Mass spectrometry method, discrimination model creation method, fiber discrimination method, program, information processing device, and fiber discrimination system

Abstract

To improve the accuracy of discrimination in the discrimination of PET fibers using MALDI-MS. [Solution] The mass spectrometry method according to the present disclosure is a method for determining whether polyethylene terephthalate fibers contained in a target fiber are recycled fibers. The mass spectrometry method includes a step T10 of preparing a sample and a step T30 of measuring the sample using matrix-assisted laser desorption / ionization mass spectrometry. The sample preparation step T10 includes a step T14 of dissolving the target fiber in a first solvent to prepare a solution, a step T16 of adding tetrahydrofuran to the solution to separate the solution into a precipitate and a supernatant, a step T18 of obtaining the supernatant, and a step T22 of preparing a mixed solution containing the supernatant and a matrix on a sample plate.

Description

[Technical Field]

[0001] The present disclosure relates to a mass spectrometry method, a discrimination model creation method, a fiber discrimination method, a program, an information processing device, and a fiber discrimination system, and more particularly to improving the accuracy of determining whether polyethylene terephthalate fibers contained in fibers are recycled fibers. [Background technology]

[0002] Polyethylene terephthalate (PET) is a general-purpose synthetic fiber polymer widely used in clothing. Clothing often uses recycled PET fibers made from recycled PET bottles.

[0003] In the apparel market, there is a trend to add value to clothing by using recycled PET fibers, and there are concerns that labeling regarding the use of recycled PET fibers may be false. Therefore, there is a need for a method to determine whether or not a garment is made using recycled PET fibers.

[0004] As a method for determining whether PET fibers are recycled fibers derived from PET bottles, Guidelines for Ensuring the Reliability of Labeling of Specific Procurement Goods, etc., 4.8. Explanation of Survey Methods for Recycled Plastic Compounds (by Resin Type), Ministry of the Environment, March 2014 edition (Non-Patent Document 1) discloses a determination method that uses the amount of cyclic oligomers of PET measured by liquid chromatography as an indicator. Furthermore, Wanderson Romao, Marcos F. Franco, Amadeu H. Iglesias, Gustavo B. Sanvido, Danilo A. Maretto, Fabio C. Gozzo, Ronei J. Poppi, Marcos N. Eberlin, Marco-Aurelio De Paoli, Fingerprinting of bottle-grade poly(ethylene terephthalate) via matrix-assisted laser desorption / ionization mass spectrometry, Polymer Degradation and Stability, Volume 95, Issue 4, 2010, Pages 666-671 (Non-Patent Document 2) discloses a discrimination method based on mass spectral data obtained using matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Guidelines for Ensuring the Reliability of Labeling of Specific Procurement Goods, etc., 4.8. Explanation of Survey Methods for Recycled Plastic Compounds (by Resin Type), Ministry of the Environment, March 2014 Edition [Non-patent document 2] Wanderson Romao, Marcos F. Franco, Amadeu H. Iglesias, Gustavo B. Sanvido, Danilo A. Maretto, Fabio C. Gozzo, Ronei J. Poppi, Marcos N. Eberlin, Marco-Aurelio De Paoli, Fingerprinting of bottle-grade poly(ethylene terephthalate) via matrix-assisted laser desorption / ionization mass spectrometry, Polymer Degradation and Stability, Volume 95, Issue 4, 2010, Pages 666-671. Summary of the Invention [Problem to be solved by the invention]

[0006] Analysis by liquid chromatography requires a longer measurement time than other analytical techniques, and therefore the discrimination method using liquid chromatography disclosed in Non-Patent Document 1 may be limited in the number of specimens that can be discriminated per unit time.

[0007] Measurements using matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS), such as MALDI-TOF MS, require shorter measurement times than liquid chromatographs. Therefore, MALDI-MS methods can more quickly identify whether PET fibers contained in a sample are recycled fibers than liquid chromatographs. However, the mass-to-charge ratio and intensity of PET oligomer-derived ions in data obtained by MALDI-MS analysis of samples containing components other than PET oligomers, which are used as indicators for identification, can be affected by these components. Using such data can reduce the accuracy of fiber identification using MALDI-MS.

[0008] The present disclosure has been made in view of the above circumstances, and its purpose is to improve the accuracy of discrimination in the discrimination of PET fibers using MALDI-MS. [Means for solving the problem]

[0009] A mass spectrometry method according to one embodiment of the present disclosure is a method for determining whether PET fibers contained in a target fiber are recycled fibers. The mass spectrometry method includes the steps of preparing a sample and measuring the sample using MALDI-MS, where the sample preparation step includes the steps of dissolving the target fiber in a first solvent to prepare a solution, adding tetrahydrofuran to the solution to separate the solution into a precipitate and a supernatant, obtaining the supernatant, and preparing a mixed solution containing the supernatant and a matrix on a sample plate.

[0010] Another aspect of the present disclosure provides a discrimination model creation method for creating a discrimination model used to determine whether a PET fiber is a recycled fiber, the method comprising the steps of: acquiring a plurality of reference mass spectral data sets obtained by measuring a plurality of reference fibers using MALDI-MS, each of the plurality of reference mass spectral data sets being associated with recycle information indicating whether the PET fiber contained in the corresponding reference fiber is a recycled fiber; acquiring a theoretical value of the mass-to-charge ratio of at least one PET oligomer; extracting a signal intensity corresponding to the theoretical value from each of the plurality of reference mass spectral data sets; performing multivariate analysis using the recycle information and the signal intensity; and creating a discrimination model using the results of the multivariate analysis. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to improve the accuracy of discrimination in discrimination of PET fibers using MALDI-MS. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a configuration of a fiber discrimination system according to an embodiment. [Figure 2] FIG. 10 is a diagram for explaining a pre-analysis process. [Figure 3] 1 is a flowchart showing a process for acquiring mass spectrum data of fibers containing PET. [Figure 4] This is an example of mass spectrum data obtained by analyzing PET oligomers. [Figure 5] FIG. 2 is a diagram for explaining a process of extracting signal intensities from mass spectrum data. [Figure 6] FIG. 1 is a diagram for explaining a method for creating a discrimination model for determining whether PET is a recycled fiber or not. [Figure 7] FIG. 10 is a diagram for explaining data used in multivariate analysis to create a discriminant model. [Figure 8] FIG. 10 is a diagram showing an example of the results of multivariate analysis. [Figure 9] 10 is a flowchart illustrating a procedure for creating a discrimination model. [Figure 10] 1 is a diagram for explaining a method for determining whether PET fibers contained in target fibers are recycled fibers using a discrimination model. FIG. [Figure 11] 10 is a flowchart illustrating a procedure for determining whether PET fibers contained in fibers are recycled fibers using a discrimination model. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0014] [Configuration of fiber discrimination system] FIG. 1 is a diagram showing the configuration of a fiber discrimination system 200 according to an embodiment. Referring to FIG. 1, the fiber discrimination system 200 includes an information processing device 100, a mass spectrometer 20, an input device 30, and a display device 40. The fiber discrimination system 200 discriminates whether PET fibers contained in the fibers to be discriminated (hereinafter referred to as target fibers) are recycled fibers based on mass spectrum data obtained by mass spectrometry of a sample prepared from the fibers to be discriminated (hereinafter referred to as target fibers). The fiber discrimination system according to this embodiment discriminates the target fibers based on the signal intensity of ions derived from PET oligomers in the mass spectrum data.

[0015] The mass spectrometer 20 is a device for performing mass analysis of a sample. Analysis using the mass spectrometer 20 includes detecting peaks in mass spectrum data and measuring the mass-to-charge ratio of substances contained in the sample. A mass spectrum is a graph in which the mass-to-charge ratio is plotted on the horizontal axis and the signal intensity of detected ions on the vertical axis. In this specification, the mass spectrometer 20 will be described as an example of a device that acquires mass spectrum data of a sample by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS). However, the method of mass analysis is not particularly limited as long as it is possible to acquire appropriate ion intensity information regarding PET oligomer components.

[0016] The mass spectrometer 20 irradiates a sample prepared on a sample plate P with a laser to ionize the components in the sample. The mass spectrometer 20 separates and detects the ions according to the time they take to fly through a flight tube. The time of flight of an ion correlates with the mass-to-charge ratio of the component from which the ion originated.

[0017] The mass spectrometer 20 includes an ionization section 21, an ion acceleration section 22, a mass separation section 23, and a detection section 24. In Fig. 1, the movement of ions S in the mass spectrometer 20 is schematically shown by arrows A1, A2, and A3.

[0018] The ionization unit 21 ionizes substances in the sample by the MALDI method. The ionization unit 21 includes an ion source having a sample plate holder (not shown) that supports the sample plate P and a laser device (not shown) that irradiates laser light onto the sample plate P. The type of laser device is not particularly limited as long as it can emit light that is absorbed by the selected matrix. The laser device is, for example, a nitrogen laser.

[0019] The sample plate P is a typical MALDI plate, such as a plate made of stainless steel or conductive resin. The sample plate P may also be subjected to surface treatments, such as water-repellent or hydrophilic treatments, to improve sensitivity. The user drops a mixed solution of a sample liquid, a matrix, and a cationizing agent onto the sample plate P. As the solvent in the mixed solution evaporates, mixed crystals of the sample liquid, matrix, and cationizing agent are formed on the sample plate P. The sample plate P with the mixed crystals formed on its surface is placed in a sample plate holder in a vacuum chamber of the ionization unit 21. The user may drop the mixed solution of the sample liquid, matrix, and cationizing agent onto the sample plate P, or may mix the sample liquid, matrix, and cationizing agent on the sample plate P to form droplets of the mixed solution. In this specification, the mixed crystals correspond to the sample for MALDI measurement.

[0020] The sample solution is a supernatant obtained by removing impurities from a solution in which PET-containing fibers have been dissolved by a dissolution-reprecipitation method. A method for preparing a sample for MALDI measurement using the supernatant will be described later.

[0021] The matrix is ​​not particularly limited as long as it can measure PET oligomers, and an example of the matrix is ​​dithranol.

[0022] The cationizing agent is not particularly limited as long as it can promote the ionization of the component by laser irradiation, and an example is sodium iodide.

[0023] The ionization unit 21 reduces the pressure of a vacuum chamber in which a sample plate P is placed, and then irradiates laser light onto the mixed crystal on the sample plate P. Ions S generated in the ionization unit 21 by the irradiation of the laser light are extracted by an electric field created by an extraction electrode (not shown) and introduced into the ion acceleration unit 22 as indicated by arrow A1 in FIG.

[0024] The ion acceleration unit 22 includes an acceleration electrode 221 and accelerates the introduced ions S. The flow of the accelerated ions S is appropriately converged by an ion lens (not shown) and introduced into the mass separation unit 23 as indicated by arrow A2 in FIG.

[0025] The mass separation unit 23 includes a flight tube 231, and separates the ions S based on the difference in flight time when each ion S flies inside the flight tube 231. While an example of a linear type flight tube 231 is shown in FIG. 1, a reflectron type or multi-turn type flight tube can also be used. Note that the method of mass analysis is not particularly limited as long as it can separate and detect ions S derived from compounds contained in the sample.

[0026] The detection unit 24 includes an ion detector, detects the ions S separated by the mass separation unit 23 as indicated by arrow A3, and outputs a detection signal having an intensity corresponding to the number of ions incident on the detection unit 24. The detection signal output from the detection unit 24 is input to the information processing device 100.

[0027] In the fiber identification system 200, the mass spectrometer 20 performs mass analysis of PET oligomers in a sample prepared from fibers. That is, by mass analysis, peaks corresponding to the mass-to-charge ratios of the PET oligomers in the sample are detected.

[0028] The mass spectrometer 20 generates mass spectrum data by analyzing the sample prepared on the sample plate P. The mass spectrometer 20 transmits the generated mass spectrum data to the information processing device 100.

[0029] The information processing device 100 includes, as its main components, a processor 10, a memory 11, a communication interface (I / F) 12, and an input / output I / F 13. These components are communicably connected to each other via a bus. The information processing device 100 is, for example, a computer. Note that the information processing device 100 does not need to be configured by a single computer, and may be configured by multiple computers.

[0030] The processor 10 is an example of an electric circuit, and controls the operation of the information processing device 100 by executing a given program. The program executed by the processor 10 may be stored in the memory 11, or may be stored in a storage device external to the information processing device 100. The processor is, for example, a CPU (Central Processing Unit).

[0031] Memory 11 non-temporarily stores programs executed by processor 10, mass spectral data obtained by mass analysis, and discrimination models. The programs, mass spectral data, and discrimination models stored in memory 11 include reference mass spectral data 111, recycle information 112, discrimination model creation program 113, discrimination model 114, target mass spectral data 115, and discrimination program 116. Memory 11 includes volatile memory (e.g., random access memory (RAM)) and non-volatile memory (e.g., read-only memory (ROM), hard disk drive, and solid state drive). The database and / or program may be stored in an external storage device accessible by processor 10.

[0032] The reference mass spectrum data 111 is mass spectrum data obtained from a fiber (hereinafter referred to as a reference fiber) for which it is clear whether the PET fiber contained therein is a recycled fiber. The recycle information 112 is information indicating whether the PET fiber contained in the reference fiber is a recycled fiber, and is stored in memory 11 in association with the corresponding reference mass spectrum data 111. The discrimination model creation program 113 is a program for creating a discrimination model 114 used to discriminate fibers, using the reference mass spectrum data 111 and the recycle information 112. The method for creating the discrimination model 114 will be described later.

[0033] The discrimination program 116 is a program that discriminates whether PET fibers contained in the target fibers are recycled fibers or not, using target mass spectrum data 115, which is mass spectrum data derived from the target fibers to be discriminated, and a discrimination model 114. The discrimination of the target fibers by the discrimination program 116 will be described later.

[0034] The communication I / F 12 is a communication interface for exchanging various data with external devices. The communication I / F 12 is realized by, for example, a network adapter. The communication method may be wireless communication such as Bluetooth (registered trademark) or wireless LAN, or wired communication using USB (Universal Serial Bus) or the like.

[0035] The input / output I / F 13 is an interface for exchanging various data between the processor 10 and external devices connected to the input / output I / F 13. The external devices include a mass spectrometer 20, an input device 30, and a display device 40.

[0036] The information processing device 100 may control the mass spectrometer 20, or the mass spectrometer 20 may be connected to a separate control device (for example, a computer) and the mass spectrometer 20 may be controlled by the separate control device.

[0037] The input device 30 includes, for example, at least one of a mouse, a keyboard, and a touch panel, and accepts operations on the information processing device 100 and input of information to the information processing device 100. The information is, for example, information regarding the recycling of the reference fiber.

[0038] The display device 40 includes, for example, a liquid crystal display or an organic EL (Electro Luminescence) display, and displays information according to instructions from the information processing device 100. The information is, for example, mass spectrum data and the discrimination results of the target fiber.

[0039] [Comparative Example] PET is a general-purpose polymer for synthetic fibers and is widely used in clothing. Clothing often uses recycled PET fibers made from recycled PET bottles.

[0040] In the apparel market, there is a trend to add value to clothing by using recycled PET fibers, and there are concerns that labeling regarding the use of recycled PET fibers may be false. Therefore, there is a need for a method to determine whether or not a garment is made using recycled PET fibers.

[0041] As a method for determining whether PET fibers are recycled fibers derived from PET bottles, Non-Patent Document 1 discloses a method using the amount of PET cyclic oligomers measured using liquid chromatography as an indicator. The amount of cyclic oligomers in PET decreases during the solid-state polymerization process used in the manufacture of PET bottles. Therefore, in a liquid chromatographic determination method, whether the PET fibers contained in the target fiber are recycled fibers is determined based on the measured amount of PET cyclic oligomers in the fiber. However, the measurement time using liquid chromatography is longer than that of other analytical methods, resulting in a smaller number of samples that can be measured per unit time. Furthermore, the amount of cyclic oligomers in PET also decreases when the PET is dyed or subjected to hot water stretching. Therefore, in a liquid chromatographic fiber determination method using the amount of PET cyclic oligomers as an indicator, the accuracy of determination may decrease for fibers that have been dyed and subjected to hot water stretching.

[0042] Non-Patent Document 2 discloses a discrimination method based on mass spectral data obtained using MALDI-TOF MS. In this discrimination method using MALDI-TOF MS, fibers are discriminated based on the signal intensity of peaks derived from PET oligomers. Because MALDI-TOF MS requires a shorter measurement time than liquid chromatographs, it can measure a greater number of samples per unit time than liquid chromatographs. However, components other than oligomers contained in the sample may affect MALDI-TOF MS measurements, which may reduce the accuracy of discrimination.

[0043] Focusing on the fact that the PET used in PET bottles is copolymerized with isophthalic acid (IPA), a method has been proposed in which signals due to isophthalic acid (IPA) are detected using FTIR or Raman spectroscopy to determine whether PET fibers are recycled fibers derived from PET bottles. However, this method may have poor accuracy when determining whether blended fabrics contain fibers other than PET.

[0044] As described above, a discrimination method using MALDI-MS such as MALDI-TOF MS requires less time for discrimination than other analytical techniques, but there is a demand for improving the discrimination accuracy of this method.

[0045] [Fiber discrimination method according to the embodiment] Therefore, the fiber identification method of the present disclosure extracts signal intensities corresponding to PET oligomers from target mass spectrum data obtained by measuring a sample prepared by pre-analysis using tetrahydrofuran (THF) using MALDI-MS, using the theoretical value of the mass-to-charge ratio of the oligomer as an index, and determines whether the PET fiber contained in the target fiber is a recycled fiber.

[0046] By using THF in the pre-analysis process, it is possible to remove components (e.g., polymers) other than PET oligomers, which are used as indicators for identification using MALDI-MS. This increases the degree of purification of oligomers in the high molecular weight region, which are used as indicators for identification using MALDI-MS. As a result, the signal-to-noise ratio of signals corresponding to oligomers in the high molecular weight region in the mass spectrum data of the target fiber is improved, thereby improving the accuracy of fiber identification.

[0047] Furthermore, in the fiber discrimination method according to the present disclosure, the theoretical mass-to-charge ratio of PET oligomers, which serves as a discrimination index, is used to extract signal intensities corresponding to PET oligomers from mass spectrum data. Therefore, there is no need to perform peak identification processes or processes to correct the mass-to-charge ratio in the obtained mass spectrum data. Furthermore, this discrimination method can prevent peaks originating from components other than the target components from being used as discrimination indexes from being mistakenly used as discrimination indexes. This makes it possible to accurately extract signal intensities corresponding to PET oligomers, which serve as discrimination indexes.

[0048] The pre-analysis process in the mass spectrometry method according to the present disclosure does not require chemical reactions such as decomposing PET polymers into monomers or esterifying the monomers, thereby reducing the burden on the user regarding pre-analysis.

[0049] Furthermore, the fiber identification method according to the present disclosure uses data obtained by MALDI-MS to identify fibers. Therefore, the time required to acquire data is shorter than with other analytical techniques. This allows for an increased number of specimens to be identified per unit time.

[0050] Specific processing contents of the fiber identification method according to the embodiment will be described below. [Pre-analysis] First, a mass spectrometry method for generating mass spectrum data will be described. FIG. 2 is a diagram for explaining an outline of pre-analysis processing in the mass spectrometry method according to the present disclosure. In the pre-analysis processing for preparing a sample to be supplied to the mass spectrometer 20, first, (1) a first solvent is added to a container containing chopped fibers to dissolve the fibers. Next, (2) THF is added to the container, causing the dissolved polymer molecules and impurities to precipitate. Then, (3) the solution after the addition of THF is centrifuged and filtered to remove the precipitate and obtain the supernatant. The supernatant obtained in (3) contains PET oligomers, which serve as an indicator for discrimination in the discrimination method according to this embodiment. The user prepares a sample using the supernatant obtained in (3) and measures it using the mass spectrometer 20.

[0051] The type of first solvent is not limited as long as it can dissolve the fibers to be subjected to mass analysis. For example, a liquid mixture of hexafluoro-2-propanol (HFIP: Hexafluoroisopropylalcohol) and chloroform in a volume ratio of 1:1 is used.

[0052] As for the amount of solution, for example, 100 mg of fibers is dissolved in 1 mL of the first solvent, and 5 mL or more of THF is added to the solution.

[0053] 3 is a flowchart showing the process of mass spectrometry according to the embodiment. Step T10 of the steps shown in FIG. 3 is performed manually by a user using laboratory equipment commonly used in scientific experiments and mass spectrometry. Step T30 of the steps shown in FIG. 3 is performed by mass spectrometer 20.

[0054] In step T10, the user prepares a sample to be subjected to MALDI-MS. In Figure 3, step T10 is subdivided into steps T12 to T24.

[0055] In step T12, the user chops the fibers and places them in a container. In step T14, the user adds the first solvent to the container to dissolve the fibers. For example, 1 mL of the first solvent is added to 100 mg of fibers.

[0056] In step T16, the user adds THF to the container to separate the solution into a precipitate and a supernatant. If the first solvent used in step T14 is 1 mL, for example, the user adds 5 mL or more of THF to adjust the total liquid volume to 10 mL.

[0057] In step T18, the user removes the precipitate and obtains the supernatant. In step T20, the user prepares a solution of the matrix and the cationizing agent. The matrix and the cationizing agent are dissolved in, for example, THF.

[0058] In step T22, the user prepares a mixture by mixing the supernatant obtained in step T16 with the solution of the matrix and cationizing agent prepared in step T18.

[0059] In step T24, the user drops the mixed liquid prepared in step T22 onto the sample plate P and dries it.

[0060] In step T30, the sample plate P prepared in step T24 is subjected to the mass spectrometer 20, which generates mass spectrum data of the samples.

[0061] According to the above-described mass spectrometry method, components other than PET oligomers, which are used as indicators for identification using MALDI-MS, are precipitated and removed. This allows for a higher degree of purification of the high-molecular-weight PET oligomers in the supernatant. As a result, the signal-to-noise ratio of the peaks derived from high-molecular-weight oligomers in the mass spectrum data of the target fiber is improved, thereby improving the accuracy of fiber identification.

[0062] [Signal intensity extraction method] Next, a method for extracting signal intensities corresponding to PET oligomers, which serve as indicators for discrimination, from the mass spectrum data obtained by the above-described processing will be described.

[0063] PET oligomers have four types of molecular structures: linear oligomers with hydroxyl groups at both ends; cyclic oligomers, which are linear oligomers with one water molecule removed from both ends to form a ring; linear DEG-added oligomers, which are linear oligomers with diethylene glycol (DEG) added to the ends; and cyclic DEG-added oligomers, which are linear DEG-added oligomers with one water molecule removed from both ends to form a ring.

[0064] Figure 4 shows an example of mass spectrum data acquired by the fiber discrimination method according to this embodiment. In Figure 4, the peak at m / z 1368.7 is derived from a cyclic heptamer oligomer, and the peak at m / z 1387.2 is derived from a linear heptamer oligomer. The peak at m / z 1413.4 is derived from a cyclic heptamer oligomer with DEG addition, and the peak at m / z 1431.4 is derived from a linear heptamer oligomer with DEG addition.

[0065] While Figure 4 shows the mass-to-charge ratio range within which peaks derived from heptamer molecules are detected among PET oligomers, the PET oligomers used as indicators for discrimination in the discrimination method according to this embodiment are not limited to heptamers. For example, trimer- to decamer oligomers may be used as indicators for discrimination. In this case, for each trimer- to decamer oligomer, there are molecules with four types of molecular structures: linear oligomer, cyclic oligomer, linear DEG-added oligomer, and cyclic DEG-added oligomer. Therefore, 8 (trimers to decamers) x 4 (four types of molecular structures) = 32 types of oligomers are used as indicators for discrimination.

[0066] FIG. 5 is a diagram illustrating a method for extracting signal intensities from the obtained mass spectrum data by referring to the theoretical values ​​of the mass-to-charge ratios of PET oligomers, which are used as indicators for discrimination.

[0067] 5, the information processing device 100 calculates theoretical values ​​of mass-to-charge ratios of ions derived from PET oligomers, which serve as indicators for discrimination, and lists the calculated theoretical values. The information processing device 100 then extracts signal intensities corresponding to the mass-to-charge ratios in the list from mass spectrum data obtained by mass spectrometry of the fibers. Therefore, the information processing device 100 can extract signal intensities corresponding to PET oligomers, which serve as indicators for discrimination, without performing peak assignment processing in the mass spectrum data.

[0068] The PET oligomers used as indicators for discrimination are mono- or higher-mer oligomers that may be specified by the user or may be predetermined. The PET oligomers used as indicators for discrimination are, for example, trimers to decamers, and there are 32 types of oligomers that are distinguished into four types of molecular structures: linear oligomers, cyclic oligomers, linear DEG-added oligomers, and cyclic DEG-added oligomers.

[0069] The theoretical value of the mass-to-charge ratio of the PET oligomer, which is used as an index for discrimination, may be input by the user or may be calculated by the information processing device 100 based on the molecular formula of the oligomer.

[0070] Generally, when a molecule is measured using a mass spectrometer 20, ions are detected that have several types of cations attached to the molecule. The mass-to-charge ratio of the ions varies depending on the type of cation attached. Therefore, in mass spectrum data, several peaks resulting from the same molecule but with different types of cations attached may be detected. In the fiber identification method according to this embodiment, to prevent this situation from occurring, the sample and matrix are mixed with a cationizing agent and then dropped onto the sample plate P. This prevents the detection of ions with multiple types of cations attached. The cationizing agent is, for example, sodium iodide, and in this case, ions with sodium ions attached are detected. In this case, the theoretical value of the mass-to-charge ratio of the PET oligomer, which serves as an indicator for identification, is the theoretical value when sodium ions are added.

[0071] In the signal intensity extraction method according to this embodiment, it is preferable that each oligomer has only one theoretical value. Therefore, it is preferable that mass spectrum data be acquired in a linear mode in which ions fly in a straight line. The acquired mass spectrum data may be subjected to a smoothing process.

[0072] According to the above-described signal intensity extraction method, the signal intensity is extracted from the mass spectrum data using the theoretical value of the mass-to-charge ratio of the PET oligomer, which is used as an index for discrimination. Therefore, there is no need to perform peak identification processing or processing to correct the mass-to-charge ratio in the obtained mass spectrum data. According to the signal intensity extraction method of this embodiment, it is possible to prevent the extracted signal intensity value from differing from the obtained mass spectrum data.

[0073] Furthermore, according to the above-described signal intensity extraction method, the signal intensity corresponding to the theoretical value of the mass-to-charge ratio of the PET oligomer, which is used as an indicator for discrimination, is extracted from the mass spectrum data, thereby preventing the erroneous use of peaks derived from components other than the PET oligomer (for example, other blended polymer fibers and surfactants mixed in during production) as an indicator for discrimination.

[0074] [Creating a discriminant model] Next, a description will be given of a procedure for creating the discriminant model 114. Fig. 6 is a block diagram for explaining a procedure for creating the discriminant model 114.

[0075] As shown in FIG. 6, the information processing device 100 executes a discrimination model creation program 113 to create a discrimination model 114. Specifically, reference mass spectrum data 111, which is mass spectrum data derived from a reference fiber, is called from the memory 11. The reference mass spectrum data 111 is associated with recycle information 112 indicating whether the PET fiber contained in the corresponding reference fiber is a recycled fiber. The information processing device 100 acquires a theoretical value of the mass-to-charge ratio of the PET oligomer, which serves as an index for discrimination. The information processing device 100 extracts the signal intensity of the PET oligomer, which serves as an index for discrimination, from the reference mass spectrum data 111 using the signal intensity extraction method described above.

[0076] The reference mass spectral data 111 is mass spectral data obtained by measuring a sample prepared from reference fibers, which are known to contain recycled PET fibers, using the above-described mass spectrometry method with the mass spectrometer 20. Specifically, the reference mass spectral data 111 includes mass spectral data of a sample prepared from a plurality of fibers containing recycled PET fibers and mass spectral data of a sample prepared from a plurality of fibers containing non-recycled PET fibers.

[0077] The recycle information 112 is information indicating whether the PET fiber contained in the reference fiber is a recycled fiber or not, and is stored in the memory 11 in association with the corresponding reference mass spectrum data 111.

[0078] The information processing device 100 performs multivariate analysis using signal intensity information and recycle information 112. FIG. 7 shows an example of data used by the discriminant model creation program 113. In FIG. 7, "cyclic" indicates a cyclic oligomer, "linear" indicates a linear oligomer, "DEG_cyclic" indicates a cyclic DEG-added oligomer, and "DEG_linear" indicates a linear DEG-added oligomer. As shown in FIG. 7, multivariate analysis is performed using data including recycle information and signal intensities extracted from reference mass spectrum data of a reference fiber corresponding to the recycle information.

[0079] The multivariate analysis is, for example, an analysis using partial least squares (PLS). The information processing device 100 uses the signal intensities of a total of 32 types of oligomers, distinguishing four types of molecular structures (linear oligomers, cyclic oligomers, linear DEG-added oligomers, and cyclic DEG-added oligomers) for each of eight types of oligomers (trimers to decamers), as variables to calculate factors and their loadings for classifying fibers into those containing recycled PET fibers and those not. Specifically, the signal intensities of the 32 types of oligomers are used as explanatory variables in the analysis, and whether the PET fibers contained in the corresponding fibers are recycled fibers or not is used as a response variable in the analysis.

[0080] Figure 8 shows a PLS score plot as an example of the results of multivariate analysis, where filled circles represent data points obtained from fibers that do not contain recycled PET fibers, and open circles represent data points obtained from recycled PET fibers.

[0081] As shown in Figure 8, the data points obtained from the fibers that do not contain recycled PET fibers are plotted within region A, and the data points obtained from the recycled PET fibers are plotted within region B, grouping the reference fibers according to whether they contain recycled PET fibers or not.

[0082] In this way, multivariate analysis reveals the type and loading of PET oligomers that are factors in distinguishing between fibers that do not contain recycled PET fibers and those that do.

[0083] The information processing device 100 generates a discriminant model 114 using the results of the multivariate analysis. Generating the discriminant model 114 means, for example, calculating the center of gravity of each of region A and region B in FIG. 8. The center of gravity is the average value of the discriminant function values ​​of each group obtained as a result of the multivariate analysis. Alternatively, it means finding the line segment separating the filled-in circles from the unfilled circles in FIG. 8. A method for discriminating fibers using the discriminant model 114 will be described later.

[0084] [Process flow (creating a discriminant model)] 9 is a flowchart for explaining the procedure for creating the discriminant model 114. The information processing device 100 causes the processor 10 to execute the discriminant model creation program 113, thereby carrying out the processing of this flowchart.

[0085] 9, in step S10, processor 10 detects an operation to start creating discriminant model 114. For example, when a user uses input device 30 to perform an operation to start creating discriminant model 114, the operation is detected in step S10.

[0086] In step S12, the processor 10 reads and acquires the reference mass spectrum data 111 from the memory 11. The reference mass spectrum data 111 is associated with recycle information 112.

[0087] In step S14, the processor 10 acquires the theoretical value of the mass-to-charge ratio of the PET oligomer used as the discrimination index. The oligomer used as the discrimination index may be specified by the user or may be predetermined. The theoretical value of the mass-to-charge ratio of the oligomer used as the discrimination index may be input by the user or may be calculated by the information processing device 100 based on the molecular formula.

[0088] In step S16, the processor 10 extracts the signal intensity of the mass-to-charge ratio corresponding to the theoretical value of the oligomer, which is used as an index for discrimination, from the reference mass spectrum data 111.

[0089] In step S18, processor 10 performs multivariate analysis using recycle information 112 acquired in step S12 and the signal intensities extracted in step S16.

[0090] In step S20, the processor 10 generates a discriminant model based on the result of the multivariate analysis in step S18.

[0091] In step S22, the processor 10 stores the discriminant model 114 generated in step S20 in the memory 11. Thereafter, the processor 10 ends the series of processes shown in FIG.

[0092] [Identification of target fibers] A method for determining whether or not PET fibers contained in target fibers are recycled fibers using the discrimination model 114 will be described.

[0093] The information processing device 100 executes the discrimination program 116 to determine whether the PET fiber contained in the target fiber is a recycled fiber. Specifically, first, the target mass spectrum data 115, which is mass spectrum data derived from the target fiber, is retrieved from the memory 11. The target mass spectrum data 115 is preferably mass spectrum data obtained from the target fiber to be discriminated by the above-described mass spectrometry method.

[0094] Next, the information processing device 100 extracts the signal intensities of the oligomers used as indicators for discrimination by the above-described signal intensity extraction method from the target mass spectrum data 115. The oligomers used as indicators for discrimination are, for example, trimers to decamers, and there are 32 types of oligomers obtained by distinguishing four types of molecular structures for each oligomer: linear oligomers, cyclic oligomers, linear DEG-added oligomers, and cyclic DEG-added oligomers.

[0095] The information processing device 100 then inputs the signal intensity of the oligomer extracted from the target mass spectrum data 115 as an index for discrimination into the discrimination model 114. Fig. 10 is a diagram for explaining a method for discriminating fibers based on the signal intensity of the target mass spectrum data obtained from the target fibers.

[0096] FIG. 10 shows a score plot from the multivariate analysis performed in the process of creating the discrimination model 114. In FIG. 10, region A represents the region where data points obtained from fibers not containing recycled PET fibers are plotted, and region B represents the region where data points obtained from fibers containing recycled PET fibers are plotted. In FIG. 10, point GA represents the center of gravity of region A, and point GB represents the center of gravity of region B. Point Q is plotted on the score plot based on the signal intensity extracted from the target mass spectrum data 115 input from the information processing device 100. The distances between point Q derived from the target mass spectrum data 115 and points GA and GB are shown by lines L1 and L2, respectively. In FIG. 10, line L1 is less than line L2, so point Q is determined to be close to region A, which is a fiber that does not contain recycled PET fibers. The discrimination program 116 then outputs a discrimination result that the target fiber does not contain recycled PET fibers.

[0097] 10 shows an example of a discrimination model in which the average value of the discriminant function values ​​for each group obtained as a result of multivariate analysis is used as the center of gravity, the distance between a point specified by the value of the discriminant function calculated from the signal intensity of the target fiber and the center of gravity of each group is calculated, and the target fiber is discriminated as belonging to the group with the center of gravity closer to the point, but the discrimination model 114 in the discrimination method according to this embodiment is not limited to this. For example, the discrimination model 114 may discriminate the target fiber by linear discrimination.

[0098] The information processing device 100 outputs a display signal for displaying the obtained discrimination result to the display device 40. By checking the content displayed on the display device 40, the user can recognize whether the PET fiber contained in the target fiber is a recycled fiber or not.

[0099] [Processing flow (identification of target fibers)] The procedure for determining whether PET fibers contained in target fibers are recycled fibers will be described with reference to a flowchart. Fig. 11 is a flowchart for explaining the procedure for determining target fibers based on target mass spectrum data 115 obtained from the target fibers using a discrimination model 114. The processing of this flowchart is realized by the processor 10 of the information processing device 100 executing a discrimination program 116.

[0100] 11, in step S40, the processor 10 reads and acquires the target mass spectrum data 115 from the memory 11. The target mass spectrum data 115 is input to the memory 11 of the information processing device 100 via a measuring device such as the mass spectrometer 20 connected to the input / output I / F 13. The data acquired in step S40 is mass spectrum data derived from the target fiber to be identified. Preferably, the target mass spectrum data 115 is mass spectrum data acquired by the mass analysis method described above.

[0101] In step S42, the processor 10 acquires the theoretical value of the mass-to-charge ratio of the oligomer used as the discrimination index. The oligomer used as the discrimination index may be specified by the user or may be predetermined. The theoretical value of the mass-to-charge ratio of the oligomer used as the discrimination index may be input by the user or may be calculated by the information processing device 100 based on the molecular formula.

[0102] In step S44, the processor 10 extracts from the target mass spectrum data 115 the signal intensity of the mass-to-charge ratio corresponding to the theoretical value of the oligomer used as an index for discrimination.

[0103] In step S46, the processor 10 inputs the signal intensity extracted in step S44 into the discrimination model 114, and determines whether the PET fiber contained in the target fiber is a recycled fiber.

[0104] In step S48, the processor 10 stores in the memory 11 the determination result obtained in step S46.

[0105] In step S50, processor 10 outputs a display signal for displaying the determination result in step S46 to display device 40. Thereafter, processor 10 ends the series of processes shown in FIG.

[0106] In the fiber identification method according to this embodiment, THF is used in the pre-analysis process. By using THF in the pre-analysis process, components other than oligomers (e.g., polymers) that serve as indicators for identification using MALDI-MS can be removed. This increases the degree of purification of oligomers in the high molecular weight region that serve as indicators for identification using MALDI-MS. As a result, the signal-to-noise ratio of peaks derived from oligomers in the high molecular weight region in the mass spectrum data of the target fiber can be improved, thereby improving the accuracy of fiber identification.

[0107] Furthermore, in the fiber identification method according to the present disclosure, the signal intensity is extracted from mass spectrum data using the theoretical mass-to-charge ratio of the oligomer, which serves as an indicator for identification. Therefore, there is no need to perform peak identification processes or processes to correct the mass-to-charge ratio in the obtained mass spectrum data. Furthermore, there is no risk of erroneously using peaks originating from components other than the target component as an indicator for identification. This makes it possible to accurately extract the signal intensity corresponding to the oligomer, which serves as an indicator for identification.

[0108] The pre-analysis process in the mass spectrometry method according to the present disclosure does not require chemical reactions such as decomposing PET polymers into monomers or esterifying the monomers, thereby reducing the burden on the user regarding pre-analysis.

[0109] Furthermore, the fiber identification method according to the present disclosure uses data obtained by MALDI-MS. Therefore, the time required for measurement is shorter than that required for other analytical techniques. This allows for an increase in the number of specimens that can be identified per unit time.

[0110] [Aspect] It will be understood by those skilled in the art that the above-described embodiment and its modifications are specific examples of the following aspects.

[0111] (Item 1) A mass spectrometry method according to one embodiment is a mass spectrometry method for determining whether polyethylene terephthalate fibers contained in target fibers are recycled fibers, and includes the steps of preparing a sample and measuring the sample using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The step of preparing the sample may include the steps of dissolving the target fibers in a first solvent to prepare a solution, adding tetrahydrofuran to the solution and separating the solution into a precipitate and a supernatant, obtaining the supernatant, and preparing a mixed solution containing the supernatant and a matrix on a sample plate.

[0112] According to the mass spectrometry method described in paragraph 1, the signal-to-noise ratio of peaks derived from oligomers in the high molecular weight region in mass spectrum data of fibers can be improved, thereby improving the accuracy of fiber identification.

[0113] (Item 2) In the mass spectrometry method described in Item 1, the first solvent may be a liquid in which hexafluoro-2-propanol and chloroform are mixed in a volume ratio of 1:1.

[0114] According to the mass spectrometry method described in paragraph 2, molecules other than PET oligomers dissolved in a liquid mixture of hexafluoro-2-propanol and chloroform in a volume ratio of 1:1 are precipitated by adding THF.

[0115] (Item 3) In the separating step in the mass spectrometry method according to item 1 or 2, 5 ml or more of the tetrahydrofuran may be added to 100 mg of the target fiber.

[0116] According to the mass spectrometry method described in item 3, it is possible to precipitate molecules other than oligomers while leaving oligomers in solution.

[0117] (Item 4) In the step of preparing the sample in the mass spectrometry method according to any one of Items 1 to 3, 5 ml or more of the tetrahydrofuran may be added to 1 mL of the first solvent.

[0118] According to the mass spectrometry method described in item 4, it is possible to precipitate molecules other than oligomers while leaving oligomers in solution.

[0119] (Item 5) In the mass spectrometry method according to any one of items 1 to 4, the matrix may contain dithranol.

[0120] According to the mass spectrometry method described in item 5, the detection efficiency of PET oligomers in MALDI-MS can be improved.

[0121] (Item 6) In the mass spectrometry method according to any one of items 1 to 5, the mixed solution may contain sodium iodide.

[0122] According to the mass spectrometry method described in paragraph 6, when PET oligomers are ionized by laser irradiation, they become ions with added sodium ions. As a result, the mass-to-charge ratios of PET oligomers in the obtained mass spectrum data correspond to the sodium-added ions of each oligomer.

[0123] (Item 7) In the mass spectrometry method according to any one of items 1 to 6, the MALDI-MS may be matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

[0124] According to the mass spectrometry method described in item 7, the fibers can be identified using mass spectrum data obtained by MALDI-TOF MS.

[0125] (Item 8) A discrimination model creation method according to one embodiment is a discrimination model creation method for creating a discrimination model used to determine whether polyethylene terephthalate (PET) fibers are recycled fibers, and includes a step of acquiring a plurality of reference mass spectral data obtained by measuring a plurality of reference fibers using MALDI-MS, each of which is associated with recycling information indicating whether the PET fibers contained in the corresponding reference fibers are recycled fibers, and may further include a step of acquiring a theoretical value of the mass-to-charge ratio of at least one oligomer of PET, a step of extracting a signal intensity corresponding to the theoretical value from each of the plurality of reference mass spectral data, a step of performing multivariate analysis using the recycling information and the signal intensity, and a step of generating a discrimination model using the results of the multivariate analysis.

[0126] By using a discrimination model created by the discrimination model creation method described in Section 8, the accuracy of fiber discrimination can be improved.

[0127] (Item 9) In the discrimination model creation method described in Item 8, the multiple reference mass spectral data may be generated by a mass spectrometry method including the steps of dissolving the reference fiber in a first solvent to prepare a solution, adding tetrahydrofuran to the solution to separate the solution into a precipitate and a supernatant, obtaining the supernatant, and preparing a mixed solution containing the supernatant and a matrix on a sample plate.

[0128] According to the discrimination model creation method described in paragraph 9, it is possible to improve the accuracy of fiber discrimination.

[0129] (Item 10) In the method for creating a discrimination model described in either item 8 or 9, the theoretical values ​​may include theoretical values ​​of the mass-to-charge ratios of PET oligomers having four types of molecular structures: a 3- to 10-mer oligomer, a linear oligomer having hydroxyl groups at both ends; a cyclic oligomer formed by removing one water molecule from both ends of the linear oligomer; a linear DEG-added oligomer having diethylene glycol (DEG) added to the ends of the linear oligomer; and a cyclic DEG-added oligomer formed by removing one water molecule from both ends of the linear DEG-added oligomer.

[0130] According to the method for creating a discrimination model described in item 10, a discrimination model can be created based on the signal intensities of PET oligomers that are 3- to 10-mer oligomers and have four types of molecular structures.

[0131] (Item 11) In the discriminant model creation method according to any one of Items 8 to 10, the multivariate analysis may include partial least squares.

[0132] According to the method for creating a discriminant model described in paragraph 11, a discriminant model can be created using the partial least squares method.

[0133] (Item 12) In the method for creating a discrimination model according to any one of Items 8 to 11, the MALDI-MS may be matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

[0134] According to the discrimination model creation method described in Item 12, a discrimination model can be created using mass spectrum data obtained by MALDI-TOF MS.

[0135] (Clause 13) A program according to one aspect may be executed by a processor installed in a computer to cause the computer to execute the discriminant model creation method according to any one of clauses 8 to 12.

[0136] According to the program described in paragraph 13, the accuracy of fiber identification can be improved. (Item 14) A fiber discrimination method according to one embodiment is a fiber discrimination method for discriminating whether polyethylene terephthalate (PET) fibers contained in target fibers are recycled fibers, and includes the steps of acquiring target mass spectrum data obtained by measuring the target fibers using matrix-assisted laser desorption / ionization mass spectrometry, acquiring a theoretical value of the mass-to-charge ratio of at least one PET oligomer, extracting a signal intensity corresponding to the theoretical value from the target mass spectrum data, and inputting the signal intensity into a discrimination model to determine whether the PET fibers contained in the target fibers are recycled fibers, and the discrimination model may be created by a discrimination model creation method described in any one of items 8 to 12.

[0137] According to the fiber identifying method described in item 14, the accuracy of identifying fibers can be improved. (Item 15) In the fiber identification method described in Item 14, each of the target mass spectral data may be generated by a mass spectrometry method including the steps of dissolving the target fiber in a first solvent to prepare a solution, adding tetrahydrofuran to the solution to separate the solution into a precipitate and a supernatant, obtaining the supernatant, and preparing a mixed solution containing the supernatant and a matrix on a sample plate.

[0138] According to the fiber identifying method described in item 15, it is possible to improve the accuracy of identifying fibers. (Item 16) In the fiber identification method described in Item 14 or 15, the theoretical values ​​may include theoretical values ​​of the mass-to-charge ratios of PET oligomers having four types of molecular structures: a 3- to 10-mer oligomer, a linear oligomer having hydroxyl groups at both ends; a cyclic oligomer formed by removing one water molecule from both ends of the linear oligomer to form a ring; a linear DEG-added oligomer formed by adding diethylene glycol (DEG) to the ends of the linear oligomer; and a cyclic DEG-added oligomer formed by removing one water molecule from both ends of the linear DEG-added oligomer to form a ring.

[0139] According to the fiber identifying method described in item 16, fibers can be identified based on the signal intensity of PET oligomers, which are tri- to decameric oligomers and have four types of molecular structures.

[0140] (Item 17) The fiber identifying method according to any one of items 14 to 16 may further include a step of displaying the identification result in the determining step.

[0141] According to the fiber discrimination method described in paragraph 17, the user can easily recognize whether the PET fiber contained in the target fiber is a recycled fiber by checking the displayed discrimination result.

[0142] (Item 18) A program according to one aspect is a program that, when executed by a processor installed in a computer, causes the computer to execute the fiber discrimination method according to any one of items 14 to 17.

[0143] According to the program described in paragraph 18, the accuracy of fiber identification can be improved. (Item 19) An information processing device according to one embodiment comprises at least one processor and a memory accessible to the one or more processors, the memory storing one or more instructions to be executed by the processor, and the processor executing the one or more instructions to acquire target mass spectral data obtained by measuring a target fiber using matrix-assisted laser desorption / ionization mass spectrometry, acquire a theoretical value of the mass-to-charge ratio of at least one oligomer of PET, extract a signal intensity corresponding to the theoretical value from the target mass spectral data, input the signal intensity into a discrimination model, and determine whether the PET fiber contained in the target fiber is a recycled fiber, and the discrimination model may be created by a discrimination model creation method described in any one of items 8 to 12.

[0144] According to the information processing device described in the 19th paragraph, it is possible to improve the accuracy of fiber identification. (Item 20) A fiber discrimination system according to one aspect may include the information processing device according to item 19 and a matrix-assisted laser desorption ionization time-of-flight mass spectrometer.

[0145] According to the fiber discrimination system described in paragraph 20, it is possible to determine whether or not PET fibers contained in target fibers are recycled fibers using mass spectrum data obtained by MALDI-TOF MS.

[0146] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0147] 10 processor, 11 memory, 12 communication interface, 20 mass analyzer, 21 ionization unit, 22 ion acceleration unit, 23 mass separation unit, 24 detection unit, 30 input device, 40 display device, 100 information processing device, 111 reference mass spectrum data, 112 recycling information, 113 discrimination model creation program, 114 discrimination model, 115 target mass spectrum data, 116 discrimination program, 200 fiber discrimination system, 221 acceleration electrode, 231 flight tube.

Claims

1. A mass spectrometry method for determining whether polyethylene terephthalate fibers contained in target fibers are recycled fibers, comprising: preparing a sample; measuring the sample using matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS); The step of preparing the sample comprises: Dissolving the target fiber in a first solvent to prepare a solution; adding tetrahydrofuran to the solution and separating the solution into a precipitate and a supernatant; obtaining the supernatant; and preparing a mixed solution containing the supernatant and a matrix on a sample plate.

2. 2. The mass spectrometry method according to claim 1, wherein the first solvent is a liquid mixture of hexafluoro-2-propanol and chloroform in a volume ratio of 1:

1.

3. 3. The mass spectrometry method according to claim 1, wherein in the separating step, 5 ml or more of the tetrahydrofuran is added to 100 mg of the target fiber.

4. 3. The mass spectrometry method according to claim 1, wherein in the step of preparing the sample, 5 ml or more of the tetrahydrofuran is added to 1 mL of the first solvent.

5. The mass spectrometry method according to claim 1 or 2, wherein the matrix contains dithranol.

6. 3. The mass spectrometry method according to claim 1, wherein the mixed solution contains sodium iodide.

7. 3. The mass spectrometry method according to claim 1, wherein the MALDI-MS is matrix-assisted laser desorption / ionization time-of-flight mass spectrometry.

8. A method for creating a discrimination model used to determine whether a polyethylene terephthalate (PET) fiber is a recycled fiber, comprising: The method includes a step of acquiring a plurality of reference mass spectrum data obtained by measuring a plurality of reference fibers by MALDI-MS, Each of the plurality of reference mass spectrum data is associated with recycle information indicating whether the PET fiber contained in the corresponding reference fiber is a recycled fiber, obtaining a theoretical mass-to-charge ratio of at least one oligomer of PET; extracting a signal intensity corresponding to the theoretical value from each of the plurality of reference mass spectrum data; performing a multivariate analysis using the recycling information and the signal intensities; and generating a discriminant model using a result of the multivariate analysis.

9. The plurality of reference mass spectral data are Dissolving the reference fiber in a first solvent to prepare a solution; adding tetrahydrofuran to the solution and separating the solution into a precipitate and a supernatant; obtaining the supernatant; The method for creating a discriminant model according to claim 8 , wherein the discriminant model is generated by a mass spectrometry method including a step of preparing a mixed solution containing the supernatant and a matrix on a sample plate.

10. 10. The method for creating a discrimination model according to claim 8 or 9, wherein the theoretical values ​​include theoretical values ​​of mass-to-charge ratios of PET oligomers having four types of molecular structures: a 3- to 10-mer oligomer, a linear oligomer having hydroxyl groups at both ends; a cyclic oligomer formed by elimination of one water molecule from both ends of the linear oligomer; a linear DEG-added oligomer formed by addition of diethylene glycol (DEG) to the ends of the linear oligomer; and a cyclic DEG-added oligomer formed by elimination of one water molecule from both ends of the linear DEG-added oligomer.

11. The discriminant model creating method according to claim 8 or 9, wherein the multivariate analysis includes a partial least squares method.

12. 10. The method for creating a discrimination model according to claim 8, wherein the MALDI-MS is matrix-assisted laser desorption / ionization time-of-flight mass spectrometry.

13. A program that, when executed by a processor mounted on a computer, causes the computer to execute the discriminant model creation method according to claim 8 or 9.

14. A fiber discrimination method for determining whether polyethylene terephthalate (PET) fibers contained in target fibers are recycled fibers, comprising: measuring the target fiber by matrix-assisted laser desorption / ionization mass spectrometry to obtain target mass spectral data; obtaining a theoretical mass-to-charge ratio of at least one oligomer of PET; extracting signal intensities corresponding to the theoretical values ​​from the target mass spectrum data; and inputting the signal intensity into a discrimination model to determine whether the PET fiber contained in the target fiber is a recycled fiber. A fiber discrimination method, wherein the discrimination model is created by the discrimination model creation method according to claim 8 .

15. Each of the target mass spectral data is Dissolving the target fiber in a first solvent to prepare a solution; adding tetrahydrofuran to the solution and separating the solution into a precipitate and a supernatant; obtaining the supernatant; The fiber identification method according to claim 14, wherein the detected fiber is generated by a mass spectrometry method including a step of preparing a mixed solution containing the supernatant and a matrix on a sample plate.

16. The theoretical values ​​include theoretical values ​​of the mass-to-charge ratios of PET oligomers having four types of molecular structures: a 3- to 10-mer oligomer, a linear oligomer having hydroxyl groups at both ends; a cyclic oligomer formed by removing one water molecule from both ends of the linear oligomer; a linear DEG-added oligomer in which diethylene glycol (DEG) is added to the ends of the linear oligomer; and a cyclic DEG-added oligomer formed by removing one water molecule from both ends of the linear DEG-added oligomer. The fiber discrimination method according to claim 14 or 15, wherein the theoretical values ​​include theoretical values ​​of the mass-to-charge ratios of PET oligomers having four types of molecular structures: a 3- to 10-mer oligomer, a linear oligomer having hydroxyl groups at both ends of the linear oligomer; a cyclic DEG-added oligomer in which diethylene glycol (DEG) is added to the ends of the linear oligomer; and a cyclic DEG-added oligomer in which one water molecule is removed from both ends of the linear DEG-added oligomer.

17. The fiber identifying method according to claim 14 or 15, further comprising a step of displaying a result of the identification in the determining step.

18. A program that, when executed by a processor mounted on a computer, causes the computer to execute the fiber determination method according to claim 14 or 15.

19. at least one processor; a memory accessible to the one or more processors; the memory stores one or more instructions for execution by the processor; The processor executes the one or more instructions to: Obtaining target mass spectrum data obtained by measuring the target fiber by matrix-assisted laser desorption / ionization mass spectrometry; obtaining a theoretical mass-to-charge ratio of at least one oligomer of PET; extracting signal intensities corresponding to the theoretical values ​​from the target mass spectrum data; inputting the signal intensity into a discrimination model to determine whether the PET fiber contained in the target fiber is a recycled fiber; The information processing device, wherein the discriminant model is created by the discriminant model creating method according to claim 8 .

20. The information processing device according to claim 19; and a matrix-assisted laser desorption ionization time-of-flight mass spectrometer.

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