Method for detecting quality stability of eucalyptus oil

Abstract

The invention provides a method for detecting quality stability of eucalyptus oil, which comprises the following steps: detecting different batches of eucalyptus oil samples by using a surface acoustic wave gas chromatograph to obtain fingerprint spectrum data of the different batches of eucalyptus oil samples, including each chromatographic peak; establishing a standard fingerprint spectrum of the eucalyptus oil based on the fingerprint spectrum data of different batches of eucalyptus oil samples; and analyzing the fingerprint data of the different batches of eucalyptus oil samples based on the standard fingerprint by using at least one of a principal component analysis method and similarity evaluation so as to determine the quality stability of the different batches of eucalyptus oil samples. According to the method for detecting the quality stability of the eucalyptus oil, different batches of eucalyptus oil samples and optionally diluted eucalyptus oil samples are rapidly detected by using the surface acoustic wave gas chromatography technology, the pretreatment is simple and convenient, the analysis speed is high, the practicability is relatively high, and the detection accuracy is high. And a novel and rapid detection method can be provided for on-site analysis of the quality consistency of the flavors and fragrances.

Description

Technical Field

[0001] The invention belongs to the technical field of natural flavor quality control, and in particular relates to a method for detecting the quality stability of eucalyptus oil. Background Art

[0002] In recent years, natural spices have played a vital role in the fields of food industry and daily chemicals. It can increase the taste and flavor of food, improve consumers' appetite and satisfaction; its aroma can cover up bad odors, optimize the environment, sterilize, etc. Spices, also known as fragrant materials, can be divided into natural spices and artificial spices. More than 3,000 natural spices have been discovered so far, and about 500 have been effectively used. Natural spices are widely distributed in the glandular sacs of plants or animals. Through different extraction methods, different products such as extracts, essential oils, absolute oils, ointments, resins, etc. can be obtained. Natural spices are difficult to match with synthetic spices because of their unique fixative, coordinating effects and unique natural fragrance.

[0003] With the rapid development of the national economy and the diversification of consumer demand, people have higher and higher requirements for the quality and flavor of natural spices. The quality of products from different origins and batches usually fluctuates to a certain extent, so the quality stability of natural spices has received more and more attention.

[0004] At present, in the process of natural flavor quality identification, physical and chemical indicators, olfactory similarity, and sensory efficacy are usually evaluated and analyzed. However, the internal composition of natural flavors is complex, and single components and small amounts of components in the sample cannot fully reflect the quality of the sample, and the subjective influence is relatively large. The commonly used fingerprint detection methods include gas chromatography-mass spectrometry, near-infrared spectroscopy, high-performance liquid chromatography-evaporative light scattering, ion chromatography, etc. The detection instruments of these conventional methods are too large and require complex pre-treatment, which makes the entire detection process more complicated, and the test takes more than 30 minutes, which is difficult to meet the needs of on-site rapid testing. At present, the sample size of the natural flavor market is large, and the ingredients of natural flavors of different varieties, different origins, and different batches are also quite different, and the uses are also different. Therefore, in order to ensure the consistency of the quality of natural flavors, it is of great practical significance to establish a fast, convenient, and accurate on-site detection method for natural flavors. Summary of the invention

[0005] In order to solve at least one of the above problems, the present invention provides a method for detecting the quality stability of natural flavor eucalyptus oil, which can quickly detect the quality stability of different batches of eucalyptus oil and / or eucalyptus oil diluted 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) using a surface acoustic wave gas chromatograph to detect different batches of eucalyptus oil samples to obtain fingerprint spectrum data including each chromatographic peak of the different batches of eucalyptus oil samples, wherein the surface acoustic wave gas chromatograph comprises 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 the different batches of eucalyptus oil samples; and (c) using at least one of principal component analysis and similarity evaluation to compare the different batches of eucalyptus oil samples based on the standard fingerprint spectrum. The fingerprint data of eucalyptus oil samples are analyzed to determine the quality stability of different batches of eucalyptus oil samples, wherein in step (a), the detection is performed according to the following steps: the eucalyptus oil sample is equilibrated at 25°C to 45°C for 5min to 25min for headspace injection; the sampling pump is started to suck the eucalyptus oil sample into the pre-concentration tube through the sampling port with a temperature of 160°C to 200°C; the six-way valve is switched 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 the detector in sequence to complete the detection, wherein the temperature of the six-way valve is 150°C to 190°C, and the carrier gas flow rate of the chromatographic column is 3mL / min to 5mL / 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) using a surface acoustic wave gas chromatograph to detect different batches of eucalyptus oil samples to obtain fingerprint spectrum data of different batches of eucalyptus oil samples including various chromatographic peaks, wherein the surface acoustic wave gas chromatograph comprises 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; (c) using a surface acoustic wave gas chromatograph to detect diluted eucalyptus oil samples to obtain fingerprint spectrum data of different batches of eucalyptus oil diluted samples including various chromatographic peaks; and (d) using at least one of principal component analysis and similarity evaluation to compare different batches of eucalyptus oil samples based on the standard fingerprint spectrum. The fingerprint data of eucalyptus oil samples and diluted eucalyptus oil samples are analyzed to determine the quality stability of different batches of eucalyptus oil samples and diluted eucalyptus oil samples, wherein in step (a) and step (c), the detection is performed according to the following steps: the eucalyptus oil sample and the diluted eucalyptus oil sample are equilibrated at 25°C to 45°C for 5 minutes to 25 minutes for headspace injection; the sampling pump is started to suck the eucalyptus oil sample and the diluted eucalyptus oil sample into the preconcentration tube through the sampling port with a temperature of 160°C to 200°C; the six-way valve is switched to allow the carrier gas to flow through the preconcentration tube, and the eucalyptus oil sample and the diluted eucalyptus oil sample in the preconcentration tube are carried into the chromatographic column and the detector in sequence to complete the detection, wherein the temperature of the six-way valve is 150°C to 190°C, and the carrier gas flow rate of the chromatographic column is 3mL / min to 5mL / min.

[0008] According to an embodiment of the present invention, in step (a), the detection can be performed according to the following steps: equilibrating the sample at 40°C for 10 minutes for headspace sampling; starting the sampling pump to suck the eucalyptus oil sample into the pre-concentrator through the sampling port at a temperature of 200°C; switching the six-way valve to allow the carrier gas to flow through the pre-concentrator and carry the eucalyptus oil sample in the pre-concentrator into the chromatographic column and the 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 heating 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 heating program of 12°C / s, and 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 executing step (a), using a surface acoustic wave gas chromatograph to detect the normal alkane standard solution to obtain a chromatogram of the normal alkane standard solution, and using the chromatogram of the normal alkane standard solution to calibrate each chromatographic peak of the fingerprint data to obtain each chromatographic peak in the form of a retention index, wherein the normal alkane in the normal alkane standard solution is at least one of n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane and n-octadecane.

[0012] According to an embodiment of the present invention, the step of establishing a standard fingerprint of eucalyptus oil may include: determining a common chromatographic peak of eucalyptus oil samples according to fingerprint data of different batches of eucalyptus oil samples; determining the common chromatographic peak as a characteristic peak with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410, respectively, according to the size of the response value of the common chromatographic peak in the form of retention index, thereby establishing a standard fingerprint of eucalyptus oil, wherein the characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 are respectively attributed to eucalyptol, p-cymene or limonene, myrtenol or verbenol, carvacrol, β-bourbonne, and β-caryophyllene.

[0013] According to an embodiment of the present invention, in the step of analyzing using the principal component analysis method, characteristic peaks with retention indexes of 1027, 1093, and 1210 in the standard fingerprint are selected as reference peaks, and the spectrum matrix with the response values ​​of the characteristic peaks with retention indexes of 1027, 1093, and 1210 as variables is converted into a score matrix with principal components PC1 and PC2 as variables to obtain a scatter plot of eucalyptus oil samples from different batches, and determine whether the quality of eucalyptus oil samples from different batches fluctuates according to the concentration degree of eucalyptus oil samples on the scatter plot, or determine whether the quality of eucalyptus oil samples from different batches and eucalyptus oil diluted samples fluctuates according to the concentration degree of eucalyptus oil samples and eucalyptus oil diluted samples on the scatter plot.

[0014] According to an embodiment of the present invention, in the step of analyzing using similarity evaluation, one eucalyptus oil sample among different batches of eucalyptus oil samples is determined as the standard sample according to the standard fingerprint, and the other eucalyptus oil samples among different batches of eucalyptus oil samples are compared with the standard sample using similarity evaluation to determine the similarity difference between the other eucalyptus oil samples among different batches of eucalyptus oil samples and the standard sample, or, the other eucalyptus oil samples among different batches of eucalyptus oil samples and the eucalyptus oil diluted sample are compared with the standard sample using similarity evaluation to determine the similarity difference between the other eucalyptus oil samples among different batches of eucalyptus oil samples and the eucalyptus oil diluted sample 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 according to the size of the response value of the characteristic peak corresponding to the characteristic peak with retention index of 1027, 1093 and 1210 in the standard fingerprint in different batches of eucalyptus oil samples, and the peak shape of the characteristic peak corresponding to the characteristic peak with retention index of 1027, 1093 and 1210 in the standard fingerprint.

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

[0017] According to the method for detecting the quality stability of eucalyptus oil of the present invention, different batches of eucalyptus oil samples and optionally diluted eucalyptus oil samples are quickly detected by using surface acoustic wave gas chromatography technology, and the pretreatment is simple, the analysis speed is fast, and the practicability is strong, and a new and fast detection method can be provided for on-site analysis of the quality consistency of flavors and fragrances. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or other features and aspects of the present invention will become clear and easily understood through the description of examples with reference to the accompanying drawings.

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

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

[0021] Figure 3 It is a structural schematic diagram of a surface acoustic wave gas chromatograph in a detection state.

[0022] Figure 4 and Figure 5 This is the calibration test chromatogram of normal alkane standard solution.

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

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

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

[0026] Fig. 9 This is a trend chart showing the impact of different sampling port temperatures on the main peak of eucalyptus oil.

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

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

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

[0030] Fig.13 This is the principal component analysis scatter plot of 6 different batches of eucalyptus oil samples and 2 eucalyptus oil dilution samples. DETAILED DESCRIPTION

[0031] Embodiments will be described below with reference to the accompanying drawings to explain the present invention. However, the present invention can be implemented in a variety of different forms and should not be construed as being limited to the exemplary embodiments set forth herein. These embodiments are provided so that the disclosure of the present invention will be thorough and complete and will fully convey the scope of the present invention to those skilled in the art.

[0032] Surface acoustic wave gas chromatograph (GC-SAW) is a device developed by using surface acoustic wave sensors based on the principle of surface acoustic wave devices as gas chromatography detectors, and is used to analyze volatile or semi-volatile chemical components. It uses the principle of gas chromatography to separate complex gas components and uses surface acoustic wave sensors to detect components. It can effectively avoid mutual interference between different gas components and realize broad-spectrum (volatile or semi-volatile organic compound) analysis of trace gases. As an acoustic-electric transducer, the surface acoustic wave sensor can be implemented in a very small interdigital transducer with an area of ​​only 12mm. 2 , plus the fast reaction speed, the detector is relatively small. The length of the chromatographic column is only 1m, and the column heating system is used, and the heating rate is fast. In summary, the portable combined detection instrument constructed by combining the gas chromatography method with the surface acoustic wave sensor has the characteristics of small size, fast reaction, and high sensitivity, and has the advantages of both large equipment and rapid detection equipment.

[0033] Since the detection time of surface acoustic wave gas chromatography is shorter and the detection limit is lower, it is more difficult to effectively separate the complex volatile components in natural fragrances and achieve accurate detection in a short time compared to ordinary gas chromatography detection. Therefore, there is no report on the rapid analysis of the stability of natural fragrances based on surface acoustic wave gas chromatography technology. The present invention innovatively proposes a rapid detection of the stability of natural fragrances (eucalyptus oil) based on surface acoustic wave gas chromatography technology.

[0034] Figure 1 This is the principle block diagram of the surface acoustic wave gas chromatograph. Figure 2 It is a structural schematic diagram of a surface acoustic wave gas chromatograph in the injection state. Figure 3 This is a schematic diagram of the structure of the surface acoustic wave gas chromatograph in the detection state. Figures 1 to 3 As shown in FIG, 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. In addition, the surface acoustic wave gas chromatograph can switch between injection and detection.

[0035] like Figure 2 As shown in , when the surface acoustic wave gas chromatograph is in the injection state, the first gas port 41 of the six-way valve 4 is connected to the first gas port 31 of the pre-concentration tube 3, the second gas port 42 of the six-way valve 4 is connected to the carrier gas bottle 5, the third gas port 43 of the six-way valve 4 is connected to the gas inlet of the chromatographic column 6, the fourth gas port 44 of the six-way valve 4 is connected to the second gas port 32 of the pre-concentration tube 3, the fifth gas port 45 of the six-way valve 4 is connected to the sampling pump 2, and the sixth gas port 46 of the six-way valve 4 is connected to the sampling port 1. Through the pressure difference formed 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 injection is completed, the six-way valve 4 can be rotated to switch the surface acoustic wave gas chromatograph to the detection state, such as Figure 2 As shown in . In the detection state, the first gas port 41 of the six-way valve 4 is connected to the second gas port 32 of the pre-concentration tube 3, the second gas port 42 of the six-way valve 4 is connected to the sampling pump 2, the third gas port 43 of the six-way valve 4 is connected to the sampling port 1, the fourth gas port 44 of the six-way valve 4 is connected to the first gas port 31 of the pre-concentration tube 3, the fifth gas port 45 of the six-way valve 4 is connected to the carrier gas bottle 5, and the sixth gas port 46 of the six-way valve 4 is connected to the gas 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 therein. The vaporized sample in the pre-concentration tube 3 can enter the chromatographic column 6 with the carrier gas to complete gas phase separation, and then enter the detector 7 to complete the detection of each gas phase component after sample separation. The data detected by the detector 7 can be sent to the data processing device 8, which processes the data and presents it to the detection 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 comprises the following steps: obtaining fingerprint data including each chromatographic peak of different batches of eucalyptus oil samples and optionally fingerprint data including each chromatographic peak of diluted eucalyptus oil samples; establishing a standard fingerprint of eucalyptus oil based on the fingerprint data of different batches of eucalyptus oil samples; and using at least one of principal component analysis and similarity evaluation to analyze the fingerprint data of different batches of eucalyptus oil samples and optionally the fingerprint data of diluted eucalyptus oil samples based on the standard fingerprint to determine the quality stability of different batches of eucalyptus oil samples and optionally the diluted eucalyptus oil samples.

[0040] In the embodiment of the present invention, the retention index is used to qualitatively characterize the eucalyptus oil. Therefore, before using the surface acoustic wave gas chromatograph to test the sample, each time the parameters such as the chromatographic column carrier gas flow rate, the sampling port temperature, the six-way valve temperature, the sample equilibrium temperature and the equilibrium time are modified, it is necessary to use the normal alkane standard solution for calibration, so as to use the chromatogram of the normal alkane standard solution to calibrate each chromatographic peak, thereby obtaining each chromatographic peak in the form of a retention index. Using the retention index to qualitatively characterize the eucalyptus oil can effectively avoid errors caused by operating factors and differences in experimental conditions.

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

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

[0043] Under the initial detection conditions of GC-SAW, the detector temperature was changed to 60 ° C. The normal alkane standard solution was used for calibration. The retention time of each normal alkane standard solution peak was recorded after each test. The retention index of each chromatographic peak of eucalyptus oil was calculated by calibration with normal alkane, and the Kovats retention index (RI) formula was used for calculation.

[0044] The Kovats retention index formula 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 contained in the previous n-alkane before the target compound is eluted, tRu is the retention time of the target compound, tRn and tR(n+1) are the retention times of the adjacent n-alkane, and tRn <tRu<tR(n+1)。

[0045] Figure 4 and Figure 5 The chromatogram of the normal alkane standard solution tested by GC-SAW is shown, wherein: Figure 4 Shown by retention time, Figure 5 Shown as retention index. The standard solution of normal alkanes contains 13 components from normal hexane (C6) to normal octadecane (C18), so 13 chromatographic characteristic peaks are detected in the chromatogram accordingly, and all characteristic peaks are detected within 10 seconds. The retention index of normal alkanes is defined as the carbon number multiplied by 100. Specifically, the retention index of normal hexane is 600, the retention index of normal heptane is 700, and the retention index of the last characteristic peak, normal octadecane, is 1800. The retention index of subsequent chromatographic peaks is directly given by the analytical data software that comes with the instrument based on the calibration results of normal alkanes and the retention time of the characteristic peaks of each component. According to the relevant theory of gas chromatography, under the same chromatographic conditions, the retention index of the same substance does not change with changes in equipment, test personnel and other external conditions, so it has relatively good stability and reliability for the qualitative identification of unknown substances.

[0046] After calibration with a normal alkane standard solution, different batches of eucalyptus oil samples and optionally (i.e., optionally) eucalyptus oil diluted samples can be detected using a surface acoustic wave gas chromatograph to obtain fingerprint data including each chromatographic peak of different batches of eucalyptus oil samples and optionally eucalyptus oil diluted samples. Specifically, different batches of eucalyptus oil samples and optionally eucalyptus oil diluted samples are added to a headspace reagent bottle, sealed and stored, and different batches of eucalyptus oil samples and optionally eucalyptus oil diluted samples are balanced at 25°C to 45°C (preferably, 25°C to 40°C) for 5min to 25min (preferably, 5min to 10min), and then the top gas is extracted at the sampling port of the surface acoustic wave gas chromatograph, and the sampling pump is started to suck different batches of eucalyptus oil samples and optionally eucalyptus oil diluted samples into the pre-concentration tube through the sampling port at a temperature of 160°C to 200°C in the manner described above. Afterwards, the six-way valve is switched as described above so that the carrier gas flows through the pre-concentration tube and carries the sample in the pre-concentration tube into the chromatographic column and the detector in sequence to complete the detection, wherein 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 3mL / min to 5mL / min.

[0047] In addition, the detection conditions of the chromatographic column are as follows: the chromatographic column can be DB-5 (1m×0.25mm×0.25µm), the initial temperature of the chromatographic column can be 40°C to 50°C, and the temperature of the chromatographic column is raised to 170°C to 180°C according to a temperature increase program of 6°C / s to 12°C / s, and the carrier gas can be nitrogen. 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. Here, the detection temperature of the detector refers to the temperature of the detector when analyzing the sample, and the baking temperature of the detector refers to the temperature when the detector is cleaned after the analysis of the sample is completed, also known as the aging temperature or the cleaning temperature. As another preferred example, chromatographic detection can be performed under the following conditions: the chromatographic column is DB-5 (1m×0.25mm×0.25µm), the initial temperature is 45°C, and the temperature of the chromatographic column is raised to 180°C according to a temperature increase program of 12°C / s; the detection temperature of the detector is 85°C, and the baking temperature of the detector is 150°C. In addition, the pumping time can be controlled to 10s; the analysis time can be controlled to 20s.

[0048] After obtaining the fingerprint data of different batches of eucalyptus oil samples, the standard fingerprint of eucalyptus oil is established based on the fingerprint data of different batches of eucalyptus oil samples. The similarity of complex samples analyzed by fingerprint is to find the chromatographic pattern of common components in the sample chromatogram. The chromatographic peaks appearing in the sample chromatogram can be regarded as "common peaks". The fingerprint of the same sample can be established with good repeatability under the same operation.

[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, Figure 6 As shown in the figure, the main components of eucalyptus oil can be quickly eluted within 15 seconds, and the separation effect of each chromatographic peak is good. The volatile components in eucalyptus oil contain 10 groups of common characteristic peaks.

[0050] Next, according to the response values ​​(specifically, peak intensities) of the common chromatographic peaks in the form of retention indices, the common chromatographic peaks were determined as characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410, respectively (corresponding to Figure 6 The characteristic peaks numbered 1 to 6 in the above analysis were used to establish the standard fingerprint of eucalyptus oil.

[0051] According to the relevant literature on GC-MS detection of eucalyptus oil and the NIST spectral library, the six groups of characteristic peaks were attributed, and the characteristic peak with retention index 1027 was attributed to eucalyptol, the characteristic peak with retention index 1093 was attributed to cymene or limonene, the characteristic peak with retention index 1210 was attributed to myrtenol or verbenol, the characteristic peak with retention index 1305 was attributed to carvacrol, the characteristic peak with retention index 1370 was attributed to β-bourbonne, and the characteristic peak with retention index 1410 was attributed to β-caryophyllene. In the subsequent investigation, the three characteristic main peaks with retention indexes 1027, 1093, and 1210 were used as experimental objects to optimize the instrument conditions.

[0052] In order to better establish the standard fingerprint of eucalyptus oil, the parameters of headspace sampling and detection conditions are optimized to obtain the best experimental conditions for detecting eucalyptus oil.

[0053] Selection of equilibrium temperature in headspace injection Take 3 10µL eucalyptus oil samples and add them to 22.4mL headspace reagent bottles, seal and store, place in a thermostat, set the equilibrium temperature to 25℃, 30℃, 35℃, 40℃ and 45℃, the equilibrium time is 10min, and directly perform headspace test to select the appropriate equilibrium temperature. Among them, the other conditions of the test are as follows: the chromatographic column is DB-5 (1m×0.25mm×0.25µm), the initial temperature is 45℃, and the temperature of the chromatographic column is raised to 180℃ according to the heating program of 12℃ / s; the detection temperature of the detector is 85℃, and the baking temperature of the detector is 150℃; the pumping time is 10s.

[0054] Figure 7 The influence trend of different equilibrium temperatures on the main peak of eucalyptus oil is shown. Figure 7It can be seen that with the increase of equilibrium temperature, the response value of the main peak with retention index 1210 increases slightly, and the response values ​​of the main peak with retention index 1027 and the main peak with retention index 1093 increase significantly. However, when the equilibrium temperature is 45°C, the response value of the main peak with retention index 1027 is as high as 17241 kCts·s -1 , the detector is saturated, which will affect the sensitivity of the detector. Therefore, according to the experimental results, the best equilibrium temperature can be selected as 40℃.

[0055] Selection of equilibration time in headspace injection Take three 10µL eucalyptus oil samples and add them to a 22.4mL headspace reagent bottle, seal and store, and at 40℃, select 5min, 10min, 15min, 20min and 25min for equilibrium time, and directly test the headspace to select the appropriate equilibrium time. Among them, the other conditions of the test are as follows: the chromatographic column is DB-5 (1m×0.25mm×0.25µm), the initial temperature is 45℃, and the temperature of the chromatographic column is raised to 180℃ according to the heating program of 12℃ / s; the detection temperature of the detector is 85℃, and the baking temperature of the detector is 150℃; the pumping time is 10s.

[0056] Figure 8 The influence trend of different equilibrium times on the main peak is shown. Figure 8 It can be seen that with the increase of equilibrium time, the response values ​​of the main peaks with retention index 1027, 1093 and 1210 increased significantly between 5 min and 10 min. After 10 min, the response values ​​of the three main peaks tended to be stable. Considering the rapid detection, the optimal equilibrium time can be selected as 10 min.

[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 and set to 200℃, 190℃, 180℃, 170℃ and 160℃ respectively to perform headspace injection test on eucalyptus oil samples. Take 5 portions of 10µL eucalyptus oil samples and add them to 22.4mL headspace reagent bottles, seal and store them. After equilibration at 40℃ for 10min, headspace test was performed directly to select the appropriate sampling port temperature. Among them, the other conditions of the test are as follows: the chromatographic column is DB-5 (1m×0.25mm×0.25µm), the initial temperature is 45℃, and the temperature of the chromatographic column is raised to 180℃ according to the heating program of 12℃ / s; the detection temperature of the detector is 85℃, and the baking temperature of the detector is 150℃; the pumping time is 10s.

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

[0059] Selection of Six-way Valve Temperature for Surface Acoustic Wave Gas Chromatograph Under the initial conditions of GC-SAW, the sampling port temperature was selected as 200℃, and the temperature of the six-way valve was changed. Since the limit temperature of the six-way valve was 200℃, in order to protect the life of the instrument, the six-way valve temperature was set to 190℃, 180℃, 170℃, 160℃, and 150℃ to test the headspace injection of eucalyptus oil. Take 5 10µL eucalyptus oil samples and add them to a 22.4mL headspace reagent bottle, seal and store them. After balancing at 40℃ for 10min, directly perform headspace testing to select the appropriate six-way valve temperature. Among them, the other conditions of the test are as follows: the chromatographic column is DB-5 (1m×0.25mm×0.25µm), the initial temperature is 45℃, and the temperature of the chromatographic column is raised to 180℃ according to the heating program of 12℃ / s; the detection temperature of the detector is 85℃, and the baking temperature of the detector is 150℃; the pumping time is 10s.

[0060] Fig.10 The influence trend of different six-way valve temperatures on the main peak of eucalyptus oil is shown. Fig.10 It can be seen that with the increase of the six-way valve temperature, the response value of the main peak of eucalyptus oil increased significantly. When the six-way valve temperature was 180℃, the response values ​​of each peak had basically stabilized, and the main peak with a retention index of 1210 decreased after 180℃, so the optimal temperature of the six-way valve could be selected as 180℃.

[0061] Selection of Carrier Gas Flow Rate in Surface Acoustic Wave Gas Chromatography 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 、4mL·min -1 and 5 mL min -1 , take 3 10µL eucalyptus oil samples and add them to 22.4mL headspace reagent bottles, seal and store, balance at 40℃ for 10min, and then perform headspace test to select the appropriate carrier gas flow rate. Among them, the other test conditions are as follows: the chromatographic column is DB-5 (1m×0.25mm×0.25µm), the initial temperature is 45℃, and the temperature of the chromatographic column is raised to 180℃ according to the heating program of 12℃ / s; the detection temperature of the detector is 85℃, and the baking temperature of the detector is 150℃; the pumping time is 10s.

[0062] Fig.11 The effect of different carrier gas flow rates on the main peak is shown, where Fig.11 a in the equation is the carrier gas flow rate of 3 mL min -1The main peak diagram of eucalyptus oil at Figure 8 b in the figure is the carrier gas flow rate of 4 mL min -1 The main peak diagram of eucalyptus oil at Figure 8 c is the carrier gas flow rate of 5 mL min -1 The main peak diagram of eucalyptus oil. Fig.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 indexes 1027, 1093 and 1210 are good, so the carrier gas flow rate can be selected as 4 mL / min.

[0063] Therefore, preferably, after the sample is balanced at 40°C for 10 minutes for headspace sampling, the top gas is extracted at the sampling port of the surface acoustic wave gas chromatograph, and the sampling pump is started to suck the sample into the pre-concentration tube through the sampling port at a temperature of 200°C in the manner described above. Afterwards, the six-way valve is switched in the manner described above so that the carrier gas flows through the pre-concentration tube, and the sample in the pre-concentration tube is carried into the chromatographic column and the detector in sequence to complete the detection, wherein the temperature of the six-way valve can be 180°C, and the flow rate of the carrier gas can be 4mL / min.

[0064] In order to evaluate the accuracy and repeatability of the method according to the present invention, the intra-day precision and inter-day repeatability were evaluated.

[0065] Under the above optimal conditions, headspace injection was performed in parallel for 6 times, and the response values ​​of the three peaks of 1027, 1093, and 1210 were recorded to calculate the intra-day precision (RSD). The results are shown in Table 1.

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

[0067] As can be seen from Table 1, the intra-day RSD of the response values ​​of the three main peaks measured six times is 3.85% to 6.36%. It can be clearly seen from the data that the precision of the main peak with a retention index of 1027 is good, with an RSD value within 3.85%, and the precision of the front retention index (i.e., compounds with lower boiling points) is good. The RSD values ​​of the main peaks with retention indexes of 1093 and 1210 are 6.13% and 6.36% respectively, and the precision RSD values ​​of the rear retention index (i.e., compounds with higher boiling points) are slightly higher.

[0068] Under the above optimal conditions, the headspace injection test was carried out for 6 consecutive days, and the response values ​​of the three main peaks of 1027, 1093, and 1210 were recorded to calculate the daily repeatability. The results are shown in Table 2.

[0069] Table 2 Repeatability data of eucalyptus oil sample retention index 1027, 1093, 1210 peaks (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 repeatability.

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

[0072] After the standard fingerprint is established, the fingerprint data of different batches of eucalyptus oil samples and optionally eucalyptus oil diluted samples are analyzed using at least one of the principal component analysis (PCA) method and the similarity evaluation to determine the quality stability of different batches of eucalyptus oil samples and eucalyptus oil diluted samples.

[0073] As an example, different batches of essential eucalyptus oil purchased from Shanghai McLean Biochemical Technology Co., Ltd. were numbered A1 to A6. 1 mL of eucalyptus oil was taken and diluted 10 times and 20 times with anhydrous ethanol (AR, Supelco), and numbered as AX1 and AX2 respectively. Then, 6 batches of eucalyptus oil samples and 2 eucalyptus oil dilution samples were tested under the above optimal detection conditions. The fingerprint data obtained by the test are as follows Fig.12 as shown in .

[0074] from Fig.12 It can be seen that the main components of eucalyptus oil can be quickly eluted within 15 seconds, and the separation effect of each characteristic peak is good, and fingerprint data can be obtained. In addition, there are obvious differences in the response values ​​of each characteristic peak of different batches of samples and diluted samples. The characteristic peaks 1370 and 1410 of the two diluted samples AX1 and AX2 have no response, indicating that the fluctuation of quality can be well detected.

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

[0076] When using the principal component analysis method for analysis, first, select characteristic peaks with larger and more stable peak intensity response values ​​from the obtained chromatogram as reference peaks. For example, select characteristic peaks with retention indices of 1027, 1093, and 1210 in the standard fingerprint as reference peaks.

[0077] Then, the spectrum matrix with the response values ​​of the characteristic peaks of retention indexes 1027, 1093, and 1210 as variables is converted into a score matrix with principal components PC1 and PC2 as variables to obtain scatter plots of different batches of eucalyptus oil samples and optionally eucalyptus oil diluted samples. For example, the reference peak data can be entered into Origin 2024b software, and the data can be analyzed using the principal component analysis method to obtain scatter plots of different batches of eucalyptus oil samples and optionally eucalyptus oil diluted samples (such as Fig.13 ).

[0078] Whether there is a fluctuation in the quality of different batches of eucalyptus oil samples is determined based on the degree of concentration of the eucalyptus oil samples and optionally the eucalyptus oil diluted samples on the scatter plot. Fig.13 It can be seen that the variance contribution of principal component PC1 is 97.2%, and the variance contribution of principal component PC2 is 2.1%. The cumulative variance contribution of two principal components is 99.3%, which is greater than 80%, indicating that the eucalyptus oil atlas matrix with the response values ​​of three characteristic peaks of 1027, 1093 and 1210 as variables can be converted into a score matrix with principal component PC1 and principal component PC2 as variables by PCA analysis, and 99.3% of the information in the eucalyptus oil atlas is retained. In addition, the more similar the sample composition is, the closer the position is on the scatter plot. In the scatter plot, except A5, other batches are relatively concentrated on the scatter plot, indicating that the eucalyptus oil sample quality of other 5 batches is relatively stable, and A5 is far away from other 5 batches, indicating that there is fluctuation in its quality. In addition, it can be clearly seen from the scatter plot that the sample landing points of diluted samples AX1 and AX2 are significantly separated from 6 different batches. The principal component analysis result shows that the stability of different batches of samples and diluted samples can be distinguished according to the method of the present invention.

[0079] The basic properties of fingerprints are integrity and fuzziness, and an effective method to evaluate this integrity and fuzziness is similarity evaluation. Similarity evaluation focuses on the analysis of macroscopic rules and the overall identification of the spectrum. Therefore, the present invention also uses similarity evaluation (for example, at least one of the Euclidean distance ratio, angle cosine and correlation coefficient method) to evaluate the similarity between samples.

[0080] Specifically, when similarity evaluation is used for analysis, one of the eucalyptus oil samples from different batches is determined as the standard sample according to the standard fingerprint (for example, the present invention determines the number A1 as the standard sample). In an embodiment of the present invention, the standard sample can be determined according to the magnitude of the response value of the characteristic peaks corresponding to the three characteristic peaks of retention indexes 1027, 1093 and 1210 in the standard fingerprint in different batches of eucalyptus oil samples, and the peak shape of the characteristic peaks corresponding to the three characteristic peaks of retention indexes 1027, 1093 and 1210 in the standard fingerprint.

[0081] Then, the other eucalyptus oil samples in different batches of eucalyptus oil samples and optionally the eucalyptus oil diluted samples were compared with the standard sample using similarity evaluation to determine the similarity differences of the other eucalyptus oil samples in different batches of eucalyptus oil samples and optionally the eucalyptus oil diluted samples relative to the standard sample. The evaluation results are shown in Table 3.

[0082] The Euclidean distance ratio calculation formula is: in, d is the Euclidean distance ratio, x i is 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 angle cosine method calculation formula is as follows: in, C is the cosine of the angle, X i is 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 calculation formula of the correlation coefficient method is as follows: in, S is the correlation coefficient; x i is 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 value of the response value of the i-th characteristic peak in the sample to be tested; is the average value of the response value of the i-th characteristic peak in the standard sample.

[0085] Table 3 Similarity evaluation results

[0086] As can be seen from Table 3, the Euclidean distance ratio method calculates the similarity of the samples A1 to A6 to be 0.9853 to 1.0924, and the qualified range of the samples to be tested is determined to be 0.9853 to 1.0924; the angle cosine method calculates the similarity of the samples A1 to A6 to be 0.9997 to 0.9999, and the qualified range of the samples to be tested is determined to be 0.9997 to 0.9999; the correlation coefficient method calculates the similarity of the samples A1 to A6 to be 0.9996 to 0.9999, and the qualified range of the samples to be tested is determined to be 0.9996 to 0.9999. From the calculation results of the Euclidean distance ratio method, the angle cosine method, and the correlation coefficient method in Table 3, it can be seen that the similarity between the A5 batch sample and the standard sample is greater than that of other batches, and the similarity between the diluted samples AX1 and AX2 and the standard sample is quite different. The similarity change trends calculated by the three methods are consistent, and it can be judged that the quality of the A5 batch fluctuates. The diluted samples AX1 and AX2 are unqualified samples, which is consistent with the results of the principal component analysis method.

[0087] In summary, the present invention conducts exploratory research on the quality detection method of different batches of eucalyptus oil essence based on surface acoustic wave gas chromatography (GC-SAW), optimizes the headspace test conditions of eucalyptus oil, investigates the main factors such as equilibrium temperature, equilibrium time, sampling port temperature, six-way valve temperature and carrier gas flow rate of the chromatographic column, and determines the optimal conditions for GC-SAW detection of eucalyptus oil: carrier gas flow rate of 4mL / min; sampling port temperature of 200℃; six-way valve temperature of 180℃; equilibrium temperature of 40℃; equilibrium time of 10min. This method is simple, rapid, efficient, accurate and has good repeatability.

[0088] Under the optimal conditions of GC-SAW, the main volatile components of 6 different batches and 2 diluted samples of eucalyptus oil were rapidly analyzed and detected, and the volatile components in eucalyptus oil were qualitatively identified using retention indices.

[0089] By performing principal component analysis (PCA) on samples from different batches and diluted samples, the resulting scatter plot can successfully distinguish the diluted samples. The similarity between different samples was calculated using the Euclidean distance ratio method, the angle cosine method, and the correlation coefficient method, all of which can reflect the differences in the main characteristic peaks of the samples, and the three reflect the same trend.

[0090] The invention has potential application value, provides an experimental basis for the quality control of eucalyptus oil, can also be applied to the quality detection of essential eucalyptus oil between different batches, and can provide a new approach for the intrinsic quality control of essential eucalyptus oil.

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

Claims

1. A method for detecting the quality stability of eucalyptus oil, the method comprising the following steps: (a) using a surface acoustic wave gas chromatograph to detect different batches of eucalyptus oil samples to obtain fingerprint data of different batches of eucalyptus oil samples including each chromatographic peak, wherein the surface acoustic wave gas chromatograph comprises 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 of eucalyptus oil based on the fingerprint data of different batches of eucalyptus oil samples; and (c) using at least one of principal component analysis and similarity evaluation to analyze the fingerprint data of different batches of eucalyptus oil samples based on the standard fingerprint to determine the quality stability of different batches of eucalyptus oil samples, Wherein, in step (a), the detection is performed according to the following steps: The eucalyptus oil sample was equilibrated at 25°C to 45°C for 5 min to 25 min for headspace injection; Start the sampling pump to draw the 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-concentrator and carry the eucalyptus oil sample in the pre-concentrator into the chromatographic column and the detector in sequence to complete the detection, wherein the temperature of the six-way valve is 150°C to 190°C, and the carrier gas flow rate of the chromatographic column is 3mL / min to 5mL / min.

2. A method for detecting the quality stability of eucalyptus oil, the method comprising the following steps: (a) using a surface acoustic wave gas chromatograph to detect different batches of eucalyptus oil samples to obtain fingerprint data of different batches of eucalyptus oil samples including each chromatographic peak, wherein the surface acoustic wave gas chromatograph comprises 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 of eucalyptus oil based on the fingerprint data of different batches of eucalyptus oil samples; (c) using a surface acoustic wave gas chromatograph to detect the diluted eucalyptus oil sample to obtain fingerprint spectrum data of the diluted eucalyptus oil sample including each chromatographic peak; and (d) using at least one of principal component analysis and similarity evaluation to analyze the fingerprint data of different batches of eucalyptus oil samples and eucalyptus oil diluted samples based on the standard fingerprint to determine the quality stability of different batches of eucalyptus oil samples and eucalyptus oil diluted samples, Wherein, in step (a) and step (c), the detection is performed according to the following steps: The eucalyptus oil sample and the eucalyptus oil diluted sample were equilibrated at 25° C. to 45° C. for 5 min to 25 min, respectively, for headspace injection; Start the sampling pump to suck the eucalyptus oil sample and the eucalyptus oil diluted sample into the pre-concentration tube through the 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-concentrator, and carries the eucalyptus oil sample and the eucalyptus oil diluted sample in the pre-concentrator into the chromatographic column and the detector in sequence to complete the detection, wherein the temperature of the six-way valve is 150°C to 190°C, and the carrier gas flow rate of the chromatographic column is 3mL / min to 5mL / min.

3. The method according to claim 1 or 2, wherein: In step (a), perform the test as follows: The samples were equilibrated at 40 °C for 10 min for headspace injection; Start the sampling pump to draw the eucalyptus oil sample into the pre-concentration tube through the sampling port at a temperature of 200°C; The six-way valve was switched to allow the carrier gas to flow through the pre-concentrator tube and carry the eucalyptus oil sample in the pre-concentrator tube into the chromatographic column and the detector in sequence to complete the detection. The temperature of the six-way valve was 180°C and the carrier gas flow rate of the chromatographic column was 4 mL / min.

4. The method according to claim 1 or 2, wherein: The detection conditions of the chromatographic column are 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, and the carrier gas is nitrogen. The detection conditions of the detector are 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.

5. The method according to claim 4, wherein: The detection conditions of the chromatographic column are 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 the heating program of 12°C / s. The detection conditions of the detector are as follows: the detection temperature of the detector is 85°C, and the baking temperature of the detector is 150°C.

6. The method according to claim 1 or 2, further comprising: Before performing step (a), a surface acoustic wave gas chromatograph is used to detect the normal alkane standard solution to obtain a chromatogram of the normal alkane standard solution, and the chromatogram of the normal alkane standard solution is used to calibrate each chromatographic peak of the fingerprint data to obtain each chromatographic peak in the form of a retention index. The normal alkane in the normal alkane standard solution is at least one of n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane and n-octadecane.

7. The method according to claim 6, wherein: The steps to establish the standard fingerprint of eucalyptus oil include: Determine the common chromatographic peaks of eucalyptus oil samples according to the fingerprint data of different batches of eucalyptus oil samples; According to the response values ​​of the common chromatographic peaks in the form of retention indices, the common chromatographic peaks are determined as characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410, respectively, thereby establishing a standard fingerprint of eucalyptus oil. Among them, the characteristic peaks with retention indices of 1027, 1093, 1210, 1305, 1370, and 1410 were attributed to eucalyptol, p-cymene or limonene, myrtenol or verbenol, carvacrol, β-bourbonne, and β-caryophyllene, respectively.

8. The method according to claim 7, wherein: In the steps of using principal component analysis, The characteristic peaks with retention indexes of 1027, 1093, and 1210 in the standard fingerprint were selected as reference peaks. The spectrum matrix with the response values ​​of the characteristic peaks with retention indexes of 1027, 1093, and 1210 as variables is converted into a score matrix with principal components PC1 and PC2 as variables to obtain scatter plots of different batches of eucalyptus oil samples, and Whether the quality of different batches of eucalyptus oil samples fluctuates is determined based on the concentration levels of the eucalyptus oil samples on the scatter plot, or whether the quality of different batches of eucalyptus oil samples and eucalyptus oil diluted samples fluctuates is determined based on the concentration levels of the eucalyptus oil samples and eucalyptus oil diluted samples on the scatter plot.

9. The method according to claim 7, wherein: In the step of analyzing using similarity evaluation, According to the standard fingerprint, one of the eucalyptus oil samples from different batches is determined as the standard sample. The other eucalyptus oil samples in different batches of eucalyptus oil samples are compared with the standard sample using similarity evaluation to determine the similarity difference between the other eucalyptus oil samples in different batches of eucalyptus oil samples and the standard sample, or the other eucalyptus oil samples in different batches of eucalyptus oil samples and the eucalyptus oil diluted sample are compared with the standard sample using similarity evaluation to determine the similarity difference between the other eucalyptus oil samples in different batches of eucalyptus oil samples and the eucalyptus oil diluted sample and the standard sample.

10. The method according to claim 9, wherein: In the step of determining the standard sample, the standard sample is determined according to the response values ​​of the characteristic peaks in different batches of eucalyptus oil samples corresponding to the characteristic peaks with retention indices of 1027, 1093 and 1210 in the standard fingerprint, and the peak shapes of the characteristic peaks corresponding to the characteristic peaks with retention indices of 1027, 1093 and 1210 in the standard fingerprint.

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