032] Wherein, when the sample powder to be tested is Dalbergia aromatica, the chromatogram of the test sample shows a main fluorescent spot of the same color at the corresponding position of the chromatogram of the control medicinal material;

[0033] Then spray a mixed solution consisting of vanillin sulfuric acid solution and anhydrous ethanol onto the surface of the thin layer plate, heat it, and then place it under a 365nm ultraviolet lamp for a second inspection;

[0034] When the sample powder to be tested is Dalbergia aromatica, the test sample chromatogram shows a main fluorescent spot of the same color at a position corresponding to the control medicinal material chromatogram, thereby achieving the identification of Dalbergia aromatica and its mixed and counterfeit products.

[0035] In the present invention, unless otherwise specified, the raw materials used are conventional commercial products in the art.

[0036] In the present invention, the ratio of the mass of the sample powder to the volume of methanol is preferably 1 g: (7-13) mL, more preferably 1 g: 10 mL.

[0037] In the present invention, the power of the ultrasound is preferably 300-600 W, more preferably 400-500 W; the ultrasound time is 28-48 min, more preferably 30-45 min. The present invention promotes the effective ingredients in the sample powder to enter the methanol through ultrasound, which is beneficial to improve the accuracy of subsequent identification and detection results.

[0038] In the present invention, the pore size of the microporous membrane is preferably 0.2-0.45 μm, more preferably 0.22-0.40 μm. The present invention removes solid impurities by filtering through the microporous membrane, which is beneficial to the subsequent development and effectively separates flavonoids and volatile oils at the same time.

[0039] In the present invention, the volume ratio of cyclohexane, ethyl acetate and acetic acid in the developing agent is preferably (5-7): (3-5): (0.05-0.15), more preferably (5.5-6.5): (3.5-4.3): (0.08-0.12), and further preferably 6:4:0.1. The present invention controls the volume ratio of cyclohexane, ethyl acetate and acetic acid in the developing agent within the above range, regulates the polarity of the developing agent and its compatibility with the active ingredients of volatile oil and flavonoids in Dalbergia odorifera, which is conducive to the effective separation of volatile oil and flavonoids at the same time, and realizes that only one developing agent is needed to meet the simultaneous identification of volatile oil and flavonoids in Dalbergia odorifera, simplifies the operation steps, and shortens the identification time.

[0040] In the present invention, the pre-saturation treatment time is 15 to 25 minutes, more preferably 18 to 23 minutes. The present invention allows the volatile components of the developing agent to fully volatilize and mix to fill the developing cylinder through forecasting and treatment, which is beneficial for the effective separation of volatile oil and flavonoids during subsequent development, and only one developing agent is needed to meet the simultaneous identification of volatile oil and flavonoids in Dalbergia odorifera.

[0041] In the present invention, the development is terminated when the front edge of the developing agent preferably moves upward to 6 cm to 10 cm from the sample point origin, and the GF254 thin layer plate is taken out. The present invention controls the development node, which is conducive to the effective separation of volatile oil and flavonoids at the same time.

[0042] In the present invention, the mass concentration of vanillin in the vanillin sulfuric acid solution is preferably 0.5-1.5%, more preferably 1%. In the present invention, the volume ratio of the vanillin sulfuric acid solution to anhydrous ethanol is preferably 1:(8-10), more preferably 1:9. The present invention sprays a mixed solution consisting of a vanillin sulfuric acid solution and anhydrous ethanol of a certain concentration and volume ratio, and inspects after heating to display fluorescent spots of different colors, thereby overcoming the problem of the original pharmacopoeia method that relies on the intensity of color and leads to weak identification ability, and provides a novel and strong identification ability volatile oil inspection method.

[0043] In the present invention, the heating temperature is 105° C. and the heating time is 2 to 3 minutes.

[0044] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example 1

[0046] A thin layer chromatography method for identifying Dalbergia woodii and its mixed and counterfeited products, comprising the following steps:

[0047] (1) After mixing 1 g of the sample powder and 10 mL of methanol, ultrasonic treatment was performed at a power of 500 W for 30 min. After standing, the supernatant was filtered through a microporous filter membrane with a pore size of 0.22 μm to obtain a test solution;

[0048] Take 1 g of Dalbergia odorifera reference medicinal material, and prepare a reference medicinal material solution in the same manner as above;

[0049] (2) 2 μL of the sample solution and the test solution obtained in step (1) are respectively spotted at different positions at the same height on the same silica gel GF254 thin layer plate to form a spotting origin, thereby obtaining a GF254 thin layer plate after spotting;

[0050] (3) A mixed solution of cyclohexane, ethyl acetate and acetic acid in a volume ratio of 6:4:0.1 is used as a developing agent, placed in a developing cylinder, and then the developing cylinder is sealed and pre-saturated for 20 minutes. Then the developing cylinder is opened, and the spotted GF254 thin layer plate obtained in step (2) is placed in the developing cylinder, so that the GF254 thin layer plate is tilted against the developing cylinder. When the front edge of the developing agent moves up to 8 cm from the spotting origin, the GF254 thin layer plate is taken out and placed under a 365 nm ultraviolet lamp for a first inspection, and the chromatograms of the test sample and the reference medicinal material are observed;

[0051] Wherein, when the sample powder to be tested is Dalbergia odorifera, the chromatogram of the test sample shows a main fluorescent spot of the same color at a position corresponding to the chromatogram of the control medicinal material;

[0052] Then, a mixed solution consisting of a vanillin sulfuric acid solution and anhydrous ethanol in a volume ratio of 1:9 was sprayed onto the surface of the thin layer plate, heated at 105° C. for 3 minutes, and then placed under a 365 nm ultraviolet lamp for a second inspection;

[0053] The concentration of vanillin in the vanillin sulfuric acid solution is 1 wt %;

[0054] When the sample powder to be tested is Dalbergia aromatica, the test sample chromatogram shows a main fluorescent spot of the same color at a position corresponding to the control medicinal material chromatogram, thereby achieving the identification of Dalbergia aromatica and its mixed and counterfeit products.

[0055] Comparative Example 1

[0056] The thin layer chromatography method of Dalbergia aromatica in the original pharmacopoeia was used to identify the samples to be tested, and the steps were as follows:

[0057] 1) Take 1g of the sample powder to be tested, add 10ml of methanol, and ultrasonically treat it at a power of 500 for 30min. Let it stand, and filter the supernatant through a microporous filter membrane with a pore size of 0.22μm to obtain the test solution;

[0058] Take 1g of Dalbergia odorifera as a control medicinal material and prepare a control medicinal material solution in the same manner as above;

[0059] 2) According to the thin layer chromatography method (General Rule 0502), 2 μl of the test solution and the control medicinal material solution obtained in step 1) are taken and spotted at different positions at the same height on the same silica gel GF254 thin layer plate to form a spotting origin, and the spotted GF254 thin layer plate is obtained. A mixed solution of toluene, ether and chloroform in a volume ratio of 7:2:1 is used as a developing agent, and the plate is placed in a developing cylinder, and developed, taken out and dried in sequence, and sprayed with a mixed solution of vanillin sulfuric acid solution with a vanillin mass concentration of 1% and anhydrous ethanol in a volume ratio of 1:9, and heated at 105°C for 2-3 minutes until the spots are clearly colored, and then placed under a 365nm ultraviolet lamp for the first inspection, and the chromatograms of the test sample and the control medicinal material are observed;

[0060] Wherein, when the sample powder to be tested is Dalbergia odorifera, the chromatogram of the test sample shows a main fluorescent spot of the same color at a position corresponding to the chromatogram of the control medicinal material;

[0061] 3) According to the thin layer chromatography method (General Rule 0502), 2 μl of the test solution and the control medicinal material solution obtained in step 1) are respectively spotted on the same silica gel GF254 thin layer plate at different positions at the same height to form a spotting origin, and the GF254 thin layer plate after spotting is obtained. A mixed solution consisting of toluene and ethyl acetate in a volume ratio of 2:1 is used as a developing agent, and the plate is placed in a developing tank, and then developed, taken out and dried in sequence, and then placed under a 365nm ultraviolet lamp for a second inspection.

[0062] Among them, when the sample powder to be tested is Dalbergia odorifera, the test sample chromatogram shows a main fluorescent spot of the same color at a position corresponding to the control medicinal material chromatogram.

[0063] Dalbergia odorifera purchased from China Food and Drug Administration (control, NO.1), collected in Dongfang County, Hainan Province (NO.2), Ledong County, Hainan Province (NO.3), and Wanning City, Hainan Province (NO.4) were used as test samples 1 to 4. First, identification was performed according to the method of Example 1. The chromatogram of the test sample obtained by the first inspection (identification of flavonoids) was as follows: Figure 1 As shown in a, the second inspection (identification of volatile oil) obtained the test sample chromatogram as shown in Figure 1 b; then according to the comparative example 1 for identification, the first inspection (identification of flavonoids) obtained by the test sample chromatogram as shown Figure 2 As shown in a, the second inspection (identification of volatile oil) obtained the test sample chromatogram as shown in Figure 2 As shown in b. Figure 1 and Figure 2 It can be seen that Figure 1 The main fluorescent spots of the Dalbergia odorifera sample and the Dalbergia odorifera control medicinal material show the same color at the corresponding position of the chromatogram. Figure 2 The difference is only in the ratio shift of the main fluorescent spot, and Figure 1 The color in b is Figure 2 b is more obvious and easier to identify.

[0064] The method of Example 1 was used to identify the above-mentioned samples to be tested and the mixed and counterfeit Dalbergia odorifera (No. i, ii, iii and iv). In the figure, 1 to 3 are Dalbergia odorifera samples collected in Dongfang County, Hainan Province, Ledong County, Hainan Province, and Wanning City, Hainan Province; i, ii, iii and iv are mixed and counterfeit Dalbergia odorifera: i is Dalbergia tonkinensis Prain, collected in Haikou City, Hainan Province; ii is Dalbergia hainanensis Merr. & Chum, collected in Lingshui County, Hainan; iii is Dalbergia benthamii Prain, from Zhaoqing City, Guangdong; iv is an unknown easily confused product, purchased from Yulin Medicinal Materials Market in Guangxi; the sample preparation method and development method of easily confused products are the same as those in Example 1. The chromatogram of the test sample obtained by the first inspection (identification of flavonoids) is as follows: Figure 3 As shown in a, the second inspection (identification of volatile oil) obtained the test sample chromatogram as shown in Figure 3 As shown in b. Figure 3It can be seen from the figure that the main spots of the Dalbergia odorifera medicinal material are partially missing in the counterfeit products under the two inspection methods: for example, when inspected under ultraviolet light (365nm), the three easily confused products all lack two white fluorescent spots; when sprayed with a mixed solution of 1% vanillin sulfuric acid and anhydrous ethanol (1:9) for color development inspection, ii Hainan Dalbergia odorifera and iii Guangdong Dalbergia odorifera lack the main red spots, i Vietnamese Dalbergia odorifera has an additional clear blue spot; iv unknown counterfeit products have two additional pink spots in the identification of volatile oils. The above counterfeit identification results show that the new Dalbergia odorifera thin layer chromatography identification method established by the present invention can effectively identify Dalbergia odorifera and its counterfeit products.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A thin layer chromatography method for distinguishing Dalbergia woodii and its counterfeits, characterized in that: The following steps are involved: (1) After mixing the sample powder and methanol, ultrasonic treatment is performed. After standing, the supernatant is filtered through a microporous filter membrane to obtain a test solution; Take Dalbergia odorifera as a control medicinal material, and prepare a control medicinal material solution according to the same method as above; (2) 2 μL of the sample solution and the test solution obtained in step (1) are respectively spotted at different positions at the same height on the same silica gel GF254 thin layer plate to form a spotting origin, thereby obtaining a GF254 thin layer plate after spotting; (3) using cyclohexane-ethyl acetate-acetic acid as a developing agent, placing it in a developing cylinder, then sealing the developing cylinder, performing a pre-saturation treatment, and then opening the developing cylinder, placing the spotted GF254 thin layer plate obtained in step (2) into the developing cylinder, sequentially developing, taking out and drying, and then placing it under a 365 nm ultraviolet lamp for a first inspection, and observing the chromatogram of the test sample and the chromatogram of the control medicinal material; Wherein, when the sample powder to be tested is Dalbergia aromatica, the chromatogram of the test sample shows a main fluorescent spot of the same color at the corresponding position of the chromatogram of the control medicinal material; Then spray a mixed solution consisting of vanillin sulfuric acid solution and anhydrous ethanol onto the surface of the thin layer plate, heat it, and then place it under a 365nm ultraviolet lamp for a second inspection; When the sample powder to be tested is Dalbergia aromatica, the test sample chromatogram shows a main spot of the same color at a position corresponding to the control medicinal material chromatogram, thereby achieving identification of Dalbergia aromatica and its mixed and counterfeit products.

2. The thin layer chromatography method for identifying Dalbergia woodii and its counterfeits according to claim 1, characterized in that: In the step (1), the ratio of the mass of the sample powder to be tested to the volume of methanol is 1 g: (7-13) mL.

3. The thin layer chromatography method for identifying Dalbergia woodii and its counterfeits according to claim 1, characterized in that: The power of ultrasound in step (1) is (300-500) W, and the time of ultrasound is 28-48 min.

4. The thin layer chromatography method for identifying Dalbergia woodii and its counterfeits according to claim 1, characterized in that: In the step (2), the volume ratio of cyclohexane, ethyl acetate and acetic acid in the developing solvent is (5-7): (3-5): (0.05-0.15).

5. The thin layer chromatography method for distinguishing Dalbergia woodii and its counterfeits according to claim 4, characterized in that: In the step (2), the volume ratio of cyclohexane, ethyl acetate and acetic acid in the developing solvent is (5.5-6.5):(3.5-4.3):(0.08-0.12).

6. The thin layer chromatography method for identifying Dalbergia woodii and its counterfeits according to claim 1, characterized in that: The time of the pre-saturation treatment in step (3) is 15 to 25 minutes.

7. The thin layer chromatography method for identifying Dalbergia woodii and its counterfeits according to claim 1, characterized in that: In the step (3), when the front edge of the developing agent moves upward to a distance of 6 cm to 10 cm from the sample spot origin, the developing is completed and the GF254 thin layer plate is taken out.

8. The thin layer chromatography method for distinguishing Dalbergia woodii and its counterfeits according to claim 1, characterized in that: The mass concentration of vanillin in the vanillin sulfuric acid solution in step (3) is 0.5-1.5%.

9. The thin layer chromatography method for distinguishing Dalbergia woodii and its counterfeits according to claim 1 or 8, characterized in that: In the step (3), the volume ratio of the vanillin sulfuric acid solution to anhydrous ethanol is 1:(8-10).

10. The thin layer chromatography method for identifying Dalbergia woodii and its counterfeits according to claim 1, characterized in that: The heating temperature in step (3) is 105° C. and the heating time is 2 to 3 minutes.

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