A rapid detection and analysis method for cardamom essential oil

Abstract

A rapid detection and analysis method of Amomum tsao-ko essential oil, comprising: preparing a first sample and a second sample of Amomum tsao-ko essential oil; detecting the first sample by using a gas chromatograph-surface acoustic wave (GC-SAW) with headspace sampling to obtain a chromatogram and an odor fingerprint; detecting the second sample by using a gas chromatograph-mass spectrometer (GC-MS) to obtain a total ion current chromatogram; obtaining a GC-MS qualitative analysis result through database retrieval; obtaining characteristic components in the Amomum tsao-ko essential oil according to the retention indices of each chromatographic peak obtained by GC-SAW detection and in combination with the GC-MS qualitative analysis result; calculating the relative percentage content of each characteristic component in the Amomum tsao-ko essential oil by using a peak area normalization method; establishing an Amomum tsao-ko essential oil qualitative and quantitative analysis database in combination with the relative percentage content of the characteristic components in the Amomum tsao-ko essential oil; detecting a to-be-tested sample by using the GC-SAW and conducting rapid quantitative analysis on the to-be-tested sample in combination with the Amomum tsao-ko essential oil qualitative and quantitative analysis database to realize identification and / or quality evaluation of the to-be-tested sample.

Description

Technical Field

[0001] This invention relates to the field of chemical analysis technology, and in particular to a rapid detection and analysis method for cardamom essential oil. Background Technology

[0002] Cardamom, belonging to the genus Cardamom in the ginger family, is a plant used for both medicinal and culinary purposes due to the aromatic and spicy scent of its fruit. Cardamom essential oil is a volatile oily mixture extracted from the fruit, stems, and other parts of the cardamom plant. Modern research shows that cardamom essential oil contains chemical components such as eucalyptol, geraniol, and citral, which are the main active ingredients in cardamom. These components possess antifungal and antibacterial properties, as well as anticancer and DPPH free radical scavenging effects, and are widely used in the pharmaceutical and fragrance industries.

[0003] The pharmacological effects of cardamom essential oil are closely related to its chemical composition and content. Differences in chemical composition are influenced by factors such as cardamom variety, growing environment, climate conditions, and extraction method. Currently, GC-MS is the primary method for detecting chemical components in cardamom essential oil. However, this method is time-consuming, taking more than half an hour to analyze a single sample. Furthermore, GC-MS instruments are expensive and require professional operation, thus limiting its time and efficiency. It also cannot be applied to rapid on-site detection of cardamom essential oil. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a rapid detection and analysis method for cardamom essential oil. This method employs surface acoustic wave gas chromatography for detection, thereby improving the detection speed and reducing the detection cost of cardamom essential oil while ensuring detection consistency.

[0005] Therefore, the following technical solutions are adopted in the embodiments of this application:

[0006] A rapid detection and analysis method for cardamom essential oil, comprising:

[0007] The initial samples for preparing cardamom essential oil include a first sample and a second sample; wherein, the first sample is a cardamom essential oil sample obtained by taking cardamom essential oil in a 5 mL volumetric flask and diluting it with methanol; the second sample is a cardamom essential oil sample obtained by taking cardamom essential oil in a 10 mL volumetric flask, diluting it with anhydrous ethanol, and then filtering it through an organic filter membrane.

[0008] The first sample was placed in a headspace vial and allowed to stand at room temperature for equilibrium. Then, the first sample was tested using a surface acoustic wave gas chromatograph (GC-SAW) to obtain a chromatogram of the first sample. The horizontal axis of the chromatogram is the chromatographic peak retention index, and the vertical axis is the chromatographic peak intensity.

[0009] The second sample was placed in a vial and tested using gas chromatography-mass spectrometry (GC-MS) to obtain the total ion chromatogram of the second sample. Components with a matching degree higher than 80% were obtained through database retrieval and used as the GC-MS qualitative analysis results.

[0010] Based on the retention index of each chromatographic peak obtained by GC-SAW detection, and by comparing and combining it with the retention index of the components obtained by GC-MS qualitative analysis, the chromatographic peaks obtained by GC-SAW detection are qualitatively analyzed to obtain the characteristic components in the first sample.

[0011] Based on the area of ​​each chromatographic peak in the chromatogram obtained by GC-SAW detection, the relative percentage content of each characteristic component in the first sample is calculated using the peak area normalization method.

[0012] A qualitative and quantitative analysis database for cardamom essential oil is established, which includes the chromatogram of the first sample, each characteristic component in the first sample, and the relative percentage content of each characteristic component.

[0013] GC-SAW was used to analyze the sample and obtain the test results. The test results were then compared with the qualitative and quantitative analysis database of cardamom essential oil to identify whether the sample was cardamom essential oil and / or to evaluate the quality of the sample.

[0014] In this embodiment, GC-SAW is an analytical method that combines a surface acoustic wave sensor with gas chromatography (GC). The analyte is introduced into the GC-SAW system via headspace injection, where it is separated in the column. The surface acoustic wave sensor then detects the signals of each component and converts them into electrical signals. This method offers advantages such as high sensitivity, speed, reliability, and ease of operation. GC-MS is an analytical method that combines gas chromatography (GC) and mass spectrometry (MS). GC separates the components in the mixture, while MS ionizes these components and performs mass spectrometry analysis. This technique offers advantages such as high efficiency, high sensitivity, high resolution, and high specificity. For complex mixtures like cardamom essential oil, the combined use of GC-SAW and GC-MS allows for comprehensive analysis. The information on the characteristic components and their relative percentages obtained from the combined GC-SAW and GC-MS analysis can be used to construct a qualitative and quantitative analysis database for cardamom essential oil. This allows for rapid quantitative analysis of the sample, achieving identification and / or quality evaluation. Simultaneously, the detection results are more accurate and reliable, improving the detection speed of cardamom essential oil and reducing its detection cost.

[0015] As an achievable implementation, the qualitative and quantitative analysis database also includes a fingerprint spectrum of cardamom essential oil, which is obtained by GC-SAW testing of a first sample. GC-SAW is used to analyze the sample to be analyzed and obtain the fingerprint spectrum of the sample to be analyzed. The fingerprint spectrum of the sample to be analyzed is compared and analyzed with the fingerprint spectrum of cardamom essential oil in the qualitative and quantitative analysis database to quickly identify whether the sample to be analyzed is cardamom essential oil.

[0016] It should be noted that a fingerprint spectrum is a spectrum describing the content and relative position of a specific component in a sample. In this embodiment, the fingerprint spectrum can be used to compare the sample to be tested with a known fingerprint spectrum of cardamom essential oil. The comparison results can be used to determine whether the sample contains cardamom essential oil, or whether it contains cardamom essential oil at all, and the relative amount. This rapid identification method can be performed in a short time, reducing the sample processing and analysis time required by traditional analytical methods and improving efficiency. Therefore, it can be applied to the quality evaluation, authenticity identification, and production process control of cardamom essential oil, and has excellent application prospects and promotional value.

[0017] As one feasible implementation method, the sample to be tested is the Chinese herbal essential oil to be tested. The sample to be tested is prepared by the following method: take an appropriate amount of the Chinese herbal essential oil to be tested into a 5 mL volumetric flask, dilute to volume with methanol to obtain a diluted Chinese herbal essential oil sample, take a certain amount of the sample into a 40 mL headspace vial, let it stand at room temperature to equilibrate, and then test it using GC-SAW.

[0018] As one feasible implementation, the GC-SAW detection conditions are as follows: the chromatographic column is a DB-5 metal capillary column, the initial column temperature is 35-60℃, and the temperature is increased to 145℃ at a rate of 4-12℃ / s; the carrier gas is high-purity nitrogen or high-purity helium, and the flow rate is 1.0-3.0 mL / min; the injection port temperature is 180-200℃, the six-way valve box temperature is 140-160℃, the detector temperature is 40-80℃, the sampling time is 5-40s, the analysis time is 20-35s, and the sample is injected into the headspace.

[0019] As one feasible implementation, the DB-5 metal capillary column has the following specifications: 1m × 0.25mm × 0.25μm.

[0020] As one feasible implementation, the GC-SAW detection conditions are as follows: the chromatographic column is a DB-5 metal capillary column, the initial column temperature is 35℃, and the temperature is increased to 145℃ at a heating rate of 5.5℃ / s; the carrier gas is high-purity helium, with a flow rate of 1.7mL / min; the injection port temperature is 180℃, the six-way valve box temperature is 140℃, the detector temperature is 40℃, the pre-concentration tube baking temperature is 250℃, and the sampling flow rate is 30mL / min; the sampling time is 10s, the analysis time is 30s, and the sample is injected into the headspace.

[0021] In this embodiment, when using GC-SAW for detection, the analysis time is greatly shortened due to the shorter column length (1-2m), faster heating rate (4-12℃ / s), and faster detector response, while ensuring a high separation effect.

[0022] As a feasible implementation method, before the initial sample testing of cardamom essential oil, retention index calibration is performed, including: headspace testing of calibration solutions C6 to C18, calibrating the retention index of the 13 peaks obtained, with the retention index of C6 calibrated to 600, the retention index of C7 calibrated to 700, and so on; then the sample is tested, with each sample being tested within 3 minutes.

[0023] As one feasible implementation, the GC-MS detection conditions are as follows: Agilent HP-5MS column (30m × 0.25mm × 0.25μm); injection port temperature 250℃; injection volume: 1μL; split ratio: 40:1; flow rate: 1mL / min; column temperature program: initial temperature 60℃, increased to 150℃ at 5℃ / min, increased to 200℃ at 2℃ / min (chromatographic separation time 43min); mass spectrometry uses an EI ion source with an ion source temperature of 230℃, ionization energy of 70eV, full scan mode, quadrupole temperature of 150℃, solvent delay time of 3min, and the mass spectrometry search library is NIST 14.L.

[0024] In this embodiment, under the above-mentioned limitations, the injection port temperature, injection volume, flow rate, and column temperature program in the GC-MS detection conditions can improve the separation effect and detection sensitivity, thereby obtaining more accurate analytical results.

[0025] As an achievable implementation, the chromatographic peaks obtained by GC-SAW detection are qualitatively identified, including: retention index 1032 is identified as eucalyptol, retention index 1249 is identified as Z-citral, retention index 1271 is identified as geraniol, retention index 1380 is identified as geraniol acetate, and retention index 1473 is identified as trans-dodecenal.

[0026] In this embodiment, the qualitative analysis results in the qualitative and quantitative analysis database of cardamom essential oil can be determined. Then, when the sample to be tested is identified, its chromatogram can be analyzed. The characteristic peaks with retention indices of 1032, 1249, 1271, 1380 and 1473 in the chromatogram can be identified as cardamom essential oil.

[0027] As a feasible implementation method, the relative percentage content of each characteristic component in cardamom essential oil is calculated using the peak area normalization method. This includes: GC-SAW testing of the sample three times consecutively, taking the average value as the peak area of ​​the characteristic peak, and calculating the relative percentage content of each major component in cardamom essential oil according to the area normalization method. The calculation formula is as follows: x% = A / ∑A i ×100%, in the calculation formula, x% is the relative percentage content of a certain component in cardamom essential oil, A is the peak area of ​​that component in the chromatogram, and ∑A i This is the sum of the peak areas of all peaks in the chromatogram.

[0028] In this embodiment, the peak area normalization method combined with the GC-SAW technique of continuously testing the sample three times can quickly and accurately calculate the relative percentage content of each major component in cardamom essential oil.

[0029] Compared with existing technologies, the technological advancements of this invention are significant. The analytical method of this invention can be used for the rapid identification and quality evaluation of cardamom essential oil compared to other types of essential oils. This invention is simple to operate, requires no pretreatment, and exhibits good precision, reproducibility, and stability. Furthermore, it boasts a fast detection speed, completing the detection of a single sample within 3 minutes, greatly improving detection efficiency. This will provide a new, rapid, and convenient detection method for the identification and quality evaluation of cardamom essential oil in the market. Attached Figure Description

[0030] Figure 1 This is a flowchart of the qualitative and quantitative detection process for cardamom essential oil provided in the embodiments of this application;

[0031] Figure 2 This is the curve showing the change in the resolution of the geraniol peak and (E)-citral peak in the cardamom essential oil of Example 1 of this application as a function of carrier gas flow rate;

[0032] Figure 3 This is a schematic diagram illustrating the effect of valve box temperature on the main peak area and total peak area of ​​cardamom essential oil in Embodiment 1 of this application;

[0033] Figure 4 This is a schematic diagram illustrating the effect of the injection port temperature on the main peak area and total peak area of ​​cardamom essential oil in Example 1 of this application;

[0034] Figure 5 This is the curve showing the change in the resolution between the geraniol peak and the (E)-citral peak in the cardamom essential oil of Example 1 of this application as a function of column initial temperature;

[0035] Figure 6 This is a schematic diagram illustrating the effect of heating rate on the separation of geraniol chromatographic peak and its (E)-citral chromatographic peak in cardamom essential oil in Example 1 of this application.

[0036] Figure 7 This is a curve showing the change in the main peak area and total peak area of ​​the cardamom essential oil in Example 1 of this application as a function of the equilibration time of the essential oil sample;

[0037] Figure 8 This is the chromatogram of the retention index calibration test in Example 2 of this application;

[0038] Figure 9 This is the headspace chromatogram of the first sample of cardamom essential oil in Example 2 of this application;

[0039] Figure 10 The total ion chromatogram of the second sample of cardamom essential oil in Example 2 of this application was measured on GC-MS.

[0040] Figure 11 This is the headspace chromatogram of the cardamom essential oil sample to be tested in Example 3 of this application;

[0041] Figure 12 This is the fingerprint spectrum of the cardamom essential oil in Example 3 of this application;

[0042] Figure 13 This is the fingerprint spectrum of fennel essential oil in Example 4 of this application;

[0043] Figure 14 This is the fingerprint spectrum of tangerine peel essential oil in Example 4 of this application;

[0044] Figure 15 This is the fingerprint spectrum of Atractylodes macrocephala essential oil in Example 4 of this application. Detailed Implementation

[0045] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0046] In the description of this application, when numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, devices, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, devices, and materials similar to or equivalent to those described, used, and materials in the embodiments of this application may be used to implement this application.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0048] The term "room temperature" as used in the embodiments of this application has a meaning known in the art, and generally refers to 24-28°C.

[0049] 1. Instruments and reagents used in the embodiments of this application

[0050] Surface acoustic wave gas chromatograph, DB-5 capillary column (1m×0.25mm×0.25μm), methanol, mixed standard solution of C6~C18 n-alkanes (calibration solution).

[0051] 2. Samples used in the embodiments of this application

[0052] Various essential oils, such as cardamom essential oil, fennel essential oil, dried tangerine peel essential oil, and atractylodes essential oil, are extracted from raw materials such as cardamom and dried tangerine peel using steam distillation.

[0053] This application provides a rapid detection and analysis method for cardamom essential oil. (See attached document for details.) Figure 1 The process includes: preparing initial samples of cardamom essential oil, followed by GC-MS and GC-SAW testing. Based on the retention indices of each peak in the GC-SAW chromatogram, and combined with the qualitative analysis results of GC-MS, the peaks obtained from the GC-SAW test were qualitatively identified. The sample was then tested three times consecutively by GC-SAW, and the average value was calculated. The relative percentage content of each major component in cardamom essential oil was calculated using the area normalization method. Thus, by testing cardamom essential oil using GC-SAW and simultaneously using GC-MS as an auxiliary method, the components of cardamom essential oil were qualitatively analyzed. Based on the characteristic components and their relative percentage contents in the tested cardamom essential oil, a qualitative and quantitative analysis database of cardamom essential oil was established. This database contains the chromatograms of the initial cardamom essential oil samples, the characteristic components in the initial samples, and the relative percentage contents of each characteristic component. Subsequently, when testing other samples, after preparing the test sample (herbal essential oil), GC-SAW testing can be performed directly, and qualitative and quantitative analysis of the test sample can be conducted using the cardamom essential oil qualitative and quantitative analysis database. Specifically:

[0054] Example 1

[0055] Optimization and selection of GC-SAW detection conditions

[0056] (1) Preparation of initial sample

[0057] Preparation of the first sample: 25 μL of cardamom essential oil was transferred into a 5 mL volumetric flask using a pipette, and the volume was adjusted to 200 times with methanol to obtain a cardamom essential oil sample diluted 200 times; 1 mL of this sample was placed in a 40 mL headspace vial and allowed to stand at room temperature for 5 min to equilibrate, ready for GC-SAW testing.

[0058] Initial conditions for GC-SAW testing: DB-5 metal capillary column (1m×0.25mm×0.25μm), initial column temperature 35℃, programmed temperature increase to 145℃ at 4℃ / s; injection port temperature 180℃, six-way valve box temperature 140℃, detector temperature 40℃, carrier gas high-purity nitrogen, flow rate 1.0mL / min; pre-concentration tube baking temperature 250℃, sampling flow rate 30mL / min; sampling time 5s, analysis time 20s; headspace injection of sample.

[0059] When testing initial samples of cardamom essential oil using GC-SAW, the instrument's retention index was first calibrated using a mixed standard solution of C6–C18 n-alkanes. To find the optimal testing conditions for initial cardamom essential oil samples, the influencing factors of the GC-SAW, including carrier gas type and flow rate, valve box temperature, injection port temperature, initial column temperature, column heating rate, sample equilibrium temperature, and equilibrium time, were investigated.

[0060] (2) Type and velocity of carrier gas

[0061] GC-SAW can use either nitrogen (N2) or helium (He) as the carrier gas. Comparative experiments showed that, compared to using N2 as the carrier gas, using He as the carrier gas resulted in narrower peak widths and higher column efficiency for the chromatographic peaks of cardamom essential oil. Therefore, He was chosen as the carrier gas for the detection and analysis of cardamom essential oil.

[0062] The separation degree between the peak of geraniol (retention index 1270) and its adjacent peak (retention index 1285, (E)-citral) was investigated when the carrier gas He flow rate was 1.0–2.2 mL / min. The optimal separation effect and maximum separation degree were observed when the carrier gas flow rate was 1.7 mL / min. Figure 2 As shown, this flow rate is selected as the optimal flow rate.

[0063] (3) Valve box temperature

[0064] Under the initial conditions of GC-SAW, the changes in the total peak area and the values ​​of main peak 1 (retention index 1270) and main peak 2 (retention index 1248) of essential oils were investigated within a valve box temperature range of 120℃ to 160℃. (See reference...) Figure 3The test results show that when the valve box temperature is within the range of 140℃ to 150℃, the total peak area and the peak areas of the two main peaks are relatively stable with small variations; moreover, the relative percentage content of main peak 1 and main peak 2 is stable within this temperature range, with a maximum variation of ≤1.4%. These results indicate that setting the GC-SAW valve box temperature within the range of 140℃ to 150℃ is suitable. Furthermore, considering the need for rapid preheating of the instrument, 140℃ is selected as the optimal valve box temperature.

[0065] (4) Inlet temperature

[0066] Under the initial conditions of GC-SAW, the injection port temperature was investigated, with temperatures set between 140℃ and 200℃. (See reference...) Figure 4 The test results show that the total peak area and the main peak area generally increase with the increase of the inlet temperature. When the inlet temperature rises from 140℃ to 180℃, the total peak area and the main peak area increase by 13.43%–19.37%. Further increases in the inlet temperature slightly decrease the area of ​​the main peak, while the increase in the total peak area and the main peak area is less than 3.0%. These results indicate that at an inlet temperature of 180℃, all volatile substances in the essential oil sample can evaporate at the inlet and enter the instrument for separation and detection. Therefore, 180℃ is selected as the optimal inlet temperature.

[0067] (5) Investigation of column initiation temperature and column heating rate

[0068] Under GC-SAW initial conditions, the resolution between the geraniol peak and the (E)-citral peak was investigated at column initiation temperatures of 35℃–45℃. The results showed that lower column initiation temperatures resulted in better resolution between the geraniol and (E)-citral peaks. Figure 5 As shown.

[0069] Under GC-SAW initial conditions, with an initial column temperature of 35℃, the effect of different chromatographic heating rates (4℃ / s~8℃ / s) on the resolution of the geraniol peak and its (E)-citral peak was investigated. Figure 6 As shown in the figure, the test results indicate that the geraniol chromatographic peak and its (E)-citral chromatographic peak have the best separation when the heating rate is 5.5℃ / s.

[0070] (6) Sample equilibrium temperature and equilibrium time

[0071] Based on the characteristics of high volatile component content and rapid volatilization in traditional Chinese medicine essential oil samples, and in order to achieve rapid detection, this method uses the method of equilibrating the sample at room temperature.

[0072] This method examines the effects of different equilibration times on the peak areas of the two main peaks and the total peak area to select the optimal equilibration time. Test results show that within an equilibration time of 5–20 minutes, both the total peak area and the main peak area increase with increasing equilibration time, but the increase is less than 10%. Figure 7 As shown. Considering the purpose of rapid detection, this method still selects 5 minutes as the optimal equilibration time for essential oil detection.

[0073] Therefore, the optimal selection of GC-SAW detection conditions was determined as follows: DB-5 metal capillary column (1m×0.25mm×0.25μm), initial column temperature 35℃, heated to 145℃ at a rate of 5.5℃ / s; carrier gas high-purity helium, flow rate 1.7mL / min; injection port temperature 180℃, six-way valve box temperature 140℃, detector temperature 40℃; pre-concentration tube baking temperature 250℃, sampling flow rate 30mL / min; sampling time 10s, analysis time 30s; headspace injection of sample.

[0074] Next, specific embodiments will be used to illustrate how to construct a qualitative and quantitative analysis database for cardamom essential oil based on the initial GC-SAW and GC-MS detection results.

[0075] Example 2

[0076] (1) Preparation of initial sample

[0077] Preparation of the first sample: 25 μL of cardamom essential oil was transferred into a 5 mL volumetric flask using a pipette, and the volume was adjusted to 200 times with methanol to obtain a cardamom essential oil sample diluted 200 times; 1 mL of this sample was placed in a 40 mL headspace vial and allowed to stand at room temperature for 5 min to equilibrate, ready for GC-SAW testing.

[0078] Preparation of the second sample: Take 50 μL of cardamom essential oil, add anhydrous ethanol to make up to 10 mL in a volumetric flask, filter the solution using a 0.45 μm organic filter membrane, and take the filtrate into a sample vial for testing by GC-MS.

[0079] (2) GC-SAW test conditions

[0080] The chromatographic column was a DB-5 metal capillary column (1m × 0.25mm × 0.25μm), with an initial column temperature of 35℃, ramped to 145℃ at a rate of 5.5℃ / s; the injection port temperature was 180℃, the valve box temperature was 140℃, the detector temperature was 40℃, the carrier gas was high-purity He, and the flow rate was 1.7mL / min; the pre-concentration tube was baked at 250℃, and the sampling flow rate was 30mL / min; the sampling time was 10s, and the analysis time was 30s; the first sample was headspace injected. Retention index calibration was performed on the first sample before testing. The test chromatogram is shown below. Figure 8As shown, the chromatogram of the cardamom essential oil sample is as follows. Figure 9 As shown.

[0081] Before the initial sample testing of cardamom essential oil, retention index calibration was performed, including: headspace testing of calibration solutions C6 to C18, calibrating the retention index of the 13 peaks obtained, with the retention index of C6 calibrated to 600, the retention index of C7 calibrated to 700, and so on; then the sample testing was carried out, with each sample testing completed within 3 minutes.

[0082] (3) GC-MS detection conditions

[0083] An Agilent HP-5MS column (30m × 0.25mm × 0.25μm); injection port temperature 250℃; injection volume: 1μL; split ratio: 40:1; flow rate: 1mL / min; column temperature program: initial temperature 60℃, ramped to 150℃ at 5℃ / min, ramped to 200℃ at 2℃ / min. Mass spectrometry was performed using an EI ion source at 230℃, ionization energy 70eV, full scan mode, quadrupole temperature 150℃, solvent delay time 3min, and the NIST 14.L mass spectrometry library. The total ion chromatogram of the second sample obtained by GC-MS is shown below. Figure 10 As shown.

[0084] (4) Qualitative analysis of the components in cardamom essential oil

[0085] An automated mass spectrometry deconvolution qualitative system was used to identify the co-current chromatographic peaks in the total ion chromatogram and to separate these peaks, obtaining purified mass spectra. The mass spectra included the retention indices of the corresponding chromatographic peaks for each component in the second sample. Each chromatographic peak in the purified mass spectra was searched and compared in the NIST 14.L mass spectrometry database, identifying a total of 19 components, of which 18 showed a matching degree of over 80%. The GC-MS qualitative results are shown in Table 1.

[0086] Understandably, the matching degree refers to the similarity between the mass spectrum of the second sample and the spectrum of a known compound in the NIST 14.L mass spectrometry database. The calculation method includes comparing factors such as peak shape and peak area in the two spectra to determine the similarity, expressed as a percentage. A higher matching degree indicates a greater similarity between the compound in the second sample and the compound in the NIST 14.L mass spectrometry database, thus making the sample more reliable.

[0087] In GC-MS qualitative analysis, a purified mass spectrum is obtained by splitting the co-current chromatographic peaks. Then, an automated mass spectrometry deconvolution qualitative system is used to identify the co-current chromatographic peaks in the total ion chromatogram and to search in the mass spectrometry library. The chemical structure with the highest matching degree is taken as the identification result, which is the GC-MS qualitative analysis result.

[0088] Table 1 Qualitative results from GC-MS

[0089]

[0090]

[0091] As shown in Table 1, based on the GC-MS qualitative analysis results, the literature review results on cardamom essential oil, and the retention index lookup results of each component, the chromatographic peaks detected by GC-SAW were assigned to specific components. Specifically, based on the retention indices of each chromatographic peak obtained from GC-SAW testing, combined with the comparative analysis of the retention indices of each component in the GC-MS qualitative analysis results, the chromatographic peaks obtained from GC-SAW testing were qualitatively identified, thereby obtaining the characteristic components in cardamom essential oil. For example, retention index 1032 was identified as eucalyptol, retention index 1249 as Z-citral, retention index 1271 as geraniol, retention index 1380 as geraniol acetate, and retention index 1473 as trans-dodecenal. The qualitative assignment results of each chromatographic peak obtained by GC-SAW detection are shown in Table 2.

[0092] (5) Quantitative analysis of each component in cardamom essential oil

[0093] The first sample was tested three times consecutively using GC-SAW, and the average value was taken. The relative percentage content of each major component in the cardamom essential oil was calculated using the area normalization method. The calculation formula is as follows: x% = A / ∑A i ×100%, in the calculation formula, x% is the relative percentage content of a certain component in cardamom essential oil, A is the peak area of ​​that component in the chromatogram, and ∑A i The sum of the peak areas of all peaks in the chromatogram is given. The three components with the highest relative content are geraniol, Z-citral, and eucalyptol, with contents of 17.60%, 17.48%, and 14.62%, respectively. The quantitative results of the relative contents of each component obtained by GC-SAW detection are shown in Table 2.

[0094] Table 2

[0095]

[0096]

[0097] It should be noted that the Retention Index (RI) in Table 2, also known as the Kovats index, is a relatively reliable parameter that uses retention values ​​as a qualitative basis. The retention index for n-alkanes is defined as 100 times their carbon number (e.g., the retention index for C6 is 600). It is usually calculated using logarithmic interpolation, based on the retention values ​​of adjacent n-alkanes flanking the analyte on the chromatogram. The formula for calculating the retention index is shown below. The retention index can be used to identify and confirm compounds in chromatograms, and also to build chromatographic libraries for convenient subsequent analysis.

[0098]

[0099] Where RI is the retention index, t R,i t R,Z t R,Z+1 These represent the retention times of the analyte and the n-alkanes with Z and Z+1 carbon atoms, respectively.

[0100] For example, the instrument was calibrated using standard solutions of C6–C18 n-alkanes. After each test, the retention time of each n-alkane standard peak was recorded. The retention index of cardamom essential oil was calculated using the Kovats Retention Index (RI) formula, based on the calibration results of 13 n-alkanes and the retention times of cardamom essential oil. The instrument's data analysis software displayed chromatograms showing the retention indices and retention times of C6–C18 alkanes, where the retention index of n-alkanes is 100 times their carbon number. The retention index of cardamom essential oil in subsequent tests was calculated directly by the instrument's built-in data analysis software using the calibration results of n-alkanes and the retention times of cardamom essential oil.

[0101] In a chromatogram, the response value refers to the signal intensity of each compound in the detector, typically expressed as peak area or peak height. The response value is directly proportional to the concentration of the compound, and therefore can be used to determine the content or concentration of the compound. Furthermore, the response value can be used to compare analytical results under different experimental conditions to evaluate the repeatability and accuracy of the analytical method.

[0102] The chromatogram of the initial sample of cardamom essential oil obtained from the above tests ( Figure 9 The database for qualitative and quantitative analysis of cardamom essential oil was established by collecting the characteristic components and their relative percentage content (Table 2). The database also includes the fingerprint spectrum of cardamom essential oil obtained by GC-SAW testing of the first sample (not shown).

[0103] In subsequent large-scale testing and analysis of cardamom essential oil, GC-SAW can be used directly to test the samples. Combined with the cardamom essential oil qualitative and quantitative analysis database, rapid quantitative analysis of the samples can be performed to obtain identification and / or quality evaluation of the samples, greatly shortening the testing time for batch samples.

[0104] Meanwhile, the fingerprint spectrum of cardamom essential oil in the qualitative and quantitative analysis database was used to quickly identify the samples to be tested for cardamom essential oil.

[0105] Next, specific embodiments will be used to illustrate how to directly use GC-SAW to detect the sample to be tested, and combine the cardamom essential oil qualitative and quantitative analysis database to perform rapid quantitative analysis of the sample to be tested.

[0106] Example 3

[0107] (1) Sample preparation: Select another different cardamom essential oil sample, dilute the cardamom essential oil 200 times according to the steps of Example 1, then use a pipette to transfer 1 mL of cardamom essential oil into a 40 mL headspace vial, seal and store, equilibrate at room temperature for 5 min, and then test using GC-SAW.

[0108] (2) GC-SAW testing conditions: The chromatographic column was a DB-5 metal capillary column (1m×0.25mm×0.25μm), with an initial column temperature of 35℃, increased to 145℃ at a heating rate of 5.5℃ / s; the injection port temperature was 180℃, the valve box temperature was 140℃, the detector temperature was 40℃, the carrier gas was high-purity He, and the flow rate was 1.7mL / min; the pre-concentration tube baking temperature was 250℃, and the sampling flow rate was 30mL / min; the pump aspiration time was 10s, and the analysis time was 30s; the sample was injected into the headspace. The chromatogram of the cardamom essential oil sample is shown below. Figure 11 As shown, the corresponding fingerprint spectrum is as follows: Figure 12 As shown.

[0109] (3) Qualitative analysis of the components in cardamom essential oil: Based on the retention indices of each chromatographic peak obtained by GC-SAW testing, and referring to the qualitative analysis results in Example 2, the components of each chromatographic peak obtained by GC-SAW testing were assigned. The component assignment results of each chromatographic peak obtained by GC-SAW detection are shown in Table 3.

[0110] (4) Quantitative analysis of each component in cardamom essential oil: The sample was tested three times consecutively by GC-SAW, and the average value was taken. The relative percentage content of each major component in cardamom essential oil was calculated according to the area normalization method. The calculation formula is as follows: x% = A / ∑A i ×100%, in the calculation formula, x% is the relative percentage content of a certain component in cardamom essential oil, A is the peak area of ​​that component in the chromatogram, and ∑A iThe sum of the peak areas of all peaks in the chromatogram is given. The three components with the highest relative content, geraniol, (Z)-citral, and eucalyptol, have contents of 19.34%, 18.39%, and 18.29%, respectively. The quantitative results of each component obtained by GC-SAW detection are shown in Table 3.

[0111] Table 3

[0112]

[0113] (5) Compared with Example 2, the cardamom essential oil sample tested in Example 3 had significantly higher contents of geraniol, (Z)-citral and eucalyptol. The relative percentage contents of the two cardamom essential oil samples are shown in Table 4.

[0114] Table 4

[0115]

[0116]

[0117] Example 4

[0118] Under the same sample preparation methods and instrument conditions as described above, other different types of Chinese herbal essential oils, including fennel essential oil, dried tangerine peel essential oil, and atractylodes macrocephala essential oil, were tested, and the corresponding fingerprint spectra were obtained directly as follows: Figures 13-15 As shown.

[0119] Based on the fingerprint spectra of different Chinese herbal essential oils Figure 12 and Figures 13-15 The significant differences between the fingerprint spectrum and the test sample can be visually observed to determine whether the tested essential oil sample is cardamom essential oil.

[0120] The rapid detection and analysis method for cardamom essential oil provided in this application embodiment, in practical application, only uses GC-MS as an auxiliary means when initially using GC-SAW to test cardamom essential oil, to perform qualitative analysis of the components of cardamom essential oil and establish a qualitative and quantitative analysis database for cardamom essential oil. In subsequent large-scale detection and analysis of cardamom essential oil, GC-SAW can be directly used for rapid quantitative analysis, greatly shortening the detection time for batch samples (a single sample can be detected within 3 minutes). When using GC-SAW for detection, the shorter column length (1-2 m), faster heating rate (4-12℃ / s), and faster detector response speed greatly shorten the analysis time while ensuring high separation efficiency. The chemical components in cardamom essential oil are highly volatile; GC-SAW detection requires no pretreatment and allows for direct and rapid headspace injection detection. Combined with the rapid analytical capabilities of GC-SAW, this greatly shortens the detection time for a single sample and effectively improves detection efficiency.

[0121] Simultaneously, by using GC-SAW to establish a fingerprint spectrum for cardamom essential oil, it is possible to quickly identify cardamom essential oil from other types of Chinese herbal essential oils.

[0122] In summary, the surface acoustic wave gas chromatography method for cardamom essential oil of the present invention is simple, rapid, and provides reliable detection results. It can effectively improve the laboratory detection efficiency of cardamom essential oil and can be used for rapid on-site identification and quality evaluation of cardamom essential oil in the market.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application. Those skilled in the art should understand that although this application has been described in detail with reference to the foregoing embodiments, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions in the embodiments of this application.

Claims

1. A rapid detection and analysis method for cardamom essential oil, characterized in that, include: The initial samples for preparing cardamom essential oil include a first sample and a second sample; wherein, the first sample is a cardamom essential oil sample obtained by taking cardamom essential oil in a 5 mL volumetric flask and diluting it with methanol to a final volume; the second sample is a cardamom essential oil sample obtained by taking cardamom essential oil in a 10 mL volumetric flask, diluting it with anhydrous ethanol to a final volume, and then filtering it through an organic filter membrane. The first sample was placed in a headspace vial and allowed to stand at room temperature for equilibrium. Then, the first sample was tested using a surface acoustic wave gas chromatograph (GC-SAW) to obtain a chromatogram of the first sample. The horizontal axis of the chromatogram is the chromatographic peak retention index, and the vertical axis is the chromatographic peak intensity. The second sample was placed in a sample vial and tested using gas chromatography-mass spectrometry (GC-MS) to obtain the total ion chromatogram of the second sample. Components with a matching degree higher than 80% were obtained through database retrieval and used as the GC-MS qualitative analysis results. Based on the retention index of each chromatographic peak obtained by GC-SAW detection, and by comparing and combining it with the retention index of the components obtained by GC-MS qualitative analysis, the chromatographic peaks obtained by GC-SAW detection are qualitatively analyzed to obtain the characteristic components in the first sample. Based on the area of ​​each chromatographic peak in the chromatogram obtained by GC-SAW detection, the relative percentage content of each characteristic component in the first sample is calculated using the peak area normalization method. A qualitative and quantitative analysis database for cardamom essential oil is established, which includes the chromatogram of the first sample, each characteristic component in the first sample, and the relative percentage content of each characteristic component. GC-SAW was used to analyze the sample and obtain the test results. The test results were then compared with the qualitative and quantitative analysis database of cardamom essential oil to identify whether the sample was cardamom essential oil and / or to evaluate the quality of the sample. The qualitative and quantitative analysis database also includes the fingerprint spectrum of cardamom essential oil, which is obtained by GC-SAW testing of the first sample. The sample to be analyzed is analyzed by GC-SAW to obtain the fingerprint spectrum of the sample to be analyzed. The fingerprint spectrum of the sample to be analyzed is compared and analyzed with the fingerprint spectrum of cardamom essential oil in the qualitative and quantitative analysis database to quickly identify whether the sample to be analyzed is cardamom essential oil. The GC-SAW detection conditions were as follows: the chromatographic column was a DB-5 metal capillary column with dimensions of 1m × 0.25mm × 0.25μm; the initial column temperature was 35℃, and the temperature was increased to 145℃ at a rate of 5.5℃ / s; the carrier gas was high-purity helium with a flow rate of 1.7mL / min; the injection port temperature was 180℃, the six-way valve box temperature was 140℃, the detector temperature was 40℃, the sampling time was 10s, and the analysis time was 30s; the sample was injected into the headspace.

2. The method according to claim 1, characterized in that, The sample to be analyzed is a traditional Chinese medicine essential oil to be tested, and the sample to be analyzed is prepared using the following method: Take an appropriate amount of the Chinese herbal essential oil to be tested into a 5 mL volumetric flask, dilute to volume with methanol to obtain a diluted Chinese herbal essential oil sample, take a certain amount of the sample and place it in a 40 mL headspace vial, let it stand at room temperature to equilibrate, and then test it using GC-SAW.

3. The method according to any one of claims 1-2, characterized in that, Before initial sample testing of cardamom essential oil, retention index calibration was performed, including: headspace testing of calibration solutions C6~C18, calibrating the retention index of the 13 peaks obtained, with the retention index of C6 calibrated to 600, the retention index of C7 calibrated to 700, and so on; then sample testing was performed, with each sample testing completed within 3 minutes.

4. The method according to any one of claims 1-2, characterized in that, The GC-MS detection conditions were as follows: Agilent HP-5MS column, 30 m × 0.25 mm × 0.25 μm; injection port temperature 250℃; injection volume: 1 μL; split ratio: 40:1; flow rate: 1 mL / min; column temperature program: initial temperature 60℃, increased to 150℃ at 5℃ / min, increased to 200℃ at 2℃ / min, chromatographic separation time 43 min; mass spectrometry used an EI ion source, ion source temperature 230℃, ionization energy 70 eV, full scan mode, quadrupole temperature 150℃, solvent delay time 3 min, and the mass spectrometry search library was NIST 14.L.

5. The method according to claim 1 or 2, characterized in that, The chromatographic peaks obtained by GC-SAW detection were qualitatively identified as follows: retention index 1032 was identified as eucalyptol, retention index 1249 was identified as Z-citral, retention index 1271 was identified as geraniol, retention index 1380 was identified as geraniol acetate, and retention index 1473 was identified as trans-dodecenal.

6. The method according to claim 1 or 2, characterized in that, The relative percentage content of each characteristic component in cardamom essential oil was calculated using the peak area normalization method, including: The sample was tested three times consecutively using GC-SAW, and the average value was taken as the peak area of ​​the characteristic peak. The relative percentage content of each major component in the cardamom essential oil was calculated using the area normalization method. The calculation formula is as follows: x% = A / ƩA i ×100%, in the calculation formula, x% is the relative percentage content of a certain component in cardamom essential oil, A is the peak area of ​​that component in the chromatogram, ƩA i This is the sum of the peak areas of all peaks in the chromatogram.

Images