Method for simultaneously determining 5-hydroxymethylfurfural and oxidation products thereof

Abstract

The invention provides a method for simultaneously determining 5-hydroxymethylfurfural and oxidation products thereof, which comprises the following steps: providing a reaction mixture obtained by oxidation reaction of 5-hydroxymethylfurfural, the reaction mixture comprising 5-hydroxymethylfurfural and oxidation products thereof; filtering the reaction mixture to obtain filtrate and filter residues; preparing the filtrate into a first to-be-detected solution, mixing the filter residue with an inorganic base so that an indissolvable oxidation product in the filter residue is subjected to a salt forming reaction to be dissolved, and preparing the solution into a second to-be-detected solution; the first to-be-detected solution and the second to-be-detected solution are subjected to high performance liquid chromatography analysis, and conditions of high performance liquid chromatography analysis are as follows: a stationary phase is an organic acid analysis column, and the column temperature is 25-60 DEG C; a mobile phase is an inorganic acid aqueous solution, and the flow velocity of the mobile phase is 0.4-1 mL / min; the sample size is 1 mu L to 20 mu L; dual-wavelength detection is adopted, the first detection wavelength ranges from 200 nm to 240 nm, and the second detection wavelength ranges from 250 nm to 300 nm. The method provided by the invention has good separation degree, relatively high accuracy and relatively high precision.

Description

Technical Field

[0001] The invention belongs to the technical field of furan bio-based compound content determination, and specifically relates to a method for simultaneously determining 5-hydroxymethylfurfural and its oxidation product. Background Art

[0002] 5-Hydroxymethylfurfural (HMF) is a bio-based intermediate with an aromatic furan structure. It is a platform compound with high technical content, great application potential, and clean and environmentally friendly. It is expected to lead the chemical industry from the "benzene era" to the cleaner and more environmentally friendly "furan era". 2,5-Furandicarboxylic acid (FDCA) is a bio-based chemical with long-term and extensive application potential. It is considered by experts to be an important candidate for sustainable chemicals to replace existing petrochemicals. It has broad application prospects in polyester plastics, coatings, fiber fabrics and other fields. Compared with traditional petrochemicals, FDCA has lower carbon emissions, better degradability and a wider range of resource sources. Finding a green and efficient method for preparing FDCA has become one of the research hotspots.

[0003] At present, there are many routes for synthesizing FDCA. Among them, the synthesis of FDCA by oxidation reaction using HMF as raw material is the most studied and most extensive route, and is also considered to be the most promising route for large-scale production of FDCA, with important economic benefits. However, this reaction is prone to produce by-products. In addition to FDCA, it usually also has oxidation by-products such as 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), 5-formyl-2-furancarboxylic acid (FFCA), fumaric acid (FA) and maleic acid (MA). Among them, FDCA, HMFCA and FFCA have similar structures, and the current high-performance liquid chromatography analysis method has a low degree of separation for the three, making it difficult to accurately determine the content of the three. In addition, the ring-opening oxidation products FA and MA cannot produce effective ultraviolet absorption at the wavelength of other oxidation products, and there are problems of qualitative and quantitative inaccuracies. It is difficult to effectively separate and determine multiple oxidation components of 5-hydroxymethylfurfural at the same time. Summary of the invention

[0004] In order to solve all or part of the above technical problems, the present invention provides the following technical solutions:

[0005] One of the objects of the present invention is to provide a method for simultaneously determining 5-hydroxymethylfurfural and its oxidation products, comprising:

[0006] Providing a reaction mixture obtained after an oxidation reaction of 5-hydroxymethylfurfural, the reaction mixture comprising 5-hydroxymethylfurfural and an oxidation product thereof, wherein the oxidation product comprises one or more of 2,5-furandicarboxylic acid, 2,5-furandicarboxaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, and maleic acid;

[0007] The reaction mixture is filtered to obtain a filtrate and a filter residue; the filtrate is prepared as a first test solution, the filter residue is mixed with an inorganic base to make the insoluble oxidation product in the filter residue undergo a salt-forming reaction and dissolve, and the mixture is prepared as a second test solution;

[0008] Performing high performance liquid chromatography analysis on the first test solution and the second test solution respectively, so as to perform qualitative and / or quantitative detection on the substances contained in the reaction mixture;

[0009] Among them, the conditions of the high performance liquid chromatography analysis include: the stationary phase is an organic acid analysis column, the column temperature is 25°C to 60°C; the mobile phase is an inorganic acid aqueous solution, the flow rate of the mobile phase is 0.4 to 1 mL / min; the injection volume is 1 μL to 20 μL; dual wavelength detection is used, the first detection wavelength is 200nm to 240nm, and the second detection wavelength is 250nm to 300nm.

[0010] There are many oxidation byproducts that may be produced in the reaction mixture of 5-hydroxymethylfurfural oxidation to 2,5-furandicarboxylic acid. 5-hydroxymethylfurfural and its various oxidation products have similar structures and are difficult to detect qualitatively and quantitatively. In addition, the reaction product obtained by oxidizing 5-hydroxymethylfurfural to synthesize 2,5-furandicarboxylic acid usually contains insoluble substances. For example, when acetic acid is used for the reaction, the oxidation product of 5-hydroxymethylfurfural has limited solubility in acetic acid, and direct detection of liquid components has the problem of inaccurate detection. The method provided by the present invention separates the filtrate and the filter residue to detect 5-hydroxymethylfurfural and its oxidation products in the filtrate and the filter residue respectively, thereby accurately detecting the reaction mixture. By adding an inorganic base such as a monobasic inorganic base, 2,5-furandicarboxylic acid, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, and maleic acid in the filter residue are dissolved into salts to improve the determination accuracy of the oxidation product of 5-hydroxymethylfurfural in the filter residue. By adopting dual wavelength detection, 5-hydroxymethylfurfural and its oxidation products can produce effective ultraviolet absorption, making the detection result more accurate. Therefore, the method provided by the present invention has high separation degree, high detection accuracy and precision for 5-hydroxymethylfurfural and its various oxidation products.

[0011] In some embodiments, the concentration of the inorganic acid in the aqueous inorganic acid solution is 1-20 mM.

[0012] In some embodiments, the inorganic acid includes one or more of hydrochloric acid, nitric acid, boric acid, sulfuric acid, carbonic acid or phosphoric acid, preferably includes one or more of boric acid, sulfuric acid or phosphoric acid.

[0013] In some embodiments, the conductivity of water in the inorganic acid aqueous solution is 0-5 μS / cm, preferably 0-2 μS / cm.

[0014] In some embodiments, the stationary phase is an Aminex HPX-87H chromatographic column.

[0015] In some embodiments, the method specifically includes: subjecting a mixture containing filter residue, inorganic base and water to ultrasonic dissolution treatment for 1 to 30 minutes, and then adding inorganic base until the oxidation product of 5-hydroxymethylfurfural in the filter residue is fully dissolved to obtain the second sample solution to be tested.

[0016] In some embodiments, the amount of the inorganic base is more than twice the amount of 2,5-furandicarboxylic acid in the filter residue, for example, twice the amount of 2,5-furandicarboxylic acid in the filter residue.

[0017] In some embodiments, the ultrasonic dissolution treatment lasts for 10 to 15 minutes, preferably 10 minutes.

[0018] In some embodiments, the amount of the filter cake is 5 to 50 mg, preferably 5 to 20 mg, and more preferably 10 mg.

[0019] Exemplarily, the preparation method of the first test solution and the second test solution includes:

[0020] The reaction mixture after oxidation of 5-hydroxymethylfurfural is filtered to obtain a filtrate and a filter cake;

[0021] The filtrate is dissolved in water and diluted to a 250 ml volumetric flask, shaken and cooled to room temperature, and then diluted twice. 100 μL-1000 μL of the solution is transferred to a 100 ml volumetric flask, dissolved in water and diluted to a 100 ml volumetric flask, shaken and cooled to room temperature, which is the first test solution;

[0022] After the filter cake is dried, a sample is taken, and water is used as the solvent and an appropriate amount of inorganic base is added until the 2,5-furandicarboxylic acid, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, and maleic acid in the filter residue are dissolved into salts. After ultrasonic dissolution, the volume is adjusted to a 100 ml volumetric flask, shaken well, and cooled to room temperature to prepare the second solution.

[0023] In some embodiments, the method performs quantitative detection based on the relationship between the chromatographic peak area of ​​the corresponding substance and its concentration.

[0024] In some embodiments, the method specifically includes: taking standard samples of 5-hydroxymethylfurfural, 2,5-furandicarboxylic acid, 2,5-furandicarboxaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, and maleic acid, preparing a series of standard sample solutions of different concentrations for each substance, performing high performance liquid chromatography under the conditions of high performance liquid chromatography analysis, and obtaining a standard curve of the relationship between peak area and concentration with the peak area as the ordinate and the concentration of the corresponding substance in the standard sample solution as the abscissa;

[0025] The corresponding substances in the first test solution and the second test solution are quantified according to the standard curve.

[0026] When preparing the standard sample solution, for 2,5-furandicarboxylic acid, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, and maleic acid, an appropriate amount of inorganic base may be added to fully dissolve them.

[0027] In some embodiments, the conditions of the HPLC analysis include: the stationary phase is an Aminex HPX-87H chromatographic column, and the column temperature is 40°C; the mobile phase is a 5 mM H2SO4 aqueous solution, and the flow rate of the mobile phase is 0.6 mL / min; the injection volume is 5 μL; dual-wavelength detection is used, the first detection wavelength is 210 nm, and the second detection wavelength is 280 nm.

[0028] In some embodiments, under the conditions of the HPLC analysis, the standard curve equation of the corresponding substance is as follows:

[0029] 5-Hydroxymethylfurfural: y=61,480.3781x+15.3701;

[0030] 2,5-Furandicarboxylic acid: y = 24,254.4768x - 59.6930;

[0031] 2,5-Furandicarboxaldehyde: y=63,226.5523x+2.9948;

[0032] 5-Hydroxymethyl-2-furancarboxylic acid: y=8,835.6258x+0.2834;

[0033] 5-Formyl-2-furancarboxylic acid: y=63,819.1784x-8.4367;

[0034] Fumaric acid: y = 57617.8012x - 46.9584;

[0035] Maleic acid: y = 56483.3873x - 177.376;

[0036] In the standard curve equation, y represents the peak area in mAu·s; x represents the concentration of the corresponding substance in g / L.

[0037] In some embodiments, under the conditions of the HPLC analysis, the retention time of 5-hydroxymethylfurfural is 33.88 min, the retention time of 2,5-furandicarboxylic acid is 18.09 min, the retention time of 2,5-furandicarboxaldehyde is 42.49 min, the retention time of 5-hydroxymethyl-2-furancarboxylic acid is 22.57 min, the retention time of 5-formyl-2-furancarboxylic acid is 25.49 min, the retention time of fumaric acid is 11.67 min, and the retention time of maleic acid is 6.19 min.

[0038] A second object of the present invention is to provide a method for simultaneously determining 5-hydroxymethylfurfural and its oxidation products, comprising:

[0039] Providing a sample to be tested, wherein the sample to be tested contains 5-hydroxymethylfurfural and further contains one or more of 2,5-furandicarboxylic acid, 2,5-furandicarboxaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid or maleic acid;

[0040] The sample to be tested is subjected to high performance liquid chromatography analysis, and the conditions of the high performance liquid chromatography analysis include: the stationary phase is an organic acid analysis column, and the column temperature is 25°C to 60°C; the mobile phase is an inorganic acid aqueous solution, and the flow rate of the mobile phase is 0.4 to 1 mL / min; the injection volume is 1 μL to 20 μL; dual-wavelength detection is adopted, the first detection wavelength is 200nm to 240nm, and the second detection wavelength is 250nm to 300nm.

[0041] In some embodiments, the method includes: adding an inorganic base to the sample to be tested to fully dissolve 2,5-furandicarboxylic acid, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, and maleic acid.

[0042] Further schemes of the method provided by the second object of the present invention, such as more specific chromatographic conditions, etc., have been described in detail in part one of the objects of the present invention and will not be repeated here.

[0043] The method of the present invention can be used for qualitative and / or quantitative detection of 2,5-furandicarboxylic acid, 5-hydroxymethylfurfural and oxidation byproducts in a reaction mixture for oxidizing 5-hydroxymethylfurfural to synthesize 2,5-furandicarboxylic acid.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects: the method provided by the present invention can simultaneously detect samples containing 5-hydroxymethylfurfural and its oxidation products, has good separation, and has high accuracy and high precision. The method is suitable for detecting a reaction mixture that uses 5-hydroxymethylfurfural as a raw material to oxidatively synthesize 2,5-furandicarboxylic acid, and can qualitatively and / or quantitatively detect 2,5-furandicarboxylic acid, 5-hydroxymethylfurfural and oxidation byproducts (2,5-furandicarboxaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, maleic acid) in the reaction mixture, solving the problem in the prior art that 5-hydroxymethylfurfural and its oxidation products have similar structures but low separation, and the qualitative and quantitative inaccuracy of the ring-opening oxidation products FA and MA. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 is a schematic flow chart of a detection method in one embodiment of the present invention;

[0047] Figure 2 is a liquid chromatogram of a sample to be tested containing HMF, FDCA, DFF, HMFCA, and FFCA simultaneously in one embodiment of the present invention;

[0048] Figure 3 It is a liquid chromatogram of detecting a sample containing both FA and MA in one embodiment of the present invention. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is described in detail below in conjunction with specific embodiments so that those skilled in the art can better understand and implement the technical solution of the present invention. The specific functional details disclosed herein should not be interpreted as limiting, but only as the basis for the claims and as a representative basis for teaching those skilled in the art to adopt the present invention in different ways in any appropriate detailed embodiment.

[0050] In addition, unless otherwise specified, the various raw materials used in the following examples can be purchased from the market, and the various production and testing equipment used are also known in the art. The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0051] Some of the raw materials and drugs used in the specific implementation are as follows:

[0052] HMF standard (purity > 99%, Aladdin); FDCA standard (purity > 98%, Aladdin); DFF standard (purity > 98%, Aladdin); HMFCA standard (purity > 98%, Aladdin); FFCA standard (purity > 98%, Aladdin); FA standard (purity > 99.5%, Aladdin); MA standard (purity > 99%, J&K); methanol (AR, Shanghai Titan Technology Co., Ltd.); deionized water.

[0053] The experimental instruments and equipment used are as follows:

[0054] High performance liquid chromatograph: Agilent 1260 (including online degasser, quaternary pump, autosampler, column oven, UV detector, chromatographic workstation); chromatographic column: Aminex HPX-87H; analytical balance 0.0001 g (Mettler-Toledo Instrument Co., Ltd.); ultrasonic cleaner (Shanghai Kedao Ultrasonic Instrument Co., Ltd.).

[0055] Example 1

[0056] In this example, high performance liquid chromatography was used to analyze the contents of related substances in a mixture containing HMF and its various oxidation products.

[0057] The chromatographic conditions used in the test process of this embodiment are:

[0058] Stationary phase: Aminex HPX-87H column;

[0059] Mobile phase: single channel, 5 mM H2SO4;

[0060] Detection wavelength: 210nm and 280nm;

[0061] Flow rate: 0.6 mL / min;

[0062] Injection volume: 5 μL;

[0063] Column temperature: 40℃.

[0064] 1. Standard curve drawing

[0065] (1) Drawing of standard curves for HMF, FDCA, DFF, HMFCA, and FFCA

[0066] Accurately weigh HMF, FDCA, DFF, HMFCA, and FFCA: 38.5 mg, 9.6 mg, 9.4 mg, 5.7 mg, and 5.6 mg respectively, add them together into a 100 mL volumetric flask, add 8.13 mg NaOH, add deionized water to dissolve and dilute to the scale line, ultrasonically dissolve, and cool to room temperature for use.

[0067] Take 6.25mL, 12.5mL, 25mL, and 50mL of the above mother solution and dilute to a 100mL volumetric flask to prepare a total of 5 standard solutions with increasing concentrations. Perform analysis under the above chromatographic conditions, inject each sample twice, and record the peak area of ​​each substance.

[0068] The standard curve was drawn with the peak area Y (mAu) axis as the ordinate and the standard sample concentration X (mg / L) axis as the abscissa, and regression processing was performed.

[0069] The standard curves of HMF, FDCA, DFF, HMFCA, and FFCA are shown in Table 1.

[0070] Table 1(2) FA and MA standard curve drawing

[0071] Related substances Regression equation <![CDATA[Coefficient of correlation R 2 > HMF y=61,480.3781x+15.3701 0.9999 FDCA y=24,254.4768x-59.6930 0.9990 DFF y=63,226.5523x+2.9948 0.9999 HMFCA y=8,835.6258x+0.2834 0.9999 FFCA y=63,819.1784x-8.4367 0.9999

[0072] Accurately weigh FA and MA: 17.7 mg and 18.1 mg respectively into a 100 mL volumetric flask, and add 24.69 mg NaOH, add deionized water to dissolve and dilute to the scale, ultrasonically dissolve, and cool to room temperature for use.

[0073] Take 6.25mL, 12.5mL, 25mL, and 50mL of the above mother solution and dilute to a 100mL volumetric flask to prepare a total of 5 standard solutions with increasing concentrations. Perform analysis under the above chromatographic conditions, inject each sample twice, and record the peak area of ​​each substance.

[0074] The standard curve was drawn with the peak area Y (mAu) axis as the ordinate and the standard sample concentration X (mg / L) axis as the abscissa, and regression processing was performed.

[0075] The standard curves of FA and MA were obtained as described in Table 2.

[0076] Table 2

[0077]

[0078]

[0079] 2. Separation test

[0080] The separation degree of the high performance liquid chromatography analysis method provided in this embodiment is tested, and the steps are as follows:

[0081] Accurately weigh HMF, FDCA, DFF, HMFCA, and FFCA: 30.0 mg, 10.0 mg, 10.0 mg, 5.0 mg, and 5.0 mg respectively into a 100 ml volumetric flask, add 5.4 mg NaOH, add deionized water to dissolve and dilute to the scale, ultrasonically dissolve, cool to room temperature and set aside, recorded as test solution A.

[0082] The above-mentioned chromatographic column conditions were used to perform HPLC detection on the test solution A, and the separation degree was calculated. The calculation formula of the separation degree is: α = 2 (t2-t1) / (w1+w2). Wherein, t1 and t2 are the retention times of the two components, and w1 and w2 are the peak widths of the two components.

[0083] The results of separation calculation are shown in Table 3.

[0084] Table 3

[0085] Peak Compound Name Separation 1 FDCA / 2 HMFCA 2.63 3 FFCA 4.39 4 DFF 5.67 5 HMF 6.65

[0086] Figure 2 is the liquid chromatogram of test solution A.

[0087] Accurately weigh 10 mg of MA and FA respectively into a 100 ml volumetric flask, add 13.8 mg of NaOH, add deionized water to dissolve and dilute to the scale, use ultrasonic dissolution, cool to room temperature and set aside, record as test solution B.

[0088] The above-mentioned chromatographic column conditions were used to perform HPLC detection on the test solution B, and the separation degree was calculated according to the same method as above. The separation degree calculation results are shown in Table 4.

[0089] Table 4

[0090] Peak Compound Name Separation 1 MA / 2 FA 13.41

[0091] Figure 3 is the liquid chromatogram of test solution B.

[0092] 3. Precision test

[0093] (1) Precision test of HMF determination (n=6)

[0094] Weigh 10 mg HMF, record the exact mass, dissolve it in water and dilute it to a 100 mL volumetric flask, prepare it into a 0.01 wt% HMF aqueous solution, shake it well, make the sample solution to be tested, filter it through a 0.45 μm filter membrane, and repeat the measurement 6 times on the machine (HPLC), and obtain the HMF content and the relative standard deviation (RSD) of HMF after conversion. The test results are shown in Table 5.

[0095] Table 5

[0096]

[0097] It can be seen from the above table that the HMF content in the sample remains basically unchanged, and its RSD value is % = 0.2386, which is less than 1%, indicating that the precision of HMF determination using this method is high.

[0098] (2) Precision test of FDCA determination (n=6)

[0099] Weigh 5 mg FDCA, record the exact mass, add 2.57 mg NaOH, dissolve with water and dilute to 100 ml volumetric flask, prepare 0.005 wt% FDCA aqueous solution, shake well, prepare the sample solution to be tested, filter through 0.45 μm filter membrane, repeat the measurement 6 times on the machine (HPLC), and obtain the FDCA content and the relative standard deviation (RSD) of FDCA after conversion. The test results are shown in Table 6.

[0100] Table 6

[0101]

[0102]

[0103] It can be seen from the above table that the FDCA content in the sample remains basically unchanged, and its RSD value is 0.1626%, which is less than 1%, indicating that the precision of FDCA determination using this method is high.

[0104] (3) Precision test of DFF measurement (n=6)

[0105] Weigh 5 mg of DFF, dissolve it in water and dilute it to a 100 ml volumetric flask, prepare it into a 0.005 wt% DFF aqueous solution, shake it well, make the sample solution to be tested, filter it through a 0.45 μm filter membrane, and repeat the measurement 6 times on the machine (HPLC), and obtain the DFF content and the relative standard deviation (RSD) of DFF after conversion. The test results are shown in Table 7.

[0106] Table 7

[0107]

[0108] It can be seen from the above table that the DFF content in the sample remains basically unchanged, and its RSD value is 0.2229%, which is less than 1%, indicating that the precision of DFF determination using this method is relatively high.

[0109] (4) Precision test of HMFCA determination (n=6)

[0110] That is, 5 mg HMFCA was weighed, the accurate mass was recorded, 1.41 mg NaOH was added, dissolved with water and fixed to a 100 ml volumetric flask, a 0.005 wt% HMFCA aqueous solution was prepared, and after shaking, a sample solution to be tested was prepared, filtered through a 0.45 μm filter membrane, and the HMFCA content and the relative standard deviation (RSD) of HMFCA were obtained after conversion. The test results are shown in Table 8.

[0111] Table 8

[0112]

[0113]

[0114] It can be seen from the above table that the HMFCA content in the sample remains basically unchanged, and its RSD value is 0.2735%, which is less than 1%, indicating that the precision of HMFCA determination using this method is relatively high.

[0115] (5) Precision test of FFCA determination (n=6)

[0116] Weigh about 5 mg FFCA, record the exact mass, add 1.43 mg NaOH, dissolve with water and dilute to 100 ml volumetric flask, prepare 0.005 wt% FFCA aqueous solution, shake well, prepare the sample solution to be tested, filter through 0.45 μm filter membrane, repeat the measurement 6 times on the machine (HPLC), and obtain the FFCA content and the relative standard deviation (RSD) of FFCA after conversion. The test results are shown in Table 9.

[0117] Table 9

[0118]

[0119] It can be seen from the above table that the FFCA content in the sample remains basically unchanged, and its RSD value is 0.4139%, which is less than 1%, indicating that the precision of determining FFCA using this method is relatively high.

[0120] (6) Precision test of FA determination (n=6)

[0121] Weigh about 5 mg FA, record the exact mass, add 3.45 mg NaOH, dissolve with water and dilute to 100 ml volumetric flask to prepare 0.005 wt% FA aqueous solution, shake well, make the sample solution to be tested, filter through 0.45 μm filter membrane, repeat the measurement 6 times on the machine (HPLC), and obtain the FA content and FA relative standard deviation (RSD) after conversion. The test results are shown in Table 10.

[0122] Table 10

[0123]

[0124] It can be seen from the above table that the FA content in the sample remains basically unchanged, and its RSD value is 0.1524%, which is less than 1%, indicating that the precision of FA determination using this method is high.

[0125] (7) Precision test of MA determination (n = 6)

[0126] Weigh about 5 mg of MA, record the exact mass, add 3.45 mg of NaOH, dissolve with water and dilute to 100 ml volumetric flask, prepare 0.005 wt% MA aqueous solution, shake well, make the sample solution to be tested, filter through 0.45 μm filter membrane, repeat the measurement 6 times on the machine (HPLC), and obtain the MA content and relative standard deviation (RSD) of MA after conversion. The test results are shown in Table 11.

[0127] Table 11

[0128]

[0129]

[0130] It can be seen from the above table that the MA content in the sample remains basically unchanged, and its RSD value is 0.1629%, which is less than 1%, indicating that the precision of MA determination using this method is relatively high.

[0131] 4. Spike recovery test

[0132] In order to determine the accuracy of the test method, spike recovery tests were carried out on HMF and its oxidation products FDCA, DFF, HMFCA, FFCA, FA, and MA.

[0133] (1) HMF sample spike recovery test (n = 3)

[0134] 1) Prepare a 0.5 g / kg HMF sample by adding 0.50 g of pure HMF to 999.5 g of water, dissolve it with ultrasound, and cool it to room temperature to prepare sample A;

[0135] 2) Take 100 g of sample A, add 0.05 g of pure HMF, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the HMF content in sample B after detection by machine (HPLC), that is, the HMF determination value, HMF recovery rate = (mass of HMF after addition - mass of HMF in sample) / HMF addition amount × 100%, repeat three times.

[0136] 3) Take 100 g of sample A, add 0.1 g of pure HMF, dissolve with ultrasonic aid, cool to room temperature to prepare sample C, take 5 g of sample C into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the HMF content in sample C after detection by machine (HPLC), that is, the HMF determination value, HMF recovery rate = (mass of HMF after spiked - mass of HMF in sample) / HMF spiked amount × 100%, repeat three times.

[0137] 4) Take 100 g of sample A, add 0.2 g of pure HMF, dissolve with ultrasonic aid, cool to room temperature to prepare sample D, take 5 g of sample D into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the HMF content in sample D after detection by machine (HPLC), that is, the HMF determination value, HMF recovery rate = (mass of HMF after spiked - mass of HMF in sample) / HMF spiked amount × 100%, repeat three times.

[0138] The results of the spike recovery test of HMF are shown in Table 12.

[0139] Table 12

[0140]

[0141]

[0142] It can be seen from the above table that in the HMF recovery test, the relative standard deviation of HMF is less than 1%; and the measured recovery rate is between 90% and 110%, which proves that this method has high accuracy.

[0143] (2) FDCA sample spike recovery test (n = 3)

[0144] 1) Prepare 0.2 g / / kg FDCA sample by adding 0.20 g FDCA and 0.10 g NaOH into 999.7 g water, dissolve with ultrasonic aid, and cool to room temperature to prepare sample A;

[0145] 2) Take 100 g of sample A, add 0.02 g of pure FDCA and 0.01 g of NaOH, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the FDCA content in sample B after detection by machine (HPLC), that is, the FDCA determination value, FDCA recovery rate = (mass of FDCA after addition - mass of FDCA in sample) / FDCA addition amount × 100%, repeat three times.

[0146] 3) Take 100 g of sample A, add 0.04 g of pure FDCA and 0.02 g of NaOH, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the FDCA content in sample B after detection by machine (HPLC), that is, the FDCA determination value, FDCA recovery rate = (mass of FDCA after addition - mass of FDCA in sample) / FDCA addition amount × 100%, repeat three times.

[0147] 4) Take 100 g of sample A, add 0.08 g of pure FDCA and 0.04 g of NaOH, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the FDCA content in sample B after detection by machine (HPLC), that is, the FDCA determination value, FDCA recovery rate = (mass of FDCA after addition - mass of FDCA in sample) / FDCA addition amount × 100%, repeat three times.

[0148] The results of the spike recovery test of FDCA are shown in Table 13.

[0149] Table 13

[0150]

[0151] It can be seen from the above table that in the FDCA recovery test, the relative standard deviation of FDCA is less than 1%; and the measured recovery rate is between 90% and 110%, proving that this method has high accuracy.

[0152] (3) DFF sample spike recovery test (n = 3)

[0153] 1) Prepare a 0.2 g / kg DFF sample by adding 0.20 g DFF to 999.8 g water, dissolve it with ultrasound, and cool it to room temperature to prepare sample A;

[0154] 2) Take 100 g of sample A, add 0.02 g of pure FDCA, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the DFF content in sample B after detection by HPLC, i.e., the DFF measurement value, DFF recovery rate = (mass of DFF after addition - mass of DFF in sample) / DFF addition amount × 100%, repeat three times.

[0155] 3) Take 100g of sample A, add 0.04g of pure DFF, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5g of sample B into a 100ml volumetric flask, dissolve with water and dilute to the scale line, and calculate the DFF content in sample B after detection by machine (HPLC), that is, the DFF measurement value, DFF recovery rate = (mass of DFF after spiked - mass of DFF in sample) / DFF spiked amount × 100%, repeat three times.

[0156] 4) Take 100g of sample A, add 0.08g of pure DFF, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5g of sample B into a 100ml volumetric flask, dissolve with water and dilute to the scale line, and calculate the DFF content in sample B after detection by HPLC, that is, the DFF measurement value, DFF recovery rate = (mass of DFF after addition - mass of DFF in sample) / DFF addition amount × 100%, repeat three times.

[0157] The results of the spike recovery test of DFF are shown in Table 14.

[0158] Table 14

[0159]

[0160] It can be seen from the above table that in the DFF recovery test, the relative standard deviation of DFF is less than 1%; and the measured recovery rate is between 90% and 110%, proving that this method has high accuracy.

[0161] (4) HMFCA sample spike recovery test (n = 3)

[0162] 1) Prepare a 0.2 g / kg HMFCA sample by adding 0.20 g HMFCA and 0.05 g NaOH to 999.75 g water, dissolve with ultrasound, and cool to room temperature to prepare sample A;

[0163] 2) Take 100 g of sample A, add 0.02 g of pure HMFCA and 0.005 g of NaOH, dissolve with ultrasonic aid, cool to room temperature, prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the HMFCA content in sample B after detection by machine (HPLC), i.e., the HMFCA determination value, HMFCA recovery rate = (mass of HMFCA after addition - mass of HMFCA in sample) / HMFCA addition amount × 100%, repeat three times.

[0164] 3) Take 100 g of sample A, add 0.04 g of pure HMFCA and 0.01 g of NaOH, dissolve with ultrasonic aid, cool to room temperature, prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and make up to the scale, calculate the HMFCA content in sample B after detection by HPLC, i.e., the HMFCA determination value, HMFCA recovery rate = (mass of HMFCA after addition - mass of HMFCA in sample) / HMFCA addition amount × 100%, repeat three times.

[0165] 4) Take 100 g of sample A, add 0.08 g of pure HMFCA and 0.02 g of NaOH, dissolve with ultrasonic aid, cool to room temperature, prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and make up to the scale, calculate the HMFCA content in sample B after detection by HPLC, i.e., the HMFCA determination value, HMFCA recovery rate = (mass of HMFCA after addition - mass of HMFCA in sample) / HMFCA addition amount × 100%, repeat three times.

[0166] The HMFCA spiked recovery samples are shown in Table 15.

[0167] Table 15

[0168]

[0169] It can be seen from the above table that in the HMFCA recovery test, the relative standard deviation of HMFCA is less than 1%; and the measured recovery rate is between 90% and 110%, which proves that this method has high accuracy.

[0170] (5) FFCA sample spike recovery test (n = 3)

[0171] 1) Prepare a 0.2 g / kg FFCA sample by adding 0.20 g FFCA and 0.05 g NaOH to 999.75 g water, dissolve with ultrasonic aid, and cool to room temperature to prepare sample A;

[0172] 2) Take 100 g of sample A, add 0.02 g of pure FFCA and 0.005 g of NaOH, dissolve with ultrasound, cool to room temperature to prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the FFCA content in sample B after detection by HPLC, i.e., the FFCA determination value, HMFCA recovery rate = (mass of FFCA after addition - mass of FFCA in sample) / FFCA addition amount × 100%, repeat three times.

[0173] 3) Take 100 g of sample A, add 0.04 g of pure FFCA and 0.01 g of NaOH, dissolve with ultrasound, cool to room temperature to prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the FFCA content in sample B after detection by HPLC, i.e., the FFCA determination value, FFCA recovery rate = (mass of FFCA after addition - mass of FFCA in sample) / FFCA addition amount × 100%, repeat three times.

[0174] 4) Take 100 g of sample A, add 0.08 g of pure FFCA and 0.02 g of NaOH, dissolve with ultrasound, cool to room temperature to prepare sample B, take 5 g of sample B into a 100 ml volumetric flask, dissolve with water and dilute to the scale, and calculate the FFCA content in sample B after detection by HPLC, i.e., the FFCA determination value, FFCA recovery rate = (mass of FFCA after addition - mass of FFCA in sample) / FFCA addition amount × 100%, repeat three times.

[0175] The results of the FFCA spike recovery experiment are shown in Table 16.

[0176] Table 16

[0177]

[0178] It can be seen from the above table that in the FFCA recovery test, the relative standard deviation of FFCA is less than 1%; and the measured recovery rate is between 90% and 110%, proving that this method has high accuracy.

[0179] (6) FA sample spike recovery test (n = 3)

[0180] 1) Prepare 0.4 g / kg FA sample by adding 0.40 g FA into 999.6 g water, dissolve it with ultrasonic aid, and cool it to room temperature to prepare sample A;

[0181] 2) Take 100g of sample A, add 0.04g of pure FA, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5g of sample B into a 100ml volumetric flask, dissolve with water and dilute to the scale line, and calculate the FA content in sample B after detection by machine (HPLC), that is, the FA determination value, FA recovery rate = (mass of FA after spiked - mass of FA in sample) / FA spiked amount × 100%, repeat three times.

[0182] 3) Take 100g of sample A, add 0.08g of pure FA, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5g of sample B into a 100ml volumetric flask, dissolve with water and dilute to the scale line, and calculate the FA content in sample B after detection by machine (HPLC), that is, the FA determination value, FA recovery rate = (mass of FA after addition - mass of FA in sample) / FA addition amount × 100%, repeat three times.

[0183] 4) Take 100g of sample A, add 0.12g of pure FA, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5g of sample B into a 100ml volumetric flask, dissolve with water and dilute to the scale line, and calculate the FA content in sample B after detection by machine (HPLC), that is, the FA determination value, FA recovery rate = (mass of FA after spiked - mass of FA in sample) / FA spiked amount × 100%, repeat three times.

[0184] The results of the FA spike recovery experiment are shown in Table 17.

[0185] Table 17

[0186]

[0187] It can be seen from the above table that in the FA recovery test, the relative standard deviation of FA is less than 1%; and the measured recovery rate is between 90% and 110%, proving that this method has high accuracy.

[0188] (7) MA sample spike recovery test (n = 3)

[0189] 1) Prepare a 0.4 g / kg MA sample by adding 0.40 g MA to 999.6 g water, dissolve it with ultrasound, and cool it to room temperature to prepare sample A;

[0190] 2) Take 100g of sample A, add 0.04g of pure MA, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5g of sample B into a 100ml volumetric flask, dissolve with water and dilute to the scale line, and calculate the MA content in sample B after detection by HPLC, that is, the MA measurement value, MA recovery rate = (mass of MA after addition - mass of MA in sample) / MA addition amount × 100%, repeat three times.

[0191] 3) Take 100g of sample A, add 0.08g of pure MA, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5g of sample B into a 100ml volumetric flask, dissolve with water and dilute to the scale line, and calculate the FA content in sample B after detection by HPLC, that is, the MA measurement value, MA recovery rate = (mass of MA after addition - mass of MA in sample) / MA addition amount × 100%, repeat three times.

[0192] 4) Take 100g of sample A, add 0.12g of pure MA, dissolve with ultrasonic aid, cool to room temperature to prepare sample B, take 5g of sample B into a 100ml volumetric flask, dissolve with water and dilute to the scale line, and calculate the MA content in sample B after detection by HPLC, that is, the MA measurement value, MA recovery rate = (mass of MA after addition - mass of MA in sample) / MA addition amount × 100%, repeat three times.

[0193] The results of the MA spike recovery experiment are shown in Table 18.

[0194] Table 18

[0195]

[0196] It can be seen from the above table that in the MA recovery test, the relative standard deviation of MA is less than 1%; and the measured recovery rate is between 90% and 110%, proving that this method has high accuracy.

[0197] 5. Real sample testing

[0198] Figure 1 A schematic flow chart of the method for detecting the reaction product of oxidizing HMF to synthesize FDCA is shown.

[0199] The test sample is the reaction product of HMF oxidation to synthesize FDCA. The synthesis reaction conditions are: 1g HMF is added to 30ml acetic acid, 0.5g catalyst is added, and the reaction is carried out at 150°C for 1h under 1Mpa oxygen atmosphere.

[0200] The reaction product after HMF oxidation was filtered to obtain a filtrate and a filter cake. Water was added to the filtrate to make up to 250 ml volumetric flask, shaken and cooled to room temperature, and then diluted twice. 1000 μ L of the solution was transferred from the secondary dilution solution to a 25 ml volumetric flask, water was added to make up to 25 ml, shaken and cooled to room temperature, and then reserved for use, filtered through a 0.451 μm filter membrane, and the first solution to be tested was obtained, and measured by machine (HPLC).

[0201] After the filter cake is partially dried, a sample is taken, 5.13 mg of NaOH is added to water as the solvent, and the volume is adjusted to a 100 ml volumetric flask after ultrasonic dissolution. The solution is shaken well, cooled to room temperature, and filtered through a 0.45 μm filter membrane to obtain a second test solution, which is then measured by HPLC.

[0202] The test results are shown in Tables 19 and 20.

[0203] Table 19

[0204]

[0205]

[0206] In summary, the present invention provides a method for simultaneously determining HMF and its oxidation products FDCA, DFF, HMFCA, FFCA, FA, and MA in a reaction mixture after 5-hydroxymethylfurfural oxidation. The method has good separation, no interference from impurities, and high feasibility; the content of HMF and its oxidation products in the reaction solution after HMF oxidation can be accurately determined simultaneously, and the method has practical application value.

[0207] The various aspects, embodiments, features and examples of the present invention should be considered as illustrative in all aspects and are not intended to limit the present invention, the scope of the present invention is defined only by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0208] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0209] Although the present invention has been described with reference to illustrative embodiments, it will be appreciated by those skilled in the art that various other changes, omissions and / or additions may be made without departing from the spirit and scope of the present invention and that the elements of the embodiments may be replaced by substantial equivalents. In addition, many modifications may be made without departing from the scope of the present invention to adapt specific circumstances or materials to the teachings of the present invention. Therefore, it is not intended herein to limit the present invention to the disclosed specific embodiments for performing the present invention, but it is intended that the present invention will include all embodiments within the scope of the appended claims. In addition, unless specifically stated, any use of the terms first, second, etc. does not indicate any order or importance, but rather uses the terms first, second, etc. to distinguish one element from another.

Claims

1. A method for simultaneously determining 5-hydroxymethylfurfural and its oxidation products, characterized in that: include: Providing a reaction mixture obtained after an oxidation reaction of 5-hydroxymethylfurfural, the reaction mixture comprising 5-hydroxymethylfurfural and an oxidation product thereof, wherein the oxidation product comprises one or more of 2,5-furandicarboxylic acid, 2,5-furandicarboxaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, and maleic acid; The reaction mixture is filtered to obtain a filtrate and a filter residue; the filtrate is prepared as a first test solution, the filter residue is mixed with an inorganic base to make the insoluble oxidation product in the filter residue undergo a salt-forming reaction and dissolve, and the mixture is prepared as a second test solution; Performing high performance liquid chromatography analysis on the first test solution and the second test solution respectively, so as to perform qualitative and / or quantitative detection on the substances contained in the reaction mixture; Among them, the conditions of the high performance liquid chromatography analysis include: the stationary phase is an organic acid analysis column, the column temperature is 25°C to 60°C, the mobile phase is an inorganic acid aqueous solution, the flow rate of the mobile phase is 0.4 to 1 mL / min, the injection volume is 1VL to 20μL, and dual wavelength detection is adopted, the first detection wavelength is 200nm to 240nm, and the second detection wavelength is 250nm to 300nm.

2. The method according to claim 1, characterized in that: The inorganic acid concentration in the inorganic acid aqueous solution is 1 to 20 mM; And / or, the inorganic acid comprises one or more of hydrochloric acid, nitric acid, boric acid, sulfuric acid, carbonic acid or phosphoric acid, preferably comprises one or more of boric acid, sulfuric acid or phosphoric acid; and / or, the conductivity of water in the inorganic acid aqueous solution is 0 to 5 μS / cm, preferably 0 to 2 μS / cm; And / or, the stationary phase is an Aminex HPPX-87H chromatographic column.

3. The method according to claim 1, characterized in that Specifically include: The mixture containing the filter residue, the inorganic base and water is subjected to ultrasonic dissolution treatment for 1 to 30 minutes, and then the inorganic base is added until the oxidation product of 5-hydroxymethylfurfural in the filter residue is fully dissolved to obtain the second sample solution to be tested.

4. The method according to claim 3, characterized in that: The amount of the inorganic base used is more than twice the amount of 2,5-furandicarboxylic acid in the filter residue.

5. The method according to claim 1, characterized in that: The method performs quantitative detection based on the relationship between the chromatographic peak area of ​​the corresponding substance and its concentration.

6. The method according to claim 5, characterized in that Specifically include: Take standard samples of 5-hydroxymethylfurfural, 2,5-furandicarboxylic acid, 2,5-furandicarboxaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid, and maleic acid, prepare a series of standard sample solutions of different concentrations for each substance, perform high performance liquid chromatography determination under the conditions of high performance liquid chromatography analysis, and use the peak area as the ordinate and the concentration of the corresponding substance in the standard sample solution as the abscissa to obtain a standard curve of the relationship between the peak area and the concentration; The contents of the corresponding substances in the first test solution and the second test solution are calculated according to the standard curve.

7. The method according to claim 1 or 6, characterized in that: The conditions of the HPLC analysis include: the stationary phase is Aminex HPX-87H, the column temperature is 40°C; the mobile phase is a 5 mM H2SO4 aqueous solution, the flow rate of the mobile phase is 0.6 mL / min; the injection volume is 5 μL; dual wavelength detection is used, the first detection wavelength is 210 nm, and the second detection wavelength is 280 nm.

8. The method according to claim 7, characterized in that Under the conditions of the HPLC analysis, the standard curve equation of the corresponding substance is as follows: 5-Hydroxymethylfurfural: y=61,480.3781x+15.3701; 2,5-Furandicarboxylic acid: y = 24,254.4768x - 59.6930; 2,5-Furandicarboxaldehyde: y=63,226.5523x+2.9948; 5-Hydroxymethyl-2-furancarboxylic acid: y=8,835.6258x+0.2834; 5-Formyl-2-furancarboxylic acid: y=63,819.1784x-8.4367; Fumaric acid: y = 57617.8012x - 46.9584; Maleic acid: y = 56483.3873x - 177.376; In the standard curve equation, y represents the peak area in mAu·s; x represents the concentration of the corresponding substance in g / L.

9. The method according to claim 7, characterized in that: Under the conditions of the HPLC analysis, the retention time of 5-hydroxymethylfurfural is 33.88 min, the retention time of 2,5-furandicarboxylic acid is 18.09 min, the retention time of 2,5-furandicarboxaldehyde is 42.49 min, the retention time of 5-hydroxymethyl-2-furancarboxylic acid is 22.57 min, the retention time of 5-formyl-2-furancarboxylic acid is 25.49 min, the retention time of fumaric acid is 11.67 min, and the retention time of maleic acid is 6.19 min.

10. A method for simultaneously determining 5-hydroxymethylfurfural and its oxidation products, characterized in that: include: Providing a sample to be tested, wherein the sample to be tested contains 5-hydroxymethylfurfural and an oxidation product thereof, wherein the oxidation product comprises one or a combination of 2,5-furandicarboxylic acid, 2,5-furandicarboxaldehyde, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, fumaric acid or maleic acid; The sample to be tested is subjected to high performance liquid chromatography analysis, wherein the conditions of the high performance liquid chromatography analysis include: the stationary phase is an organic acid analysis column, and the column temperature is 25° C. to 60° C.; The mobile phase is an inorganic acid aqueous solution, and the flow rate of the mobile phase is 0.4-1 mL / min; the injection volume is 1 μL-20 μL; dual-wavelength detection is adopted, the first detection wavelength is 200 nm-240 nm, and the second detection wavelength is 250 nm-300 nm.

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