Liquid chromatography separation and detection method for impurities in 2, 5-furandicarboxylic acid

Abstract

The invention relates to the technical field of chemical analysis, and discloses a liquid chromatography separation and detection method for impurities in 2, 5-furandicarboxylic acid, which comprises the following steps: detecting a 2, 5-furandicarboxylic acid sample by liquid chromatography: adopting a chromatographic column of pentafluorophenyl bonded silica gel filler; a mobile phase A and a mobile phase B are adopted as a mixed mobile phase for elution, the mobile phase A is a trifluoroacetic acid aqueous solution, and the mobile phase B is methanol; wherein when isocratic elution is adopted, the number of theoretical plates of a chromatographic column is greater than 46000; when gradient elution is adopted, the number of theoretical plates of the chromatographic column is greater than 37000. According to the present invention, the FDCA and the plurality of impurities in the sample can be separated and quantitatively determined at one time, the condition that the impurity peaks are completely or partially covered due to the overhigh FDCA content is avoided, the problem that the impurity peaks are severely overlapped and cannot be quantitatively determined is also avoided, the analysis precision is high, and the method is simple, rapid and effective.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical analysis, in particular to a liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid. Background Art

[0002] 2,5-Furandicarboxylic acid (FDCA) is an important bio-based platform compound that has garnered widespread attention from both academia and industry in recent years. Furandicarboxylic acid, with its rigid furan ring structure, can replace petroleum-based terephthalic acid (PTA) in the synthesis of polymer materials. The resulting polymers exhibit enhanced barrier properties and heat resistance, promising broad market prospects. The synthesis of FDCA primarily involves dehydrating biomass sugars to produce 5-hydroxymethylfurfural (HMF), which is then oxidized to FDCA. Due to the chemically active nature of HMF, the oxidation process produces, in addition to the main product FDCA, various trace impurities, including 2,5-furandicarboxaldehyde (DFF), 5-formyl-2-furoic acid (FFCA), and furoic acid (FCA). These impurities affect both the color of the FDCA product and the polymerization efficiency of FDCA during polymer synthesis.

[0003] At present, there is no perfect analysis method for impurities in FDCA. Patent publication number CN116087157B discloses a method for detecting trace colored impurities in 2,5-furandicarboxylic acid, but this method can only perform a qualitative analysis of the colored impurities in the FDCA product as a whole, and cannot specifically confirm the compound structure of the colored impurities, nor can it confirm the exact content of the compound. Patent publication number CN105974022B discloses a method for determining 5-hydroxymethylfurfural and its derivatives based on normal phase and reverse phase high performance liquid chromatography, which can achieve efficient separation of FDCA, FFCA, DFF, 5-hydroxymethyl-2-furoic acid (HMFCA), 5-hydroxymethylfurfural (HMF), and 2,5-furan dimethanol (BHMF). However, this method requires the use of two liquid chromatographs in combination to achieve this, with large equipment and capital investment and long analysis time. In addition, the substances analyzed by this method are not completely suitable for the products and impurities in the production of FDCA prepared by oxidation of HMF. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid. The method can simultaneously separate 2,5-furandicarboxylic acid (FDCA) and multiple impurities therein, including but not limited to maleic acid (MA), fumaric acid (FA), 5-hydroxymethylfurfural (HMF), 5-hydroxymethyl-2-furoic acid (HMFCA), 2,5-furandicarboxaldehyde (DFF), 5-formyl-2-furoic acid (FFCA), furoic acid (FCA), 5-methyl-2-furoic acid (MFCA), monomethyl 2,5-furandicarboxylate (MCFCA), and 5-bromo-2-furoic acid (Br-FCA) in a single test, thereby achieving qualitative and quantitative analysis of FDCA and all of the above impurities.

[0005] The purpose of the present invention is achieved through the following technical solutions: The invention provides a liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid, comprising the following steps: detecting a 2,5-furandicarboxylic acid sample by liquid chromatography: using a chromatographic column filled with pentafluorophenyl bonded silica gel; using a mobile phase A and a mobile phase B as a mixed mobile phase for elution, wherein the mobile phase A is a trifluoroacetic acid aqueous solution and the mobile phase B is methanol; wherein when isocratic elution is used, the theoretical plate number of the chromatographic column is greater than 46,000; and when gradient elution is used, the theoretical plate number of the chromatographic column is greater than 37,000.

[0006] The liquid chromatography column of the present invention uses a pentafluorophenyl bonded silica filler, which can better separate compounds with aromatic rings. In addition, using a specific mobile phase A and a mobile phase B as a mixed mobile phase for elution can achieve a better elution effect. FDCA and 10 major impurities in the sample can be separated and quantitatively determined at one time, avoiding the situation where impurity peaks are completely or partially masked due to excessive FDCA content, and also avoiding the problem of severe overlap between impurity peaks that cannot be quantified.

[0007] Preferably, the size of the chromatographic column is 2.1-4.6 mm×50-250 mm×1.9-4 μm.

[0008] The particle size of the chromatographic column is 1.9 to 4 μm, more preferably 2.7 to 4 μm. The inner diameter of the chromatographic column is 2.1 to 4.6 mm, more preferably 4.0 to 4.6 mm. The length of the chromatographic column is 50 to 250 mm, more preferably 200 to 250 mm.

[0009] This type of chromatographic column has a large size and a large column capacity, which can effectively avoid the possibility of FDCA, which has low solubility and precipitates in the chromatographic column and blocks the chromatographic column during FDCA sample analysis.

[0010] Preferably, the temperature of the chromatographic column is 20-60°C, more preferably 25-35°C.

[0011] Preferably, the mobile phase A is a trifluoroacetic acid aqueous solution with a mass fraction of 0.1 to 0.5%, more preferably a trifluoroacetic acid aqueous solution with a mass fraction of 0.2 to 0.3%; and the mobile phase B is methanol.

[0012] Preferably, during the isocratic elution, the volume percentage of mobile phase A to mobile phase B is 70-95%:5-30%, more preferably the volume percentage of mobile phase A to mobile phase B is 80%:20%.

[0013] When performing isocratic elution, a column with a theoretical plate number > 46,000 is preferred. If the theoretical plate number is < 46,000, some impurities may not be separated.

[0014] Preferably, during the isocratic elution, the flow rate of the mobile phase is 0.6 to 1.2 mL / min, more preferably 0.8 to 1.0 mL / min.

[0015] Preferably, the gradient elution program is set as follows: isocratic elution is adopted from 0 min to 4 to 6 min, and the volume percentages of mobile phase A and mobile phase B are 92 to 98%:2 to 8%; from 4 to 6 min to 17 to 19 min, the volume percentage of mobile phase A gradually decreases to 87 to 93%; from 17 to 19 min to 20 to 22 min, the volume percentage of mobile phase A gradually decreases to 30 to 70%; from 20 to 22 min to 26 to 28 min, isocratic elution is adopted, and the volume percentages of mobile phase A and mobile phase B are 30 to 70%:30 to 70%.

[0016] The gradient elution procedure in this invention does not use the conventional linear gradient elution method. Instead, it adopts an "isocratic 1 - gradient 1 - gradient 2 - isocratic 2" method. This ensures that the substances can be completely separated without mutual interference, while also ensuring a short testing time, meeting the testing requirements of the production process. The use of this gradient elution procedure reduces the requirements of the chromatographic column for isocratic elution. When performing gradient elution, the requirement for the theoretical plate number of the chromatographic column is lower, and the theoretical plate number >37,000 is sufficient.

[0017] The impurity phase in the sample has been basically separated within 26 to 28 minutes of gradient elution. Then the ratio of mobile phase A and B is adjusted to the initial ratio of the mobile phase and maintained for a period of time to allow the baseline to level out: from 26 to 28 minutes to 29 to 31 minutes, the volume percentage of mobile phase A gradually increases to 92 to 98%; from 29 to 31 minutes to 34 to 36 minutes, isocratic elution is used, and the volume percentages of mobile phase A and mobile phase B are 92 to 98%: 2 to 8%.

[0018] Preferably, during the gradient elution, the flow rate of the mobile phase is 0.6 to 1.2 mL / min.

[0019] Preferably, the detector of the liquid chromatography method is an ultraviolet detector (VWD) or a diode array detector (DAD); the detection wavelengths are three wavelengths detected simultaneously, namely 190-220 nm, 250-265 nm, and 275-290 nm.

[0020] Among them, 190-220nm is used to detect MA and FA, 250-265nm is used to detect FDCA, HMFCA, FCA, Br-FCA, and 275-290nm is used to detect HMF, DFF, and FFCA.

[0021] Preferably, the 2,5-furandicarboxylic acid sample in the liquid chromatography method is prepared by dissolving in a solvent, and the solvent is one or more of water, methanol, ethanol, acetonitrile, dioxane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and alkali solution.

[0022] Preferably, the alkali solution includes aqueous ammonia, sodium hydroxide solution or potassium hydroxide solution.

[0023] Preferably, the impurities in the 2,5-furandicarboxylic acid sample include one or more of maleic acid, fumaric acid, 5-hydroxymethylfurfural, 5-hydroxymethyl-2-furoic acid, 2,5-furandicarboxaldehyde, 5-formyl-2-furoic acid, furoic acid, 5-methyl-2-furoic acid, monomethyl 2,5-furandicarboxylate and 5-bromo-2-furoic acid.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention adopts specific high performance liquid chromatography analysis conditions to separate and quantitatively determine FDCA and 10 major impurities in a sample at one time, avoiding the situation where the impurity peaks are completely or partially masked due to excessive FDCA content, and also avoiding the problem of severe overlap between impurity peaks that cannot be quantified.

[0025] (2) The present invention can be used for the analysis of refined FDCA products as well as for the analysis of crude products, reaction solutions, residues, and other materials during the FDCA production process.

[0026] (3) The high performance liquid chromatography analysis method of the present invention has high analytical accuracy, and the minimum detection concentration can reach 0.01 ppm. In addition, the method is simple, rapid and effective, and avoids multiple detections of the same sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a chromatogram of the isocratic elution of the mixed standard sample using a chromatographic column with a theoretical plate number >46,000 in Example 1.

[0028] Figure 2 This is a chromatogram of an actual sample obtained by isocratic elution using a chromatographic column with a theoretical plate number >46,000 in Example 2.

[0029] Figure 3 This is the chromatogram of the actual sample obtained by isocratic elution using a chromatographic column with a theoretical plate number of <46,000 in Comparative Example 1.

[0030] Figure 4 The chromatogram is a chromatogram of FDCA and its impurities in the reaction solution separated by a gradient elution procedure in Example 3.

[0031] Figure 5 The chromatogram is obtained by separating FDCA and its impurities in the reaction solution using a conventional gradient elution procedure in Comparative Example 3. DETAILED DESCRIPTION

[0032] The technical solutions of the present invention are described below with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid of the present invention comprises the following steps: The 2,5-furandicarboxylic acid sample is detected by liquid chromatography. The 2,5-furandicarboxylic acid sample is prepared by solvent dissolution. The solvent is one or more of water, methanol, ethanol, acetonitrile, dioxane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and alkali solution (including ammonia water, sodium hydroxide solution or potassium hydroxide solution). The impurities in the 2,5-furandicarboxylic acid sample include one or more of maleic acid (MA), fumaric acid (FA), 5-hydroxymethylfurfural (HMF), 5-hydroxymethyl-2-furoic acid (HMFCA), 2,5-furandicarboxaldehyde (DFF), 5-formyl-2-furoic acid (FFCA), furoic acid (FCA), 5-methyl-2-furoic acid (MFCA), 2,5-furandicarboxylic acid monomethyl ester (MCFCA) and 5-bromo-2-furoic acid (Br-FCA).

[0034] Liquid chromatography conditions are as follows: (1) Chromatographic column: a column with pentafluorophenyl bonded silica gel packing, with dimensions of 2.1-4.6 mm × 50-250 mm × 1.9-4 μm; (2) Mobile phase: Isocratic or gradient elution; mobile phase A and mobile phase B are mixed for elution, where mobile phase A is trifluoroacetic acid aqueous solution and mobile phase B is methanol; (3) Flow rate: When using isocratic elution, the flow rate of the mobile phase is 0.6-1.2 mL / min; when using gradient elution, the flow rate of the mobile phase is 0.6-1.2 mL / min; (4) Detection wavelength: UV detector or diode array detector; detection wavelengths are 3 wavelengths detected simultaneously, namely 190-220 nm, 250-265 nm, and 275-290 nm; (5) Injection volume: 50 μL; (6) Column temperature: 20-60°C.

[0035] When isocratic elution is adopted, the volume percentages of mobile phase A and mobile phase B are 70-95%:5-30%, the flow rate of the mobile phase is 0.6-1.2 mL / min, and the theoretical plate number of the chromatographic column is greater than 46,000.

[0036] As shown in Table 1, the gradient elution program in the present invention does not adopt the conventional linear gradient elution method, but adopts the "isocratic 1-Gradient 1-Gradient 2-Isocratic 2" method. The program is set as follows: isocratic elution is adopted from 0 min to 4-6 min, and the volume percentages of mobile phase A and mobile phase B are 92-98%:2-8%; from 4-6 min to 17-19 min, the volume percentage of mobile phase A gradually decreases to 87-93%; from 17-19 min to 20-22 min, the volume percentage of mobile phase A gradually decreases to 30-70%; from 20-22 min to 26-28 min, isocratic elution is adopted, and the volume percentages of mobile phase A and mobile phase B are 30-70%:30-70%.

[0037] The gradient elution program sets "Isocratic 1" with a high proportion of phase A to quickly elute highly polar substances without π-π interactions (such as FA and MA elution) to prevent these substances and parts from interfering with subsequent characteristic peaks; then, "Gradient 1" slowly reduces the proportion of phase A from 92-98% to 87-93%. This is by slowly increasing the proportion of organic phase B in the mobile phase, which elutes substances with certain π-π interactions or dipole-dipole interactions with the chromatographic column more quickly and slowly separates impurity peaks such as HMF, HMFCA, DFF, FFCA, FCA, and FDCA; then, "Gradient 2" continues to gradually increase the proportion of organic phase B in the mobile phase, while avoiding large baseline fluctuations caused by direct switching; finally, "Isocratic 2" is to elute substances with strong π-π interactions and dipole-dipole interactions with the chromatographic column (MCFCA, Br-FCA) at a higher organic phase B concentration. Therefore, this gradient elution procedure ensures that all substances can be completely separated without mutual interference, while also ensuring a short testing time, meeting the testing requirements of the production process. The use of this gradient elution procedure reduces the requirements for the chromatographic column of isocratic elution. When performing gradient elution, the requirement for the theoretical plate number of the chromatographic column is lower, and the theoretical plate number >37,000 is sufficient.

[0038] Within 26 to 28 minutes of gradient elution, the impurity phase in the sample has been basically separated. Then the ratio of mobile phase A and B is adjusted to the initial ratio of the mobile phase and maintained for a period of time to allow the baseline to level out: from 26 to 28 minutes to 29 to 31 minutes, the volume percentage of mobile phase A gradually increases to 92 to 98%; from 29 to 31 minutes to 34 to 36 minutes, isocratic elution is used, and the volume percentages of mobile phase A and mobile phase B are 92 to 98%: 2 to 8%.

[0039] Table 1 Time (minutes) Mobile phase A (%) Mobile phase B (%) 0 92～98 2～8 4～6 92～98 2～8 17～19 87～93 7～13 20～22 30～70 30～70 26～28 30～70 30～70 29～31 92～98 2～8 34～36 92～98 2～8 Example 1 (isocratic elution) Experimental instrument: Agilent 1260 Infinity II high performance liquid chromatograph, diode array detector (DAD).

[0040] Test samples: a mixture of standard samples of fumaric acid (FA), 5-hydroxymethylfurfural (HMF), maleic acid (MA), 5-hydroxymethyl-2-furoic acid (HMFCA), 2,5-furandicarboxaldehyde (DFF), furoic acid (FCA), 5-formyl-2-furoic acid (FFCA), 2,5-furandicarboxylic acid (FDCA), 5-methyl-2-furoic acid (MFCA), 2,5-furandicarboxylic acid monomethyl ester (MCFCA), and 5-bromo-2-furoic acid (Br-FCA), all with a concentration of 0.05 wt%. The samples were prepared by diluting with a mixture of DMSO and water (the volume ratio of DMSO to water was 1:100).

[0041] Liquid chromatography conditions are as follows: (1) Chromatographic column: Agilent InfinityLab Poroshell 120PFP, 4.6 × 250 mm, 4 μm, theoretical plate number = 46004; (2) Mobile phase: Isocratic elution was used; mobile phase A and mobile phase B were used as a mixed mobile phase for elution, mobile phase A was 0.2 wt% trifluoroacetic acid in water, mobile phase B was methanol, and the volume percentage of mobile phase A to mobile phase B was 80%:20%; (3) Flow rate: The flow rate of the mobile phase is 0.8 mL / min; (4) Detection wavelength: The detection wavelength is 3 wavelengths detected simultaneously, namely 210nm, 260nm, and 283nm; (5) Injection volume: 50 μL; (6) Column temperature: 30°C.

[0042] The test results are as follows Figure 1As shown in the figure. In order of retention time, peaks 1-11 are FA, HMF, MA, HMFCA, DFF, FFCA, FCA, FDCA, MFCA, MCFCA, and Br-FCA. Compounds 1-5 have very close retention times, but because adjacent peaks within peaks 1-5 are observed at different wavelengths (peaks 1 and 3 are observed at 210 nm, peaks 2 and 4 are observed at 260 nm, and peak 5 is observed at 283 nm), this does not affect the qualitative and quantitative analysis of the sample.

[0043] Example 2 (isocratic elution) The experimental method and conditions were the same as those in Example 1, except that the test sample was changed to the FDCA crude product 1 in the actual production process.

[0044] Experimental instrument: Agilent 1260 Infinity II high performance liquid chromatograph, diode array detector (DAD).

[0045] Test sample: FDCA crude product 1 (FFCA content: 3047 ppm, FCA content: 106 ppm). Sample preparation was performed by diluting the crude product 1 with a mixture of DMSO and water (the volume ratio of DMSO to water was 1:100). The crude product 1 was diluted 1000-fold before injection.

[0046] Liquid chromatography conditions are as follows: (1) Chromatographic column: Agilent InfinityLab Poroshell 120PFP, 4.6 × 250 mm, 4 μm, theoretical plate number = 46004; (2) Mobile phase: Isocratic elution was used; mobile phase A and mobile phase B were used as a mixed mobile phase for elution, mobile phase A was 0.2 wt% trifluoroacetic acid in water, mobile phase B was methanol, and the volume percentage of mobile phase A to mobile phase B was 80%:20%; (3) Flow rate: The flow rate of the mobile phase is 0.8 mL / min; (4) Detection wavelength: The detection wavelength is 3 wavelengths detected simultaneously, namely 210nm, 260nm, and 283nm; (5) Injection volume: 50 μL; (6) Column temperature: 30°C.

[0047] The test results are as follows Figure 2 As shown, in the crude FDCA product 1, the impurity peaks of FDCA, FFCA and FCA can be clearly separated, and the chromatographic peaks of FFCA and FCA do not overlap, which can achieve a high degree of separation.

[0048] Comparative Example 1 (isocratic elution) The experimental method and conditions were the same as those in Example 2, except that the chromatographic column was replaced with an Agilent InfinityLab Poroshell 120PFP, 4.6×250 mm, 4 μm column with a theoretical plate number of 42780, and the test sample was changed to crude FDCA 2.

[0049] Experimental instrument: Agilent 1260 Infinity II high performance liquid chromatograph, diode array detector (DAD).

[0050] Test sample: FDCA crude product 2 (FFCA content: 1277 ppm, FCA content: 211 ppm). Sample preparation was performed by diluting the crude product with a mixture of DMSO and water (the volume ratio of DMSO to water was 1:100). The crude FDCA product was diluted 1000-fold before injection.

[0051] Liquid chromatography conditions are as follows: (1) Chromatographic column: Agilent InfinityLab Poroshell 120PFP, 4.6 × 250 mm, 4 μm, theoretical plate number = 42780; (2) Mobile phase: Isocratic elution was used; mobile phase A and mobile phase B were used as a mixed mobile phase for elution, mobile phase A was 0.2 wt% trifluoroacetic acid in water, mobile phase B was methanol, and the volume percentage of mobile phase A to mobile phase B was 80%:20%; (3) Flow rate: The flow rate of the mobile phase is 0.8 mL / min; (4) Detection wavelength: The detection wavelength is 3 wavelengths detected simultaneously, namely 210nm, 260nm, and 283nm; (5) Injection volume: 50 μL; (6) Column temperature: 30°C.

[0052] Compared with Example 2, Comparative Example 1 uses a chromatographic column with a lower theoretical plate number, and the FFCA content in the test sample used in Comparative Example 1 is lower than that in the test sample used in Example 2. When the lower concentration sample enters the chromatographic column, the mass transfer process of the solute molecules between the stationary phase and the mobile phase is more complete, which is more conducive to the separation of the chromatographic peaks. The test results are as follows: Figure 3 As shown in the figure, it can be seen that FFCA primarily overwhelms the FCA signal, making the FFCA content more influential. In Comparative Example 1, where the FFCA content is lower than in Example 2, the FFCA and FCA chromatographic peaks overlap, preventing complete separation and affecting quantitative analysis. This indicates that when using isocratic elution, the theoretical plate number of the liquid chromatography column needs to be set to >46,000 to ensure good elution and separation.

[0053] Example 3 (gradient elution) The experimental method and conditions were the same as those in Example 1, except that the test sample was changed to the FDCA oxidation reaction solution and the mobile phase was changed to the gradient elution program in Table 2.

[0054] Experimental instrument: Agilent 1260 Infinity II high performance liquid chromatograph, diode array detector (DAD).

[0055] Test sample: FDCA oxidation reaction solution. When preparing the sample, a mixture of DMSO and water was used for dilution (the volume ratio of DMSO to water was 1:100). The FDCA oxidation reaction solution was diluted 20 times before injection.

[0056] Liquid chromatography conditions are as follows: (1) Chromatographic column: Agilent InfinityLab Poroshell 120PFP, 4.6×250 mm, 4 μm, theoretical plate number = 46004; (2) Mobile phase: Gradient elution; mobile phase A and mobile phase B were used as a mixed mobile phase for elution, mobile phase A was a 0.2 wt% trifluoroacetic acid aqueous solution, and mobile phase B was methanol; the gradient elution program shown in Table 2 was used, and the program settings were as follows: isocratic elution was used from 0 min to 5 min, with the volume percentage of mobile phase A and mobile phase B being 95%:5%; from 5 min to 18 min, the volume percentage of mobile phase A and mobile phase B was 95%:5%. Within 1 minute, the volume percentage of mobile phase A gradually decreased to 90%; within 18 minutes to 21 minutes, the volume percentage of mobile phase A gradually decreased to 40%; within 21 minutes to 27 minutes, isocratic elution was adopted, and the volume percentages of mobile phase A and mobile phase B were 40%:60%; within 27 minutes to 30 minutes, the volume percentage of mobile phase A gradually increased to 95%; within 30 minutes to 35 minutes, isocratic elution was adopted, and the volume percentages of mobile phase A and mobile phase B were 95%:5%.

[0057] Table 2 Time (minutes) Mobile phase A (%) Mobile phase B (%) 0 95 5 5 95 5 18 90 10 21 40 60 27 40 60 30 95 5 35 95 5 (3) Flow rate: The flow rate of the mobile phase is 0.8 mL / min; (4) Detection wavelength: The detection wavelength is 3 wavelengths detected simultaneously, namely 210nm, 260nm, and 283nm; (5) Injection volume: 50 μL; (6) Column temperature: 30°C.

[0058] The precision and accuracy of this analytical method were determined by calculating spiked recoveries. After background determination of the homogenized sample, three sets of mixed standard samples with varying concentrations were added. Six replicates were performed at each concentration to obtain the average recoveries and relative standard deviations (RSDs). The results are shown in Table 3. Due to the lack of a standard, MCFCA was not quantified (only qualitative analysis of its chromatographic peak was possible).

[0059] Table 3 Object under test Linear range (mg / kg) Correlation coefficient R RSD (%) Average spike recovery (%) FDCA 5～100 0.9992 0.64 99.56 FA 1～50 0.9989 0.85 98.94 MA 0.1～5 0.9986 0.79 99.48 HMF 0.5～10 0.9995 0.31 99.70 HMFCA 0.01～0.5 0.9986 0.77 99.31 DFF 0.1～5 0.9980 0.91 98.65 FCA 0.01～0.5 0.9990 0.71 99.35 FFCA 0.01～0.5 0.9991 0.58 100.22 MCFCA none none none none Br-FCA 0.5～10 0.9997 0.81 99.64 The results show that the experimental data is accurate and reliable, and the test sample has a good quantitative ability even for materials with low concentrations (~0.01ppm). Using this method, the various substances in the FDCA oxidation reaction solution were determined, and the experimental results are as follows Figure 4 As shown, FDCA and various impurity components in the reaction solution can be well separated ( Figure 1 The order of "FA, HMF, MA" is the same as Figure 4 The order of “FA, MA, HMF” in the elution is different, which is mainly due to the slight difference caused by the different proportions of mobile phase in the elution process). The contents of each component are shown in Table 4.

[0060] Table 4 Object under test Content in test sample (ppm) Content in reaction solution (ppm) FDCA 69.9 1426.0 FA 44.7 911.1 MA 0.7 14.0 HMF 6.6 134.5 HMFCA 0.2 3.6 DFF 2.5 50.2 FCA 0.3 5.4 FFCA 0.5 9.6 MCFCA Unquantified Unquantified Br-FCA 5.2 105.8 Comparative Example 2 (gradient elution) The experimental method and conditions were the same as those in Example 1, except that the test sample was changed to the FDCA oxidation reaction solution and the mobile phase was changed to the gradient elution program in Table 5.

[0061] Experimental instrument: Agilent 1260 Infinity II high performance liquid chromatograph, diode array detector (DAD).

[0062] Test sample: FDCA oxidation reaction solution. When preparing the sample, a mixture of DMSO and water was used for dilution (the volume ratio of DMSO to water was 1:100). The FDCA oxidation reaction solution was diluted 20 times before injection.

[0063] Liquid chromatography conditions are as follows: (1) Chromatographic column: Agilent InfinityLab Poroshell 120PFP, 4.6×250 mm, 4 μm, theoretical plate number = 46004; (2) Mobile phase: Gradient elution; mobile phase A and mobile phase B were used as a mixed mobile phase for elution, mobile phase A was a 0.2 wt% trifluoroacetic acid aqueous solution, and mobile phase B was methanol; the gradient elution program shown in Table 5 was used, and the program was set as follows: the initial volume percentage of mobile phase A and mobile phase B was 95%:5%; gradient elution was performed from 0 min to 15 min, and the volume percentage of mobile phase A was gradually reduced to 40%; after the elution was completed, the volume percentage of mobile phase A was gradually increased back to 95% from 15 min to 16 min; then the volume percentage of mobile phase A and mobile phase B was maintained at 95%:5% from 16 min to 20 min, and the baseline was flat.

[0064] Table 5 Time (minutes) Mobile phase A (%) Mobile phase B (%) 0 95 5 15 40 60 16 95 5 20 95 5 (3) Flow rate: The flow rate of the mobile phase is 0.8 mL / min; (4) Detection wavelength: The detection wavelength is 3 wavelengths detected simultaneously, namely 210nm, 260nm, and 283nm; (5) Injection volume: 50 μL; (6) Column temperature: 30°C.

[0065] Comparative Example 5 was tested by liquid chromatography using a conventional linear gradient elution procedure. Figure 5 As shown, the adjacent impurity peaks of HMFCA, FFCA, and DFF cannot be separated, and the characteristic peak of FDCA cannot be separated from the impurity peak of HMF. In contrast, Example 3 uses the same test sample as Comparative Example 5 and adopts the elution program of "isocratic 1 - gradient 1 - gradient 2 - isocratic 2". This ensures that all substances can be completely separated and all impurity peaks are completely separated without mutual interference, while also ensuring a short test time, meeting the testing requirements of the production process.

[0066] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the description of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid, characterized in that: The method comprises the following steps: a 2,5-furandicarboxylic acid sample is detected by liquid chromatography: a chromatographic column is used which is a chromatographic column with pentafluorophenyl bonded silica gel filler; a mobile phase A and a mobile phase B are used as a mixed mobile phase for elution, wherein the mobile phase A is a trifluoroacetic acid aqueous solution and the mobile phase B is methanol; wherein when isocratic elution is used, the theoretical plate number of the chromatographic column is greater than 46,000; and when gradient elution is used, the theoretical plate number of the chromatographic column is greater than 37,000.

2. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1, characterized in that: The dimensions of the chromatographic column are 2.1 ~ 4.6 mm × 50 ~ 250 mm × 1.9 ~ 4 μm.

3. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1 or 2, characterized in that, The temperature of the chromatographic column is 20-60°C.

4. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1, characterized in that: During the isocratic elution, the volume percentages of mobile phase A and mobile phase B are 70-95%:5-30%.

5. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1 or 4, characterized in that: During the isocratic elution, the flow rate of the mobile phase is 0.6 to 1.2 mL / min.

6. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1, characterized in that: The gradient elution program is set as follows: isocratic elution is used from 0 min to 4-6 min, and the volume percentages of mobile phase A and mobile phase B are 92-98%:2-8%; from 4-6 min to 17-19 min, the volume percentage of mobile phase A gradually decreases to 87-93%; from 17-19 min to 20-22 min, the volume percentage of mobile phase A gradually decreases to 30-70%; from 20-22 min to 26-28 min, isocratic elution is used, and the volume percentages of mobile phase A and mobile phase B are 30-70%:30-70%.

7. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1 or 6, characterized in that: During the gradient elution, the flow rate of the mobile phase is 0.6-1.2 mL / min.

8. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1, characterized in that: The detector of liquid chromatography is an ultraviolet detector or a diode array detector; the detection wavelengths are three wavelengths detected simultaneously, namely 190~220nm, 250~265nm, and 275~290nm.

9. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1, characterized in that: In the liquid chromatography method, a 2,5-furandicarboxylic acid sample is prepared by dissolving in a solvent, and the solvent is one or more of water, methanol, ethanol, acetonitrile, dioxane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and alkali solution.

10. The liquid chromatography separation and detection method for impurities in 2,5-furandicarboxylic acid according to claim 1, 8 or 9, characterized in that: The impurities in the 2,5-furandicarboxylic acid sample include one or more of maleic acid, fumaric acid, 5-hydroxymethylfurfural, 5-hydroxymethyl-2-furoic acid, 2,5-furandicarboxaldehyde, 5-formyl-2-furoic acid, furoic acid, 5-methyl-2-furoic acid, monomethyl 2,5-furandicarboxylate and 5-bromo-2-furoic acid.

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