Method for analyzing oxygen stable isotope ratio of water in highly alcoholic beverage

Abstract

The invention provides a method for analyzing the oxygen stable isotope ratio of water in a highly alcoholic beverage, and relates to the technical field of oxygen isotope analysis. The analysis method comprises the following steps: selecting at least two water samples with known oxygen isotope ratios and different values as additive water; diluting the same high-alcohol beverage to be detected by adding water to obtain a diluted sample; measuring an oxygen isotope ratio; and according to the oxygen isotope ratio of the added water and the oxygen isotope ratio of the diluted sample, calculating the oxygen isotope ratio of the water in the highly alcoholic beverage to be measured. According to the analysis method, the concentration of ethanol is reduced through dilution, so that interference of isobaric elements is avoided; and physical separation is replaced by mass conservation equation calculation, and a complex distillation device is not needed. According to the method, pretreatment is remarkably simplified, cost and errors are reduced, and rapid and accurate analysis of the water oxygen isotope in the highly alcoholic beverage is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oxygen isotope analysis, and particularly relates to a method for analyzing oxygen stable isotope ratios of water in high-alcohol beverages. BACKGROUND

[0002] In the production process of high-alcohol beverages (such as Chinese liquor, brandy, whiskey, vodka, etc.), water is not only a key raw material but also a necessary medium, which plays a crucial role in fermentation, distillation and the formation of final flavor. With the increasing demand for food safety and authenticity identification, the use of stable isotope technology for origin identification, adulteration detection and water source tracking of liquor products has become an important analysis means in the industry. Generally, the oxygen stable isotope ratio (δ 18 O) of water is one of the core indicators in such analysis.

[0003] At present, the conventional technical means for determining the oxygen isotope ratio in water mainly relies on the isotope gas equilibrium method (H2O-CO2 equilibrium method). This method usually uses an online gas preparation-stable isotope mass spectrometer (Gasbench-IRMS) to balance the oxygen isotope exchange between water in the sample and CO2 gas at a constant temperature, and then determine the isotope ratio of CO2 in the gas phase after equilibrium, so as to indirectly calculate the oxygen isotope ratio in water.

[0004] However, when the above conventional gas equilibrium method is directly applied to the detection of high-alcohol beverages, significant technical obstacles are encountered. Since Chinese liquor and other high-alcohol beverages contain high concentrations of ethanol, the molecular mass number (46) of ethanol is the same as that of CO2 gas (especially CO2 molecules containing 18 O) used for determination. Therefore, when using the gas equilibrium method for determination, the volatilized ethanol in the sample will enter the mass spectrometer, causing serious isobaric interference, which makes it impossible to directly and accurately determine the oxygen isotope ratio of water in the sample.

[0005] To overcome the interference of ethanol, existing technologies typically employ physical separation pretreatment strategies, such as offline methods like atmospheric / vacuum distillation or azeotropic distillation to separate water from the wine matrix. However, these methods have significant theoretical drawbacks: First, there's the isotope fractionation effect: water inevitably undergoes isotope fractionation during phase transitions like evaporation and condensation. Since ethanol and water readily form azeotropes, physical separation is often incomplete. The isotope ratios of water remaining in the wine or separated water can easily deviate from the true values ​​of water in the original wine, leading to inaccurate results. Second, operational errors are introduced: these offline separation methods are cumbersome, requiring manual setup of the equipment, making automated online detection impossible. The complex manual pretreatment steps are highly susceptible to contamination from environmental water (such as moisture absorption or evaporation) and sample loss, resulting in poor reproducibility and being time-consuming and labor-intensive, making it difficult to meet the needs of rapid detection of large batches of samples.

[0006] Therefore, existing technologies struggle to obtain true 'standard values' for comparison, necessitating an online analysis method that requires no physical separation, avoids fractionation effects in principle, and is easy to operate. In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide an analytical method for the oxygen stable isotope ratio of water in high-alcohol beverages. This method utilizes dilution to eliminate ethanol interference and combines mass conservation calculations with physical separation, achieving a simple, rapid, and accurate determination of the water-oxygen isotope ratio in high-alcohol beverages without complex pretreatment.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages, comprising: Select at least two water samples with known and different oxygen isotope ratios as additive water; dilute the same high-alcohol beverage to be tested with the at least two additive waters respectively to obtain at least two diluted samples; Determine the oxygen isotope ratio of the at least two diluted samples; Based on the oxygen isotope ratio of the added water and the oxygen isotope ratio of the diluted sample, a set of equations was established using the principle of isotope mass conservation to calculate the oxygen isotope ratio of water in the high-alcohol beverage to be tested.

[0009] In an optional embodiment, the volume concentration of ethanol in the diluted sample is 5% to 20%; and / or, The dilution process includes: mixing the high-alcohol beverage to be tested with the added water and letting it stand; wherein the mixing time is 3 minutes to 10 minutes; and / or, the standing time is 8 hours to 24 hours.

[0010] In an optional implementation, the dilution process is further followed by a filtration step: The diluted mixture is filtered through a microporous membrane to obtain the diluted sample; and / or, the determination step is performed using an online gas preparation-stable isotope mass spectrometer.

[0011] In an optional embodiment, among the at least two water samples with known and different oxygen isotope ratios, at least one of the water samples is a laboratory-prepared water sample. The laboratory-prepared water sample was prepared through the following steps: Ultrapure water is added to the container and evaporated and concentrated under constant temperature heating conditions to enrich the heavy oxygen isotope. Preferably, the temperature of the constant temperature heating condition is not less than 100°C; Preferably, the evaporation and concentration time is not less than 10 hours.

[0012] In an optional implementation, the measurement step includes: A mixture of CO2 and He gas is introduced into the container containing the diluted sample to purge impurities. The sample was equilibrated under constant temperature conditions to ensure that the water content in the diluted sample was... 18 O and CO2 16 O reaches an isotopic equilibrium state; The oxygen isotope ratio of CO2 gas after equilibrium was measured.

[0013] Preferably, the temperature of the constant temperature condition is 20℃~30℃; Preferably, the balancing time is no less than 10 hours.

[0014] In an optional embodiment, the volume percentage concentration of CO2 in the CO2 and He mixture is 0.2% to 1%; and / or, The flow rate of the CO2 and He mixture is 80 mL / min to 120 mL / min; and / or, The blowing time for the CO2 and He mixture is 4 to 6 minutes.

[0015] In an optional implementation, a calibration step is further included before or after determining the oxygen isotope ratios of the at least two diluted samples: Oxygen isotope calibration curves in water were plotted using a variety of standard substances with known oxygen isotope ratios. The oxygen isotope ratio of the diluted sample obtained by measurement is calibrated using the calibration curve to obtain a calibration value for calculation.

[0016] In an optional implementation, the formula for calculating the oxygen isotope ratio of water in the tested high-alcohol beverage is: ; in, ; ; ; In the formula, The oxygen isotope ratio of water in the tested high-alcohol beverage is represented by the oxygen isotope ratio. The oxygen isotope ratio representing the first type of added water; The oxygen isotope ratio representing the second type of added water; The oxygen isotope ratio of the sample after dilution with water (the first additive) of the high-alcohol beverage being tested. The oxygen isotope ratio represents the sample of the high-alcohol beverage to be tested after dilution with a second type of added water.

[0017] Secondly, the present invention provides an application of the method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages as described in any of the foregoing embodiments in the identification of the origin of high-alcohol beverages, detection of adulteration, or tracing of water sources. Preferably, the high-alcohol beverage includes Chinese baijiu, brandy, whiskey, vodka, or rum.

[0018] Thirdly, the present invention provides an analytical system for the oxygen stable isotope ratio of water in high-alcohol beverages, comprising: The dilution unit is used to select at least two water samples with known and different oxygen isotope ratios as added water; and to dilute the same high-alcohol beverage to be tested with the at least two added waters respectively to obtain at least two diluted samples. A measuring unit is used to measure the oxygen isotope ratio of the at least two diluted samples; The calculation unit is used to establish a set of equations based on the oxygen isotope ratio of the added water and the oxygen isotope ratio of the diluted sample obtained by measurement, and to calculate the oxygen isotope ratio of the water in the high-alcohol beverage to be tested.

[0019] This invention provides an analytical method for the oxygen stable isotope ratio of water in high-alcohol beverages. The method involves diluting the high-alcohol beverage with at least two water samples of known but different oxygen isotope ratios, significantly reducing the ethanol concentration in the sample matrix. Since the mass number of ethanol is the same as that of carbon dioxide gas used in gas balance methods, high concentrations of ethanol typically cause severe isotopic interference in mass spectrometry. This analytical method effectively avoids the interference of high-concentration ethanol on oxygen isotope determination in water through dilution, thus enabling accurate acquisition of detection data from the diluted sample using conventional gas balance methods, ensuring the accuracy of the final analytical results.

[0020] By utilizing the principle of isotope mass conservation, a system of equations was established based on the measurement results after different dilutions with added water to calculate the oxygen isotope ratio of water in high-alcohol beverages directly without physical component separation. This strategy of replacing physical separation with mathematical calculation overcomes the shortcomings of traditional detection methods that rely on cumbersome and time-consuming distillation or offline separation devices to remove ethanol. This method eliminates the need for complex pretreatment equipment, greatly simplifying sample pretreatment procedures, reducing measurement costs, and significantly shortening the detection cycle. The simplicity of the operation not only reduces errors that may be introduced by complex pretreatment processes and enhances the stability and reliability of the measurement results, but also makes this method suitable for the rapid analysis of large batches of samples. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a calibration curve of oxygen isotopes in water plotted using three standard substances in Example 1 of the present invention; Figure 2 This is an ion flow spectrum obtained during Gasbench-IRMS analysis in Example 1 of the present invention. Detailed Implementation

[0023] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0024] This application provides a method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages, including: Step S1: Select at least two water samples with known and different oxygen isotope ratios as added water; dilute the same high-alcohol beverage to be tested with the at least two added waters respectively to obtain at least two diluted samples.

[0025] This step refers to preparing at least two types of water as diluents and the sample pretreatment steps before conducting the experiment.

[0026] The phrase "oxygen isotope ratio known" above refers to the oxygen isotope ratio (δ) of these water samples before they were used for dilution. 18 O) must be an accurate value that has been determined by standard methods or a certified value recognized by an authoritative body.

[0027] The aforementioned "different numerical values" are a crucial condition for constructing an effective system of mathematical equations. If the two water samples have the same isotopic values, the resulting system of equations will be linearly related (equivalent), making it impossible to solve for the unknowns. Therefore, it is essential to ensure that the isotopic values ​​of the two water samples are significantly different.

[0028] For example, it can be implemented as follows: Method 1 (Commercially Available Mineral Water): Collect natural mineral water from different brands and sources. Due to differences in geographical environment, their natural oxygen isotope background values ​​vary. For example, one sample could be selected from the delta range. 18 A water sample with an oxidation state of approximately -19‰ and a δ sample 18 A water sample with an oxygen content of approximately -10‰.

[0029] Method Two (Laboratory Preparation): If the differences in natural water samples are not significant enough, artificial differences can be created. For example, ultrapure water can be evaporated at a constant temperature (e.g., 150°C) for a long time (e.g., 20 hours). Utilizing the difference in evaporation rates between light and heavy isotopes, the heavy oxygen isotope in the remaining water sample can be increased. 18 O) enrichment, thereby obtaining water samples with significantly different isotope values ​​(such as high values).

[0030] The phrase “dilute separately” refers to dividing the same bottle of high-alcohol beverage to be tested into at least two portions, adding a first type of added water to one portion and a second type of added water to the other portion, and then physically mixing them.

[0031] The result of the above-mentioned "obtain at least two diluted samples" treatment is to obtain two (or more) bottles of mixture with reduced ethanol concentration.

[0032] The process involves mixing a high-concentration alcoholic beverage with added water, then mixing (e.g., for 3-10 minutes) and allowing it to stand (e.g., for 8-24 hours) to allow the ethanol and water molecules to fully integrate. The resulting "diluted sample" will have a lower volume percentage concentration of ethanol (e.g., reduced to 5%-20% vol).

[0033] By reducing the ethanol concentration in the matrix through dilution, the interference of high ethanol concentration on subsequent isotope determinations (especially gas balance methods) can be effectively reduced or avoided.

[0034] Step S2: Determine the oxygen isotope ratio of the at least two diluted samples.

[0035] This step utilizes instruments to obtain experimental data from the diluted mixture.

[0036] Specifically, measurements can be performed using an online gas preparation-stable isotope mass spectrometer (Gasbench-IRMS).

[0037] The diluted sample can be placed in a sample bottle, filled with a CO2 / He mixture, and equilibrated at a constant temperature (e.g., 28℃) for a certain period of time (e.g., 24 hours) to allow the oxygen isotopes in the water to reach an exchange equilibrium with the CO2 in the gas phase. Finally, the oxygen isotope ratio of the CO2 in the gas phase is measured.

[0038] To ensure data accuracy, standard substances are usually used to plot calibration curves to calibrate the raw data measured by the instrument, thereby obtaining the oxygen isotope ratio of the sample after the first dilution with water and the oxygen isotope ratio of the sample after the second dilution with water.

[0039] Step S3: Based on the oxygen isotope ratio of the added water and the oxygen isotope ratio of the diluted sample obtained by measurement, a set of equations is established using the principle of isotope mass conservation to calculate the oxygen isotope ratio of water in the high-alcohol beverage to be tested.

[0040] The above steps are the core algorithmic steps of this method, namely, replacing physical separation with mathematical inversion.

[0041] Step S3 specifically involves using a mathematical model to invert and calculate the target value. Its core principle is the law of conservation of isotopic mass, which states that the oxygen isotope ratio of the diluted sample is the mass-weighted sum of the isotope ratios of water in the original wine sample and the added water. The specific principle is shown in the following reaction equation: C 16 O2 + H2 18 O C 16 O 18 O+H2 16 O.

[0042] The reaction formula intuitively demonstrates the core detection principle of this method, which is to dilute the same wine sample with water with two different isotopic backgrounds to construct two independent mass conservation systems, thereby using mathematical geometry or algebraic relationships to solve for the original oxygen isotope ratio of water in the wine sample.

[0043] In this step, it is not necessary to know or measure the specific mass ratio of the original liquor to the added water during the dilution process beforehand; instead, it is treated as an unknown intermediate variable (e.g., a mass fraction f). Through dilution experiments conducted using at least two different isotopic backgrounds of added water in the preceding steps, a system of linear equations containing two unknowns (i.e., the mixing ratio f and the desired water isotope value in the liquor) can be constructed for the same test subject. Because the isotope values ​​of the added water differ, this system of equations is linearly independent. By solving this system of equations simultaneously and eliminating the intermediate variable f representing the mixing ratio using mathematical elimination, a unique solution can be precisely derived. This solution represents the oxygen isotope ratio of water in the tested high-alcohol beverage.

[0044] In some embodiments, the volume concentration of ethanol in the diluted sample is 5% to 30%. For example, it can be 5%, 8%, 10%, 12%, 15%, 20%, 22%, 25%, 28%, 30%, etc.

[0045] This method specifies the exact range of ethanol (alcohol) content in the mixed solution after the dilution step. Specifically, by adding water, the alcohol content of the high-alcohol beverage being tested (typically with a high ethanol concentration) is reduced to between 5% and 30% (volume percentage).

[0046] The required dilution ratio can be calculated based on the original alcohol content of the high-alcohol beverage to be tested (e.g., 50% vol or 53% vol) and the selected amount of water to be added. In operation, a certain volume of the high-alcohol beverage to be tested and a certain volume of water to be added are mixed so that the ethanol concentration in the final mixture falls within this specific range, thereby obtaining a test liquid environment with a significantly reduced ethanol concentration.

[0047] This concentration range is one of the core control parameters of this method. Reducing the ethanol concentration to below 30% (preferably 5%–20%) can effectively suppress or eliminate the interference of high-concentration ethanol on subsequent oxygen isotope determination processes (for example, in mass spectrometry, ethanol molecules may generate isotope interference). If the concentration is too high, the interference cannot be eliminated; if the concentration is too low, it may lead to a weak signal in the water sample or introduce other dilution errors. This range ensures the accuracy and feasibility of the determination.

[0048] Specifically, a volumetric flask or pipette can be used to add the wine sample to be tested into a container containing water, or vice versa, according to the pre-calculated volume ratio.

[0049] In some embodiments, the dilution process includes: mixing the high-alcohol beverage to be tested with the added water and allowing it to stand; wherein the mixing time is 3 to 10 minutes. For example, it can be 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0050] This method specifies the duration of physical stirring or shaking after combining the high-alcohol beverage to be tested with added water. After adding the two liquids (alcohol and water) to the same container, they can be continuously stirred and mixed by mechanical vibration, vortexing, or manual shaking for a duration controlled between 3 and 10 minutes. This eliminates the potential stratification caused by differences in density and viscosity between the two liquids, resulting in a homogeneous and stable single-phase solution.

[0051] Since alcohol and water may have microscopic inhomogeneities in the initial stage of mixing, sufficient mixing time can ensure that ethanol and water molecules are fully integrated at the molecular level, ensuring that the isotope ratios are consistent throughout the sample during sampling and measurement, thereby improving the repeatability and reliability of the measurement data.

[0052] Specifically, a vortex oscillator or a horizontal oscillator can be used to continuously oscillate a container containing a mixture.

[0053] Furthermore, the settling time is 8 to 24 hours. For example, it can be 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 23 hours, 24 hours, etc.

[0054] This feature specifies the duration for which the mixture is left undisturbed in a static state after the mixing operation is completed. The homogenized sample container can be placed on a test bench or in a constant temperature chamber and left undisturbed for 8 to 24 hours to allow the mixture to reach complete thermodynamic and physical stability.

[0055] A settling period of 8 to 24 hours helps to further eliminate microbubbles that may be generated during mixing and allows the components within the solution (especially the hydrogen bond network formed by ethanol and water) to reach a stable equilibrium. This is particularly important for high-precision isotope analysis, as it effectively reduces measurement fluctuations caused by system instability and ensures consistent matrix background during subsequent sampling and analysis.

[0056] Simply place the sealed sample vials in a vibration-free environment with a relatively constant temperature.

[0057] In some embodiments, the dilution process is further followed by a filtration step: The diluted mixture is filtered through a microporous membrane to obtain the diluted sample; and / or, the determination step is performed using an online gas preparation-stable isotope mass spectrometer.

[0058] The above method specifies a physical purification step that must be performed after completing pretreatment operations such as dilution, mixing, and settling, and before instrumental analysis. The pore size of the filter medium can be at least 0.45 micrometers (μm).

[0059] For example, a syringe or filtration device can be used to force the mixture of alcoholic beverage and water, after mixing and settling, through a microporous membrane with a pore size of 0.45 μm. This process traps particulate matter, suspended matter, or precipitated impurities larger than 0.45 μm in the mixture, resulting in a clear, transparent filtrate free of particulate impurities, which is the "diluted sample" ultimately used for instrumental analysis.

[0060] This filtration step is crucial for protecting precision analytical instruments. It effectively prevents tiny particles in the sample from clogging subsequent analytical instruments (such as injection needles, capillary lines, or valves in gas preparation devices), thus ensuring the smoothness and stability of sample introduction. At the same time, removing impurities also helps reduce background noise, ensuring the accuracy of isotope ratio determination results.

[0061] The term "online" refers to the fact that sample preparation (such as gas equilibration) and mass spectrometry detection are performed continuously and automatically, rather than manually offline; "gas preparation" refers to the process of transferring oxygen isotopes from liquid water to gaseous CO2; and "stable isotope mass spectrometer" is the core of the final detection.

[0062] The processing involves placing a sample vial containing the sample onto the instrument's autosampler tray. The system automatically executes the entire process, including purging impurities (introducing a CO2 / He mixture), isothermal equilibration (allowing oxygen isotope exchange between water and CO2), and introducing the equilibrated gas into the mass spectrometer for ion current detection. This allows for the direct, rapid, and continuous acquisition of oxygen isotope ratio data for a large number of samples.

[0063] Compared to offline methods, this technology enables fully automated online analysis, greatly improving detection efficiency and sample throughput (suitable for large-scale determination), reducing errors and cumbersome steps introduced by manual operation, and offering higher sensitivity and accuracy.

[0064] For example, this can be achieved in the laboratory by connecting a Gasbench (a multi-purpose online gas preparation device) to an IRMS (isotope ratio mass spectrometer). For instance, a Thermo Fisher Scientific Gasbench II coupled with a DeltaV series mass spectrometer system can be used.

[0065] In some embodiments, of the at least two water samples with known and different oxygen isotope ratios, at least one of the water samples is a laboratory-prepared water sample.

[0066] This method involves specific selection of the source of the "added water." Among the at least two added waters used to construct the equations, the selection is not entirely limited to naturally occurring water bodies (such as mineral water), but rather introduces at least one special water sample prepared through artificial experimental means. In the experimental preparation stage, a water sample is artificially prepared using specific physicochemical methods, and its oxygen isotope ratio is calibrated to ensure a significant difference between its value and that of the other added water (usually natural water). The result obtained is an isotope ratio (δ¹⁸O₁₀)... 18 O) is usually a positive value or has a specific high value for added water.

[0067] The oxygen isotope ratios of natural water bodies are typically negative and vary only slightly (e.g., -19‰ to -10‰). δ¹⁹‰ can be obtained by introducing laboratory-prepared water samples. 18 Water samples with positive O values ​​(e.g., around +16‰) significantly widen the numerical difference between the two types of added water. When establishing a system of equations using the principle of isotope mass conservation, the greater the isotopic difference between the added waters, the higher the stability of the solution to the system of equations, and the more accurate the calculated oxygen isotope ratio of water in the tested high-alcohol beverage.

[0068] The laboratory-made water sample was prepared by the following steps: adding ultrapure water to a container and evaporating and concentrating it under constant temperature heating conditions to enrich the heavy oxygen isotope.

[0069] The above-mentioned method for preparing self-made water samples utilizes the isotope fractionation effect during physical evaporation. The process involves adding a certain volume (e.g., 2000 mL) of ultrapure water to a container (such as a beaker), placing it on a heating device for continuous heating. As the water evaporates, the volume of the water sample decreases, and the isotopic composition of the remaining water sample changes, with the heavy oxygen isotope (…) becoming more concentrated. 18 The relative abundance of O increased.

[0070] Utilizing the light isotope (H2) in water molecules 16 O) specific gravity isotope (H2) 18 O's higher volatility allows for the effective enrichment of deuterium isotopes through simple physical heating and evaporation. This method eliminates the need for complex chemical synthesis, is inexpensive, and easy to operate, and can produce high-value isotope water samples that meet the aforementioned numerical difference requirements. For example, it can be performed using a standard laboratory temperature-controlled hot plate or heating mantle in conjunction with a heat-resistant glass container.

[0071] Furthermore, the temperature of the constant-temperature heating condition is not less than 100°C. This feature specifies the lower limit of the heating temperature during the evaporation process, ensuring that the water is in a state of vigorous evaporation or boiling. The temperature of the heating device (such as a constant-temperature electric heating plate) is set to maintain a temperature value of 100°C or higher (e.g., 150°C mentioned in the embodiment), thereby providing sufficient heat energy so that the water sample can undergo a phase change (from liquid to gas) at a relatively fast rate.

[0072] Setting the temperature to at least 100℃ (the boiling point of water) ensures a high evaporation rate, allowing the preparation process to be completed within a reasonable time and improving experimental efficiency. Maintaining a constant temperature helps stabilize the evaporation rate, ensuring good reproducibility of the isotopic values ​​in the prepared water sample.

[0073] Furthermore, the evaporation and concentration time is no less than 10 hours. This feature specifies a lower limit for the duration of the evaporation and concentration process to ensure enrichment effect. By maintaining the above-mentioned constant temperature heating state and continuously carrying out the evaporation operation for 10 hours or longer (e.g., 20 hours as mentioned in the embodiment), a large amount of water is removed after a sufficiently long evaporation period, allowing the heavy oxygen isotopes in the residual water sample to be sufficiently enriched, thereby achieving the expected isotope ratio level (e.g., changing from a negative value in natural water to a positive value).

[0074] Isotope fractionation is a gradual process. Setting an evaporation time of no less than 10 hours ensures that a sufficient proportion of water evaporates, thereby producing a significant isotope fractionation accumulation effect and obtaining a water sample with a high isotope ratio that is clearly distinguishable from natural water, thus meeting the requirements for accurate solution of the equation system.

[0075] In some embodiments, the measurement step includes: A mixture of CO2 and He gas is introduced into the container holding the diluted sample to purge impurities; equilibration is then carried out under constant temperature conditions to ensure that the water content in the diluted sample is... 18 O and CO2 16 O reaches isotopic equilibrium; the oxygen isotope ratio of CO2 gas after equilibrium is measured.

[0076] The aforementioned step of filling the sample vial with a mixture of CO2 and He refers to a gas displacement process, which involves using a specific gas mixture to purge the original air from the headspace of the sample vial and establish a specific gaseous environment for subsequent isotope exchange. The sample vial (usually a headspace vial) containing the diluted sample to be tested can be sealed. An automated sample introduction system is then used to continuously fill the vial with a mixture of carbon dioxide (CO2) and helium (He) through a gas needle. The airflow purges and removes the original air (impurities) from the vial, thus completely filling the headspace above the liquid surface of the sample vial with the CO2 and He mixture, removing impurities such as oxygen and nitrogen from the air.

[0077] This is a physicochemical equilibrium process based on the principle of isotope fractionation, specifically utilizing the carbon dioxide-water (CO2-H2O) isotope exchange equilibrium method to reflect liquid-phase information through the gas phase. After aeration, the sample vial is placed in a strictly temperature-controlled environment and kept static. During this process, oxygen atoms in the diluted sample (liquid water) exchange with oxygen atoms in the headspace carbon dioxide (gaseous). This causes the heavy oxygen isotopes in the water (…) to… 18 O) is transferred to CO2 molecules, until it reaches the liquid phase. 18 O / 16 O ratio and CO2 in gas phase 18 O / 16 The O ratio reaches a constant chemical equilibrium state.

[0078] By blowing out impurities, the potential interference of atmospheric background on the measurement results was eliminated. Simultaneously, CO2 was introduced into the bottle as a medium for exchanging oxygen isotopes with the water, and He was introduced as an inert carrier gas, creating the necessary sample introduction conditions for subsequent mass spectrometry analysis. This step allows researchers to indirectly obtain oxygen isotope information of liquid water by measuring the isotope ratio of gaseous CO2, thus avoiding the contamination or interference caused by directly analyzing complex liquid mixtures (containing ethanol). The isothermal conditions ensured the constant isotope fractionation coefficient, guaranteeing the accuracy and repeatability of the data.

[0079] Specifically, the sample tray can be placed in a device with constant temperature control function for temperature-controlled incubation.

[0080] The above-mentioned "determination of the oxygen isotope ratio of CO2 gas after equilibrium" is the final data acquisition step, which uses a precision analytical instrument to detect the isotope ratio of the gas phase components after equilibrium.

[0081] After isotope exchange reaches equilibrium, CO2 gas from the headspace of the sample vial is drawn using a sampling needle and introduced into an isotope ratio mass spectrometer (IRMS). The mass spectrometer measures the oxygen isotope ratio in the gas (…). 18 O / 16 The CO2 gas is then analyzed to obtain its oxygen isotope ratio after equilibrium. Since the CO2 has reached equilibrium with the water in the sample, this value directly correlates with and reflects the oxygen isotope characteristics of the water in the diluted sample. This step provides high-precision, high-sensitivity measurement data, providing the necessary input parameters for subsequent calculation of the water isotope ratio in the original wine sample using the mass conservation equations. Method sequences can be created on instrument control software such as Isodat to automatically run the test program.

[0082] Furthermore, the isothermal condition is maintained at a temperature of 20°C to 30°C; for example, it can be 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, etc. This temperature range (e.g., 28°C) ensures that the isotope exchange reaction has an appropriate rate while avoiding excessively high temperatures that could lead to excessive evaporation of water or ethanol, thus affecting headspace pressure or causing fractionation errors. A constant temperature ensures that the isotope fractionation coefficient between the gas and liquid phases remains unchanged, which is crucial for accurate calculations.

[0083] Furthermore, the equilibration time is no less than 10 hours. For example, it can be 24 hours. Isotope exchange is a dynamic process; if the time is insufficient, the system will not reach equilibrium, and the measurement results will be biased. Setting an equilibration time of no less than 10 hours (e.g., 24 hours in the example) can eliminate the uncertainty caused by kinetic factors and ensure that the measured gas isotope ratios can truly and accurately reflect the isotopic information of the aqueous phase.

[0084] In some embodiments, the volume percentage concentration of CO2 in the CO2 and He mixture is 0.2% to 1%. For example, it can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc.

[0085] This concentration range is an optimized ratio for the detection sensitivity of a stable isotope mass spectrometer. An appropriate amount of CO2 ensures sufficient CO2 molecules participate in the isotope exchange reaction, generating a signal intensity strong enough to be captured by the detector; the concentration does not exceed 1%, preventing excessive CO2 entering the mass spectrometer from saturating the ion source or causing the signal to exceed the linear range, thus ensuring the accuracy and linearity of the test data. A high proportion of helium as a carrier gas helps stabilize the gas flow and protects the mass spectrometer's vacuum system.

[0086] In some embodiments, the flow rate of the CO2 and He mixture is 80 mL / min to 120 mL / min. For example, it can be 80 mL / min, 90 mL / min, 100 mL / min, 110 mL / min, 120 mL / min, etc.

[0087] The output flow rate of the mixed gas can be adjusted and stabilized within an acceptable range, such as 100 ml per minute, through the instrument's flow controller. This allows the gas to be injected into the bottom of the sample vial at a constant rate through the gas needle and discharged from the exhaust port, forming a stable displacement gas flow.

[0088] Within the aforementioned range, a flow rate of 100 mL / min is sufficient to generate adequate purging force, rapidly agitating and removing residual dead volume air from the vial. This moderate flow rate ensures purging efficiency without causing excessive splashing or evaporation of the liquid sample due to excessive airflow.

[0089] In some embodiments, the blowing time of the CO2 and He mixture is 4 to 6 minutes. For example, it can be 4 minutes, 4.2 minutes, 4.5 minutes, 4.8 minutes, 5 minutes, 5.2 minutes, 5.5 minutes, 5.8 minutes, 6 minutes, etc.

[0090] A purging time of 4 to 6 minutes is sufficient to completely remove residual air (including atmospheric oxygen, nitrogen, and moisture) from the vial, ensuring the purity of the headspace background and preventing interference from impurity gases in isotope determination. This time range ensures effective replacement while avoiding the waste of expensive standard gas mixtures or unnecessary extension of the analysis cycle due to excessively long purging times.

[0091] In some embodiments, a calibration step is included before or after determining the oxygen isotope ratios of the at least two diluted samples: Oxygen isotope calibration curves in water were plotted using a variety of standard substances with known oxygen isotope ratios.

[0092] The oxygen isotope ratio of the diluted sample obtained by measurement is calibrated using the calibration curve to obtain a calibration value for calculation.

[0093] This step refers to the data standardization process. It requires that while testing unknown samples, a set of "benchmark" samples (i.e., standard substances) with authoritatively recognized values ​​must also be tested to establish a mathematical mapping relationship between instrument measurements and true values.

[0094] At least two (usually three or more to cover high, medium, and low values) nationally or internationally certified reference materials (CRMs) for oxygen isotopes in water can be selected. These materials can have precisely known δ values. 18 Certificate values ​​(e.g., GBW04458, GBW04459, GBW04460, etc.) are used. These standard reference materials are then measured using the exact same instrument conditions (Gasbench-IRMS) and methods as the diluted samples being tested, yielding the "raw measurement values" output by the instrument. A linear regression analysis is performed with the raw values ​​measured by the instrument on the x-axis and the true values ​​from the standard reference material certificate on the y-axis, generating a straight line, the "calibration curve." This yields a specific linear regression equation (calibration equation), typically in the form y = kx + b. Here, y represents the calibrated true value, x represents the instrument measurement value, k is the slope, and b is the intercept.

[0095] For example, the fitted equation might be y = 0.9842x - 33.144, with a correlation coefficient R0. 2 =0.9988.

[0096] The raw measurements from a spectrometer are typically relative to the working reference gas and may be subject to drift or compression / expansion effects. By plotting calibration curves, the instrument-specific raw data can be normalized to internationally recognized isotope temperature scales (such as the VSMOW / SLAP scale), eliminating systematic errors and ensuring data accuracy and international comparability.

[0097] Then, the established "scale" is applied to the actual sample to be tested, correcting the original data of the sample. The original instrument readings (i.e., the uncalibrated δ) of the "diluted sample" obtained in the aforementioned method steps are then used as the basis for correction. 18 O), and substitute it into the calibration equation obtained in the above steps to calculate, thereby obtaining the "calibration value".

[0098] For example, if the instrument reading for a sample is 14.667‰, after substituting it into the equation y=0.9842x-33.144, the calibration value y≈-18.709‰ is obtained.

[0099] Only calibrated values ​​are physically accurate isotope ratios. If this step is omitted and raw instrument data is directly substituted into the aforementioned mass conservation equations, the calculated isotope values ​​for water in highly alcoholic beverages will be seriously flawed due to systematic biases in the raw data. This step is a necessary prerequisite for ensuring the accuracy of the final calculation results.

[0100] It can be directly calculated using algebra. The formula is δ. 18 O 校准后 =k×δ 18 O 仪器测定值 +b, where k and b are the coefficients obtained from the regression analysis in the previous step. This calibrated value is taken as δ. 18 O total1 and δ 18 O total2 Substitute the values ​​into the formula to solve.

[0101] In some embodiments, the formula for calculating the oxygen isotope ratio of water in the tested high-alcohol beverage (Formula 1) is: .

[0102] This formula is an analytical solution derived from the principle of isotope mass conservation. In the experiment, although dilution was performed, the "mass fraction of water in the original wine sample (denoted as f)" was an unknown quantity that was difficult or unnecessary to measure precisely. This formula eliminates this unknown variable $f$ representing the mixing ratio by simultaneously solving two mass conservation equations based on different amounts of added water, using algebraic methods, thus directly establishing a functional relationship between the known quantity and the unknown quantity.

[0103] in, Calculate the isotopic difference between the two types of water added as diluents. This value reflects the "gradient spurious difference" of the constructed equation system; the larger the difference, the more stable the calculation result.

[0104] ; Calculate the difference between the measured value of the first diluted sample and the background value of the first added water.

[0105] ; Calculate the difference between the measured values ​​of two different diluted samples.

[0106] In the formula, The oxygen isotope ratio of water in the tested high-alcohol beverage is represented by the oxygen isotope ratio. The oxygen isotope ratio representing the first type of added water; The oxygen isotope ratio representing the second type of added water; The oxygen isotope ratio of the sample after dilution with water (the first additive) of the high-alcohol beverage being tested. The oxygen isotope ratio represents the sample of the high-alcohol beverage to be tested after dilution with a second type of added water.

[0107] The above formula can be written as the following expression (Formula 2): .

[0108] The oxygen isotope ratio of water in the tested high-alcohol beverage can be directly obtained through calculation. This is the true isotopic value after eliminating ethanol interference and without requiring physical separation of water.

[0109] The greatest advantage of this formula is that it does not require knowledge of the specific dilution ratio. In practice, precisely controlling or measuring the ratio (mass fraction) of water and alcohol added is extremely tedious and prone to error. This formula, through mathematical elimination, ensures that the final result depends only on the measured isotope ratio, independent of the mixing ratio, thus greatly simplifying the operation and improving accuracy. This calculation step mathematically achieves the "separation" of water and ethanol, avoiding the complex distillation operations of traditional methods.

[0110] In this application embodiment, an analytical method for the oxygen stable isotope ratio of water in high-alcohol beverages as described in any of the foregoing embodiments is also provided for the application of the method for identifying the origin of high-alcohol beverages, detecting adulteration, or tracing the source of water. Preferably, the high-alcohol beverage includes Chinese baijiu, brandy, whiskey, vodka, or rum.

[0111] This application embodiment also provides an analysis system for the oxygen stable isotope ratio of water in high-alcohol beverages, including: The dilution unit is used to select at least two water samples with known and different oxygen isotope ratios as added water; and to dilute the same high-alcohol beverage to be tested with the at least two added waters respectively to obtain at least two diluted samples. A measuring unit is used to measure the oxygen isotope ratio of the at least two diluted samples; The calculation unit is used to establish a set of equations based on the oxygen isotope ratio of the added water and the oxygen isotope ratio of the diluted sample obtained by measurement, and to calculate the oxygen isotope ratio of the water in the high-alcohol beverage to be tested.

[0112] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0113] Example 1 1. Instruments and reagents: Delta V Advantage stable isotope ratio mass spectrometer (equipped with Trance GC, Gasbench), Milli-Q ultrapure water system, 2 mL brown vials, pipettes, volumetric flasks.

[0114] Water oxygen isotope standard material (GBW04458, δ) 18 O = -0.15‰; GBW04459, δ 18 O = -8.61‰; GBW04460, δ 18 O = -19.13‰), high-purity He and CO2 standard gas, mixed gas (0.3% CO2 + He).

[0115] Water sample collection and calibration of oxygen isotope ratios: Natural mineral water samples were collected from Tibet (sample number A). The δ¹⁸O₂ ratio in the water was determined. 18 The calibration value of O was -19.003‰; Laboratory-prepared water sample (C): 2000 mL of ultrapure water was added to a beaker and evaporated on a 150℃ heated plate for 20 hours. The δ-value of the water was... 13 The calibration value of C is +16.232‰.

[0116] 2. Sample pretreatment: High-proof liquor was diluted with Tibetan natural mineral water (No. A) and laboratory-made water (No. C) to ethanol concentrations of 5, 10, 15, 20, 25, 30, 35, and 40% vol, respectively. The solutions were mixed for 3 min, allowed to stand for 8 hr, filtered through a 0.45 μm filter membrane, and 0.5 mL was transferred to a 12 mL glass tube for testing.

[0117] 3. Plot the oxygen isotope calibration curve in water: Three water oxygen isotope standard materials (GBW04458, δ) were used. 18 O = -0.15‰; GBW04459, δ 18 O = -8.61‰; GBW04460, δ 18 O = -19.13‰), the oxygen isotopes in water of the standard material were determined using Gasbench-IRMS, and the results are shown in Table 1. A calibration curve for oxygen isotopes in water was plotted with the instrument readings on the x-axis and the certificate readings on the y-axis, yielding the fitting equation y = 0.9842x - 33.144, with a correlation coefficient R0. 2 =0.9999. (For example...) Figure 1 As shown, the calibration curve plotted with instrument measurements on the x-axis and standard substance certificate values ​​on the y-axis exhibits a very high linear relationship (R0). 2 =1), indicating that the instrument is stable. The fitting equation (y=0.9842x-33.144) can be used to accurately calibrate the measurement data of subsequent samples.

[0118] Table 1. Calibration curves of oxygen isotopes in water

[0119] 4. Gasbench-IRMS analysis: Table 2. Oxygen isotope values ​​of water in high-proof liquor determined by Gasbench-IRMS

[0120] Turn on the Gasbench and IRMS instruments. Place the diluted high-proof liquor sample bottles sequentially on the sample tray of the autosampler. Start the Flushing mode and run the Flushing sequence. The sample bottles are automatically filled with a CO2 / He cylinder mixture (CO2:He = 0.2%~1%) through the gas needle fixed to the magnetic sleeve of the autosampler, and impurities are blown out. The CO2 / He mixture flow rate is 100 mL / min, and each sample is blown for 5 min. The sample is then kept at 28℃ for 24 hr to allow the H2O to settle. 18 O is transferred to CO2, until it is absorbed into CO2. 18 O / 16 O and H2O 18 O / 16 O reaches isotopic equilibrium; remove the blowing needle from the autosampler's magnetic sleeve, attach the headspace gas sampling needle (to collect a CO2 / He mixture, with He carrier gas flow rate of 0.5 mL / min), and create a determination on the Isodat software. 18 O / 16The O~CO2 method sequence was tested. The instrument measurement results are shown in Table 2.

[0121] like Figure 2 The figure shows typical ion current spectra obtained during Gasbench-IRMS analysis. The CO2 ion current peaks with mass numbers 44, 45, and 46 are sharp and well-separated, with stable baselines. This indicates that the pretreatment method of this invention effectively avoids interference from ethanol peaks in mass spectrometry, resulting in high-quality detection signals.

[0122] 5. Conversion of the mass conservation equation: The oxygen isotope values ​​of water in high-proof liquor were calibrated using the oxygen isotope calibration curve of water in Table 1, and the results are shown in Table 3.

[0123] Table 3. Oxygen isotope calibration values ​​of water in Baijiu (Chinese liquor)

[0124] The oxygen isotope ratio of water in high-proof liquor was calculated using the mass conservation equation (4), and the results are shown in Table 4: Table 4. Calculation results of oxygen isotopes in water in high-proof liquor.

[0125] Example 2: Determination of other types of high-alcohol beverages (brandy, rum) To verify the applicability of this method to different categories of high-alcohol beverages, commercially available brandy and rum were selected as test samples and measured using the same double-standard method as in Example 1.

[0126] 1. Experimental conditions and pretreatment: Two types of water with different oxygen isotope ratios were selected as diluents (water added): (1) Add water 1: δ 18 The measured value of O was -17.71‰; (2) Add Water 2: δ 18 The measured value of O was +15.57‰.

[0127] The brandy and rum samples were diluted at different ratios (2:1 and 3:1, i.e., alcohol:water volume ratio), respectively. The mixtures were then mixed, allowed to stand, filtered, and analyzed by Gasbench-IRMS according to the steps described in Example 1.

[0128] 2. Measurement results: The oxygen isotope ratio (δ) of water in each sample was calculated using the mass conservation equation. 18 O Baijiu_water The results are shown in Table 5.

[0129] Table 5. Results of oxygen isotope analysis of water in brandy and rum.

[0130] The results show that the oxygen isotope ratios of water in brandy and rum measured by this method are highly consistent at different dilution ratios, proving that this method can effectively eliminate ethanol interference and is applicable to the analysis of other categories of high-alcohol beverages such as brandy and rum.

[0131] Example 3: Accuracy verification of the method (recovery rate experiment) Given that there is currently no standard physical separation method that can completely avoid isotope fractionation effects (e.g., distillation cannot avoid isotope deviations caused by azeotropy and fractionation), the accuracy cannot be directly determined by comparing it with existing methods. Therefore, this embodiment uses the most rigorous 'spiking recovery method' in chemometrics for verification, that is, constructing a 'simulated wine sample' with known isotope true values ​​to demonstrate the accuracy of this method.

[0132] 1. Preparation of simulated wine samples: Using anhydrous ethanol and water with a known oxygen isotope ratio (theoretical true value δ) 18 O True = -8.36‰) are mixed in a certain proportion to prepare a sample of simulated high-alcohol beverage. Since anhydrous ethanol does not contain water, the theoretical true value of the oxygen isotope of water in this simulated sample is the isotope ratio of the added water.

[0133] 2. Measurement and Calculation: The dual-standard method described in this invention was used to analyze simulated wine samples at two dilution ratios of 2:1 and 3:1, and the recovery rate was calculated. The formula for calculating the recovery rate is as follows: Recovery rate (%) = (measured value / theoretical true value) × 100%.

[0134] 3. Experimental Results: The experimental data are shown in Table 6.

[0135] Table 6. Results of Recovery Determination Using the Double Standard Method for Simulated Wine Samples

[0136] Note: The measured value is the average of 5 independent repeated measurements.

[0137] Experimental results show that, at different dilution ratios, the measured values ​​of the simulated wine samples are in high agreement with the theoretical true values, with an average recovery rate between 99.8% and 101.9%. This strongly demonstrates that the dual-standard method proposed in this invention, combined with the conversion based on the mass conservation equation, can accurately eliminate ethanol interference and truly reflect the oxygen isotope ratio of water in high-alcohol beverages, exhibiting extremely high analytical accuracy.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages, characterized in that, include: Select at least two water samples with known and different oxygen isotope ratios as the additive water; The same high-alcohol beverage to be tested was diluted with at least two types of added water to obtain at least two diluted samples. Determine the oxygen isotope ratio of the at least two diluted samples; Based on the oxygen isotope ratio of the added water and the oxygen isotope ratio of the diluted sample, a set of equations was established using the principle of isotope mass conservation to calculate the oxygen isotope ratio of water in the high-alcohol beverage to be tested.

2. The method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages as described in claim 1, characterized in that, The volume concentration of ethanol in the diluted sample is 5%–20%; and / or, The dilution process includes: mixing the high-alcohol beverage to be tested with the added water and letting it stand; wherein the mixing time is 3 minutes to 10 minutes; and / or, the standing time is 8 hours to 24 hours.

3. The method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages as described in claim 1, characterized in that, The dilution process is followed by a filtration process: The diluted mixture is filtered through a microporous membrane to obtain the diluted sample; and / or, the determination step is performed using an online gas preparation-stable isotope mass spectrometer.

4. The method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages as described in claim 1, characterized in that, Among the water samples with at least two known and different oxygen isotope ratios, at least one of the water samples is a laboratory-prepared water sample. The laboratory-prepared water sample was prepared through the following steps: Ultrapure water is added to the container and evaporated and concentrated under constant temperature heating conditions to enrich the heavy oxygen isotope. Preferably, the temperature of the constant temperature heating condition is not less than 100°C; Preferably, the evaporation and concentration time is not less than 10 hours.

5. The method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages as described in claim 1, characterized in that, The determination steps include: A mixture of CO2 and He gas is introduced into the container containing the diluted sample to purge impurities. The sample was equilibrated under constant temperature conditions to ensure that the water content in the diluted sample was... 18 O and CO2 16 O reaches an isotopic equilibrium state; Measure the oxygen isotope ratio of CO2 gas after equilibrium; Preferably, the temperature of the constant temperature condition is 20℃~30℃; Preferably, the balancing time is no less than 10 hours.

6. The method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages as described in claim 5, characterized in that, In the CO2 and He mixture, the volume percentage concentration of CO2 is 0.2% to 1%; and / or, The flow rate of the CO2 and He mixture is 80 mL / min to 120 mL / min; and / or, The blowing time for the CO2 and He mixture is 4 to 6 minutes.

7. The method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages as described in claim 1, characterized in that, A calibration step is also included before or after determining the oxygen isotope ratios of the at least two diluted samples: Oxygen isotope calibration curves in water were plotted using a variety of standard substances with known oxygen isotope ratios. The oxygen isotope ratio of the diluted sample obtained by measurement is calibrated using the calibration curve to obtain a calibration value for calculation.

8. The method for analyzing the oxygen stable isotope ratio of water in high-alcohol beverages as described in claim 1, characterized in that, The formula for calculating the oxygen isotope ratio of water in the tested high-alcohol beverage is as follows: ； in, ; ； ； In the formula, The oxygen isotope ratio of water in the tested high-alcohol beverage is represented by the oxygen isotope ratio. The oxygen isotope ratio representing the first type of added water; The oxygen isotope ratio representing the second type of added water; The oxygen isotope ratio of the sample after dilution with water (the first additive) of the high-alcohol beverage being tested. The oxygen isotope ratio represents the sample of the high-alcohol beverage to be tested after dilution with a second type of added water.

9. The application of an analytical method for the oxygen stable isotope ratio of water in a high-alcohol beverage as described in any one of claims 1-8 in the identification of the origin of high-alcohol beverages, detection of adulteration, or tracing of water sources; Preferably, the high-alcohol beverage includes Chinese baijiu, brandy, whiskey, vodka, or rum.

10. An analytical system for the oxygen stable isotope ratio of water in high-alcohol beverages, characterized in that, include: The dilution unit is used to select at least two water samples with known and different oxygen isotope ratios as the added water. The same high-alcohol beverage to be tested was diluted with at least two types of added water to obtain at least two diluted samples. A measuring unit is used to measure the oxygen isotope ratio of the at least two diluted samples; The calculation unit is used to establish a set of equations based on the oxygen isotope ratio of the added water and the oxygen isotope ratio of the diluted sample obtained by measurement, and to calculate the oxygen isotope ratio of the water in the high-alcohol beverage to be tested.

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