JP6209133B2 - Isotope ratio analysis system and analysis method - Google Patents

Description

  The present invention relates to an isotope ratio analysis method and an isotope ratio analysis system used for discriminating / estimating information related to origins of food production and beverages, etc., and origins of production history. Specifically, the present invention relates to an isotope ratio analysis method using laser spectroscopy and an isotope ratio analysis system.

  In recent years, in order to deter labeling for food and beverage production areas, manufacturing methods, and ingredients, we analyze scientifically the stable isotope ratios of food and beverages to provide scientific information on the origin of production areas, manufacturing methods and ingredients. Discrimination / estimation techniques are attracting attention.

  It is known that the oxygen and hydrogen isotope ratio of terrestrial water caused by rainfall is closely related to its geographical conditions, so oxygen or hydrogen isotope analysis of food and beverages is It is used as a means for discriminating and estimating. Especially for alcoholic beverages such as wine, labeling systems such as the place of origin control system have been emphasized for a long time, and efforts to protect brand image by suppressing the distribution of counterfeit goods by analyzing the isotope ratio of moisture in alcoholic beverages (For example, see Patent Document 1 and Non-Patent Documents 1 and 2).

  However, in order to perform isotope ratio analysis, it is expensive and large-sized, and is difficult to operate, such as isotope ratio mass spectrometry (IRMS) and nuclear magnetic resonance spectroscopy (NMR). Since it is necessary to use a complicated measuring device, there is a problem that it takes time and cost, and this is one factor that hinders the spread.

  On the other hand, in recent years, a laser spectroscopic device that can be used for isotope ratio analysis has been developed due to the advancement of high sensitivity technology of laser spectroscopy. For example, a technique called Tunable Diode Laser Spectroscopy (hereinafter referred to as laser spectroscopy) (Non-Patent Document 3), which uses a semiconductor laser as a light source for spectroscopy and is applied to a gas analyzer or the like, has attracted attention. Yes. In particular, the laser spectroscopic water oxygen and hydrogen isotope ratio analyzer is small, inexpensive, excellent in operability and portability, and has a measurement accuracy equivalent to or superior to that of conventional methods. Therefore, it is attracting attention and is being introduced in various fields.

  FIG. 1 illustrates the general operating principle of laser spectroscopy. In laser spectroscopy, the oscillation wavelength of the laser light source 1 is swept as shown in FIG. When there is an absorption line corresponding to the molecular vibration of the gaseous object 3 within the swept wavelength range, the received light intensity received by the photodetector 4 corresponds to the absorption line of the object 3 as shown in FIG. 1c. A dip (recessed light intensity) appears. The basic operation principle of laser spectroscopy is to measure and analyze the gas type and concentration of the object to be measured based on the position and depth of the dip.

  In actual application, a wavelength modulation spectroscopy (Wavelength Modulation Spectroscopy) in which a sine wave having a higher repetition frequency is superimposed on a sawtooth wave as shown in FIG. A method called Frequency Modulation Spectroscopy (Non-Patent Document 4), or a cavity ring that increases the effective optical path length and increases sensitivity by confining the gas to be measured in an optical cavity using a high-reflectance mirror. Various high-sensitivity techniques such as down-spectrometry (CRDS: Cavity Ring-Down Spectroscopy) (Non-Patent Document 5) and cavity-enhanced absorption spectroscopy (CEAS) (Non-Patent Document 6) are often used. ing.

  Regarding the isotope ratio analysis of water in alcoholic beverages such as wine, if a laser spectroscopic water oxygen and hydrogen isotope ratio analyzer can be used, it is extremely useful and is expected to be widely spread.

JP 2012-173000 A

S. Kelly, K. Heaton, and J. Hoogewerff, "Tracing the geographical origin of food: The application of multi-element and multi-isotope analysis", Trends in Food Science & Technology, 16, pp. 555-567, 2005 . J. West, J. Ehleringer, and T. Cerling, "Geography and vintage predicted by a novel GIS model of wine δ18O", Agricultural and Food Chemistry, 55 (17), pp. 7075-7083, 2007. Yoshimura, Shintoku, Fujii, Sakamoto, KAI: “High-sensitivity laser gas sensing technology and isotope ratio analysis application,” NTT Technical Journal, Vol.26, No.2, pp.27-30, 2014. G. C. Bjorklund, "Frequency-modulation spectroscopy: a new method for measuring weak absorption and dispersion," Opt. Lett. 5 (1), pp. 15-17, 1980. A. O’Keefe and D. A. G. Deacon: “Cavity ring-down optical spectrometer for absorption measurements using pulsed laser sources,” Rev. Sci. Instrum., Vol.59, No.12, pp.2544-2551, 1988. HR Barry, L. Corner, G. Hancock, R. Peverall, and GAD Ritchie: “Cavity-enhanced absorption spectroscopy of methane at 1.73 μm,” Chem. Phys. Lett., Vol.333, No.3-4, pp .285-289, 2001.

  However, organic compounds such as ethanol contained in alcoholic beverages include those containing hydroxyl groups that are similar in structure to water molecules. For this reason, absorption lines of these organic compounds appear in the vicinity of the absorption lines of water vapor used for isotope ratio analysis, which causes interference and significantly degrades the accuracy of isotope ratio analysis by laser spectroscopy. was there.

  As a method of separating only water from alcoholic beverages, there is a method of distillation. However, since this method has a problem of azeotropic distillation, about several percent of ethanol remains in the water separated by distillation. Since the remaining ethanol still causes interference, there is a problem that the accuracy of isotope ratio analysis by laser spectroscopy is significantly deteriorated. Moreover, there also existed a problem that the isotope ratio itself of the water contained in alcoholic beverage would change by distillation.

  In order to solve the above-described problems, the present invention provides an evaporation apparatus that vaporizes a liquid object to be measured containing water, and a laser beam is irradiated to the object to be measured vaporized by the evaporation apparatus to perform laser spectroscopy. Laser spectroscopic isotope ratio analyzer for analyzing oxygen and / or hydrogen isotope ratio of water contained in the measurement object, and treatment with the adsorbent before the liquid measurement object is put into the evaporation apparatus And an isotope ratio analysis system comprising a pretreatment device for removing organic compounds.

  In one embodiment of the present invention, the adsorbent may be made of a hydrophobic zeolite. In one embodiment of the invention, the organic compound is ethanol.

  Furthermore, in one embodiment, the system of the present invention is an isotope obtained by pretreating water having an ethanol concentration of 1% by weight or less using the pretreatment device, and measuring using the evaporation device and the isotope ratio analysis device. The difference between the body ratio and the isotope ratio measured using the evaporator and the isotope ratio analyzer without pretreatment of the ethanol concentration of 1% by weight or less with the pretreatment device is corrected. And a data processing apparatus using an algorithm for correcting the isotope ratio of the liquid object to be measured.

The present invention also includes a step of treating a liquid measurement object containing water with an adsorbent to remove an organic compound,
Vaporizing the liquid object to be measured and irradiating the vaporized object to be measured with a laser beam and performing laser spectroscopy to obtain an isotope ratio of oxygen and / or hydrogen of water contained in the liquid, or both. And a step of analyzing the water isotope ratio analysis method. In one embodiment of the invention, the adsorbent may consist of a hydrophobic zeolite. In one embodiment of the invention, the organic compound is ethanol.

  In one embodiment, the present invention further provides an isotope obtained by pretreating water having an ethanol concentration of 1% by weight or less using the pretreatment device and using the evaporation device and the isotope ratio analysis device. The difference between the ratio and the isotope ratio measured using the evaporation apparatus and the isotope ratio analyzer without pretreatment of the ethanol concentration of 1% by weight or less with the pretreatment apparatus And processing the data using an algorithm for correcting the isotope ratio of the liquid object to be measured.

As another embodiment, the present invention includes an evaporation device that vaporizes a liquid measurement object including water;
Laser spectroscopic isotope for analyzing the isotope ratio of oxygen and / or hydrogen of water contained in the measurement object by irradiating the measurement object vaporized by the evaporator with laser light and performing laser spectroscopy. A pretreatment device in an isotope ratio analysis system, comprising: a body ratio analysis device; and a pretreatment device for treating the liquid measurement object, wherein the pretreatment device performs the liquid measurement object. The present invention relates to a pretreatment apparatus that removes an organic compound by treatment with an adsorbent before insertion into the evaporation apparatus. In one embodiment of the invention, the adsorbent comprises a hydrophobic zeolite and the organic compound is ethanol.

  By using the structure proposed in the present invention, an organic compound such as ethanol, which is an interference factor of water isotope ratio analysis by laser spectroscopy, is separated from alcoholic beverages, and then isotope is separated from almost pure water. Since ratio analysis can be performed, the accuracy of isotope ratio analysis by laser spectroscopy can be improved to a practical level. Therefore, the isotope ratio analysis of moisture in alcoholic beverages can be performed using a laser spectroscopic water oxygen and hydrogen isotope ratio analyzer that is small, inexpensive, and has excellent operability and portability.

(A) It is a schematic diagram of a structure of a wavelength tunable laser spectroscopy. (B) It is a figure explaining the drive method (relationship of time and a wavelength) of a light source. (C) It is a figure explaining the light reception intensity which a photodetector receives. It is the schematic showing the structure of the pretreatment apparatus for isotope ratio analysis. It is a figure showing the ethanol concentration dependence of the influence which ethanol has on the measured value of oxygen-hydrogen isotope ratio of water.

  The present invention relates to a method for discriminating / estimating information about the origin of a production area, production history, and the like of foods and beverages using a stable isotope ratio analysis method of water, and an isotope ratio analysis system thereof. Embodiments of the present invention will be described below.

  Isotopes are nuclides that have the same atomic number and different mass numbers. Stable isotopes exist in nature at an approximately constant ratio. However, isotopic fractionation occurs in the process of reaction and phase transition in nature due to the difference in mass, so the abundance ratio between stable isotopes (stable isotope ratio) varies depending on the environment and history in which stable isotopes exist. For example, the stable isotope ratios of hydrogen and oxygen in natural water (rivers, lakes, glaciers, all surface water including groundwater in various depths of the lithosphere infiltrated into underground rock layers) vary from region to region. It is known that In view of this, the present invention discriminates information relating to the origin of the production area, production history, and the like of foods and beverages from stable isotope ratio analysis of water.

  In the present invention, the production area of food or beverage refers to an area where the food or beverage is produced and manufactured. Moreover, the information regarding origins, such as a production history, refers to information regarding the origin of raw materials used in the production and production of the food or beverage. The production area or information to be discriminated may be either in Japan or outside Japan.

The stable isotope ratio to be measured in the present invention may be the ratio of oxygen, hydrogen, or both naturally occurring non-radioactive isotopes. Usually, the oxygen stable isotope ratio is ¹⁶ O and ¹⁸ O. The ratio may be used, and the ratio of ¹ H and D may be used as the hydrogen stable isotope ratio. These stable isotope ratios are usually expressed not by absolute ratios but by δ values represented by the following formulas as a thousandths deviation from the isotope ratio of the standard sample.

  The oxygen isotope ratio can be expressed by the following formula (I).

  The hydrogen stable isotope ratio can be expressed by the following formula (II).

(In the above formula, SAMP indicates the isotope ratio in the sample, and STD indicates the isotope ratio in the standard sample.)

  As the standard sample of stable isotope ratio, standard standard sea water (Vienna Standard Mean Ocean Water (VSMOW)) can be used as the standard sample of oxygen / hydrogen stable isotope ratio.

  Then, by comparing the measured stable isotope ratio of the measured sample with the stable isotope ratio of a control sample whose production area is known, information on the origin of the measurement sample such as the production area and production history can be determined. The present invention provides a method and system for analyzing the stable isotope ratio of water more easily using laser spectroscopy.

  In one embodiment of the present invention, an evaporation apparatus that vaporizes a liquid object to be measured containing water, and a measurement object vaporized by the evaporation apparatus are irradiated with laser light to perform laser spectroscopy. A laser spectroscopic isotope ratio analyzer for analyzing the oxygen and / or hydrogen isotope ratio of water contained therein, and the liquid object to be measured is treated with an adsorbent before being inserted into the evaporator. The present invention relates to an isotope ratio analysis system including a pretreatment device for removing a compound. In the present invention, the system may be a combination of each of the above-established devices, or may be a system in which a single device is built.

  The liquid measurement object measured by the isotope ratio measurement system of the present invention is a liquid containing at least water. Preferably, it is a food or beverage containing water, and may contain an organic compound such as alcohol or carboxylic acid.

  Examples of liquid objects to be measured by the isotope ratio measurement system of the present invention are not limited to these, but include alcoholic beverages such as wine, sake and beer, fruit and / or vegetable juices, mineral water, hot springs, and the like. Of water.

  The evaporator of the present invention may be any device that can vaporize water in the liquid measurement object. Preferably, it is a heating vaporization apparatus for analytical instruments. In one embodiment of the present invention, the measurement object vaporized by the evaporator is introduced into the isotope ratio analyzer through a tube. In another embodiment, the evaporation apparatus may be installed in the sample cell of the isotope ratio analyzer, and the object to be measured may be vaporized in the sample cell.

  The laser spectroscopic isotope ratio analyzer of the present invention analyzes the isotope ratios of oxygen and / or hydrogen of water contained in an object to be measured, or both. As shown in FIG. 1 a, the isotope ratio analyzer of the present invention includes a laser light source 1, a sample cell containing an object to be measured 3, and a light detection device 4.

  The laser light source 1 of the present invention preferably has a semiconductor laser (not shown). The semiconductor laser has a very narrow oscillation wavelength spectrum line width of the laser beam to be output, and can change the oscillation wavelength by changing the laser temperature and the drive current, and can measure only a specific absorption peak.

  The principle of laser gas spectroscopy will be described with reference to FIG. The light 2 emitted from the laser light source 1 passes through the sample cell where the measurement object 3 vaporized by the evaporator is present, and is detected by the light detection device 4. As the light detection device 4, a device that is normally used for detecting laser light in this field can be used. When there is an absorption line corresponding to the molecular vibration of the gaseous inspection object 3 within the swept wavelength range, the received light intensity received by the photodetector 4 corresponds to the absorption line of the measurement object 3 as shown in FIG. A dip (recessed light intensity) appears. The gas type and concentration of the DUT 3 are measured and analyzed based on the position and depth of the dip. Here, the wavelength sweep as shown in FIG. 1B may be performed continuously or may be performed discretely.

  In one embodiment, the laser spectroscopic isotope ratio analyzer of the present invention is made highly sensitive using techniques such as wavelength modulation spectroscopy, CRDS, and CEAS. When CRDS is used for high sensitivity, the laser beam 2 incident on the sample cell is a pulsed laser beam having a fixed wavelength, and the laser beam is formed in the sample cell using a high reflectance mirror. The optical resonance cavity resonates and is trapped in the sample cell. The light leaking from the cavity is detected by the photodetector 4, and the decay time (ring-down time) of the detected light becomes shorter as the absorption of the object 3 to be measured in the cavity becomes larger. By measuring the down time, it is possible to know the absorption intensity of the DUT 3 at the fixed wavelength. By sweeping the wavelength of the laser beam 2 discretely and repeating the measurement of the ring-down time, the type and concentration of the object to be measured 3 can be specified.

  The pretreatment apparatus of the present invention has a function of removing organic compounds by treating with an adsorbent before inserting the liquid measurement object into the evaporation apparatus. By removing the organic compound with the pretreatment device, it is possible to remove the noise of the detection result and obtain a measurement result with high accuracy and high sensitivity.

  The adsorbent is desirably capable of adsorbing all organic compounds. Preferably, those capable of adsorbing alcohols, carboxylic acids, esters and aldehydes are preferable, and those capable of adsorbing alcohols are particularly preferable. The adsorbent of the present invention preferably adsorbs lower alcohols such as ethanol and methanol and / or low molecular weight carboxylic acids such as citric acid, malic acid and tartaric acid.

  Specific examples of the adsorbent of the present invention include, but are not limited to, zeolite, silica gel, and alumina. In the present invention for measuring the isotope ratio of water, the adsorbent is preferably hydrophobized. As the hydrophobizing treatment, a treatment usually performed on the adsorbent can be used. In one embodiment of the invention, the adsorbent is a hydrophobic zeolite. A person skilled in the art can appropriately adjust the amount of the adsorbent used in accordance with the adsorbent and the liquid object to be measured. In another embodiment, the pretreatment is performed at least once on the liquid object to be measured, and may optionally be performed a plurality of times.

  FIG. 2 is a schematic diagram showing an embodiment of the pretreatment apparatus of the present invention. The pretreatment device includes a syringe 5, a filter 6, a powdery hydrophobic zeolite 7, an adapter 9, and a tube 10. Put the liquid measurement object 8 on the zeolite 7, plug it with the adapter 9, inject the compressed air 11 into the syringe 5 from the tube 19 attached to the adapter 9, and filter the liquid measurement object 8. Do. An organic compound such as ethanol is adsorbed on the zeolite 7, and a pretreated object 12 containing mainly water is dropped from the tip of the syringe 5 and collected in a container 13.

  In one embodiment of the present invention, in order to further improve the analysis accuracy, the measurement value may be corrected in consideration of the influence on the analysis value due to the adsorbent adsorbing water. For example, since hydrophobicity of hydrophobic zeolite is not perfect, a slight amount of moisture is adsorbed during the filtration process. Since the moisture adsorption rate varies depending on the isotope, the slight water adsorption changes the water isotope ratio before and after filtration. The amount of change in the water isotope ratio depends on the type of hydrophobic zeolite used, so the change in the isotope ratio before and after pretreatment is analyzed using the hydrophobic zeolite used, and the difference is corrected. As described above, the isotope ratio of the object to be measured may be corrected. In order to measure the amount of change in the isotope ratio of water before and after pretreatment, that is, the correction term, water with negligible content of organic compounds such as ethanol, such as tap water, is used, and the isotope ratio before and after filtration is determined. Just measure it.

  FIG. 3 shows an aqueous ethanol solution prepared by adding ethanol to tap water having an organic compound content of 0.5 mg / L or less, and the oxygen / hydrogen isotope ratio of the aqueous ethanol solution is determined by laser spectroscopic water oxygen.・ Measured using a hydrogen isotope ratio analyzer, and shows the effect of ethanol on the measured oxygen / hydrogen isotope ratio of water as a function of ethanol concentration. From FIG. 3, when the ethanol concentration is 1% by weight or less, the influence on the measured value of the oxygen / hydrogen isotope ratio is negligible and is negligible in many cases. However, when the ethanol concentration exceeds 1% by weight, It turns out that a big influence appears. Therefore, it is desirable that the water in which the content of the organic compound such as ethanol used for measuring the correction term is negligible has an ethanol concentration of 1% by weight or less.

  The isotope ratio analysis system of the present invention can further include a data processing device that uses an algorithm that corrects the isotope ratio of the object to be measured using the obtained correction term.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
The pretreatment of the alcohol-containing aqueous solution 8 having an ethanol concentration of 4.8% by weight, which is the alcohol concentration of a general beer beverage, is performed using the pretreatment apparatus of FIG. 2, and the oxygen and hydrogen isotopes of the water 12 obtained are obtained. The ratio was analyzed.

  A syringe 5 is filled with 48 g of a filter 6 and a powdery hydrophobic molecular sieve 7 (Union Showa Co., Ltd .: HiSiv3000 (powder)) in this order, and then 20 g of an alcohol-containing aqueous solution 8 as the object to be measured is put into the syringe. Did. Compressed air 11 was injected from the tube 10 attached to the adapter 9 into the syringe 5 to apply pressure, and the alcohol-containing aqueous solution 8 was filtered. Since organic compounds such as ethanol are adsorbed to the hydrophobic molecular sieve 7, filtered water 12 was dropped from the tip of the syringe and collected in the container 13.

A portion of the filtered water 12 collected in the container 13 is refilled into a sample bottle, and a laser spectroscopic water oxygen / hydrogen isotope analyzer (sampled by Picarro: L2120-i) equipped with a sampler and an evaporator. ) And oxygen and hydrogen isotope ratio analysis. An oxygen isotope ratio (δ ¹⁸ O _VSMOW ) and a hydrogen isotope ratio (δD _VSMOW ) were calculated using standard average seawater (VSMOW) as a standard sample. The results are shown in Table 1.

(Comparative Example 1)
The isotope ratio analysis was performed in the same manner as in Example 1 except that the pretreatment was not performed on the alcohol-containing aqueous solution 8 used in Example 1. Table 1 shows the results.

(Comparative Example 2)
The alcohol-containing aqueous solution 8 used in Example 1 was subjected to water isotope ratio analysis using an isotope ratio mass spectrometer. Table 1 shows the results.

  As can be seen from Table 1, the oxygen and hydrogen isotope ratio (Comparative Example 1) analyzed without pretreatment was far from the IRMS analytical value (Comparative Example 2) which seems to be close to the true value. On the other hand, the oxygen and hydrogen isotope ratio (Example 1) analyzed after the pretreatment according to the present invention was close to the analysis value by IRMS, and was found to be at a sufficiently reference level. .

(Example 2)
Tap water was pretreated using the pretreatment apparatus according to the present invention, and the oxygen and hydrogen isotope ratio analysis of water was performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 3)
The tap water subjected to Example 2 was subjected to isotope ratio analysis in the same manner as in Example 2 except that no pretreatment was performed. Table 2 shows the results.

  From the results in Table 2, it can be seen that in the case of the hydrophobic zeolite used this time, the oxygen and hydrogen isotope ratios were changed in the positive direction by about 0.5 ‰ and 3.0 ‰, respectively, by the pretreatment.

When the isotope ratio of Example 1 was corrected using this correction term, the corrected oxygen isotope ratio (δ ¹⁸ O _VSMOW ) and hydrogen isotope ratio (δD _VSMOW ) were −8.2 ‰ and −49, respectively. It was found to be 1 ‰ and substantially coincided with the analysis value of Comparative Example 2.

1. 1. Laser light source 2. Laser light DUT 4 4. Photodetector Syringe 6. Filter 7. Hydrophobic zeolite8. 8. An alcohol-containing aqueous solution as a measurement object Adapter 10. Tube 11. Compressed air12. Filtered water13. container

Claims (10)

An evaporation device for vaporizing a liquid object to be measured including water;
Laser spectroscopic isotope for analyzing the isotope ratio of oxygen and / or hydrogen of water contained in the measurement object by irradiating the measurement object vaporized by the evaporation apparatus with laser light and performing laser spectroscopy. A body ratio analyzer,
A water isotope ratio analysis system comprising: a pretreatment device that removes an organic compound by treating with an adsorbent before inserting the liquid measurement object into the evaporation device.   The isotope ratio analysis system according to claim 1, wherein the adsorbent is made of hydrophobic zeolite.   The isotope ratio analysis system according to claim 1, wherein the organic compound is ethanol. Water having an ethanol concentration of 1% by weight or less is pretreated using the pretreatment device, and isotope ratio measured using the evaporation device and the isotope ratio analyzer, and the ethanol concentration is 1% by weight or less. Using the difference from the isotope ratio measured using the evaporation apparatus and the isotope ratio analysis apparatus without pretreatment using the pretreatment apparatus as a correction term, water is included in the liquid measurement object . The isotope ratio analysis system according to any one of claims 1 to 3, further comprising a data processing device using an algorithm that corrects the isotope ratio of the water to be generated. A step of removing an organic compound by treating a liquid measurement object containing water with an adsorbent;
Vaporizing the liquid object to be measured;
By laser spectroscopy is irradiated with laser light to the vaporized measured object, that comprises the step of analyzing the oxygen or hydrogen or isotopic ratios of both the water contained in the liquid to be measured in Characteristic water isotope ratio analysis method.   The isotope ratio analysis method according to claim 5, wherein the adsorbent is made of a hydrophobic zeolite.   The isotope ratio analysis method according to claim 5 or 6, wherein the organic compound is ethanol. The handles with sorbent relative ethanol concentration 1 wt% water, and isotope ratio measured by laser spectroscopy is vaporized, the adsorbent the ethanol concentration 1 wt% water vaporized without treatment was used with the difference between the isotope ratio measured by laser spectroscopy as a correction term, using an algorithm to correct the isotope ratio of water contained in the liquid measured object The isotope ratio analysis method according to any one of claims 5 to 7, wherein the data processing is performed. An evaporation device for vaporizing a liquid object to be measured including water;
Laser spectroscopic isotope for analyzing the isotope ratio of oxygen and / or hydrogen of water contained in the measurement object by irradiating the measurement object vaporized by the evaporation apparatus with laser light and performing laser spectroscopy. A body ratio analyzer,
A pretreatment device in an isotope ratio analysis system, comprising a pretreatment device for treating the liquid object to be measured,
The pretreatment apparatus removes an organic compound by treating the liquid object to be measured with an adsorbent before inserting the liquid measurement object into the evaporation apparatus.   The pretreatment apparatus according to claim 9, wherein the adsorbent is a hydrophobic zeolite and the organic compound is ethanol.

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