Method for detecting quality stability of eucalyptus leaf oil

Abstract

The present application provides a method for detecting the quality stability of eucalyptus oil, which comprises: detecting different batches of eucalyptus oil samples using a surface acoustic wave gas chromatograph to obtain fingerprint data of the different batches of eucalyptus oil samples including each chromatographic peak; establishing a standard fingerprint of eucalyptus oil based on the fingerprint data of the different batches of eucalyptus oil samples; and analyzing the fingerprint data of the different batches of eucalyptus oil samples based on the standard fingerprint using at least one of principal component analysis and similarity evaluation to determine the quality stability of the different batches of eucalyptus oil samples. According to the method for detecting the quality stability of eucalyptus oil of the present application, different batches of eucalyptus oil samples and optionally eucalyptus oil dilution samples are rapidly detected by using surface acoustic wave gas chromatography technology, the pretreatment is simple, the analysis speed is fast, the practicability is relatively strong, and a new and fast detection method can be provided for on-site analysis of the quality consistency of fragrances and flavors.

Description

Technical Field

[0001] This invention belongs to the field of natural fragrance quality control technology, specifically, it relates to a method for detecting the quality stability of eucalyptus oil. Background Technology

[0002] In recent years, natural flavorings have played a vital role in the food industry and daily chemical products. They enhance the taste and flavor of food, increasing consumer appetite and satisfaction; their aroma can mask unpleasant odors, achieving environmental optimization and sterilization effects. Flavorings, also known as aromatic materials, can be divided into natural and synthetic flavorings. To date, over 3,000 natural flavorings have been discovered, with approximately 500 being effectively utilized. Natural flavorings are widely distributed in the glands of plants and animals. Different extraction methods yield various products such as extracts, essential oils, absolutes, balms, and resins. Natural flavorings, due to their unique fixing and harmonizing effects and distinctive natural aroma, are unmatched by synthetic flavorings.

[0003] With the rapid development of the national economy and the diversification of consumer demand, people have increasingly higher requirements for the quality and flavor of natural spices. Product quality often fluctuates between different origins and batches, therefore the stability of natural spice quality is receiving increasing attention.

[0004] Currently, the quality identification of natural fragrances typically involves evaluating and analyzing physicochemical indicators, olfactory similarity, and sensory effects. However, the internal composition of natural fragrances is complex, and single or small components in a sample cannot fully reflect its quality, and subjective factors have a significant impact. Commonly used fingerprinting methods include gas chromatography-mass spectrometry, near-infrared spectroscopy, high-performance liquid chromatography-evaporative light scattering, and ion chromatography. These conventional methods require bulky instruments and complex pretreatment processes, making the entire testing process more complicated and time-consuming (over 30 minutes), which is insufficient for rapid on-site testing. Given the large sample size in the natural fragrance market, and the significant differences in composition and intended use among different varieties, origins, and batches, establishing rapid, convenient, and accurate on-site testing methods for natural fragrances is of paramount practical importance to ensure consistent quality. Summary of the Invention

[0005] To address at least one of the aforementioned problems, the present invention provides a method for detecting the quality stability of natural eucalyptus oil, which can rapidly detect the quality stability of different batches of eucalyptus oil and / or diluted eucalyptus oil samples.

[0006] According to one aspect of the present invention, a method for detecting the quality stability of eucalyptus oil is provided, the method comprising the following steps: (a) detecting different batches of eucalyptus oil samples using a surface acoustic wave gas chromatograph to obtain fingerprint data of different batches of eucalyptus oil samples including each chromatographic peak, wherein the surface acoustic wave gas chromatograph includes a sampling port, a sampling pump, a pre-concentration tube, a six-way valve, a carrier gas bottle, a chromatographic column, a detector, and a data processing device; (b) establishing a standard fingerprint spectrum of eucalyptus oil based on the fingerprint spectrum data of different batches of eucalyptus oil samples; and (c) using at least one of principal component analysis and similarity evaluation based on the standard fingerprint spectrum to detect the quality stability of different batches of eucalyptus oil samples. The fingerprint data of eucalyptus oil samples were analyzed to determine the quality stability of different batches of eucalyptus oil samples. In step (a), the detection was performed as follows: the eucalyptus oil samples were equilibrated at 25°C to 45°C for 5 min to 25 min for headspace injection; the sampling pump was started to draw the eucalyptus oil samples into the pre-concentration tube through the sampling port at a temperature of 160°C to 200°C; the six-way valve was switched to allow the carrier gas to flow through the pre-concentration tube and carry the eucalyptus oil samples in the pre-concentration tube into the chromatographic column and detector in sequence to complete the detection. The temperature of the six-way valve was 150°C to 190°C, and the carrier gas flow rate of the chromatographic column was 3 mL / min to 5 mL / min.

[0007] According to another aspect of the present invention, a method for detecting the quality stability of eucalyptus oil is provided, the method comprising the following steps: (a) detecting different batches of eucalyptus oil samples using a surface acoustic wave gas chromatograph to obtain fingerprint data of different batches of eucalyptus oil samples including each chromatographic peak, wherein the surface acoustic wave gas chromatograph includes a sampling port, a sampling pump, a pre-concentration tube, a six-way valve, a carrier gas bottle, a chromatographic column, a detector, and a data processing device; (b) establishing a standard fingerprint spectrum of eucalyptus oil based on the fingerprint data of different batches of eucalyptus oil samples; (c) detecting diluted eucalyptus oil samples using a surface acoustic wave gas chromatograph to obtain fingerprint data of diluted eucalyptus oil samples including each chromatographic peak; and (d) using at least one of principal component analysis and similarity evaluation based on the standard fingerprint spectrum to detect different batches of eucalyptus oil samples. The fingerprint data of eucalyptus oil samples and diluted eucalyptus oil samples were analyzed to determine the quality stability of different batches of eucalyptus oil samples and diluted eucalyptus oil samples. In steps (a) and (c), the detection was performed as follows: the eucalyptus oil samples and diluted eucalyptus oil samples were equilibrated at 25°C to 45°C for 5 min to 25 min for headspace injection; the sampling pump was started to draw the eucalyptus oil samples and diluted eucalyptus oil samples into the pre-concentration tube through the sampling port at a temperature of 160°C to 200°C; the six-way valve was switched to allow the carrier gas to flow through the pre-concentration tube, carrying the eucalyptus oil samples and diluted eucalyptus oil samples in the pre-concentration tube into the chromatographic column and detector in sequence to complete the detection. The temperature of the six-way valve was 150°C to 190°C, and the carrier gas flow rate of the chromatographic column was 3 mL / min to 5 mL / min.

[0008] According to an embodiment of the present invention, in step (a), the detection can be performed by the following steps: equilibrating the sample at 40°C for 10 min for headspace injection; starting the sampling pump to draw the eucalyptus oil sample into the pre-concentration tube through a sampling port at 200°C; switching the six-way valve to allow the carrier gas to flow through the pre-concentration tube and carry the eucalyptus oil sample in the pre-concentration tube into the chromatographic column and detector in sequence to complete the detection, wherein the temperature of the six-way valve is 180°C and the carrier gas flow rate of the chromatographic column is 4 mL / min.

[0009] According to an embodiment of the present invention, the detection conditions of the chromatographic column can be as follows: the initial temperature of the chromatographic column is 40°C to 50°C, and the temperature of the chromatographic column is increased to 170°C to 180°C according to a temperature increase program of 6°C / s to 12°C / s, the carrier gas is nitrogen, and the detection conditions of the detector can be as follows: the detection temperature of the detector is 30°C to 100°C, and the baking temperature of the detector is 140°C to 150°C.

[0010] According to an embodiment of the present invention, the detection conditions of the chromatographic column can be as follows: the initial temperature of the chromatographic column is 45°C, and the temperature of the chromatographic column is increased to 180°C according to a temperature increase program of 12°C / s. The detection conditions of the detector can be as follows: the detection temperature of the detector is 85°C, and the baking temperature of the detector is 150°C.

[0011] According to an embodiment of the present invention, the method may further include: before performing step (a), detecting the n-alkane standard solution using a surface acoustic wave gas chromatograph to obtain a chromatogram of the n-alkane standard solution, calibrating each chromatographic peak of the fingerprint data using the chromatogram of the n-alkane standard solution to obtain each chromatographic peak in the form of a retention index, wherein the n-alkane in the n-alkane standard solution is at least one selected from n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecanane, n-hexadecane, n-heptadecane, and n-octadecane.

[0012] According to an embodiment of the present invention, the step of establishing a standard fingerprint spectrum for eucalyptus oil may include: determining the common chromatographic peaks of eucalyptus oil samples based on fingerprint spectrum data from different batches of eucalyptus oil samples; and identifying the common chromatographic peaks as characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 based on the magnitude of the response values ​​of the common chromatographic peaks in the form of retention indices, thereby establishing a standard fingerprint spectrum for eucalyptus oil. The characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 are respectively assigned to eucalyptol, p-cymene or limonene, myrtol or verbenaenool, carvacrol, β-boronene, and β-caryophyllene.

[0013] According to an embodiment of the present invention, in the step of using principal component analysis, characteristic peaks with retention indices of 1027, 1093, and 1210 in the standard fingerprint spectrum are selected as reference peaks. The spectral matrix with the response values ​​of the characteristic peaks with retention indices of 1027, 1093, and 1210 as variables is converted into a score matrix with principal components PC1 and PC2 as variables, so as to obtain scatter plots of different batches of eucalyptus oil samples. The concentration of eucalyptus oil samples among themselves in the scatter plot is used to determine whether there is a fluctuation in the quality of different batches of eucalyptus oil samples. Alternatively, the concentration of eucalyptus oil samples and diluted eucalyptus oil samples among themselves in the scatter plot is used to determine whether there is a fluctuation in the quality of different batches of eucalyptus oil samples and diluted eucalyptus oil samples.

[0014] According to an embodiment of the present invention, in the step of performing analysis using similarity evaluation, a eucalyptus oil sample from different batches of eucalyptus oil samples is determined as a standard sample based on a standard fingerprint spectrum. The similarity evaluation is then used to compare other eucalyptus oil samples from different batches of eucalyptus oil samples with the standard sample to determine the similarity differences between the other eucalyptus oil samples from different batches of eucalyptus oil samples and the standard sample. Alternatively, the similarity evaluation is used to compare other eucalyptus oil samples from different batches of eucalyptus oil samples and diluted eucalyptus oil samples with the standard sample to determine the similarity differences between the other eucalyptus oil samples from different batches of eucalyptus oil samples and diluted eucalyptus oil samples and the standard sample.

[0015] According to an embodiment of the present invention, in the step of determining the standard sample, the standard sample can be determined based on the magnitude of the response value of the characteristic peaks corresponding to the characteristic peaks with retention indices of 1027, 1093 and 1210 in the standard fingerprint spectrum of different batches of eucalyptus oil samples, and the peak shape of the characteristic peaks corresponding to the characteristic peaks with retention indices of 1027, 1093 and 1210 in the standard fingerprint spectrum.

[0016] According to embodiments of the present invention, similarity evaluation may include at least one of the Euclidean distance ratio method, the cosine similarity method, and the correlation coefficient method.

[0017] The method for detecting the quality stability of eucalyptus oil according to the present invention rapidly detects different batches of eucalyptus oil samples and optionally diluted eucalyptus oil samples using surface acoustic wave gas chromatography. The method features simple pretreatment, fast analysis speed, and strong practicality, providing a novel and rapid detection method for on-site analysis of the consistency of flavor and fragrance quality. Attached Figure Description

[0018] The above and / or other features and aspects of the invention will become clear and readily understood through the description of examples in conjunction with the accompanying drawings.

[0019] Figure 1 This is a block diagram of the principle of a surface acoustic wave gas chromatograph.

[0020] Figure 2 This is a schematic diagram of a surface acoustic wave gas chromatograph in the sample injection state.

[0021] Figure 3 This is a schematic diagram of a surface acoustic wave gas chromatograph in detection mode.

[0022] Figure 4 and Figure 5 This is a chromatogram of a standard solution for calibrating n-alkanes.

[0023] Figure 6 This is a headspace test spectrum of eucalyptus oil.

[0024] Figure 7 This is a trend diagram showing the influence of different equilibrium temperatures on the main peak of eucalyptus oil.

[0025] Figure 8 This is a trend chart showing the influence of different equilibrium times on the main peak of eucalyptus oil.

[0026] Figure 9 This is a trend graph showing the influence of different sampling port temperatures on the main peak of eucalyptus oil.

[0027] Figure 10 This is a trend chart showing the effect of different six-way valve temperatures on the main peak of eucalyptus oil.

[0028] Figure 11 This is a trend chart showing the influence of different carrier gas flow rates on the main peak of eucalyptus oil.

[0029] Figure 12 These are fingerprint data from 6 different batches of eucalyptus oil samples and 2 diluted eucalyptus oil samples.

[0030] Figure 13 The images show scatter plots of principal component analysis for six different batches of eucalyptus oil samples and two diluted eucalyptus oil samples. Detailed Implementation

[0031] The present invention will now be explained by referring to the accompanying drawings, which illustrate embodiments. However, the invention may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These embodiments are provided so that the disclosure of the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0032] Surface acoustic wave (SAW) gas chromatography is a device developed using surface acoustic wave (SAW) sensors as gas chromatograph detectors, based on the principle of SAW devices, for analyzing volatile or semi-volatile chemical components. It utilizes gas chromatography principles to separate complex gas components and uses SAW sensors to detect these components, effectively avoiding interference between different gas components and enabling broad-spectrum (volatile or semi-volatile organic compound) analysis of trace gases. The SAW sensor, as an acoustic-electric transducer, can be implemented in a very small interdigital transducer with an area of ​​only 12 mm². 2 Furthermore, the rapid reaction speed allows for a relatively small detector size. The chromatographic column is only 1m long and employs a column heating system with a fast heating rate. In summary, the portable coupled detection instrument constructed by combining gas chromatography with a surface acoustic wave sensor features small size, rapid reaction, and high sensitivity, combining the advantages of both large-scale equipment and rapid detection devices.

[0033] Because surface acoustic wave (SAW) gas chromatography-mass spectrometry (SAW-GC) offers shorter detection times and lower detection limits, it is more difficult to effectively separate and accurately detect the complex volatile components in natural fragrances within a short timeframe compared to conventional gas chromatography. Therefore, there are currently no reports on rapid analysis of the stability of natural fragrances using SAW-GC. This invention innovatively proposes a rapid detection method for the stability of natural fragrances (eucalyptus oil) using SAW-GC.

[0034] Figure 1 This is a block diagram of the principle of a surface acoustic wave gas chromatograph. Figure 2 This is a schematic diagram of a surface acoustic wave gas chromatograph in the sample injection state. Figure 3 This is a schematic diagram of a surface acoustic wave gas chromatograph in detection mode. (Example:) Figures 1 to 3 As shown, the surface acoustic wave gas chromatograph includes a sampling port 1, a sampling pump 2, a pre-concentration tube 3, a six-way valve 4, a carrier gas bottle 5, a chromatographic column 6, a detector 7, and a data processing device 8. Furthermore, the surface acoustic wave gas chromatograph can switch between sample injection and detection.

[0035] like Figure 2 As shown, when the surface acoustic wave gas chromatograph is in the sample injection state, the first port 41 of the six-way valve 4 is connected to the first port 31 of the pre-concentration tube 3, the second port 42 of the six-way valve 4 is connected to the carrier gas bottle 5, the third port 43 of the six-way valve 4 is connected to the inlet of the chromatographic column 6, the fourth port 44 of the six-way valve 4 is connected to the second port 32 of the pre-concentration tube 3, the fifth port 45 of the six-way valve 4 is connected to the sampling pump 2, and the sixth port 46 of the six-way valve 4 is connected to the sampling port 1. Through the pressure difference generated by the sampling pump 2, the sample enters the pre-concentration tube 3 through the sampling port 1 to complete the injection.

[0036] After the sample injection is complete, the six-way valve 4 can be rotated to switch the surface acoustic wave gas chromatograph to detection mode, such as... Figure 2 As shown in the diagram. In the detection state, the first port 41 of the six-way valve 4 is connected to the second port 32 of the pre-concentration tube 3, the second port 42 of the six-way valve 4 is connected to the sampling pump 2, the third port 43 of the six-way valve 4 is connected to the sampling port 1, the fourth port 44 of the six-way valve 4 is connected to the first port 31 of the pre-concentration tube 3, the fifth port 45 of the six-way valve 4 is connected to the carrier gas bottle 5, and the sixth port 46 of the six-way valve 4 is connected to the inlet of the chromatographic column 6. Therefore, a gas path is formed starting from the carrier gas bottle 5, sequentially passing through the pre-concentration tube 3, the chromatographic column 6, and the detector 7.

[0037] During the detection process, the pre-concentration tube 3 is heated to vaporize the sample within. The vaporized sample in the pre-concentration tube 3 can then enter the chromatographic column 6 with the carrier gas to complete gas phase separation, and subsequently enter the detector 7 to detect the individual gas phase components after sample separation. The data obtained by the detector 7 can be sent to the data processing device 8, which processes the data and presents it to the testing personnel.

[0038] The method for detecting the quality stability of eucalyptus oil according to an embodiment of the present invention will be described in detail below.

[0039] The method for detecting the quality stability of eucalyptus oil according to an embodiment of the present invention includes the following steps: obtaining fingerprint chromatographic data including each chromatographic peak of different batches of eucalyptus oil samples and fingerprint chromatographic data including each chromatographic peak of optionally diluted eucalyptus oil samples; establishing a standard fingerprint chromatogram of eucalyptus oil based on the fingerprint chromatographic data of different batches of eucalyptus oil samples; and analyzing the fingerprint chromatographic data of different batches of eucalyptus oil samples and optionally diluted eucalyptus oil samples based on the standard fingerprint chromatogram using at least one of principal component analysis and similarity evaluation to determine the quality stability of different batches of eucalyptus oil samples and optionally diluted eucalyptus oil samples.

[0040] In the embodiments of this invention, retention indices are used to qualitatively identify eucalyptus oil. Therefore, before testing samples using a surface acoustic wave gas chromatograph, calibration with a n-alkane standard solution is required after each modification of parameters such as column carrier gas flow rate, sampling port temperature, six-way valve temperature, sample equilibration temperature, and equilibration time. This calibration utilizes the chromatograms of the n-alkane standard solution to calibrate each chromatographic peak, thereby obtaining peaks in the form of retention indices. Using retention indices to qualitatively identify eucalyptus oil effectively avoids errors caused by operational factors and differences in experimental conditions.

[0041] The n-alkane in the n-alkane standard solution can be at least one of n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecanane, n-hexadecane, n-heptadecane, and n-octadecane. Preferably, the n-alkane can be all of n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecanane, n-hexadecane, n-heptadecane, and n-octadecane.

[0042] First, a standard solution of n-alkane can be prepared. Specifically, 10.0 mL of n-hexane, 5.0 mL of n-heptane, 1 mL of n-octane, 100.0 µL of n-nonane, 40.0 µL of n-decane, 20.0 µL of n-undecane, 10.0 µL of n-dodecane, 5.0 µL of n-tridecane, 5.0 µL of n-tetradecane, 5.0 µL of n-pentadecane, 3.0 µL of n-hexadecane, 3.0 µL of n-heptadecane, and 3.0 µL of n-octadecane can be transferred to a 100 mL volumetric flask, diluted to volume with methanol, and mixed well to obtain the standard solution of n-alkane.

[0043] Under the initial GC-SAW detection conditions, the detector temperature was changed to 60℃. Calibration was performed using n-alkane standard solutions. After each test, the retention time of each n-alkane standard solution peak was recorded. The retention index of each chromatographic peak of eucalyptus oil was calculated using the Kovats retention index (RI) formula after the n-alkane standard solution was calibrated.

[0044] The formula for the Kovats retention index is as follows: RI=100n+100[(tRu-tRn) / (tR(n+1)-tRn)] Where RI is the retention index of the target compound in eucalyptus oil, n is the number of carbon atoms in the preceding n-alkane from which the target compound eluted, tRu is the retention time of the target compound, and tRn and tR(n+1) are the retention times of adjacent n-alkanes. <tRu<tR(n+1)。

[0045] Figure 4 and Figure 5 The chromatogram of the n-alkane standard solution as determined by GC-SAW is shown, wherein... Figure 4 Indicated by retention time, Figure 5 Retention indices are used to represent the values. The n-alkane standard solution contains 13 components, ranging from n-hexane (C6) to n-octadecane (C18), resulting in 13 corresponding characteristic peaks detected in the chromatogram. All characteristic peaks were detected within 10 seconds. The retention index for n-alkane is defined as the carbon number multiplied by 100. Specifically, the retention index for n-hexane is 600, for n-heptane it is 700, and so on, until the last characteristic peak, n-octadecane, has a retention index of 1800. The retention indices of subsequent chromatographic peaks are directly provided by the instrument's built-in analysis software based on the calibration results of the n-alkane and the retention times of each component's characteristic peaks. According to relevant gas chromatography theories, under the same chromatographic conditions, the retention index of the same substance does not change with variations in equipment, personnel, or other external conditions. Therefore, it exhibits relatively good stability and reliability for the qualitative analysis of unknown substances.

[0046] After calibration using a n-alkane standard solution, a surface acoustic wave gas chromatograph (SAWG) can be used to detect different batches of eucalyptus oil samples and optionally (i.e., selectively) diluted eucalyptus oil samples to obtain fingerprint data including each chromatographic peak for different batches of eucalyptus oil samples and fingerprint data including each chromatographic peak for optional diluted eucalyptus oil samples. Specifically, different batches of eucalyptus oil samples and optional diluted eucalyptus oil samples are added to headspace reagent bottles, sealed, and equilibrated at 25°C to 45°C (preferably 25°C to 40°C) for 5 min to 25 min (preferably 5 min to 10 min). The head gas is then extracted to the sampling port of the SAWG, and the sampling pump is started to draw the different batches of eucalyptus oil samples and optional diluted eucalyptus oil samples into the pre-concentration tube through the sampling port at a temperature of 160°C to 200°C in the manner described above. Then, the six-way valve is switched as described above to allow the carrier gas to flow through the pre-concentration tube and carry the sample in the pre-concentration tube into the chromatographic column and detector in sequence to complete the detection. The temperature of the six-way valve can be 150°C to 190°C (preferably 150°C to 180°C), and the carrier gas flow rate of the chromatographic column can be 3 mL / min to 5 mL / min.

[0047] Furthermore, the detection conditions for the chromatographic column are as follows: the column can be a DB-5 (1m × 0.25mm × 0.25µm), the initial temperature of the column can be 40℃ to 50℃, and the temperature of the column is increased to 170℃ to 180℃ according to a temperature program of 6℃ / s to 12℃ / s; the carrier gas can be nitrogen. The detection conditions for the detector are as follows: the detector detection temperature is 30℃ to 100℃, and the detector baking temperature is 140℃ to 150℃. Here, the detector detection temperature refers to the temperature at which the detector analyzes the sample, and the detector baking temperature refers to the temperature at which the detector is cleaned after the sample analysis is completed; it is also called the aging temperature or cleaning temperature. As another preferred example, chromatographic detection can be performed under the following conditions: the chromatographic column is a DB-5 (1m × 0.25mm × 0.25µm), the initial temperature is 45℃, and the temperature of the column is increased to 180℃ according to a temperature program of 12℃ / s; the detector detection temperature is 85℃, and the detector baking temperature is 150℃. In addition, the pump suction time can be controlled to 10 seconds; the analysis time can be controlled to 20 seconds.

[0048] After obtaining fingerprint chromatogram data from different batches of eucalyptus oil samples, a standard fingerprint chromatogram for eucalyptus oil was established based on these data. Analyzing the similarity of complex samples using fingerprint chromatograms requires identifying chromatographic patterns of common components in the sample chromatograms. Chromatographic peaks appearing in the sample chromatograms can be considered "common peaks." For the same sample, good repeatability under the same operating conditions is sufficient to establish a fingerprint chromatogram.

[0049] First, the common chromatographic peaks of eucalyptus oil samples were determined based on the fingerprint data of different batches of eucalyptus oil samples. Specifically, such as... Figure 6 As shown, the main components of eucalyptus oil rapidly elute within 15 seconds, and the separation of each chromatographic peak is good. The volatile components in eucalyptus oil contain 10 common characteristic peaks.

[0050] Next, based on the magnitude of the response values ​​(specifically, peak intensities) of the common chromatographic peaks in the form of retention indices, the common chromatographic peaks were identified as characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 (corresponding to...). Figure 6 Characteristic peaks numbered 1 to 6 were used to establish a standard fingerprint spectrum for eucalyptus oil.

[0051] Based on relevant literature on GC-MS detection of eucalyptus oil and the NIST spectral library, the six characteristic peaks were assigned as follows: the peak with a retention index of 1027 was assigned to eucalyptol; the peak with a retention index of 1093 was assigned to p-cymene or limonene; the peak with a retention index of 1210 was assigned to myrbutenol or verbenaenool; the peak with a retention index of 1305 was assigned to carvacrol; the peak with a retention index of 1370 was assigned to β-boronene; and the peak with a retention index of 1410 was assigned to β-caryophyllene. In the subsequent investigation, the instrument conditions were optimized using the three main characteristic peaks with retention indices of 1027, 1093, and 1210 as experimental subjects.

[0052] To better establish a standard fingerprint spectrum for eucalyptus oil, the parameters for headspace sampling and detection conditions were optimized to obtain the best experimental conditions for detecting eucalyptus oil.

[0053] Selection of equilibrium temperature in headspace sampling Three 10µL eucalyptus oil samples were added to 22.4mL headspace reagent bottles, sealed, and placed in an incubator. Equilibrium temperatures were set at 25℃, 30℃, 35℃, 40℃, and 45℃, with an equilibrium time of 10 min. Direct headspace analysis was performed to select the appropriate equilibrium temperature. Other detection conditions were as follows: DB-5 column (1m×0.25mm×0.25µm), initial temperature 45℃, with the column temperature increased to 180℃ according to a temperature ramp program of 12℃ / s; detector detection temperature 85℃, detector baking temperature 150℃; pump aspiration time 10s.

[0054] Figure 7 The influence trend of different equilibrium temperatures on the main peak of eucalyptus oil is shown. From Figure 7It can be seen that as the equilibrium temperature increases, the response value of the main peak with a retention index of 1210 increases slightly, while the response values ​​of the main peaks with retention indices of 1027 and 1093 increase more significantly. However, at an equilibrium temperature of 45℃, the response value of the main peak with a retention index of 1027 reaches as high as 17241 kCts·s. -1 The detector exhibits saturation, which affects its sensitivity. Therefore, based on experimental results, the optimal equilibrium temperature can be selected as 40℃.

[0055] Selection of equilibration time in headspace sampling Three 10µL eucalyptus oil samples were added to 22.4mL headspace reagent bottles, sealed, and stored at 40℃. Equilibration times of 5 min, 10 min, 15 min, 20 min, and 25 min were selected for direct headspace analysis to determine the appropriate equilibration time. Other detection conditions were as follows: DB-5 column (1m × 0.25mm × 0.25µm), initial temperature 45℃, with the column temperature increased to 180℃ using a temperature ramp program of 12℃ / s; detector detection temperature 85℃, detector baking temperature 150℃; pump aspiration time 10s.

[0056] Figure 8 The influence trend of different equilibrium times on the main peak is shown. From Figure 8 It can be seen that as the equilibration time increases, the response values ​​of the retention indices 1027, 1093 and 1210 peaks increase significantly between 5 and 10 minutes. After 10 minutes, the response values ​​of the three peaks tend to stabilize. Considering rapid detection, the optimal equilibration time can be selected as 10 minutes.

[0057] Selection of sampling port temperature for surface acoustic wave gas chromatograph Under the initial conditions of GC-SAW, the sampling port temperature was changed to 200℃, 190℃, 180℃, 170℃, and 160℃ for headspace sampling of eucalyptus oil samples. Five 10µL aliquots of eucalyptus oil sample were added to 22.4mL headspace reagent bottles, sealed, and equilibrated at 40℃ for 10 min before direct headspace sampling to select a suitable sampling port temperature. Other detection conditions were as follows: the chromatographic column was DB-5 (1m×0.25mm×0.25µm), the initial temperature was 45℃, and the column temperature was increased to 180℃ according to a temperature program of 12℃ / s; the detector detection temperature was 85℃, the detector baking temperature was 150℃, and the pump aspiration time was 10s.

[0058] Figure 9 The influence trend of different sampling port temperatures on the main peak is shown. From Figure 9It can be seen that the response values ​​of the three main peaks of eucalyptus oil increase significantly with the increase of the sampling port temperature. The response of the three main peaks of eucalyptus oil is the highest when the sampling port temperature is 200℃, so the optimal sampling port temperature can be selected as 200℃.

[0059] Temperature selection for the six-way valve of a surface acoustic wave gas chromatograph Under the initial conditions of GC-SAW, the sampling port temperature was set to 200℃. The six-way valve temperature was varied. Since the six-way valve's limiting temperature is 200℃, to protect the instrument's lifespan, the six-way valve temperature was set to 190℃, 180℃, 170℃, 160℃, and 150℃ for headspace sampling of eucalyptus oil. Five 10µL eucalyptus oil samples were added to 22.4mL headspace reagent bottles, sealed, and equilibrated at 40℃ for 10 min before direct headspace testing to select the appropriate six-way valve temperature. Other detection conditions were as follows: the chromatographic column was a DB-5 (1m × 0.25mm × 0.25µm), with an initial temperature of 45℃, and the column temperature was increased to 180℃ according to a temperature ramp program of 12℃ / s; the detector detection temperature was 85℃, and the detector baking temperature was 150℃; the pump aspiration time was 10s.

[0060] Figure 10 The influence trend of different six-way valve temperatures on the main peak of eucalyptus oil is shown. From Figure 10 It can be seen that the response value of the main peak of eucalyptus oil increases significantly with the increase of the six-way valve temperature. When the six-way valve temperature is 180℃, the response values ​​of each peak have basically stabilized, and the main peak with a retention index of 1210 decreases after 180℃. Therefore, the optimal temperature for the six-way valve can be selected as 180℃.

[0061] Selection of carrier gas flow rate for surface acoustic wave gas chromatograph Under the initial conditions of GC-SAW, the carrier gas flow rate of the chromatographic column was changed, and the carrier gas flow rate was set to 3 mL·min. -1 4 mL·min -1 and 5 mL·min -1 Three 10µL eucalyptus oil samples were added to 22.4mL headspace reagent bottles, sealed, and equilibrated at 40℃ for 10 min before headspace testing to select an appropriate carrier gas flow rate. Other detection conditions were as follows: DB-5 column (1m×0.25mm×0.25µm), initial temperature 45℃, with the column temperature increased to 180℃ using a temperature ramp program of 12℃ / s; detector detection temperature 85℃, detector baking temperature 150℃; pump aspiration time 10s.

[0062] Figure 11 The effect of different carrier gas flow rates on the main peak is shown, where, Figure 11 In this context, 'a' represents a carrier gas flow rate of 3 mL / min. -1The main peak diagram of eucalyptus oil at that time. Figure 8 In this context, 'b' represents a carrier gas flow rate of 4 mL / min. -1 The main peak diagram of eucalyptus oil at that time. Figure 8 In this context, 'c' represents the carrier gas flow rate of 5 mL / min. -1 The main peak diagram of eucalyptus oil at that time. From Figure 11 It can be seen that when the carrier gas flow rate is 4 mL / min, the separation effect and response of the three main peaks with retention indices of 1027, 1093 and 1210 are good. Therefore, a carrier gas flow rate of 4 mL / min can be selected.

[0063] Therefore, preferably, after equilibrating the sample at 40°C for 10 minutes for headspace injection, the head gas is extracted to the sampling port of the surface acoustic wave gas chromatograph, and the sampling pump is started to draw the sample into the pre-concentration tube through the sampling port at 200°C as described above. Then, the six-way valve is switched as described above to allow the carrier gas to flow through the pre-concentration tube, carrying the sample in the pre-concentration tube sequentially into the chromatographic column and detector to complete the detection. The temperature of the six-way valve can be 180°C, and the carrier gas flow rate can be 4 mL / min.

[0064] To evaluate the accuracy and repeatability of the method according to the present invention, intraday precision and interday repeatability were evaluated.

[0065] Under the above optimal conditions, six parallel headspace sampling tests were performed, and the response values ​​of the three peaks at 1027, 1093, and 1210 were recorded to calculate the intraday precision (RSD). The results are shown in Table 1.

[0066] Table 1. Precision data of retention indices 1027, 1093, and 1210 peaks in eucalyptus oil samples (n=6)

[0067] As shown in Table 1, the intra-day RSD of the response values ​​of the three main peaks in six measurements ranged from 3.85% to 6.36%. The data clearly indicate that the main peak with a retention index of 1027 exhibited good precision, with an RSD value within 3.85%. Compounds with higher retention indices (i.e., lower boiling points) generally showed good precision. The RSD values ​​of the main peaks with retention indices of 1093 and 1210 were 6.13% and 6.36%, respectively, with compounds with lower retention indices (i.e., higher boiling points) showing slightly higher precision RSD values.

[0068] Under the above optimal conditions, headspace sampling tests were conducted for 6 consecutive days, and the response values ​​of the three main peaks (1027, 1093, and 1210) were recorded to calculate the daytime repeatability. The results are shown in Table 2.

[0069] Table 2. Repeatability data of retention indices 1027, 1093, and 1210 peaks in eucalyptus oil samples (n=6)

[0070] As can be seen from Table 2, the RSD values ​​of the three peaks are 3.63%, 8.25%, and 5.67%, respectively, which indicates that the method according to the present invention has good reproducibility.

[0071] In summary, the method according to the present invention has good precision and good repeatability, and can be used to establish a standard fingerprint spectrum for eucalyptus oil.

[0072] After establishing the standard fingerprint spectrum, at least one of principal component analysis (PCA) and similarity evaluation was used to analyze the fingerprint data of different batches of eucalyptus oil samples and optionally diluted eucalyptus oil samples to determine the quality stability of different batches of eucalyptus oil samples and diluted eucalyptus oil samples.

[0073] As an example, different batches of eucalyptus oil purchased from Shanghai Maclean Biochemical Technology Co., Ltd. were numbered A1 to A6. 1 mL of eucalyptus oil was taken and diluted 10-fold and 20-fold with anhydrous ethanol (AR, Supelco), and these were numbered AX1 and AX2, respectively. Then, under the aforementioned optimal detection conditions, six batches of eucalyptus oil samples and two diluted eucalyptus oil samples were tested. The obtained fingerprint data are shown below. Figure 12 As shown in the image.

[0074] from Figure 12 It can be seen that the main components of eucalyptus oil can achieve rapid peak elution within 15 seconds, and the separation of each characteristic peak is good, enabling the acquisition of fingerprint spectral data. Furthermore, there are significant differences in the response values ​​of each characteristic peak among different batches and diluted samples. The characteristic peaks 1370 and 1410 of the two diluted samples AX1 and AX2 showed no response, indicating that quality fluctuations can be well detected.

[0075] In embodiments of the present invention, in order to better determine the quality stability of different batches of eucalyptus oil samples and diluted eucalyptus oil samples, at least one of principal component analysis and similarity evaluation can be used for further analysis.

[0076] When using principal component analysis, firstly, select characteristic peaks with larger and more stable peak intensity responses from the obtained chromatograms as reference peaks. For example, select characteristic peaks with retention indices of 1027, 1093, and 1210 from the standard fingerprint spectrum as reference peaks.

[0077] Then, the spectral matrix with the response values ​​of the characteristic peaks of retention indices 1027, 1093, and 1210 as variables is transformed into a score matrix with principal components PC1 and PC2 as variables, to obtain scatter plots of different batches of eucalyptus oil samples and selectively diluted eucalyptus oil samples. For example, reference peak data can be entered into Origin 2024b software, and principal component analysis can be used to analyze the data to obtain scatter plots of different batches of eucalyptus oil samples and selectively diluted eucalyptus oil samples (e.g., ...). Figure 13 (As shown in the image).

[0078] The presence of quality fluctuations in different batches of eucalyptus oil samples is determined by the concentration of eucalyptus oil samples and, optionally, diluted eucalyptus oil samples relative to each other on a scatter plot. For example, from... Figure 13 It can be seen that the variance contribution rate of principal component PC1 is 97.2%, and that of principal component PC2 is 2.1%. The cumulative variance contribution rate of the two principal components is 99.3%, which is greater than 80%, indicating that PCA analysis can transform the eucalyptus oil spectral matrix with the response values ​​of the three characteristic peaks 1027, 1093, and 1210 as variables into a score matrix with principal components PC1 and PC2 as variables, while retaining 99.3% of the information in the eucalyptus oil spectral matrix. Furthermore, the more similar the sample components, the closer they are in the scatter plot. In the scatter plot, except for A5, the other batches are relatively concentrated, indicating that the quality of the other five batches of eucalyptus oil samples is relatively stable, while A5 is far from the other five batches, indicating that its quality fluctuates. In addition, it can be clearly seen from the scatter plot that the landing points of diluted samples AX1 and AX2 are significantly separated from the six different batches of samples. The results of principal component analysis show that the method according to the present invention can distinguish the stability of different batches of samples and diluted samples.

[0079] The basic attributes of fingerprint spectra are wholeness and ambiguity. An effective method for evaluating this wholeness and ambiguity is similarity evaluation. Similarity evaluation focuses on the analysis of macroscopic patterns and the overall identification of the spectra. Therefore, this invention also uses similarity evaluation (e.g., at least one of Euclidean distance ratio, cosine of the included angle, and correlation coefficient) to evaluate the similarity between samples.

[0080] Specifically, when using similarity evaluation for analysis, a standard eucalyptus oil sample from different batches is determined as the standard sample based on a standard fingerprint spectrum (for example, in this invention, sample A1 is designated as the standard sample). In embodiments of this invention, the standard sample can be determined based on the magnitude of the response values ​​of the characteristic peaks corresponding to the three characteristic peaks of retention indices 1027, 1093, and 1210 in the standard fingerprint spectrum from different batches of eucalyptus oil samples, as well as the peak shapes of the characteristic peaks corresponding to the three characteristic peaks of retention indices 1027, 1093, and 1210 in the standard fingerprint spectrum.

[0081] Then, a similarity evaluation was used to compare other eucalyptus oil samples from different batches of eucalyptus oil samples, as well as optionally diluted eucalyptus oil samples, with the standard sample to determine the similarity differences between the other eucalyptus oil samples from different batches of eucalyptus oil samples and optionally diluted eucalyptus oil samples and the standard sample. The evaluation results are shown in Table 3.

[0082] The formula for calculating the Euclidean distance ratio is: in, d The ratio of Euclidean distances. x i Let be the response value of the i-th characteristic peak in the sample to be tested. i =1, 2, 3, ..., n; y i is the response value of the i-th characteristic peak in the standard sample.

[0083] The formula for calculating the included angle using the cosine method is as follows: in, C The cosine of the included angle X i Let be the response value of the i-th characteristic peak of the sample to be tested; Y i is the response value of the i-th characteristic peak of the standard sample.

[0084] The formula for calculating the correlation coefficient is as follows: in, S The correlation coefficient; x i Let be the response value of the i-th characteristic peak of the sample to be tested; y i is the response value of the i-th characteristic peak in the standard sample; is the average response value of the i-th characteristic peak in the test sample; is the average response value of the i-th characteristic peak in the standard sample.

[0085] Table 3 Similarity evaluation results

[0086] As shown in Table 3, the similarity of samples A1 to A6 calculated by the Euclidean distance ratio method is 0.9853 to 1.0924, which determines the acceptable range of the samples. The similarity of samples A1 to A6 calculated by the cosine similarity method is 0.9997 to 0.9999, which determines the acceptable range of the samples. The similarity of samples A1 to A6 calculated by the correlation coefficient method is 0.9996 to 0.9999, which determines the acceptable range of the samples. The results calculated by the Euclidean distance ratio method, the cosine of the included angle method, and the correlation coefficient method in Table 3 show that the similarity between batch A5 and the standard sample is greater than that of other batches. The similarity between diluted samples AX1 and AX2 and the standard sample is also significantly different. The similarity change trends calculated by the three methods are consistent, and all three methods can be used to determine that the quality of batch A5 fluctuates. Diluted samples AX1 and AX2 are unqualified samples, which is consistent with the results of principal component analysis.

[0087] In summary, this invention conducts an exploratory study on the quality detection method of different batches of eucalyptus oil flavoring based on surface acoustic wave gas chromatography-mass spectrometry (GC-SAW). The headspace testing conditions for eucalyptus oil were optimized, and key factors such as equilibrium temperature, equilibrium time, sampling port temperature, six-way valve temperature, and carrier gas flow rate of the chromatographic column were investigated. The optimal conditions for GC-SAW detection of eucalyptus oil were determined as follows: carrier gas flow rate of 4 mL / min; sampling port temperature of 200℃; six-way valve temperature of 180℃; equilibrium temperature of 40℃; and equilibrium time of 10 min. This method is simple, rapid, efficient, accurate, and has good repeatability.

[0088] Under optimal GC-SAW conditions, the main volatile components of 6 different batches and 2 diluted samples of eucalyptus oil were rapidly analyzed and detected. The retention index was used to qualitatively identify the volatile components in eucalyptus oil.

[0089] Principal component analysis (PCA) was performed on different batches of samples and diluted samples, and the resulting scatter plots successfully distinguished the diluted samples. Similarity calculations using the Euclidean distance ratio method, the cosine similarity method, and the correlation coefficient method all reflected the differences in the main characteristic peaks of the samples, and the three methods showed the same trend.

[0090] This invention has potential application value, providing an experimental basis for the quality control of eucalyptus oil. It can also be applied to the quality testing of flavored eucalyptus oil between different batches, and can provide a new approach for the intrinsic quality control of flavored eucalyptus oil.

[0091] While the invention has been specifically shown and described with reference to exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the claims and their equivalents. The embodiments should be considered only in a descriptive sense and not for limiting purposes. Therefore, the scope of the invention is not defined by the specific embodiments thereof, but by the claims, and all differences within that scope will be construed as included in the invention.

Claims

1. A method for detecting the quality stability of eucalyptus oil, the method comprising the following steps: (a) Surface acoustic wave gas chromatographs were used to detect different batches of eucalyptus oil samples to obtain fingerprint data of each chromatographic peak of different batches of eucalyptus oil samples. The surface acoustic wave gas chromatograph included a sampling port, a sampling pump, a pre-concentration tube, a six-way valve, a carrier gas bottle, a chromatographic column, a detector and a data processing device. (b) To establish a standard fingerprint spectrum for eucalyptus oil based on fingerprint data from different batches of eucalyptus oil samples; and (c) Using at least one of principal component analysis and similarity assessment based on standard fingerprint spectroscopy, analyze the fingerprint data of different batches of eucalyptus oil samples to determine the quality stability of different batches of eucalyptus oil samples. In step (a), the detection is performed according to the following steps: Eucalyptus oil samples were equilibrated at 25°C to 45°C for 5 to 25 minutes before headspace injection. Start the sampling pump to draw the eucalyptus oil sample into the pre-concentration tube through a sampling port with a temperature of 160°C to 200°C; Switching the six-way valve allows the carrier gas to flow through the pre-concentration tube, carrying the eucalyptus oil sample from the pre-concentration tube sequentially into the chromatographic column and detector to complete the detection. The temperature of the six-way valve is set to 150℃ to 190℃, and the carrier gas flow rate of the chromatographic column is 3 mL / min to 5 mL / min. In step (a), the detection is performed as follows: the sample is equilibrated at 40°C for 10 min for headspace injection; the sampling pump is started to draw the eucalyptus oil sample into the pre-concentration tube through a sampling port at 200°C; the six-way valve is switched to allow the carrier gas to flow through the pre-concentration tube, carrying the eucalyptus oil sample in the pre-concentration tube into the chromatographic column and detector sequentially to complete the detection. The temperature of the six-way valve is 180°C, and the carrier gas flow rate of the chromatographic column is 4 mL / min. The detection conditions for the chromatographic column are as follows: the initial temperature of the column is 45℃, and the temperature is increased to 180℃ according to a temperature ramping program of 12℃ / s. The detection conditions for the detector are as follows: the detection temperature of the detector is 85℃, and the detector baking temperature is 150℃. The method further includes: before performing step (a), detecting the n-alkane standard solution using a surface acoustic wave gas chromatograph to obtain a chromatogram of the n-alkane standard solution; calibrating each chromatographic peak of the fingerprint data using the chromatogram of the n-alkane standard solution to obtain each chromatographic peak in the form of a retention index; wherein the n-alkane in the n-alkane standard solution is n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecanane, n-hexadecane, n-heptadecane, and n-octadecane. The steps for establishing a standard fingerprint spectrum for eucalyptus oil include: determining the common chromatographic peaks of eucalyptus oil samples based on fingerprint data from different batches; identifying the common chromatographic peaks as characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 based on the response values ​​of the common chromatographic peaks in the form of retention indices, thereby establishing a standard fingerprint spectrum for eucalyptus oil. Among them, the characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 were assigned to eucalyptol, p-cymene or limonene, myrtol or verbenaenool, carvacrol, β-boronene, and β-caryophyllene, respectively.

2. A method for detecting the quality stability of eucalyptus oil, the method comprising the following steps: (a) Surface acoustic wave gas chromatographs were used to detect different batches of eucalyptus oil samples to obtain fingerprint data of each chromatographic peak of different batches of eucalyptus oil samples. The surface acoustic wave gas chromatograph included a sampling port, a sampling pump, a pre-concentration tube, a six-way valve, a carrier gas bottle, a chromatographic column, a detector and a data processing device. (b) Establish a standard fingerprint spectrum for eucalyptus oil based on fingerprint data from different batches of eucalyptus oil samples; (c) Surface acoustic wave gas chromatography was used to analyze diluted eucalyptus oil samples to obtain fingerprint data of each chromatographic peak; and (d) Using at least one of principal component analysis and similarity evaluation based on standard fingerprint spectral data, analyze the fingerprint spectral data of different batches of eucalyptus oil samples and diluted eucalyptus oil samples to determine the quality stability of different batches of eucalyptus oil samples and diluted eucalyptus oil samples. In steps (a) and (c), the detection is performed according to the following steps: Eucalyptus oil samples and diluted eucalyptus oil samples were equilibrated at 25℃ to 45℃ for 5 min to 25 min respectively before headspace injection. The sampling pump is started to draw the eucalyptus oil sample and the diluted eucalyptus oil sample into the pre-concentration tube through the sampling port at a temperature of 160°C to 200°C. Switching the six-way valve allows the carrier gas to flow through the pre-concentration tube, carrying the eucalyptus oil sample and the diluted eucalyptus oil sample sequentially into the chromatographic column and detector to complete the detection. The temperature of the six-way valve is 150℃ to 190℃, and the carrier gas flow rate of the chromatographic column is 3 mL / min to 5 mL / min. In step (a), the detection is performed as follows: the sample is equilibrated at 40°C for 10 min for headspace injection; the sampling pump is started to draw the eucalyptus oil sample into the pre-concentration tube through a sampling port at 200°C; the six-way valve is switched to allow the carrier gas to flow through the pre-concentration tube, carrying the eucalyptus oil sample in the pre-concentration tube into the chromatographic column and detector sequentially to complete the detection. The temperature of the six-way valve is 180°C, and the carrier gas flow rate of the chromatographic column is 4 mL / min. The detection conditions for the chromatographic column are as follows: the initial temperature of the column is 45℃, and the temperature is increased to 180℃ according to a temperature ramping program of 12℃ / s. The detection conditions for the detector are as follows: the detection temperature of the detector is 85℃, and the detector baking temperature is 150℃. The method further includes: before performing step (a), detecting the n-alkane standard solution using a surface acoustic wave gas chromatograph to obtain a chromatogram of the n-alkane standard solution; calibrating each chromatographic peak of the fingerprint data using the chromatogram of the n-alkane standard solution to obtain each chromatographic peak in the form of a retention index; wherein the n-alkane in the n-alkane standard solution is n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecanane, n-hexadecane, n-heptadecane, and n-octadecane. The steps for establishing a standard fingerprint spectrum for eucalyptus oil include: determining the common chromatographic peaks of eucalyptus oil samples based on fingerprint data from different batches; identifying the common chromatographic peaks as characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 based on the response values ​​of the common chromatographic peaks in the form of retention indices, thereby establishing a standard fingerprint spectrum for eucalyptus oil. Among them, the characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 were assigned to eucalyptol, p-cymene or limonene, myrtol or verbenaenool, carvacrol, β-boronene, and β-caryophyllene, respectively.

3. The method according to claim 1 or 2, wherein, In the steps of using principal component analysis, The characteristic peaks with retention indices of 1027, 1093, and 1210 in the standard fingerprint spectrum were selected as reference peaks. The spectral matrix, with the response values ​​of the characteristic peaks at retention indices of 1027, 1093, and 1210 as variables, was transformed into a score matrix with principal components PC1 and PC2 as variables, to obtain scatter plots of eucalyptus oil samples from different batches. The concentration of eucalyptus oil samples among different batches can be used to determine whether there are quality fluctuations in eucalyptus oil samples. Alternatively, the concentration of eucalyptus oil samples and diluted eucalyptus oil samples among different batches can be used to determine whether there are quality fluctuations in eucalyptus oil samples and diluted eucalyptus oil samples.

4. The method according to claim 1 or 2, wherein, In the steps of analysis using similarity evaluation, Based on the standard fingerprint spectrum, one eucalyptus oil sample from different batches was selected as the standard sample. Similarity evaluation is used to compare other eucalyptus oil samples from different batches of eucalyptus oil samples with standard samples to determine the similarity differences between other eucalyptus oil samples from different batches of eucalyptus oil samples and standard samples. Alternatively, similarity evaluation is used to compare other eucalyptus oil samples from different batches of eucalyptus oil samples and diluted eucalyptus oil samples with standard samples to determine the similarity differences between other eucalyptus oil samples from different batches of eucalyptus oil samples and diluted eucalyptus oil samples and standard samples.

5. The method according to claim 4, wherein, In the step of determining the standard sample, the standard sample is determined based on the magnitude of the response value of the characteristic peak corresponding to the characteristic peaks with retention indices of 1027, 1093 and 1210 in the standard fingerprint spectrum in different batches of eucalyptus oil samples, as well as the peak shape of the characteristic peaks corresponding to the characteristic peaks with retention indices of 1027, 1093 and 1210 in the standard fingerprint spectrum.

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