Method for detecting acrylamide content and use thereof

Abstract

The application discloses a detection method of acrylamide content and application thereof, and the detection method comprises the following steps: preparing acrylamide standard solutions with different concentrations; obtaining standard samples with different concentrations; performing high performance liquid chromatography ultraviolet detection on the standard samples with different concentrations to obtain peak areas of acrylamide in the standard samples with different concentrations; obtaining a linear equation of acrylamide mass x and peak area y according to the standard samples with different concentrations and the corresponding peak areas; obtaining a sample to be detected; performing high performance liquid chromatography ultraviolet detection on the sample to be detected to obtain a peak area of acrylamide in the sample to be detected; and substituting the peak area of acrylamide in the sample to be detected into the linear equation to calculate the content of acrylamide in the sample to be detected. The application can efficiently extract acrylamide in water-in-oil polyacrylamide emulsion, so that the detection limit is reduced, and the accuracy and precision are improved.

Description

Technical Field

[0001] This application relates to the field of analytical chemistry, specifically to a method for detecting acrylamide content and its application. Background Technology

[0002] Water-in-oil polyacrylamide emulsions are commonly used as emulsifiers and thickeners in daily chemical products, exhibiting good dispersibility and stability. Currently, water-in-oil polyacrylamide emulsions are produced by reacting acrylamide as a monomer, and acrylamide, as a monomer in this polymer component, will remain in the emulsion. However, acrylamide is a risk substance with neurotoxicity, immunotoxicity, reproductive toxicity, and potential carcinogenicity; therefore, accurate detection of the acrylamide content in water-in-oil polyacrylamide emulsions is necessary.

[0003] Existing technologies for the detection of acrylamide include chemical titration, liquid chromatography, and gas chromatography. Before detection, the sample needs to be pretreated to extract the acrylamide. The national standard GB / T 17514-2017 also discloses a method for determining the content of acrylamide monomers, which involves extracting acrylamide using a mixture of isopropanol, water, and ethanol.

[0004] However, the above method is for polyacrylamide solutions. For water-in-oil polyacrylamide emulsions, if common solvents such as methanol are used for extraction, the system will be gel-like because the hydrophilic polymer chains extend into the aqueous phase at the interface, resulting in good fluidity. When the water-in-oil polyacrylamide emulsion is placed in an aqueous solution, the water droplets will reverse, causing the hydrophilic polymer chains to interact outwards and produce a thickening effect. This makes the system difficult to extract and the detection limit cannot be lowered by increasing the sample amount.

[0005] Therefore, this application provides a method for detecting acrylamide content. Summary of the Invention

[0006] The purpose of this application is to provide a method for detecting acrylamide content and its application.

[0007] To achieve the above objectives, the embodiments of this application propose the following technical solutions:

[0008] In a first aspect, embodiments of this application provide a method for detecting acrylamide content, the detection method comprising:

[0009] Prepare acrylamide standard solutions of different concentrations; under acidic conditions, react the acrylamide standard solutions of different concentrations with saturated potassium bromide and potassium bromate in a water bath, respectively. After the reaction is completed, add acetonitrile for extraction, take the acetonitrile layer and filter to obtain standard samples of different concentrations.

[0010] High-performance liquid chromatography with ultraviolet detection was performed on standard samples of different concentrations to obtain the peak area of ​​acrylamide in the standard samples of different concentrations. Based on the standard samples of different concentrations and the corresponding peak areas, a linear equation for the acrylamide mass x and peak area y was obtained.

[0011] Under acidic conditions, water-in-oil polyacrylamide emulsion was heated and reacted with saturated potassium bromide and potassium bromate in a water bath. After the reaction was completed, acetonitrile was added for extraction. The acetonitrile layer was then filtered to obtain the sample to be tested.

[0012] The peak area of ​​acrylamide in the sample was obtained by high performance liquid chromatography with ultraviolet detection. The peak area of ​​acrylamide in the sample was then substituted into the linear equation to calculate the content of acrylamide in the sample.

[0013] In one embodiment, under acidic conditions, standard solutions of acrylamide at different concentrations are reacted with saturated potassium bromide and potassium bromate in a water bath. After the reaction is complete, acetonitrile is added for extraction, and the acetonitrile layer is filtered to obtain standard samples of different concentrations, including:

[0014] Acid reagent, potassium bromide solution, and potassium bromate solution were added to acrylamide standard solutions of different concentrations, and the solutions were heated in a 60°C water bath to react. After the reaction was completed, acetonitrile was added for extraction. The acetonitrile layer was then filtered through a filter membrane to obtain standard samples of different concentrations.

[0015] In one embodiment, under acidic conditions, a water-in-oil polyacrylamide emulsion is reacted with saturated potassium bromide and potassium bromate in a water bath. After the reaction is complete, acetonitrile is added for extraction. The acetonitrile layer is then filtered to obtain the sample to be tested, comprising:

[0016] Take a water-in-oil polyacrylamide emulsion in a container, add acid reagent, saturated potassium bromide solution and potassium bromate solution, and heat the mixture in a 60°C water bath to react. After the reaction is complete, add acetonitrile for extraction. After extraction, take the acetonitrile layer and filter it through a filter membrane to obtain the sample to be tested.

[0017] In one embodiment, the acid reagent is a phosphoric acid solution.

[0018] In one implementation, the linear equation is a linear equation relating the acrylamide mass x and peak area y in a double logarithmic coordinate system; the linear equation is: Correlation coefficient R 2=0.9999.

[0019] As one implementation method, the chromatographic column used for the high performance liquid chromatography ultraviolet detection is an Agilent ZORBAX SB-C8.

[0020] In one embodiment, the column temperature of the chromatographic column is 30°C.

[0021] As one implementation method, the chromatographic conditions for high-performance liquid chromatography with ultraviolet detection include:

[0022] The detection wavelength is 210~220nm, and the injection volume is 20μL;

[0023] Mobile phase A is acetonitrile;

[0024] Mobile phase B is a mixed solution of acetonitrile, water and phosphoric acid in a volume ratio of 100:898:2.

[0025] As one implementation, the gradient elution procedure for mobile phase A and mobile phase B is as follows:

[0026] Within 0-10 minutes, the volume ratio of mobile phase A increased from 0% to 30%, while the volume ratio of mobile phase B decreased from 100% to 70%.

[0027] Within 10-11 minutes, the volume ratio of mobile phase A increased from 30% to 80%, while the volume ratio of mobile phase B decreased from 70% to 20%.

[0028] Elute for 4 minutes with 80% (v / v) mobile phase A and 20% (v / v) mobile phase B over a period of 11-15 minutes.

[0029] Within 15-16 minutes, the volume ratio of mobile phase A decreased from 80% to 0%, while the volume ratio of mobile phase B increased from 20% to 100%.

[0030] Elute for 4 minutes with 0% (v / v) mobile phase A and 100% (v / v) mobile phase B over a period of 16-20 minutes.

[0031] The flow rate was 1.0 mL / min.

[0032] Secondly, embodiments of this application provide the use of the detection method described in the first aspect in the quality control of water-in-oil polyacrylamide emulsion products.

[0033] Compared with the prior art, the embodiments of this application have at least the following beneficial effects:

[0034] This application addresses water-in-oil polyacrylamide emulsion systems. During the derivatization reaction, a saturated potassium bromide solution is used, which effectively inhibits the phase inversion of the water-in-oil polyacrylamide, maintaining the system's fluidity and facilitating the derivatization reaction. Derivatization in a fluid system allows for a more complete reaction between elemental bromine and acrylamide, thereby lowering the detection limit. Simultaneously, elemental bromine generated from saturated potassium bromide and potassium bromate under acidic conditions reacts with acrylamide to form 2,3-dibromopropionamide. The derivatized 2,3-dibromopropionamide is readily separated by high-performance liquid chromatography (HPLC), enabling its detection.

[0035] Furthermore, in this embodiment, acetonitrile is used as the extractant to extract the derivatized product 2,3-dibromopropionamide from the mixture into the acetonitrile phase. This avoids dissolving the oil phase in the emulsion, thereby improving the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion during pretreatment, ensuring sufficient extraction of components, and thus improving the accuracy and precision of the detection results. Meanwhile, the detection method in this embodiment has a wider linear range and a lower detection limit, making it suitable for applications with more stringent and demanding requirements for acrylamide content detection.

[0036] In summary, the detection method of this application can improve the extraction efficiency of acrylamide in water-in-oil polyacrylamide emulsions during pretreatment, thereby lowering the detection limit and solving the problems of high detection limits and low precision and accuracy in existing acrylamide detection methods when detecting acrylamide in water-in-oil polyacrylamide emulsions. Therefore, the detection method of this application, tailored to the characteristics of water-in-oil polyacrylamide emulsions, can more efficiently extract acrylamide from water-in-oil polyacrylamide emulsions during pretreatment, thereby improving the accuracy and precision of the detection results.

[0037] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0038] Figure 1 A schematic diagram illustrating the effect of derivatization reaction temperature and time on acrylamide recovery rate in the examples is shown.

[0039] Figure 2 The chromatogram of acrylamide in the examples is shown;

[0040] Figure 3 A schematic diagram of the linear equations for acrylamide mass and peak area in a double logarithmic coordinate system is shown. Detailed Implementation

[0041] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0042] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0043] It should also be understood that the terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. As used in the embodiments of this application and the appended claims, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms.

[0044] The detection method for acrylamide content and its application in the embodiments of this application will be described in detail below.

[0045] First, let me explain the detection method of the first aspect of this embodiment.

[0046] Detection methods

[0047] Those skilled in the art will know that, since acrylamide is an organic compound with neurotoxicity, immunotoxicity, reproductive toxicity, and potential carcinogenicity, its residual amount in water-in-oil polyacrylamide emulsions should be limited when using acrylamide as a raw material to produce such emulsions.

[0048] Currently, common methods for detecting acrylamide content include chemical titration, liquid chromatography (LC), and gas chromatography (GC). Taking LC as an example, the pretreatment step in LC involves directly extracting acrylamide from the polymer using an extractant. For instance, GB / T 22312-2008 uses methanol-water solution extraction, with a detection limit of ≥0.01%; or, according to the relevant provisions in GB / T 17514-2017, a mixed solvent of isopropanol, water, and ethanol is used for extraction, with a minimum detection limit of 0.02% (dry basis).

[0049] However, according to the relevant requirements of the "Cosmetic Safety Technical Specifications (2015 Edition)," the maximum residue limit for acrylamide in products is 0.1 mg / kg (for leave-on body products) and 0.5 mg / kg (for other products). Specifically, when water-in-oil polyacrylamide emulsions are used as thickeners in cosmetics, the addition amount can reach 5%. Calculations show that when water-in-oil polyacrylamide emulsions are the sole source of acrylamide in leave-on body products, the acrylamide limit is 2 mg / kg (0.0002%). Therefore, the detection limits of the above-mentioned testing methods are far from meeting the testing requirements for cosmetics.

[0050] Meanwhile, the addition of common solvents such as methanol and water to water-in-oil polyacrylamide emulsions thickens the system, causing it to become gel-like. This is because water-in-oil polyacrylamide emulsions are inherently water-in-oil systems, where the hydrophilic polymer chains extend into the aqueous phase at the interface, resulting in good system fluidity. When water-in-oil polyacrylamide is placed in an aqueous solution, the water droplets undergo an inversion, causing the hydrophilic polymer chains to interact outwards, producing a thickening effect. These factors make it difficult for solvent extraction methods to lower the detection limit by increasing the sample amount. Furthermore, according to the principle of "like dissolves like," removing the oil phase that provides fluidity from the emulsion will leave acrylamide trapped in the coagulated polyacrylamide gel, making the pretreatment process even more difficult.

[0051] In view of this, this embodiment provides a method for detecting the acrylamide content in water-in-oil polyacrylamide emulsions.

[0052] Specifically, the detection method includes:

[0053] S1. Prepare acrylamide standard solutions of different concentrations; under acidic conditions, react the acrylamide standard solutions of different concentrations with saturated potassium bromide and potassium bromate in a water bath. After the reaction is complete, add acetonitrile for extraction, filter the acetonitrile layer, and obtain standard samples of different concentrations.

[0054] The purpose of step S1 is to prepare a standard sample. Before preparing the standard sample, a derivatization reaction is performed. The product of the derivatization reaction, 2,3-dibromopropionamide, is easily separated in high-performance liquid chromatography (HPLC). HPLC can achieve the purpose of separation and detection, thus easily eliminating interference from impurities and improving the accuracy and precision of the detection results.

[0055] S2. Perform high performance liquid chromatography with ultraviolet detection on standard samples of different concentrations to obtain the peak area of ​​acrylamide in the standard samples of different concentrations. Based on the standard samples of different concentrations and the corresponding peak areas, obtain the linear equation of acrylamide mass x and peak area y.

[0056] Step S2 involves performing high-performance liquid chromatography with ultraviolet detection on the standard sample prepared in step S1 to obtain the relationship between the concentration and peak area of ​​the standard sample. Since the concentration of the standard sample is related to the mass of the standard sample, a linear equation between the mass x of acrylamide in the standard sample and the peak area y can be obtained based on the relationship between the concentration and peak area of ​​the standard sample.

[0057] Based on this linear equation, when testing the content of the sample, the content of acrylamide in the water-in-oil polyacrylamide emulsion can be quickly calculated according to the peak area of ​​the sample.

[0058] S3. Under acidic conditions, the water-in-oil polyacrylamide emulsion is heated and reacted with saturated potassium bromide and potassium bromate in a water bath. After the reaction is completed, acetonitrile is added for extraction. The acetonitrile layer is then filtered to obtain the sample to be tested.

[0059] In step S3, considering the characteristics of the water-in-oil polyacrylamide emulsion system, saturated potassium bromide is added to inhibit thickening of the system, ensuring a more complete derivatization reaction. As one of the reactants for the derivatization reagent, potassium bromide, together with potassium bromate, converts acrylamide into the derivatization product 2,3-dibromopropionamide. The derivatization product 2,3-dibromopropionamide is easily separated in subsequent high-performance liquid chromatography (HPLC), achieving the purpose of separation and detection.

[0060] Secondly, acetonitrile is added after the derivatization reaction. On the one hand, after the derivatization reaction, the mixture system (including saturated potassium bromide, potassium bromate, 2,3-dibromopropionamide, etc.) is still in a viscous fluid state. The increased viscosity of the system will affect the degree of extraction and limit the choice of extractant. In this embodiment, acetonitrile is added to the system after the derivatization reaction. Acetonitrile acts as an extractant to extract the derivatized product 2,3-dibromopropionamide in the mixture system into the acetonitrile phase, and can avoid dissolving the oil phase in the emulsion. This can better improve the extraction efficiency of acrylamide in water-in-oil polyacrylamide emulsion during the pretreatment process. Moreover, during the extraction, the acetonitrile and the mixture are dispersed into small droplets by shaking, which increases the contact area between the acetonitrile and the mixture, ensuring sufficient extraction of components, thereby improving the accuracy and precision of the detection results.

[0061] S4. Perform high performance liquid chromatography with ultraviolet detection on the sample to be tested to obtain the peak area of ​​acrylamide in the sample to be tested; substitute the peak area of ​​acrylamide in the sample to be tested into the linear equation obtained in step S2 to calculate the content of acrylamide in the sample to be tested.

[0062] In step S4, after testing the sample, the test results are substituted into the linear equation obtained in step S2 to calculate the acrylamide content in the sample. Since the reactions and experiments in steps S1-S3 have high accuracy and precision, the results calculated in step S4 also have high accuracy and precision.

[0063] Understandably, this embodiment, considering the characteristics of water-in-oil polyacrylamide emulsions, uses a saturated potassium bromide solution during the derivatization reaction. This effectively suppresses the phase inversion of the water-in-oil polyacrylamide, allowing the derivatization reaction to proceed in a flowing system. Conducting the derivatization reaction in a flowing system enables a more complete reaction between elemental bromine and acrylamide, thus improving the extraction efficiency of acrylamide from the water-in-oil polyacrylamide emulsion and lowering the detection limit. Simultaneously, elemental bromine generated from saturated potassium bromide and potassium bromate under acidic conditions reacts with acrylamide to generate 2,3-dibromopropionamide. The 2,3-dibromopropionamide generated by derivatization is easily separated by high-performance liquid chromatography (HPLC), achieving the purpose of separation and detection.

[0064] It is important to note that although saturated potassium bromide solution can effectively inhibit the phase inversion of water-in-oil polyacrylamide emulsions, the mixture system (including saturated potassium bromide, potassium bromate, 2,3-dibromopropionamide, etc.) remains a viscous fluid after the derivatization reaction is completed. The increased viscosity of the system will affect the degree of extraction. In this embodiment, acetonitrile is used as the extractant to extract the derivatized product 2,3-dibromopropionamide into the acetonitrile phase. During the extraction, the mixture is shaken to disperse the acetonitrile and the mixture into small droplets, thereby increasing the contact area between the acetonitrile and the mixture, ensuring sufficient extraction of components, avoiding the dissolution of excessive oil phase, and avoiding solvent effects in liquid chromatography.

[0065] Therefore, the detection method of this embodiment can improve the accuracy and precision of the detection results. Furthermore, based on the steps of the above-described detection method, the detection method of this embodiment has a wider linear range and a lower detection limit, thus making it suitable for applications with more stringent and demanding requirements for acrylamide content detection.

[0066] The following will further explain the relevant steps of the above detection method.

[0067] In step S1, acrylamide standard solutions of different concentrations are prepared; under acidic conditions, the acrylamide standard solutions of different concentrations are heated with saturated potassium bromide and potassium bromate in a water bath, then removed and cooled, and ferrous sulfate solution, anhydrous sodium sulfate, and acetonitrile are added; extraction is performed, and the acetonitrile layer is filtered to obtain standard samples of different concentrations, including:

[0068] Acid reagent, saturated potassium bromide solution, and potassium bromate solution were added to acrylamide standard solutions of different concentrations, respectively, and the mixture was heated in a 60°C water bath. After the reaction was completed, the mixture was removed and cooled. Ferrous sulfate solution, anhydrous sodium sulfate, and acetonitrile were then added. The purpose of adding ferrous sulfate solution was to remove excess bromine and prevent bromine from being extracted into acetonitrile. Anhydrous sodium sulfate was added for subsequent extraction to separate acetonitrile from water, so that less acetonitrile dissolves in the aqueous phase, thus ensuring that more volume of acetonitrile can be used for subsequent testing, thereby ensuring the accuracy of the test results. The purpose of adding acetonitrile was to extract the derivatized product. After extraction, the acetonitrile layer was filtered through a filter membrane to obtain standard samples of different concentrations.

[0069] Typically, the heating time is 15 min to 240 min, preferably 30 min to 240 min, and more preferably 2 h (120 min).

[0070] Specifically, in one embodiment of this application, the steps for preparing acrylamide standard solutions of different concentrations can be performed as follows:

[0071] Weigh 1g of acrylamide standard, dissolve it in distilled water, and pour the solution into a 100mL volumetric flask. Dilute to volume with distilled water and mix well. Transfer 10mL of the solution to another 100mL volumetric flask, dilute to volume, and mix well to obtain the stock solution. The mass concentration of this acrylamide standard stock solution is 1mg / mL. For example, the mass concentration of the acrylamide standard stock solution can also be 2mg / mL-5mg / mL. To facilitate the subsequent preparation of standard working solutions, the mass concentration of the standard stock solution is usually prepared as an integer, such as 1mg / mL.

[0072] Typically, after obtaining the stock solution, different acrylamide standard solutions can be prepared based on the stock solution. After obtaining the standard solutions, saturated potassium bromide and potassium bromate can be added under acidic conditions, heated in a water bath, then removed and cooled. Ferrous sulfate solution, anhydrous sodium sulfate, and acetonitrile are then added; extraction is performed, and the acetonitrile layer is filtered to obtain standard samples of different concentrations.

[0073] Specifically, the acidic conditions described in this embodiment are pH values ​​less than 7. In this embodiment, an acidic environment is created by adding phosphoric acid.

[0074] More specifically, during the preparation of the test sample, when preparing the water-in-oil polyacrylamide emulsion solution, because the sample is a water-in-oil emulsion, the hydrophilic polymer chains extend into the internal aqueous phase at the interface, resulting in good system fluidity. After adding water, the water-in-oil droplets undergo an inversion, and the hydrophilic polymer chains interact outward, producing a thickening effect, leading to a viscous solution. To avoid it becoming too viscous and making it difficult to extract acrylamide from the sample, a high concentration of salt solution needs to be added to inhibit the inversion process. However, since potassium bromate is a toxic compound and its solubility in water is low, this embodiment uses a high concentration of potassium bromide solution to suppress the possible thickening phenomenon of the test sample.

[0075] Specifically, this embodiment uses a saturated potassium bromide solution; the saturated potassium bromide solution mentioned in this embodiment refers to a potassium bromide solution with a mass fraction concentration of 40% at around 20°C.

[0076] Furthermore, after adding ferrous sulfate solution, anhydrous sodium sulfate, and acetonitrile, extraction is performed. The acetonitrile layer after extraction is then filtered using a 0.45 μm filter membrane.

[0077] Specific examples are as follows:

[0078] Using a pipette, transfer 10 μL of the above-matched standard solutions of different concentrations into 15 mL round-bottom centrifuge tubes, add distilled water to make up to 0.5 mL, add 2 mL of saturated potassium bromide solution, 1 mL of 10% phosphoric acid solution, and 0.4 mL of potassium bromate solution [c(1 / 6KBrO3)=0.4 mol / L], seal and shake well.

[0079] It is important to note that if the system does not turn yellow after shaking, potassium bromate solution needs to be added until the system turns pale yellow. This is because this step is to generate elemental bromine from potassium bromide and potassium bromate under acidic conditions. Elemental bromine dissolves in water to form yellow bromine water. If the system does not turn yellow or pale yellow, it means the reaction is not complete. Since the potassium bromide solution is saturated, potassium bromate is the least abundant initial reactant. Therefore, if the system does not turn yellow or pale yellow, potassium bromate solution needs to be added.

[0080] Once the solution turns pale yellow, place the round-bottom centrifuge tube in a water bath for heating. Specifically, as follows... Figure 1 As shown in the figure, this embodiment found through relevant experiments that the recovery rate of acrylamide at a temperature of 60°C for 2 hours is higher than that at a reaction time of 30 minutes. Therefore, the preferred reaction conditions are: water bath temperature of 60°C and heating time of 2 hours.

[0081] For example, in one embodiment of this application, the mixture is heated for 2 hours; after 2 hours, it is taken out and cooled, and 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate and 4 mL of acetonitrile are added to the system. The mixture is shaken or vortexed for 1 minute, placed in a centrifuge, and centrifuged at 3000 rpm for 5 minutes. The acetonitrile layer is then filtered through a 0.45 μm filter membrane to obtain a standard sample.

[0082] More specifically, in this embodiment, the purpose of adding ferrous sulfate solution after cooling is to remove excess elemental bromine and prevent bromine from being extracted into acetonitrile. Anhydrous sodium sulfate is added for subsequent extraction; specifically, acetonitrile is added as an extractant to dissolve the target product from the system without dissolving other solutes, and to avoid the solvent effect of other organic solvents in liquid chromatography. Since acetonitrile and water are miscible, during extraction, the dissolution of acetonitrile in the aqueous phase reduces its volume, thus affecting subsequent tests. Therefore, adding anhydrous sodium sulfate separates acetonitrile from water, reducing its dissolution in the aqueous phase and ensuring a larger volume of acetonitrile is available for subsequent tests, thereby guaranteeing the accuracy of the test results.

[0083] In step S1, in this embodiment, elemental bromine generated by the reaction of potassium bromide and potassium bromate under acidic conditions is reacted with acrylamide to generate 2,3-dibromopropionamide. The derivatized product 2,3-dibromopropionamide is easily separated in high-performance liquid chromatography (HPLC). HPLC can achieve the purpose of separation and detection, thus easily eliminating interference from impurities and improving the accuracy and precision of the detection results.

[0084] In step S2, after obtaining the standard samples of different concentrations, high performance liquid chromatography with ultraviolet detection is performed on the standard samples of different concentrations to obtain the peak area of ​​acrylamide in the standard samples of different concentrations; and based on the mass of the standard samples of different concentrations and the corresponding peak area, a linear equation for the acrylamide mass x and peak area y is obtained.

[0085] Step S2 involves performing high-performance liquid chromatography with ultraviolet detection on the standard samples of different concentrations obtained in step S1 to obtain the peak area of ​​acrylamide in the standard samples of different concentrations. Based on the mass of the standard samples in the standard samples of different concentrations and the corresponding peak area, a linear equation between the mass of acrylamide x and the peak area y is obtained.

[0086] Specifically, the linear equation can be a linear equation relating the acrylamide mass x and the peak area y in a double logarithmic coordinate system. More specifically, the linear equation described above is: Correlation coefficient R 2 =0.9999.

[0087] It should be noted that the double logarithmic coordinate system is used in this embodiment to obtain the detection limit (1-10000 mg / kg). Based on this detection limit range, the detection method of this embodiment has the advantages of low detection limit and large linear range.

[0088] In addition, when conducting actual tests on other samples, a common coordinate system can also be used, and this embodiment does not impose too many restrictions.

[0089] In step S2, the standard sample after the above derivatization reaction is separated and detected by high performance liquid chromatography-ultraviolet method. Among them, the 2,3-dibromopropionamide generated by derivatization is easily separated in high performance liquid chromatography. The separation and detection can be achieved by high performance liquid chromatography, thus easily eliminating the interference of impurities and improving the accuracy of the detection results.

[0090] Meanwhile, based on the above test results, in step S2, a linear equation can be obtained in the double logarithmic coordinate system to determine the relationship between acrylamide mass x and peak area y. Based on this linear equation, when detecting the content of the sample to be tested, the content of acrylamide in water-in-oil polyacrylamide can be calculated according to the peak area of ​​the sample to be tested.

[0091] It is understood that the high-performance liquid chromatography (HPLC) ultraviolet detection in this embodiment can be performed in an HPLC instrument, such as the Agilent 1260 HPLC instrument.

[0092] In step S3, under acidic conditions, the water-in-oil polyacrylamide emulsion is heated with saturated potassium bromide and potassium bromate in a water bath, then cooled, and ferrous sulfate solution, anhydrous sodium sulfate, and acetonitrile are added; extraction is performed, and the acetonitrile layer is filtered to obtain the sample to be tested, including:

[0093] Take a water-in-oil polyacrylamide emulsion in a container, add acid reagent, saturated potassium bromide solution and potassium bromate solution, and heat in a 60°C water bath to react; after the reaction is complete, add ferrous sulfate solution, anhydrous sodium sulfate and acetonitrile; perform extraction, and after extraction, take the acetonitrile layer and filter it through a filter membrane to obtain the sample to be tested.

[0094] In this embodiment, the container is preferably made of PP material, i.e., polypropylene. The reason for choosing PP material in this embodiment is that PP material is more acetonitrile-friendly and will not adhere to the container wall during the shaking process in the aqueous system, which can better ensure the integrity of the extraction and thus ensure the accuracy of the detection results.

[0095] Typically, the heating time is 15 min to 240 min, preferably 30 min to 240 min, and more preferably 2 h (120 min).

[0096] Specifically, the above steps can be:

[0097] Weigh 0.5 g of water-in-oil polyacrylamide emulsion into a 15 mL round-bottom centrifuge tube, add 2 mL of saturated potassium bromide solution, 1 mL of 10% phosphoric acid solution, and 0.4 mL of potassium bromate solution [c(1 / 6KBrO3)=0.4 mol / L]. Seal and shake well.

[0098] It is important to note that if the system does not turn yellow after shaking, potassium bromate solution needs to be added until the system turns pale yellow. This is because this step is to generate elemental bromine from potassium bromide and potassium bromate under acidic conditions. Elemental bromine dissolves in water to form yellow bromine water. If the system does not turn yellow or is pale yellow, it means that the amount of bromine is insufficient to completely react with acrylamide, i.e., the reaction is not complete. Since the potassium bromide solution is a saturated potassium bromide solution, the initial reactant is potassium bromate, so when the system does not turn yellow or is pale yellow, potassium bromate solution needs to be added.

[0099] Once the solution turns light yellow, place the round-bottom centrifuge tube in a water bath for heating. Specifically, the heating time and water bath temperature are the same as in step S1, heating for 2 hours at a water bath temperature of 60°C.

[0100] After heating for 2 hours, remove and cool. Add 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate and 4 mL of acetonitrile to the system. Shake or vortex for 1 minute. Place in a centrifuge and centrifuge at 3000 rpm for 5 minutes. Take the acetonitrile layer and filter it through a 0.45 μm filter membrane to obtain the sample to be tested.

[0101] Those skilled in the art will know that, since water-in-oil polyacrylamide emulsions are essentially water-in-oil systems, the hydrophilic polymer chains in this polymer extend into the internal aqueous phase at the interface, resulting in good system fluidity. When water-in-oil polyacrylamide is placed in an aqueous solution, the water-in-oil droplets undergo a reverse rotation, causing the hydrophilic polymer chains to interact outwards and produce a thickening effect (gel-like structure), making the entire system viscous. Acrylamide remains in the viscous system, making it difficult to extract acrylamide from the water-in-oil polyacrylamide emulsion. In other words, the acrylamide extraction efficiency from the water-in-oil polyacrylamide emulsion is low, leading to a relatively high detection limit.

[0102] In step S3, firstly, a saturated potassium bromide solution is added to the water-in-oil polyacrylamide emulsion. On one hand, the high concentration of potassium bromide effectively inhibits the phase inversion of the water-in-oil polyacrylamide emulsion, thus effectively preventing the thickening effect of the emulsion, maintaining the fluidity of the system, which is conducive to the derivatization reaction (better derivatization effect) and improves the accuracy of the detection results. On the other hand, under acidic conditions, in the fluid system maintained by the high concentration of potassium bromide solution, potassium bromide and potassium bromate will first react to generate elemental bromine, which then undergoes a derivatization reaction with acrylamide to generate 2,3-dibromopropionamide. It is understood that the 2,3-dibromopropionamide generated by derivatization is easily separated in subsequent high-performance liquid chromatography (HPLC), achieving the purpose of separation and detection through HPLC.

[0103] In other words, the potassium bromide solution used in this embodiment can not only effectively prevent the thickening effect of the emulsion, thus maintaining the fluidity of the system, but also serve as one of the reaction raw materials for the derivatization reagent, together with another reaction raw material, potassium bromate, to convert acrylamide into 2,3-dibromopropionamide. Therefore, this embodiment not only facilitates the derivatization reaction but also effectively avoids the introduction of new impurities that could interfere with subsequent detection.

[0104] Secondly, acetonitrile is added after the derivatization reaction. On the one hand, after the derivatization reaction, the mixture system (including saturated potassium bromide, potassium bromate, 2,3-dibromopropionamide, etc.) is still in a viscous fluid state. The increased viscosity of the system will affect the degree of extraction. In this embodiment, acetonitrile is added to the mixture system after the derivatization reaction. Acetonitrile acts as an extractant to extract the derivatized product 2,3-dibromopropionamide in the mixture system into the acetonitrile phase, and can avoid dissolving the oil phase in the emulsion. This can better improve the extraction efficiency of acrylamide in water-in-oil polyacrylamide emulsion during the pretreatment process. Moreover, during the extraction, the acetonitrile and the mixture are dispersed into small droplets by shaking, which increases the contact area between the acetonitrile and the mixture, ensuring sufficient extraction of components, thereby improving the accuracy and precision of the detection results.

[0105] In step S4, the sample to be tested is subjected to high-performance liquid chromatography with ultraviolet detection to obtain the peak area of ​​acrylamide in the sample; the peak area of ​​acrylamide in the sample is substituted into the linear equation to calculate the mass of acrylamide in the sample, specifically including:

[0106] The sample to be tested obtained in step S3 is injected into a high-performance liquid chromatograph for high-performance liquid chromatography with ultraviolet light detection to obtain the peak area of ​​acrylamide; the obtained peak area of ​​acrylamide is substituted into the linear equation obtained in step S2 to calculate the content of acrylamide.

[0107] Therefore, in this embodiment, the sample after the above derivatization reaction is separated and detected by high performance liquid chromatography-ultraviolet (HPLC-UV) to obtain the peak area of ​​acrylamide in the sample. Simultaneously, based on the linear equation obtained in step S2, the content of acrylamide in water-in-oil polyacrylamide can be calculated according to the peak area of ​​the sample.

[0108] Therefore, the detection method of this embodiment has higher extraction efficiency during preprocessing, thereby improving the accuracy and precision of the test method of this embodiment.

[0109] It is understandable that in the testing process of steps S2 and S4, the sample (standard sample or sample to be tested) is injected into the high performance liquid chromatograph for high performance liquid ultraviolet detection.

[0110] As one implementation method, the chromatographic column used for the above-mentioned high performance liquid chromatography ultraviolet detection is an Agilent ZORBAX SB-C8, and the column temperature is 30°C.

[0111] As one implementation method, the chromatographic conditions for the above-mentioned high-performance liquid chromatography-ultraviolet detection include:

[0112] The detection wavelength is 210~220nm (e.g., 214nm), and the injection volume is 20μL.

[0113] Mobile phase A is acetonitrile;

[0114] Mobile phase B is a mixed solution of acetonitrile, water and phosphoric acid (e.g., phosphoric acid with a mass concentration of 85%) in a volume ratio of 100:898:2.

[0115] In this embodiment, the gradient elution procedure for mobile phase A and mobile phase B is as follows:

[0116] Within 0-10 minutes, the volume ratio of mobile phase A increased from 0% to 30%, while the volume ratio of mobile phase B decreased from 100% to 70%.

[0117] Within 10-11 minutes, the volume ratio of mobile phase A increased from 30% to 80%, while the volume ratio of mobile phase B decreased from 70% to 20%.

[0118] Elute for 4 minutes with 80% (v / v) mobile phase A and 20% (v / v) mobile phase B over a period of 11-15 minutes.

[0119] Within 15-16 minutes, the volume ratio of mobile phase A decreased from 80% to 0%, while the volume ratio of mobile phase B increased from 20% to 100%.

[0120] Elute for 4 minutes with 0% (v / v) mobile phase A and 100% (v / v) mobile phase B over a period of 16-20 minutes.

[0121] The flow rate was 1.0 mL / min.

[0122] In summary, the detection method of this embodiment can improve the extraction efficiency of acrylamide in water-in-oil polyacrylamide emulsions during pretreatment, thereby lowering the detection limit and solving the problems of high detection limits and low precision and accuracy of existing acrylamide detection methods when detecting acrylamide in water-in-oil polyacrylamide emulsions. Therefore, the detection method of this embodiment, tailored to the characteristics of water-in-oil polyacrylamide emulsions, can more efficiently extract acrylamide from water-in-oil polyacrylamide emulsions during pretreatment, thereby improving the accuracy and precision of the detection results. Simultaneously, this detection method has a wider linear range (1-10000 mg / kg) and a lower detection limit, thus making it suitable for applications with more stringent and demanding requirements for acrylamide content detection.

[0123] Next, the application of the above-mentioned detection method in the quality control of water-in-oil polyacrylamide emulsions will be explained.

[0124] use

[0125] It is understandable that water-in-oil polyacrylamide emulsions produced using acrylamide as a raw material will have a certain amount of acrylamide residue. Since water-in-oil polyacrylamide is commonly used as an emulsifier and thickener in daily chemical products, this can easily lead to direct or indirect contact with the human body. Therefore, when producing water-in-oil polyacrylamide using acrylamide as a raw material, the residual amount of acrylamide in the emulsion should be limited.

[0126] As mentioned above, the detection method provided in this embodiment can extract acrylamide more efficiently, thereby achieving accurate and rapid detection of acrylamide content in water-in-oil polyacrylamide emulsions with low detection limits, and the detection method is highly efficient. Therefore, it can meet the needs of safety risk screening of acrylamide in water-in-oil polyacrylamide emulsions, and provide good technical support for the quality control and safety monitoring of water-in-oil polyacrylamide emulsions, indicating that this detection method has better application prospects in the quality control of water-in-oil polyacrylamide emulsions.

[0127] The present application will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustration / explanation only and are not intended to limit the scope of the present application.

[0128] Unless otherwise specified, all materials, reagents and instruments used in the following embodiments are commercially available.

[0129] It should be noted that, unless otherwise specified, the water used in the following embodiments is distilled water; the methods and conditions for analysis (separation and detection) using high-performance liquid chromatography in the following embodiments are as follows:

[0130] The high-performance liquid chromatograph used was an Agilent 1260 liquid chromatograph, and the concentration of phosphoric acid solution in mobile phase B was 85%.

[0131] Mobile phase A is acetonitrile; mobile phase B is a mixed solution of acetonitrile, water and phosphoric acid in a volume ratio of 100:898:2.

[0132] The gradient elution procedure is shown in Table 1 below:

[0133] Table 1: Gradient elution procedure

[0134]

[0135] Specifically, as shown in Table 1, within 0-10 min, the volume ratio of mobile phase A increased from 0% to 30%, while the volume ratio of mobile phase B decreased from 100% to 70%. That is, the volume ratio of mobile phase A increased linearly from 0% at 0 min to 30% at 10 min, while the volume ratio of mobile phase B decreased linearly from 100% at 0 min to 70% at 10 min.

[0136] Within 10-11 minutes, the volume ratio of mobile phase A increased from 30% to 80%, while the volume ratio of mobile phase B decreased from 70% to 20%. That is, the volume ratio of mobile phase A increased linearly from 30% at 10 minutes to 80% at 11 minutes, while the volume ratio of mobile phase B decreased linearly from 100% at 10 minutes to 20% at 11 minutes.

[0137] Elute for 4 minutes with mobile phase A (80% by volume) and mobile phase B (20% by volume) over a period of 11-15 minutes; that is, elute while keeping the volume ratio of mobile phase A to mobile phase B constant over a period of 11-15 minutes.

[0138] Within 15-16 minutes, the volume ratio of mobile phase A decreased from 80% to 0%, while the volume ratio of mobile phase B increased from 20% to 100%. That is, the volume ratio of mobile phase A decreased linearly from 80% at 15 minutes to 0% at 16 minutes, while the volume ratio of mobile phase B increased linearly from 20% at 15 minutes to 100% at 16 minutes.

[0139] Elute for 4 minutes with 0% (v / v) mobile phase A and 100% (v / v) mobile phase B over a period of 16-20 minutes; understandably, elution is performed with 0% (v / v) mobile phase A and 100% (v / v) mobile phase B over a period of 16-20 minutes.

[0140] In this embodiment, the chromatographic column used is an Agilent ZORBAX SB-C8 with a length of 250 mm, an inner diameter of 4.6 mm, and a packing particle diameter of 5 μm. The detection wavelength is set to 214 nm, the column temperature is 30 °C, and the injection volume is 20 μL.

[0141] Examples 1-10:

[0142] This embodiment found through relevant experiments that the derivatization temperature and time of acrylamide are related to its peak area. Therefore, a group experiment was set up to verify the derivatization conditions, specifically:

[0143] Ten 15 mL polypropylene round-bottom centrifuge tubes were used as containers for the examples. Approximately 0.5 g of water-in-oil polyacrylamide emulsion sample was weighed into the centrifuge tubes of Examples 2-5 and 7-10. An acrylamide standard solution with a concentration of 1728 mg / L was prepared, and 100 μL was added to the centrifuge tubes of Examples 1, 3-6, and 8-10, respectively. Then, 2 mL of 40% potassium bromide solution, 1 mL of 10% phosphoric acid solution, and 0.4 mL of potassium bromate solution [c(1 / 6KBrO3)=0.4 mol / L] were added to Examples 1-10, respectively. The tubes were sealed and shaken well. Examples 1-5 were placed at room temperature (20°C), and Examples 6-10 were placed in a water bath at 60°C. Examples 3 and 8 were removed after 0.5 h, Examples 4 and 9 after 1 h, and the remaining examples after 2 h. All examples were cooled to room temperature, then 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate and 4 mL of acetonitrile were added, and the mixture was shaken or vortexed for 1 min. After centrifugation at 3000 rpm for 5 min, the upper organic phase was passed through a 0.45 μm filter membrane into a sample vial, and the sample vial was injected into a high performance liquid chromatograph for separation and detection.

[0144] Recovery rate is calculated using the following formula (ignoring the effect of sample mass on peak area): ;

[0145] in:

[0146] The peak areas are those of Examples 3-5 and 8-10;

[0147] The peak areas of Examples 2 and 7 are given at the corresponding temperatures.

[0148] The peak areas of Examples 1 and 6 are given at the corresponding temperatures.

[0149] The experimental results are shown in Table 2:

[0150] Table 2: Experimental Results of Examples 1-10

[0151]

[0152] Based on Table 2 and Figure 1 The test results show that the peak area and recovery rate of acrylamide are better at 60℃ than at room temperature (20℃). Therefore, the reaction temperature is chosen to be 60℃. Meanwhile, the recovery rate obtained at 60℃ for 0.5 h (30 min) is lower than that obtained at 2 h; therefore, the preferred reaction time is 2 h (120 min).

[0153] Accuracy experiment:

[0154] Examples 11-15

[0155] Weigh 0.4742 g of acrylamide standard into a 100 mL volumetric flask and dilute to volume with water to obtain a stock solution with an acrylamide concentration of 4742 mg / L. Transfer 10.00 mL of the stock solution to another 100 mL volumetric flask and dilute to volume with water to obtain a first working standard solution with a concentration of 474.2 mg / L. Take 10.00 mL of the first working standard solution into a new 100 mL volumetric flask and dilute to volume with water to obtain a second working standard solution with a concentration of 47.42 mg / L. Take 10 mL of the second working standard solution into a new 100 mL volumetric flask and dilute to volume with water to obtain a third working standard solution with a concentration of 4.742 mg / L. Take 10 mL of the third working standard solution into a new 100 mL volumetric flask and dilute to volume with water to obtain a fourth working standard solution with a concentration of 0.4742 mg / L.

[0156] Measure 1.00 mL of the stock solution, the first working standard solution, the second working standard solution, the third working standard solution, and the fourth working standard solution into five 15 mL polypropylene round-bottom centrifuge tubes. Add 2 mL of 40% potassium bromide solution, 1 mL of 10% phosphoric acid solution, and 0.4 mL of potassium bromate solution [c(1 / 6KBrO3)=0.4 mol / L] to each tube. Seal and shake well, place in a 60℃ water bath for 2 hours, remove and cool to room temperature. Add 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate, and 4 mL of acetonitrile. Shake or vortex for 1 min, centrifuge at 3000 rpm for 5 min, and filter the acetonitrile phase through a 0.45 μm filter membrane into a sample vial. Inject into a high-performance liquid chromatograph for detection. The relationship between the peak area and the mass of acrylamide is shown in Table 3.

[0157] Table 3: Relationship between chromatographic peak area and acrylamide mass

[0158]

[0159] Taking Example 13 as an example, the chromatogram of Example 13 was obtained, and the chromatogram is as follows: Figure 2 As shown, according to Figure 2 It can be seen that the retention time of acrylamide is about 8 minutes, and no obvious interference peaks appear before and after. This means that the detection method in this embodiment can eliminate the influence of impurities and ensure the accuracy of the detection results.

[0160] Next, a linear regression was performed with the common logarithm of acrylamide mass as the x-axis and the common logarithm of peak area as the y-axis, yielding the following linear equation: Correlation coefficient R 2 =0.9999, the linear equation is as follows Figure 3 As shown.

[0161] It should be noted that the double logarithmic coordinate system is used in this embodiment to obtain the detection limit (1-10000 mg / kg). Based on this detection limit range, the detection method of this embodiment has the advantages of low detection limit and large linear range.

[0162] In addition, when conducting actual tests on other samples, a common coordinate system can also be used, and this embodiment does not impose too many restrictions.

[0163] according to Figure 3 The results show that acrylamide exhibits good linearity in the mass range of 0.4742-4742 μg in this embodiment; therefore, the detection method used in this embodiment has a wider linear range.

[0164] Examples 16-18:

[0165] Accurately weigh three portions of water-in-oil polyacrylamide emulsion into 15 mL polypropylene round-bottom centrifuge tubes (weights shown in Table 4, accurate to 1 mg). Add 2 mL of 40% potassium bromide solution, 1 mL of 10% phosphoric acid solution, and 0.4 mL of potassium bromate solution [c(1 / 6KBrO3)=0.4 mol / L]. Seal and shake well, then place in a 60℃ water bath for 2 hours. Remove and cool to room temperature. Add 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate, and 4 mL of acetonitrile. Shake or vortex for 1 min, then centrifuge at 3000 rpm for 5 min. Transfer the upper organic phase through a 0.45 μm filter membrane to a sample vial. The obtained samples were injected into a high-performance liquid chromatograph for detection, and the peak area of ​​acrylamide was obtained. Substituting these values ​​into the linear equations obtained in Examples 11-15 above, the mass of acrylamide detected in each sample was calculated. Dividing this mass by the sample weight gave the content of the target substance in Examples 16-18, i.e., the acrylamide content (mg / kg), denoted as ω, as shown in Table 4.

[0166] Table 4: Experimental Results of Examples 16-18

[0167]

[0168] Examples 19-27:

[0169] Nine portions of the aforementioned water-in-oil polyacrylamide emulsion were accurately weighed into 15 mL polypropylene round-bottom centrifuge tubes (weights shown in Table 5, accurate to 1 mg). Three portions were grouped together, and 0.1 mL (parallel group 1), 0.3 mL (parallel group 2), and 0.6 mL (parallel group 3) of 172.8 mg / L acrylamide working solution were added. Then, 2 mL of 40% potassium bromide solution, 1 mL of 10% phosphoric acid solution, and 0.4 mL of potassium bromate solution [c(1 / 6KBrO3)=0.4 mol / L] were added. The tubes were sealed and shaken well, then placed in a 60℃ water bath for 2 hours. After removal, the tubes were cooled to room temperature. 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate, and 4 mL of acetonitrile were added. The tubes were shaken or vortexed for 1 min, then centrifuged at 3000 rpm for 5 min. The upper organic phase was filtered through a 0.45 μm filter membrane into a sample vial. The obtained sample was injected into a high-performance liquid chromatograph for detection. The peak area of ​​acrylamide was obtained and substituted into the linear equation calculated according to Examples 11-15 above to calculate the mass of acrylamide in the sample. (μg).

[0170] Specifically, the preparation method for the above-mentioned acrylamide working solution can be as follows:

[0171] Take 10 mL of the acrylamide standard solution prepared in Examples 1-10 and put it into a 100 mL volumetric flask, and dilute to volume.

[0172] Recovery rate calculation: ;

[0173] In the formula: The mass of the sample weighed for the example is in grams.

[0174] The concentration (mg / L) of the acrylamide working solution added.

[0175] This represents the volume (mL) of acrylamide working solution added.

[0176] Triples were prepared for each concentration, and three parallel experiments were performed. The recovery rates were determined according to the assay criteria, and the results are shown in Table 5 below.

[0177] Table 5: Experimental Results of Examples 19-27

[0178]

[0179] The results in Table 5 show that, based on the average recovery rate and the overall RSD of the three parallel groups, the RSD < 3%, indicating good accuracy.

[0180] Furthermore, based on the conclusion that acrylamide exhibits good linearity within the mass range of 0.4742-4742 μg, and considering the sample weight of the water-in-oil polyacrylamide emulsion in Table 4, the detection limit of the detection method in this embodiment can be determined for the sample weight of the water-in-oil polyacrylamide emulsion in Table 4. Through calculation, the detection limits of the detection method in this embodiment are 1-10000 mg / kg.

[0181] Therefore, the detection limit of the detection method of this application can reach 1 mg / kg, which is lower than the residue limit required in the "Cosmetic Safety Technical Specifications (2015 Edition)" (2 mg / kg, calculated based on the amount of water-in-oil polyacrylamide added and the maximum residue limit of acrylamide in the product); thus, the detection method of this embodiment can meet the detection requirements of cosmetics and has the advantage of low detection limit.

[0182] Precision test

[0183] Examples 28-33:

[0184] The sample solution from Example 23 was injected six times consecutively, and the precision of the acrylamide peak area was recorded as shown in Table 6 below:

[0185] Table 6: Precision Experiment Results

[0186]

[0187] The experimental results in Table 6 show that the detection method of this embodiment has excellent precision and repeatability.

[0188] Solution stability testing

[0189] Examples 34-38:

[0190] The sample solution from Example 23 was injected at room temperature for 4, 8, 12, 24, and 48 hours, and the changes in the peak area of ​​the main component were recorded. The results are shown in Table 7 below:

[0191] Table 7: Results of Solution Stability Test

[0192]

[0193] The experimental results in Table 7 show that the derivatized solution of the detection method in this embodiment has excellent stability at room temperature for 48 hours.

[0194] In summary, the detection method of this embodiment targets the water-in-oil polyacrylamide emulsion system. By adding saturated potassium bromide solution during pretreatment, the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion can be improved, thereby lowering the detection limit. This addresses the problems of high detection limits and low precision and accuracy in existing acrylamide detection methods when detecting acrylamide in water-in-oil polyacrylamide emulsions. Furthermore, using acetonitrile as the extractant further enhances the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion, further improving the accuracy and precision of the detection results. Therefore, the detection method of this embodiment has a wider linear range and a lower detection limit, making it suitable for applications with more stringent and demanding requirements for acrylamide content detection.

[0195] Therefore, the acrylamide detection method provided in this embodiment can meet the needs of acrylamide safety risk screening in water-in-oil polyacrylamide emulsions, and provides good technical support for the quality control and safety monitoring of water-in-oil polyacrylamide emulsions, suggesting that this detection method has better application prospects in the quality control of water-in-oil polyacrylamide emulsions.

[0196] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used in this document to illustrate the principles and implementation methods of the embodiments of this application. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for detecting the acrylamide content, characterized by, The detection method comprises: Different concentrations of acrylamide standard solution are prepared; under acidic conditions, different concentrations of acrylamide standard solution are respectively reacted with saturated potassium bromide and potassium bromate in a water bath; after the reaction is completed, acetonitrile is added for extraction; the acetonitrile layer is filtered to obtain standard samples of different concentrations; Different concentrations of standard samples are subjected to high performance liquid chromatography ultraviolet detection to obtain the peak area of acrylamide in different concentrations of standard samples; according to different concentrations of standard samples and corresponding peak areas, a linear equation of acrylamide mass x and peak area y is obtained; Under acidic conditions, the water-in-oil polyacrylamide emulsion is reacted with saturated potassium bromide and potassium bromate in a water bath; after the reaction is completed, acetonitrile is added for extraction; the acetonitrile layer is filtered to obtain the sample to be tested; The sample to be tested is subjected to high performance liquid chromatography ultraviolet detection to obtain the peak area of acrylamide in the sample to be tested; the peak area of acrylamide in the sample to be tested is substituted into the linear equation to calculate the content of acrylamide in the sample to be tested.

2. The detection method according to claim 1, characterized in that, The step of obtaining different concentrations of standard samples under acidic conditions by reacting different concentrations of acrylamide standard solution with saturated potassium bromide and potassium bromate in a water bath, adding acetonitrile for extraction after the reaction is completed, and filtering the acetonitrile layer, comprises: Acid reagent, potassium bromide solution and potassium bromate solution are added to different concentrations of acrylamide standard solution respectively, and the mixture is heated in a 60 DEG C water bath; after the reaction is completed, acetonitrile is added for extraction; after extraction, the acetonitrile layer is filtered through a filter membrane to obtain standard samples of different concentrations.

3. The method of claim 1, wherein, The step of obtaining the sample to be tested by reacting the water-in-oil polyacrylamide emulsion with saturated potassium bromide and potassium bromate in a water bath under acidic conditions, adding acetonitrile for extraction after the reaction is completed, and filtering the acetonitrile layer, comprises: The water-in-oil polyacrylamide emulsion is taken in a container, acid reagent, saturated potassium bromide solution and potassium bromate solution are added, and the mixture is heated in a 60 DEG C water bath; after the reaction is completed, acetonitrile is added for extraction; after extraction, the acetonitrile layer is filtered through a filter membrane to obtain the sample to be tested.

4. The detection method according to claim 2 or 3, characterized in that, The acid reagent is a phosphoric acid solution.

5. The method of claim 1, wherein The linear equation is a linear equation of acrylamide mass x and peak area y in a double logarithmic coordinate system; The linear equation is: The correlation coefficient R 2 = 0.9999.

6. The method of claim 1, wherein The chromatographic column used in the high performance liquid chromatography ultraviolet detection is an Agilent ZORBAX SB-C8.

7. The detection method according to claim 6, characterized in that, The column temperature of the chromatographic column is 30 DEG C.

8. The method of claim 1, wherein, The chromatographic conditions of the high performance liquid chromatography ultraviolet detection comprise: The detection wavelength is 210-220 nm, and the injection amount is 20 μL; The mobile phase A is acetonitrile; The mobile phase B is a mixed solution of acetonitrile, water and phosphoric acid in a volume ratio of 100:898:

2.

9. The detection method according to claim 8, characterized in that, The gradient elution program of the mobile phase A and the mobile phase B comprises: Within 0-10 min, the volume ratio of the mobile phase A increases from 0% to 30%, and the volume ratio of the mobile phase B decreases from 100% to 70%; Within 10-11 min, the volume ratio of the mobile phase A increases from 30% to 80%, and the volume ratio of the mobile phase B decreases from 70% to 20%; Within 11-15 min, the mobile phase A with a volume ratio of 80% and the mobile phase B with a volume ratio of 20% are eluted for 4 min; The volume ratio of mobile phase A was decreased from 80% to 0% and the volume ratio of mobile phase B was increased from 20% to 100% within 15-16 min; Within 16-20 min, elute with 0% volume ratio of mobile phase A and 100% volume ratio of mobile phase B for 4 min; The flow rate is 1.0 mL / min.

10. Use of the detection method according to any one of claims 1-9 in the quality control of water-in-oil polyacrylamide emulsion products.

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