A solid phase extraction material and its preparation method and use

Abstract

The present invention relates to the technical field of solid phase extraction, and in particular to a solid phase extraction material, a preparation method thereof and a use thereof. The raw materials of the solid phase extraction material include biomass, silane containing quaternary ammonium groups and pyrrolidone. The biomass is rich in phenolic hydroxyl groups, and thus can react with silane containing quaternary ammonium groups and pyrrolidone, so that the solid phase extraction material has a moderate ion exchange capacity and hydrophobic retention effect, thereby having a high recovery rate when performing solid phase extraction on synthetic colorants in food, and can more accurately detect the content of synthetic colorants in food. The invention solves the problem that the ion exchange capacity of the solid phase extraction material in the prior art is too low or too high, resulting in a low recovery rate when it is used to extract colorants in food.

Description

Technical Field

[0001] The invention relates to the technical field of solid phase extraction, in particular to a solid phase extraction material and a preparation method and application thereof. Background Art

[0002] Synthetic colorants are a type of food colorants made by chemical synthesis, including azo colorants, triphenylmethane colorants, indigo colorants, azophenol colorants, nitro colorants, etc. These synthetic colorants are widely used in food, medicine, cosmetics and other industries due to their bright colors, strong coloring power, good stability and low cost. Especially in the food industry, food color is closely related to food safety, nutritional science and national food culture, and many countries generally use synthetic colorants in the food processing industry.

[0003] However, in recent years, food safety incidents have been reported, and the use of synthetic colorants in food has exceeded the standard. This has aroused people's concern about the safety of synthetic colorants. Some synthetic colorants are considered to have general toxicity, sensitization, laxative, carcinogenicity and mutagenicity. For example, some ingredients in azo colorants are believed to cause allergic reactions, and some studies have even shown that some synthetic colorants may be associated with children's ADHD. In addition, some synthetic colorants may cause damage to organs such as the liver and kidneys when accumulated in the body. In order to protect the health of consumers, countries have strictly regulated the use of synthetic colorants. For example, in my country, the use of synthetic colorants in food additives must comply with national food safety standards, and the use of synthetic colorants in other fields is also subject to corresponding supervision and regulations. Food producers must comply with the maximum usage regulations of the country or region when using synthetic colorants to ensure the safety of consumers, so we need to test synthetic colorants in food. Research has found that common synthetic colorants include tartrate yellow (CAS number 1934-21-0), quinoline yellow (CAS number 8004-92-0), new red (CAS number 220658-76-4), amaranth (CAS number 915-67-3), carmine (CAS number 2611-82-7), allura red (CAS number 25956-17-6), acid red (CAS number 3734-67-6), erythrosine (CAS number 568-63-8), indigo (CAS number 860-22-0), brilliant blue (CAS number 3844-45-9), and sunset yellow (CAS number 2783-94-0).

[0004] In order to detect synthetic colorants in food, it is first necessary to extract and enrich the synthetic colorants from the food. In the prior art, solid phase extraction columns are usually used to extract and enrich the synthetic colorants in food. The ion exchange capacity of common solid phase extraction columns is usually too low or too high. When the ion exchange capacity is too low, the synthetic colorant will be lost during the loading or elution process. If it is too high, the synthetic colorant will not be eluted in the solid phase extraction column, which reduces the recovery rate of the synthetic colorant.

[0005] Therefore, how to develop solid phase extraction materials with moderate ion exchange capacity to improve the recovery rate of synthetic colorants while improving the accuracy of quantitative testing and comparison of the content of synthetic colorants in food is an urgent problem that needs to be solved. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a solid phase extraction material and a preparation method and use thereof. The solid phase extraction material described in the present application solves the problem that the ion exchange capacity of the solid phase extraction material in the prior art is too low or too high, resulting in a low recovery rate when it is used to extract the colorant in the food, and cannot more accurately quantitatively test and compare the content of the synthetic colorant in the food.

[0007] To achieve the above objectives and other related objectives, the present invention is achieved through the following technical solutions.

[0008] The first aspect of the present invention discloses a solid phase extraction material, the raw materials of which include biomass, silane containing quaternary ammonium groups and pyrrolidone. The biomass is rich in phenolic hydroxyl groups, so it can react with silane containing quaternary ammonium groups and pyrrolidone, so that the solid phase extraction material has a moderate ion exchange capacity, and the silane containing quaternary ammonium groups makes the solid phase extraction material and the synthetic colorant have a weak anion exchange effect and a hydrophobic retention effect; pyrrolidone makes the hydrophilicity of the solid phase extraction material good. The above-mentioned hydrophobic retention effect and moderate ion exchange capacity enable the solid phase extraction material described in this application to have a high recovery rate when performing solid phase extraction on synthetic colorants in food, and can more accurately detect the content of synthetic colorants in food.

[0009] Preferably, the biomass is obtained by grinding biomass raw materials, and the raw materials of the biomass are selected from one or more of camellia oleifera shells, grape seeds, pomegranate seeds and hawthorn seeds.

[0010] Preferably, the particle size of the biomass is less than or equal to 150 μm. For example, the particle size of the biomass may be 3-30 μm, 30-60 μm, 60-90 μm, 90-120 μm, or 120-150 μm.

[0011] Preferably, the specific surface area of ​​the biomass is 20 to 45 m2 / g. The specific surface area of ​​the biomass can be 20 to 25 m 2 / g, 25~27m 2 / g, 27~32.18m 2 / g, 32.18~40m 2 / g, 40~45m 2 / g.

[0012] Preferably, the surface phenolic hydroxyl content of the biomass is 0.5 mmol / g to 0.7 mmol / g. For example, the surface phenolic hydroxyl content of the biomass may be 0.5 mmol / g to 0.55 mmol / g, 0.55 mmol / g to 0.6 mmol / g, 0.6 mmol / g to 0.65 mmol / g, or 0.65 mmol / g to 0.7 mmol / g.

[0013] Preferably, the silane containing a quaternary ammonium group is selected from one or more of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, tetradecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, and trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride.

[0014] Preferably, the pyrrolidone is selected from one or more of N-methoxyethyl-2-pyrrolidone, N-methylpyrrolidone and N-ethylpyrrolidone.

[0015] Preferably, the mass ratio of the pyrrolidone, the silane containing a quaternary ammonium group and the biomass is (0.8-1.2): (0.7-1.5): 1. For example, the mass ratio of the pyrrolidone, the silane containing a quaternary ammonium group and the biomass can be 0.8:0.7:1, 0.8:0.7:1, 0.8:1:1, 0.8:1.2:1, 0.8:1.5:1, 1:0.7:1, 1:1:1, 1:1.2:1, 1:1.5:1, 1.2:0.7:1, 1.2:1:1, 1.2:1.5:1.

[0016] The second aspect of the present invention discloses a method for preparing the solid phase extraction material as described above. The preparation method comprises the following steps:

[0017] a1) mixing biomass with silane containing a quaternary ammonium group and pyrrolidone to obtain a mixed substance;

[0018] a2) adding the mixed substance into an organic solvent for reaction to obtain the solid phase extraction material.

[0019] Preferably, in step a2), the organic solvent is selected from one or both of methanol and ethanol.

[0020] Preferably, in step a2), the solid-liquid ratio of the mixed substance to the organic solvent is 1 g: (7-20) ml. For example, the solid-liquid ratio of the biomass to the organic solvent may be 1 g: (7-12) ml, 1 g: (12-15) ml, or 1 g: (15-20) ml.

[0021] Preferably, step a2) is performed under a protective atmosphere. More preferably, the protective atmosphere is an oxygen-free atmosphere. In a specific embodiment, the oxygen-free atmosphere is an N2 atmosphere.

[0022] Preferably, in step a2), the reaction temperature is 70-200° C. For example, the reaction temperature may be 70-100° C., 100-120° C., 120-150° C., 150-180° C., or 180-200° C.

[0023] Preferably, in step a2), the reaction time is 6 to 48 hours. For example, the reaction time can be 6 to 12 hours, 12 to 15 hours, 15 to 18 hours, 18 to 21 hours, 21 to 30 hours, 30 to 40 hours, or 40 to 48 hours.

[0024] The third aspect of the present invention discloses a use of the solid phase extraction material as described above in extracting and / or detecting synthetic colorants in food.

[0025] The fourth aspect of the present invention discloses a method for extracting synthetic colorants in food, the extraction method comprising the following steps: first extracting the synthetic colorants in the food to form an extract, and the extraction method uses the solid phase extraction material as described above to contact the extract to extract the synthetic colorants therein.

[0026] Preferably, the food is selected from one or more of beverages, prepared liquors, modulated milk, flavored syrups, and flavored fermented milk.

[0027] The fifth aspect of the present invention discloses a method for eluting a synthetic colorant from a solid phase extraction material, wherein the solid phase extraction material adsorbed with the synthetic colorant is eluted with an eluent, wherein the eluent is one or both of ammonia water and methanol.

[0028] Preferably, the synthetic colorant is selected from one or more of lemon yellow (CAS No. 1934-21-0), quinoline yellow (CAS No. 8004-92-0), new red (CAS No. 220658-76-4), amaranth (CAS No. 915-67-3), carmine (CAS No. 2611-82-7), allura red (CAS No. 25956-17-6), acid red (CAS No. 3734-67-6), erythrosine (CAS No. 568-63-8), indigo (CAS No. 860-22-0), brilliant blue (CAS No. 3844-45-9), and sunset yellow (CAS No. 2783-94-0).

[0029] The sixth aspect of the present invention discloses a method for detecting the content of synthetic colorants in food, wherein the eluate formed by the method for eluting synthetic colorants in solid phase extraction materials as described above is dried and mixed with ammonium acetate solution as a sample solution for detection.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The biomass used in the solid phase extraction material of the present invention naturally contains abundant phenolic hydroxyl groups. After reacting with silane and pyrrolidone containing quaternary ammonium groups, the solid phase extraction material has a moderate ion exchange capacity. In addition to the weak anion exchange effect, the solid phase extraction material also has a hydrophobic retention effect, so it has a higher recovery rate for synthetic colorants in food, thereby more accurately detecting the content of synthetic colorants in food. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Shown is a schematic diagram of the activation, loading, washing and elution steps in the extraction method described in this application. DETAILED DESCRIPTION

[0033] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0034] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods in the following examples without specifying specific conditions are generally carried out under conventional conditions or under conditions recommended by the manufacturers.

[0035] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any methods, equipment, and materials of the prior art similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention can also be used to realize the present invention.

[0036] In this application, the applicant aims to solve the problem that the ion exchange capacity of the solid phase extraction material in the prior art is too low or too high, resulting in a low recovery rate when it is used to extract the colorant in food. The applicant provides a solid phase extraction material and its preparation method and use, wherein the raw materials of the solid phase extraction material include raw biomass, silane containing quaternary ammonium groups and pyrrolidone; the solid phase extraction material has a moderate ion exchange capacity, specifically, the ion exchange capacity is 0.1~0.15mmol / g; and the solid phase extraction material has a hydrophobic retention effect in addition to a weak anion exchange effect. Therefore, when the solid phase extraction material is used to extract the extract of the synthetic colorant in the food, the synthetic colorant can be accurately adsorbed by the solid phase extraction material; during elution, the synthetic colorant can be completely eluted from the solid phase extraction material, and the eluate formed thereby enters the chromatograph as a loading liquid, which can more accurately detect or compare the content of the synthetic colorant in the food.

[0037] The applicant found that an ion exchange capacity that is too high (such as 0.2 mmol / g) makes it impossible to destroy the ion exchange reaction between the synthetic colorant and the solid phase extraction material during elution, and some synthetic colorants cannot be eluted from the solid phase extraction material. Therefore, the recovery rate of the synthetic colorant is low, and the content of the synthetic colorant in the eluate formed is much lower than the content of the synthetic colorant in the food, and the content of the synthetic colorant in the food cannot be detected or compared more accurately; an ion exchange capacity that is too low (such as 0.05 mmol / g) makes it impossible for some synthetic colorants to produce ion exchange with the solid phase extraction material, and they will be eluted during the loading and elution process. Therefore, the recovery rate of the synthetic colorant is low, and the content of the synthetic colorant in the eluate formed is much lower than the content of the synthetic colorant in the food, and the content of the synthetic colorant in the food cannot be detected or compared more accurately. Specifically, the ion exchange capacity of the solid phase extraction material that can solve the above technical problems in the present application can be 0.1mmol / g~0.11mmol / g, 0.11mmol / g~0.12mmol / g, 0.12mmol / g~0.13mmol / g, 0.13mmol / g~0.14mmol / g, 0.14mmol / g~0.15mmol / g.

[0038] In a specific embodiment, the preparation method of the extract of the synthetic colorant in food is as follows:

[0039] b1) mixing the food with the extractant, and performing solid-liquid separation to obtain a first supernatant and a solid phase;

[0040] b2) mixing the solid phase with the extractant, and then separating the solid and the liquid to obtain a second supernatant;

[0041] b3) combining the first supernatant and the second supernatant to obtain a mixed supernatant, and concentrating the mixed supernatant to obtain a concentrated solution;

[0042] b4) mixing the concentrated solution with methanol-water solution to obtain an extract.

[0043] In a more specific embodiment, in b1), the solid-liquid ratio of the food to the extractant is 1 g: (5-20) ml. For example, the solid-liquid ratio of the food to the extractant can be 1 g: (5-8) ml, 1 g: (8-12.5) ml, 1 g: (12.5-15) ml, 1 g: (15-18) ml, or 1 g: (18-20) ml.

[0044] In a more specific embodiment, in b2), the solid-liquid ratio of the solid phase to the extractant is 1 g: (5-30) ml. For example, the solid-liquid ratio of the solid phase to the extractant can be 1 g: (5-8) ml, 1 g: (8-12.5) ml, 1 g: (12.5-15) ml, 1 g: (15-18) ml, 1 g: (18-20) ml, 1 g: (20-25) ml, or 1 g: (25-30) ml.

[0045] In a more specific embodiment, the extractant is an aqueous solution of an ammoniated organic solvent, wherein the ammoniated organic solvent is a mixture of 25wt% ammonia water and ethanol in a volume ratio of (2-6):700, and the volume ratio of the ammoniated organic solvent to water in the aqueous solution of the ammoniated organic solvent is 7:(2-4). For example, the volume ratio of the 25wt% ammonia water to ethanol can be (2-3):700, (3-4):700, (4-5):700, (5-6):700. For example, the volume ratio of the ammoniated organic solvent to water is 7:(2-3), 7:(3-4).

[0046] In a more specific embodiment, in b1), b2) and b4), the mixing is vortex mixing, the rotation speed of the vortex mixing is 1000-3000 times / min, and the mixing time is 0.5-2min. For example, the rotation speed of the vortex mixing can be 1000-2000 times / min, 2000-3000 times / min. For example, the mixing time can be 0.5-1min, 1-1.5min, 1.5-2min.

[0047] In a more specific embodiment, in b1) and b2), the solid-liquid separation is centrifugation, the centrifugation time is 2 to 8 min, and the centrifugation speed is 3000 r / min to 8000 r / min. For example, the centrifugation time can be 2 min to 3 min, 3 min to 4 min, 4 min to 5 min, 5 min to 6 min, 6 min to 7 min, 7 min to 8 min. For example, the centrifugation speed can be 3000 r / min to 4000 r / min, 4000 r / min to 5000 r / min, 5000 r / min to 6000 r / min, 6000 r / min to 7000 r / min, 7000 r / min to 8000 r / min.

[0048] In a more specific embodiment, in b3), the extractant is used to fix the volume, the concentration is evaporation concentration, the volume ratio of the concentrate to the mixed supernatant is (2-5):10, and the concentration temperature is 25-60°C. For example, the volume ratio of the concentrate to the mixed supernatant can be (2-3):10, (3-4):10, (4-5):10. For example, the concentration temperature can be 25°C-30°C, 30°C-35°C, 35°C-40°C, 40°C-45°C, 45°C-50°C, 50°C-55°C, 55°C-60°C.

[0049] In a more specific embodiment, in b4), the concentration of the methanol aqueous solution is 3-8 wt %, and the volume ratio of the concentrated solution to the methanol aqueous solution is (2-5):10. For example, the volume ratio of the concentrated solution to the methanol aqueous solution may be (2-3):10, (3-4):10, or (4-5):10.

[0050] In a specific embodiment, the solid phase extraction material of the present application is contacted with the extract of the synthetic colorant in the food to extract the synthetic colorant therein, and then eluted to form a loading solution.

[0051] Specifically, the specific steps of the above extraction include:

[0052] c1) packing the solid phase extraction material into a column to obtain a solid phase extraction column, wherein the specification of the solid phase extraction column is that the ratio of the filler amount to the volume of the column tube is (100-200) mg / 6 ml, and the filler is the solid phase extraction material;

[0053] c2) Activation: methanol and water are sequentially flowed into the solid phase extraction column and then discarded;

[0054] c3) adding the extract into a solid phase extraction column.

[0055] In a more specific embodiment, the specification of the solid phase extraction column is that the ratio of the filler amount to the volume of the column tube can be (100-150) mg / 6 ml or (150-200) mg / 6 ml.

[0056] In a more specific embodiment, in c2), the volume ratio of the methanol to the column tube is (1-2):1, and the volume ratio of the water to the column tube is (1-2):1.

[0057] Specifically, the specific steps of eluting to form the loading solution include:

[0058] d1) washing the solid phase extraction column after the extraction with formic acid water and methanol in sequence, and discarding the column;

[0059] d2) eluting the solid phase extraction column with a mixed solution of 25 wt % ammonia water and methanol to obtain an eluent;

[0060] d3) drying the eluate, and adding ammonium acetate solution to redissolve it to obtain a loading solution.

[0061] In a more specific embodiment, in d1), the concentration of the formic acid water is 2~5wt%, the volume ratio of the formic acid water to the column tube of the solid phase extraction column is (1~2):1, and the volume ratio of the methanol to the column tube of the solid phase extraction column is (1~2):1.

[0062] In a more specific embodiment, in d2), the volume content of the 25wt% ammonia water in the mixed solution is 1~6%, the volume ratio of the mixed solution to the column tube of the solid phase extraction column is (1~2):1, and the elution flow rate is 1~5s / drop.

[0063] In a more specific embodiment, in d3), the concentration of the aqueous ammonium acetate solution is 10 mmol / L to 30 mmol / L. For example, the concentration of the aqueous ammonium acetate solution can be 10 mmol / L to 20 mmol / L, or 20 mmol / L to 30 mmol / L.

[0064] In a more specific embodiment, in said d3), the volume of said aqueous ammonium acetate solution is 1-5 ml.

[0065] In the following specific embodiments, the steps and principles for determining the ion exchange capacity of the solid phase extraction material are as follows:

[0066] A. Determination steps

[0067] 1) Sample preparation: Sample pretreatment: Weigh an appropriate amount of solid phase extraction material sample into the sand core, rinse with deionizer for about 5-10 times the volume, completely soak and drain, slowly rinse with 0.1mol / L hydrochloric acid solution (about 10 times the volume), then rinse with a large amount of deionized water until the eluate is neutral, and dry. Weigh 150mg of the dried sample (recorded as M1), add 500mg of sodium nitrate, and 15ml of water into the measuring cup; stir for 2min.

[0068] 2) Prepare standard solution: 0.01 mol / L silver nitrate solution: take 0.4225 g of silver nitrate and dilute to 250 ml with water; 0.01 mol / L sodium chloride solution: take 0.1460 g of sodium chloride and dilute to 250 ml with water.

[0069] 3) Calibrate the concentration of silver nitrate solution: Take 10ml or 10g of 0.01mol / L sodium chloride solution in a measuring cup, add distilled water to immerse the electrode, measure the concentration of chloride ions with an automatic potentiometer, and then titrate with silver nitrate solution. When the concentration of chloride ions measured by the automatic potentiometer is 0, record the consumed volume as V1 (V1 is about 10ml), and calculate the accurate concentration C1 of the silver nitrate solution (in mmol / ml).

[0070] 4) Sample determination: Measure the chloride ion concentration of the prepared sample with an automatic potentiometer and titrate with silver nitrate solution. When the chloride ion concentration measured by the automatic potentiometer is 0, record the consumed volume V2 (in ml).

[0071] 5) Calculation: Ion exchange capacity C = V2*C1 / M1.

[0072] B. Determination principle: The solid phase extraction material is slowly rinsed with a large amount of hydrochloric acid solution, so that the chloride ions in the hydrochloric acid produce weak anion exchange with the functional groups in the solid phase extraction material and are retained in the solid phase extraction material. Then, the excess hydrochloric acid is rinsed with a large amount of water. At this time, the chloride ions retained in the solid phase extraction material reach saturation. Finally, silver nitrate is used for titration to calculate the concentration of the retained chloride ions, thereby obtaining the ion exchange capacity of the material. Since the 11 colorants are also in the state of anions when passing through the solid phase extraction material, the retention principle is the same as that of the chloride ions in this experiment, so the ion exchange capacity of the solid phase extraction material can be determined through the above steps.

[0073] In the following specific embodiments, the recovery rate detection using high performance liquid chromatography specifically includes the following steps:

[0074] 1) Prepare the chromatographic column:

[0075] The preparation method of the chromatographic filler comprises the following steps: 10.0 g of silica gel and 90 ml of toluene are placed in a 100 ml three-necked flask, stirred and refluxed at 120° C. for 2 h, and the evaporated water is separated by a water separator. Then, the mixture is cooled to room temperature, 8.0 g of premixed silane (m(glucose):m((3,3,3-trifluoropropyl)triethoxysilane):m(octadecyltrichlorosilane)=1:1:0.8) is added under N2 protection, and the mixture is reacted for 18 h under reflux conditions.

[0076] The chromatographic column has a particle size of 5 μm, a pore size of 120A, and a size of 4.6 x 250 mm.

[0077] 2) Prepare the mobile phase

[0078] Using 20 mmol / L ammonium acetate solution and methanol as raw materials, different mobile phases were prepared at different times according to Table 1, and Table 1 is a mobile phase gradient table.

[0079] Use a high performance liquid chromatograph, set the flow rate as shown in Table 1, the detector is a UV detector, the detection wavelengths are 415nm, 520nm, and 610nm, the column temperature is 30°C, and the injection volume is 10μl. The detection wavelength for detecting blue colorants is 610nm; the detection wavelength for detecting yellow colorants is 415nm; and the detection wavelength for detecting red colorants is 520nm.

[0080] In the following specific examples, the average recovery rate is calculated as follows:

[0081] Standard stock solution of synthetic colorants (1000 mg / L): Weigh 10 mg each of tartrazine, quinoline yellow, new red, amaranth, carmine, allura red, acid red, erythrosine, indigo, brilliant blue, and sunset yellow, add water to make up to 10 ml. Indigo is prepared and used immediately as the standard stock solution of synthetic colorants.

[0082] Synthetic colorant mixed standard working solution (50 mg / L): Pipette 0.5 ml of each of the 11 standard stock solutions, add water to make up to 10 ml to obtain the synthetic colorant mixed standard working solution (referred to as standard solution).

[0083] Spike: 0.2 ml of 50 mg / L synthetic colorant mixed standard working solution is added to 2 g of sample.

[0084] Recovery rate A=S 上样液 / S 标液

[0085] Average recovery rate A'=(A1+A2+A3) / 3

[0086] S 上样液 : The content of synthetic colorant in the sample solution after spike addition;

[0087] S 标液 : The content of synthetic colorant in the synthetic colorant mixed standard working solution, the standard solution concentration is 1mg / L;

[0088] A1 is the recovery rate of the first test, A2 is the recovery rate of the second test, and A3 is the recovery rate of the third test.

[0089] Table 1

[0090]

[0091] Example 1

[0092] This embodiment provides a solid phase extraction material and a preparation method thereof, the preparation method comprising the following steps:

[0093] 1) The dried camellia husks were crushed into particles using a crusher, sieved using a 100-mesh screen, and then dried in an oven at 80°C to obtain camellia husk powder, the specific surface area of ​​which was 32.18 m 2 / g, and the average content of surface phenolic hydroxyl groups is 0.6mmol / g.

[0094] 2) Weigh and mix (N-methylpyrrolidone), dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride) and camellia oleifera shell powder in a mass ratio of 1:1:1 to obtain 9 g of a mixed substance.

[0095] 3) The mixed substance was placed in a 250 ml three-necked flask, 150 ml of methanol was added, and the mixture was stirred and refluxed at 110° C. for 12 h under the protection of N2 to obtain a solid powder. The solid powder was washed with toluene, methanol and acetone respectively, and the filter cake was filtered and collected. The filter cake was dried under vacuum drying conditions at 100° C. for 12 h to obtain a solid phase extraction material. The ion exchange capacity determination method was used to obtain that the ion exchange capacity of the solid phase extraction material in this embodiment was 0.13 mmol / g.

[0096] Example 2

[0097] The difference from Example 1 is that the grape seeds are replaced by the camellia oleifera shell powder. The ion exchange capacity of the solid phase extraction material in this example is 0.12 mmol / g as determined by the above ion exchange capacity determination method.

[0098] Example 3

[0099] The difference from Example 1 is that the oil-tea camellia shell powder replaces the pomegranate seeds. According to the above ion exchange capacity determination method, the ion exchange capacity of the solid phase extraction material in this example is 0.15 mmol / g.

[0100] Example 4

[0101] The difference from Example 1 is that the oil-tea camellia shell powder replaces the hawthorn seeds. According to the above ion exchange capacity determination method, the ion exchange capacity of the solid phase extraction material in this example is 0.12 mmol / g.

[0102] Example 5

[0103] The difference from Example 1 is that the biomass powder, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride) and (N-methylpyrrolidone) are weighed and mixed according to a mass ratio of 1:0.8:0.8. The ion exchange capacity of the solid phase extraction material in this example is 0.13 mmol / g as determined by the above ion exchange capacity determination method.

[0104] Example 6

[0105] The difference from Example 1 is that the biomass powder, dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride) and (N-methylpyrrolidone) are weighed and mixed according to a mass ratio of 1:1.2:1.2. The ion exchange capacity of the solid phase extraction material in this example is 0.12 mmol / g as determined by the above ion exchange capacity determination method.

[0106] Application Example 1

[0107] This application example 1 uses the solid phase extraction material obtained in Example 1 to extract the colorant in yogurt, and uses a liquid chromatography method for detection, including the following:

[0108] 1.1 Extraction steps

[0109] 1) Taking yogurt as food: weigh 2g of sample, first add 0.2ml of 50mg / L of the synthetic colorant mixed standard working solution, then add 25ml of extractant, vortex mix at 2000 times / min for 1min, centrifuge at 5000r / min for 5min to obtain a first supernatant; add 15ml of extractant to the solid phase after centrifugation, repeat extraction once to obtain a second supernatant; combine the first supernatant and the second supernatant, use the extractant to make the volume to 50ml, absorb 10ml of the fixed supernatant and concentrate it to about 3ml in a 50℃ water bath with nitrogen blowing, then add 10ml of 5wt% methanol aqueous solution, vortex mix at 2000 times / min for 30s to obtain an extract; the extractant is an aqueous solution of an ammoniated organic solvent, the ammoniated organic solvent is a mixture of 25wt% ammonia water and ethanol in a volume ratio of 4:700, and the volume ratio of the ammoniated organic solvent to water in the aqueous solution of the ammoniated organic solvent is 7:3.

[0110] 2) Extraction: The solid phase extraction material obtained in Example 1 was loaded into a column, the ion exchange capacity was 0.13 mmol / g, the specification of the solid phase extraction column was filler amount / column volume = 150 mg / 6 ml, and the schematic diagram after loading the column was as follows: Figure 1 As shown;

[0111] Activation: 6 ml of methanol and 6 ml of water flow into the extraction column in sequence, discard them, and activate the filler. The activation diagram is shown in the figure below. Figure 1 As shown;

[0112] Sample loading: Add the extract described in step 1) into the solid phase extraction column. The sample loading diagram is as follows: Figure 1 As shown;

[0113] Wash to remove impurities: Wash the solid phase extraction column with 6 ml of 2 wt% formic acid water and 6 ml of methanol in turn, discard the washed solution, and drain. The washing diagram is shown in the figure. Figure 1 As shown;

[0114] Elution: Use 6 ml of a mixed solution of ammonia water and methanol to elute the solid phase extraction column, control the flow rate to 2s / drop, the concentration of the ammonia water is 25wt%, and the volume content of the ammonia water in the mixed solution is 2%. The elution diagram is as follows: Figure 1 As shown;

[0115] Concentration: Blow the eluate to dryness in a nitrogen bath at 50°C, accurately pipette 1 ml of 20 mmol / L ammonium acetate solution to re-dissolve it to obtain the loading solution.

[0116] According to the above chromatographic conditions, the sample solution was injected, the chromatogram was recorded, and the above steps were repeated three times.

[0117] The average recovery rate of the solid phase extraction material described in this application example is obtained through calculation and analysis, as shown in Table 2.

[0118] Table 2

[0119]

[0120] Results As shown in Table 2, the solid phase extraction material described in Example 1 has a high recovery rate for synthetic colorants in food, which can reach 86.11-110.90%, and can well extract synthetic colorants in food.

[0121] Application Example 2

[0122] The difference between this application example and application example 1 is that the colorant in milk is extracted using the solid phase extraction material obtained in Example 2. According to the above chromatographic conditions, the sample solution is injected, the chromatogram is recorded, and the average recovery rate of the solid phase extraction material in this application example is obtained through calculation and analysis as shown in Table 3.

[0123] Table 3

[0124]

[0125] Results From Table 3, it can be seen that the solid phase extraction material described in Example 2 has a high recovery rate for synthetic colorants in food, which can reach 84.56-109.19%, and can well extract synthetic colorants in food.

[0126] Application Example 3

[0127] The difference between this application example and application example 1 is that the colorant in milk is extracted using the solid phase extraction material obtained in Example 3. According to the above chromatographic conditions, the sample solution is injected, the chromatogram is recorded, and the average recovery rate of the solid phase extraction material in this application example is obtained through calculation and analysis as shown in Table 4.

[0128] Table 4

[0129]

[0130] Results From Table 4, it can be seen that the solid phase extraction material described in Example 4 has a high recovery rate for synthetic colorants in food, which can reach 81.81-108.23%, and can well extract synthetic colorants in food.

[0131] Application Example 4

[0132] The difference between this application example and application example 1 is that orange juice is used to extract the colorant. According to the above chromatographic conditions, the sample solution is injected, and the chromatogram is recorded. The average recovery rate of the solid phase extraction material in this application example is obtained through calculation and analysis as shown in Table 5.

[0133] Table 5

[0134]

[0135] Results From Table 5, it can be seen that the solid phase extraction material described in Example 1 has a high recovery rate of synthetic colorants in orange juice, which can reach 86.07-98.71%, and can well extract synthetic colorants in food.

[0136] Comparative Example 1

[0137] The difference between this comparative example and application example 1 is that when preparing the solid phase extraction material, 9g of camellia oleifera shell powder / dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride) and (N-methylpyrrolidone) are weighed according to a mass ratio of 1:0.5:0.5, and the obtained solid phase extraction material has an ion exchange capacity of 0.05 mmol / g as measured by the above ion exchange capacity determination method. According to the above chromatographic conditions, the sample solution is injected, the chromatogram is recorded, and the average recovery rate of the solid phase extraction material in this application example is obtained by calculation and analysis as shown in Table 6.

[0138] Table 6

[0139]

[0140] As shown in Table 6, when the content of silane and pyrrolidone containing quaternary ammonium groups is too low, the ion exchange capacity of the solid phase extraction material is too low, and the recovery rate of the solid phase extraction material for synthetic colorants in food reaches 72.99-95.82%, and some are lower than 80%.

[0141] Compared with the results in Example 1, the ion exchange capacity is much smaller than that in Example 1. Some synthetic colorants cannot produce ion exchange with the solid phase extraction material and will be eluted during the loading and elution process. Therefore, compared with Example 1, the recovery rate of the solid phase extraction material is lower, and the content of synthetic colorants in food cannot be accurately detected.

[0142] Comparative Example 2

[0143] The difference between this comparative example and application example 1 is that, when preparing the solid phase extraction material, 9g of camellia oleifera shell powder / dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride) and (N-methylpyrrolidone) are weighed according to a mass ratio of 1:2:1.5, and the obtained solid phase extraction material has an ion exchange capacity of 0.2 mmol / g as measured by the above ion exchange capacity determination method. According to the above chromatographic conditions, the sample solution is injected, the chromatogram is recorded, and the average recovery rate of the solid phase extraction material in this application example is obtained by calculation and analysis as shown in Table 7.

[0144] Table 7

[0145]

[0146] Results As shown in Table 7, when the content of silane and pyrrolidone containing quaternary ammonium groups is too high, the ion exchange capacity of the solid phase extraction material is too high, and the recovery rate of the solid phase extraction material for synthetic colorants in food reaches 72.87-94.34%, and some are lower than 80%.

[0147] Compared with the results in Example 1, the ion exchange capacity of the solid phase extraction material is much larger than that of Example 1. The ion exchange effect between the synthetic colorant and the solid phase extraction material cannot be destroyed during elution, so that part of the colorant cannot be eluted from the column. Therefore, compared with Example 1, the recovery rate of the solid phase extraction material is lower, and the content of the synthetic colorant in the food cannot be accurately detected.

[0148] In summary, the biomass used in the solid phase extraction material of the present invention naturally contains abundant phenolic hydroxyl groups. After reacting with silane and pyrrolidone containing quaternary ammonium groups, the solid phase extraction material has a moderate ion exchange capacity, and the solid phase extraction material also has a hydrophobic retention effect in addition to a weak anion exchange effect. Therefore, it has a higher recovery rate for synthetic colorants in food. When used to extract the extract of synthetic colorants in food, the synthetic colorants can be accurately adsorbed by the solid phase extraction material; during elution, the synthetic colorants can be completely eluted from the solid phase extraction material, and the eluate thus formed enters the chromatograph as a loading liquid, which can more accurately detect or compare the content of synthetic colorants in food.

[0149] The present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0150] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A solid phase extraction material for extracting and / or detecting a synthetic colorant, characterized in that: The raw materials of the solid phase extraction material include biomass, silane containing quaternary ammonium groups and pyrrolidone; the silane containing quaternary ammonium groups is selected from one or two of dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride and tetradecyl dimethyl (3-trimethoxysilylpropyl) ammonium chloride; the mass ratio of the pyrrolidone, the silane containing quaternary ammonium groups and the biomass is (0.8~1.2): (0.7~1.5): 1; the surface phenolic hydroxyl content of the biomass is 0.5mmol / g~0.7mmol / g.

2. The solid phase extraction material according to claim 1, characterized in that: The biomass is obtained by grinding biomass raw materials, and the raw materials of the biomass are selected from one or more of camellia oleifera shells, grape seeds, pomegranate seeds and hawthorn seeds; And / or, the particle size of the biomass is less than or equal to 150 μm; And / or, the specific surface area of ​​the biomass is 20 to 45 m 2 / g; And / or, the pyrrolidone is selected from one or more of N-methoxyethyl-2-pyrrolidone, N-methylpyrrolidone, and N-ethylpyrrolidone.

3. A method for preparing a solid phase extraction material according to any one of claims 1 to 2, characterized in that: The preparation method comprises the following steps: a1) mixing biomass with silane containing a quaternary ammonium group and pyrrolidone to obtain a mixed substance; a2) adding the mixed substance into an organic solvent for reaction to obtain the solid phase extraction material.

4. The preparation method according to claim 3, characterized in that: In the step a2), the organic solvent is selected from one or both of methanol and ethanol; And / or, in step a2), the solid-liquid ratio of the mixed substance to the organic solvent is 1 g: (7-20) ml; And / or, step a2) is carried out under a protective atmosphere; And / or, in the step a2), the reaction temperature is 70-200°C; And / or, in the step a2), the reaction time is 6 to 48 hours.

5. The preparation method according to claim 4, characterized in that: The protective atmosphere is an oxygen-free atmosphere.

6. Use of the solid phase extraction material according to any one of claims 1 to 2 in extracting and / or detecting synthetic colorants in food.

7. A method for extracting synthetic colorants in food, characterized in that: The extraction method comprises the following steps: firstly extracting the synthetic colorant in the food to form an extracting solution, and the extraction method uses the solid phase extraction material as described in any one of claims 1 to 2 to contact the extracting solution to extract the synthetic colorant therein.

8. A method for eluting a synthetic colorant from a solid phase extraction material, characterized in that: The solid phase extraction material according to any one of claims 1 to 2 adsorbed with a synthetic colorant is eluted with an eluent, wherein the eluent is one or both of ammonia water and methanol.

9. A method for detecting the content of synthetic colorants in food, characterized in that: The eluate formed by the method for eluting the synthetic colorant in the solid phase extraction material as claimed in claim 8 is dried and mixed with an ammonium acetate solution as a sample solution for detection.

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