Acrylamide content detection method and application thereof

Abstract

The embodiment of the invention provides an acrylamide content detection method and application thereof. 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 the peak areas of acrylamide of the standard samples with different concentrations, and obtaining a linear equation of the mass x and the peak area y of acrylamide according to the standard samples with different concentrations and the corresponding peak areas; obtaining a to-be-detected sample; performing high performance liquid chromatography ultraviolet detection on the to-be-detected sample to obtain the peak area of acrylamide in the to-be-detected sample; and substituting the peak area of the acrylamide in the sample to be detected into the linear equation, and calculating to obtain the content of the acrylamide in the sample to be detected. According to the embodiment of the invention, the acrylamide in the water-in-oil polyacrylamide emulsion can be efficiently extracted, so that the detection limit value is reduced, and the accuracy and the precision are improved.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of analytical chemistry, in particular to a detection method of acrylamide content and application thereof. BACKGROUND

[0002] The water-in-oil polyacrylamide emulsion is commonly used as an emulsifying thickener in daily chemical products, and has good dispersibility and stability. At present, the water-in-oil polyacrylamide emulsion is generated by reacting acrylamide as a monomer, and acrylamide as a monomer of the polymer component will remain in the emulsion. However, acrylamide is a risk substance with neurotoxicity, immunotoxicity, reproductive toxicity and potential carcinogenicity, so it is necessary to accurately detect the content of acrylamide in the water-in-oil polyacrylamide emulsion.

[0003] In the prior art, the detection methods of acrylamide include chemical titration, liquid chromatography and gas chromatography, etc. Before detection, the sample to be detected needs to be pretreated to extract acrylamide in the sample for detection. The national standard GB / T 17514-2017 also discloses a method for determining the content of acrylamide monomer, which extracts acrylamide by mixing isopropyl alcohol, water and ethanol.

[0004] However, the above method is for polyacrylamide solution. For water-in-oil polyacrylamide emulsion, if a commonly used solvent such as methanol is used for extraction, since the water-in-oil polyacrylamide emulsion is essentially a water-in-oil system, the hydrophilic polymer chains in the polymer stretch towards the internal water phase at the interface, and the system has good fluidity. Placing the water-in-oil polyacrylamide emulsion in water will cause phase inversion of the water-in-oil droplets, so that the hydrophilic chains of the polymer interact to produce thickening effect, which will make the system gel-like, resulting in difficulty in extraction, and the detection limit cannot be reduced by increasing the sample amount.

[0005] Therefore, the embodiment of the present application provides a detection method of acrylamide content. SUMMARY

[0006] The purpose of the embodiment of the present application is to provide a detection method of acrylamide content and application thereof.

[0007] To achieve the above purpose, the technical scheme of the embodiment of the present application is as follows: In a first aspect, the embodiment of the present application provides a detection method of acrylamide content, which comprises: Different concentrations of acrylamide standard solution are prepared; under acidic conditions, different concentrations of acrylamide standard solution are respectively heated and reacted with saturated potassium bromide and potassium bromate in a water bath, acetonitrile is added after the reaction is completed for extraction, the acetonitrile layer is taken for filtration, and different concentrations of standard samples are obtained; The standard samples of different concentrations are subjected to high performance liquid chromatography ultraviolet detection to obtain the peak area of acrylamide in the standard samples of different concentrations, and a linear equation of mass x and peak area y of acrylamide is obtained according to the standard samples of different concentrations and the corresponding peak areas; Under acidic conditions, the water-in-oil polyacrylamide emulsion is heated and reacted with saturated potassium bromide and potassium bromate in a water bath, acetonitrile is added after the reaction is completed 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.

[0008] As an embodiment, the standard solution of acrylamide of different concentrations is heated and reacted with saturated potassium bromide and potassium bromate in a water bath under acidic conditions, acetonitrile is added after the reaction is completed for extraction, the acetonitrile layer is filtered to obtain the standard samples of different concentrations, including: The acid reagent, potassium bromide solution and potassium bromate solution are added to the standard solution of acrylamide of different concentrations, and heated and reacted in a 60℃ water bath; acetonitrile is added after the reaction is completed for extraction, and the acetonitrile layer is filtered through a filter membrane after extraction to obtain the standard samples of different concentrations.

[0009] As an embodiment, the water-in-oil polyacrylamide emulsion is heated and reacted with saturated potassium bromide and potassium bromate in a water bath under acidic conditions, acetonitrile is added after the reaction is completed for extraction, and the acetonitrile layer is filtered to obtain the sample to be tested, including: The water-in-oil polyacrylamide emulsion is taken in a container, the acid reagent, saturated potassium bromide solution and potassium bromate solution are added, and heated and reacted in a 60℃ water bath; acetonitrile is added after the reaction is completed for extraction, and the acetonitrile layer is filtered through a filter membrane after extraction to obtain the sample to be tested.

[0010] As an embodiment, the acid reagent is a phosphoric acid solution.

[0011] As an embodiment, the linear equation is a linear equation of mass x and peak area y of acrylamide in a double logarithmic coordinate system; the linear equation is: , and the correlation coefficient R 2 = 0.9999.

[0012] As an embodiment, the chromatographic column used in the high performance liquid chromatography ultraviolet detection is an Agilent ZORBAX SB-C8.

[0013] As an embodiment, the column temperature of the chromatographic column is 30℃.

[0014] As an implementation form, the chromatographic conditions of the high performance liquid chromatography ultraviolet detection include: 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.

[0015] As an implementation form, the gradient elution program of the mobile phase A and the mobile phase B is as follows: In 0-10 min, the volume ratio of the mobile phase A is increased from 0% to 30%, and the volume ratio of the mobile phase B is decreased from 100% to 70%; In 10-11 min, the volume ratio of the mobile phase A is increased from 30% to 80%, and the volume ratio of the mobile phase B is decreased from 70% to 20%; In 11-15 min, elute with the mobile phase A in a volume ratio of 80% and the mobile phase B in a volume ratio of 20% for 4 min; In 15-16 min, the volume ratio of the mobile phase A is decreased from 80% to 0%, and the volume ratio of the mobile phase B is increased from 20% to 100%; In 16-20 min, elute with the mobile phase A in a volume ratio of 0% and the mobile phase B in a volume ratio of 100% for 4 min; The flow rate is 1.0 mL / min.

[0016] In a second aspect, the embodiments of the present application provide the use of the detection method in the first aspect in the quality control of the water-in-oil polyacrylamide emulsion product.

[0017] Compared with the prior art, the embodiments of the present application have at least the following beneficial effects: The present application is directed to the water-in-oil polyacrylamide emulsion system, and when the derivatization reaction is performed, the saturated potassium bromide solution is used, which can effectively inhibit the phase inversion of the water-in-oil polyacrylamide, so that the system remains flowable, which is beneficial to the derivatization reaction. The derivatization reaction in the flowable system can make the reaction of bromine monomer and acrylamide more complete, thereby reducing the detection limit. At the same time, the bromine monomer generated by the 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 in high performance liquid chromatography, and the separation and detection purposes can be achieved through high performance liquid chromatography.

[0018] In addition, in the embodiments of the present application, acetonitrile is used as the extractant to extract the derivatized product 2,3-dibromopropionamide in the mixture system into the acetonitrile phase, which can avoid the dissolution of the oil phase in the emulsion, thereby better improving the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion in the pretreatment process, ensuring the extraction of sufficient components, and further improving the accuracy and precision of the detection results. At the same time, the detection method of the embodiments of the present application has a larger linear range and a lower detection limit, and therefore can be applied to more stringent and higher requirement application scenarios for acrylamide content detection.

[0019] In summary, the detection method of the embodiments of the present application can improve the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion in the pretreatment process, thereby reducing the detection limit, solving the problems of high detection limit of the existing acrylamide detection method and low precision and accuracy in detecting acrylamide in the water-in-oil polyacrylamide emulsion. Therefore, the detection method of the present application can more efficiently extract acrylamide in the water-in-oil polyacrylamide emulsion in the pretreatment process according to the characteristics of the water-in-oil polyacrylamide emulsion, thereby improving the accuracy and precision of the detection results.

[0020] Additional aspects and advantages of the present application will be described in the following description and will be apparent from the following description and the organization of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A schematic diagram showing the influence of the derivatization reaction temperature and time on the recovery rate of acrylamide in the embodiments is shown; Figure 2 A chromatogram of acrylamide in the embodiments is shown; Figure 3 A schematic diagram of the linear equation of the mass and peak area of acrylamide in the double logarithmic coordinate system is shown. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments will be described clearly and completely in the embodiments of the present application and the accompanying drawings. Obviously, the following described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] It should be understood that when used in the specification and the appended claims, the terms "comprise" and "include" indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or collections thereof.

[0024] It should also be understood that the terms used in the description of the present embodiments are merely for the purpose of describing particular embodiments and are not intended to limit the present embodiments. As used in the description of the present embodiments and the appended claims, "a", "an" and "the" are intended to include plural references unless the context clearly indicates otherwise.

[0025] The detection method of the acrylamide content and the use thereof in the present embodiments will be described in detail below.

[0026] First, the detection method of the first aspect of the present embodiments will be described.

[0027] Detection method As known by those skilled in the art, since acrylamide is an organic compound with neurotoxicity, immunotoxicity, reproductive toxicity and potential carcinogenicity, when acrylamide is used as a raw material to produce water-in-oil polyacrylamide emulsion, the residual amount thereof in the water-in-oil polyacrylamide emulsion should be limited.

[0028] At present, the commonly used methods for detecting the content of acrylamide include chemical titration, liquid chromatography and gas chromatography, etc. Taking the liquid chromatography as an example, the pretreatment step of the liquid chromatography is to extract acrylamide in the polymer directly with an extractant. For example, methanol aqueous solution is used for extraction in GB / T 22312-2008, and the detection limit of this detection standard is 0.01% or more; or according to the relevant provisions in GB / T 17514-2017, a mixed solvent of isopropyl alcohol, water and ethanol is used for extraction, and the minimum detection limit of this detection standard is 0.02% (dry basis).

[0029] However, according to the relevant requirements in the "Cosmetic Safety Technical Specification (2015 Edition)", the maximum residual amount of acrylamide in the product is required to be 0.1 mg / kg (for resident body product) and 0.5 mg / kg (for other products). Among them, when the water-in-oil polyacrylamide emulsion is used for thickening of cosmetics, the addition amount can be up to 5%, and through calculation, when the water-in-oil polyacrylamide emulsion is the single source of acrylamide in the resident body product, the acrylamide limit is 2 mg / kg (0.0002%). Therefore, the detection limit of the above detection method cannot meet the detection needs required by the cosmetics.

[0030] Meanwhile, adding common solvents such as methanol and water to the water-in-oil polyacrylamide emulsion will thicken the system to form a gel, because the water-in-oil polyacrylamide emulsion is essentially a water-in-oil system, the hydrophilic polymer chains in the polymer stretch to the internal water phase on the interface, and the system has good fluidity. Placing the water-in-oil polyacrylamide in the water phase causes the water-in-oil droplets to reverse, so that the hydrophilic chains of the polymer interact to produce a thickening effect. The above reasons make it difficult to reduce the detection limit by increasing the sample amount by solvent extraction method. Moreover, according to the principle of similar solubility, removing the oil phase that provides fluidity in the emulsion will cause the acrylamide to remain in the condensed polyacrylamide gel, making the pretreatment process more difficult.

[0031] Therefore, the embodiment provides a method for detecting the content of acrylamide in a water-in-oil polyacrylamide emulsion.

[0032] Specifically, the detection method comprises: S1, preparing acrylamide standard solutions with different concentrations; under acidic conditions, the acrylamide standard solutions with different concentrations are respectively reacted with saturated potassium bromide and potassium bromate in a water bath, acetonitrile is added after the reaction is completed for extraction, the acetonitrile layer is taken for filtration, and standard samples with different concentrations are obtained; The purpose of step S1 is to prepare standard samples. Before preparing the standard samples, a derivatization reaction is performed, and the product 2,3-dibromopropionamide of the derivatization reaction is easy to separate in high performance liquid chromatography, and can achieve the purpose of separation and detection through high performance liquid chromatography, so as to easily eliminate impurity interference and improve the accuracy and precision of the detection result.

[0033] S2, performing high performance liquid chromatography ultraviolet detection on the standard samples with different concentrations to obtain the peak area of acrylamide in the standard samples with different concentrations, and obtaining a linear equation of the mass x and the peak area y of acrylamide according to the standard samples with different concentrations and the corresponding peak areas; Step S2 obtains the relationship between the concentration and the peak area of the standard sample by performing high performance liquid chromatography ultraviolet detection on the standard sample prepared in step S1, and since the concentration of the standard sample is related to the mass of the standard sample, the linear equation of the mass x and the peak area y of acrylamide of the standard sample can be obtained based on the relationship between the concentration and the peak area of the standard sample. Based on the linear equation, when the content of the sample to be tested is tested, the content of acrylamide in the water-in-oil polyacrylamide emulsion can be quickly calculated according to the peak area of the sample to be tested.

[0034] S3, under acidic conditions, the water-in-oil polyacrylamide emulsion is reacted with saturated potassium bromide and potassium bromate in a water bath, acetonitrile is added after the reaction is completed for extraction, the acetonitrile layer is taken for filtration, and the sample to be tested is obtained; In step S3, according to the characteristics of the water-in-oil polyacrylamide emulsion system, saturated potassium bromide is added to inhibit thickening of the system, ensure more complete derivatization reaction, and as one of the reaction raw materials of the derivatization reagent, together with potassium bromate, acrylamide is converted into the derivatization product 2,3-dibromopropionamide. Among them, the derivatization product 2,3-dibromopropionamide is extremely easy to separate in the subsequent high performance liquid chromatography, and can achieve the purpose of separation and detection through high performance liquid chromatography; Secondly, after the derivatization reaction is completed, acetonitrile is added, on the one hand, after the derivatization reaction is completed, the mixture system (including saturated potassium bromide, potassium bromate, 2,3-dibromopropionamide, etc.) is still a viscous fluid, and the thickening of the system will affect the fullness of extraction and limit the selection of extractants; in this embodiment, after the derivatization reaction, acetonitrile is added to the system, acetonitrile as an extractant, extracts the derivatization product 2,3-dibromopropionamide in the mixture system into the acetonitrile phase, and can avoid dissolving the oil phase in the emulsion, so as to better improve the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion in the pretreatment process; and when extracting, the acetonitrile and the mixture are dispersed into small droplets through shaking, so that the contact area between acetonitrile and the mixture is larger, which ensures that enough components are extracted, and thus improves the accuracy and precision of the detection results.

[0035] S4, performing high performance liquid chromatography ultraviolet detection on the sample to be tested 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 obtained in step S2 to calculate the content of acrylamide in the sample to be tested; After step S4 detects the sample to be tested, the detection result is substituted into the linear equation obtained in step S2, and the content of acrylamide in the sample to be tested is calculated. Since the reactions and experiments of steps S1-S3 have high accuracy and precision, the result calculated in step S4 also has high accuracy and precision.

[0036] It can be understood that, according to the characteristics of the water-in-oil polyacrylamide emulsion, saturated potassium bromide solution is used in the derivatization reaction, which can effectively inhibit the phase inversion of the water-in-oil polyacrylamide, so that the derivatization reaction is carried out in a flowing system, and the reaction of bromine and acrylamide in the flowing system is more complete, that is, the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion is improved, and the detection limit is reduced; at the same time, the bromine generated by saturated potassium bromide and potassium bromate under acidic conditions reacts with acrylamide to generate 2,3-dibromopropionamide. Among them, the derivatization product 2,3-dibromopropionamide is extremely easy to separate in the high performance liquid chromatography, and can achieve the purpose of separation and detection through high performance liquid chromatography.

[0037] It should be noted that although the saturated potassium bromide solution can effectively inhibit the phase inversion of the water-in-oil polyacrylamide emulsion, after the derivatization reaction is completed, the mixture system (including saturated potassium bromide, potassium bromate, 2, 3-dibromopropionamide, etc.) is still a viscous fluid, and the system becomes viscous, which affects the fullness of extraction; in this embodiment, acetonitrile is used as an extractant to extract the derivatization product 2, 3-dibromopropionamide in the system into the acetonitrile phase, and when extracting, the acetonitrile and the mixture are shaken to disperse into small droplets, so that the contact area between the acetonitrile and the mixture is larger, ensuring that the extraction is sufficient for the components, and avoiding dissolving too much oil phase and avoiding solvent effect in liquid chromatography.

[0038] Therefore, the detection method of the embodiment can improve the accuracy and precision of the detection result. At the same time, based on the related steps of the above detection method, the detection method of the embodiment has a larger linear range and a lower detection limit, so it can be applied to more stringent and higher requirement application scenarios for acrylamide content detection.

[0039] In the following, the related steps of the above detection method will be further described.

[0040] 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, and then taken out and cooled, and ferrous sulfate solution, anhydrous sodium sulfate and acetonitrile are added; extraction is performed, the acetonitrile layer is filtered, and standard samples of different concentrations are obtained, including: In the acrylamide standard solutions of different concentrations, acid reagent, saturated potassium bromide solution and potassium bromate solution are added respectively, and heated in a 60°C water bath for reaction. After the reaction is completed, it is taken out and cooled; ferrous sulfate solution, anhydrous sodium sulfate and acetonitrile are added; the purpose of adding ferrous sulfate solution is to remove excess bromine element to prevent bromine from being extracted into acetonitrile; anhydrous sodium sulfate is added for subsequent extraction, which is to separate acetonitrile from water, so that acetonitrile is less soluble in the water phase, so that more volume of acetonitrile can be used for subsequent testing, thereby ensuring the accuracy of the subsequent test results; the purpose of adding acetonitrile is to extract the derivatization product, and after extraction, the acetonitrile layer is filtered through a filter membrane to obtain standard samples of different concentrations.

[0041] Generally, the heating time is 15 min to 240 min, preferably the heating time is 30 min to 240 min, more preferably the heating time is 2 h (120 min).

[0042] Specifically, in one of the embodiments of the present application, the step of preparing acrylamide standard solutions of different concentrations can be operated as follows: Take 1 g of acrylamide standard, dissolve in distilled water, and pour into a 100 mL volumetric flask, use distilled water to constant volume, shake well; use a pipette to transfer 10 mL to another 100 mL volumetric flask, constant volume, shake well, get the stock solution, the mass concentration of the acrylamide standard stock solution is 1 mg / mL. For example, the mass concentration of the acrylamide standard stock solution can also be 2 mg / mL-5 mg / mL, for the convenience of subsequent preparation of standard working solution, the mass concentration of the standard stock solution is usually an integer such as 1 mg / mL, etc.

[0043] Generally, after obtaining the stock solution, different acrylamide standard solutions can be prepared based on the stock solution. After obtaining the standard solution, under acidic conditions, saturated potassium bromide and potassium bromate are added, heated in a water bath, then taken out and cooled, ferrous sulfate solution, anhydrous sodium sulfate and acetonitrile are added; extraction is carried out, the acetonitrile layer is filtered to obtain standard samples of different concentrations.

[0044] Specifically, the acidic condition in this embodiment is pH less than 7, in this embodiment, an acidic environment is created by adding phosphoric acid.

[0045] More specifically, since in the preparation of the sample to be tested, when preparing the water-in-oil polyacrylamide emulsion solution, since the sample is a water-in-oil emulsion, the hydrophilic polymer chain stretches to the internal water phase on the interface, the system has good fluidity, after adding water, the water-in-oil droplets undergo phase inversion, the hydrophilic polymer chain interacts to produce thickening effect, resulting in a viscous solution, in order to avoid the sample being too viscous to extract acrylamide from the sample, a high concentration of salt solution needs to be added to inhibit the phase inversion process, and since potassium bromate is a toxic compound and its solubility in water is not high; therefore, a high concentration of potassium bromide solution is selected in this embodiment to inhibit the thickening phenomenon that may occur in the sample to be tested.

[0046] Specifically, a saturated potassium bromide solution is selected in this embodiment; the saturated potassium bromide solution in this embodiment refers to a potassium bromide solution with a mass fraction concentration of 40% at about 20°C.

[0047] Further, after adding ferrous sulfate solution, anhydrous sodium sulfate and acetonitrile, extraction is carried out, and after extraction, the acetonitrile layer is filtered, which can be filtered using a 0.45 μm filter membrane.

[0048] Specific examples are as follows: Use a pipette to transfer 10 μL of the above matched standard solution of different concentrations to a 15 mL round-bottom centrifuge tube, 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, 0.4 mL of potassium bromate solution [c(1 / 6KBrO3)=0.4 mol / L], seal and shake well.

[0049] It should be noted that if the system is not yellow after shaking, potassium bromate solution needs to be added to the system to make it light yellow, because this step is to generate bromine element under acidic conditions, and bromine element dissolved in water will form yellow bromine water. If the system is not yellow or light yellow, it means that the reaction is not complete. Since the bromide solution is a saturated potassium bromide solution, the amount of potassium bromate is less in the initial reaction. Therefore, when the system is not yellow or light yellow, potassium bromate solution needs to be added.

[0050] After the above solution is light yellow, the round-bottom centrifuge tube is placed in a water bath for heating. Specifically, as shown in Figure 1 It is found through relevant tests that the recovery rate of acrylamide is higher when the reaction time is 2h than when the reaction time is 30min at a temperature of 60℃. Therefore, the preferred reaction conditions are: the water bath temperature is 60℃, and the heating time is 2h.

[0051] For example, in one of the embodiments of the present application, heating is performed for 2h; after 2h, cooling is performed, 1mL of 20% ferrous sulfate solution, 0.5g of anhydrous sodium sulfate and 4mL of acetonitrile are added to the system, and the system is shaken or vortexed for 1min. Then, the system is placed in a centrifuge and centrifuged at 3000rpm for 5min. The acetonitrile layer is filtered through a 0.45μm filter membrane to obtain a standard sample.

[0052] More specifically, the purpose of adding ferrous sulfate solution after cooling in this embodiment is to remove excess bromine element to prevent bromine from being extracted into acetonitrile; anhydrous sodium sulfate is added for subsequent extraction needs. Specifically, acetonitrile is added as an extractant to dissolve the target product from the system without dissolving other solutes in the system, and to avoid the influence of solvent effect of other organic solvents in liquid chromatography; since acetonitrile and water have a certain mutual solubility, during the extraction process, the dissolution of acetonitrile in the aqueous phase will reduce the volume of acetonitrile, thereby affecting the subsequent test; therefore, the addition of anhydrous sodium sulfate can separate acetonitrile from water, so that acetonitrile is less dissolved in the aqueous phase, thereby ensuring that more volume of acetonitrile can be used for subsequent testing, thereby ensuring the accuracy of the subsequent test results.

[0053] In step S1, the bromine element generated by the reaction of potassium bromide and potassium bromate under acidic conditions reacts with acrylamide to generate 2,3-dibromopropionamide. Among them, the derivative product 2,3-dibromopropionamide is easy to separate in high performance liquid chromatography, which can achieve the purpose of separation and detection, and thus it is easy to exclude impurity interference and improve the accuracy and precision of the detection results.

[0054] In step S2, after the standard samples of different concentrations are prepared, the standard samples of different concentrations are subjected to high performance liquid chromatography ultraviolet detection 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 of the mass x of acrylamide and the peak area y is obtained.

[0055] In step S2, the peak area of acrylamide in the standard samples of different concentrations is obtained by subjecting the standard samples of different concentrations obtained in step S1 to high performance liquid chromatography ultraviolet detection, and based on the mass of the standard samples of different concentrations and the corresponding peak area, a linear equation of the mass x of acrylamide and the peak area y is obtained.

[0056] Specifically, the linear equation can be a linear equation of the mass x of acrylamide and the peak area y in a double logarithmic coordinate system, and more specifically, the linear equation is: , the correlation coefficient R 2 = 0.9999.

[0057] It should be noted that the double logarithmic coordinate system is used in this embodiment to obtain the upper and lower detection limits (1-10000 mg / kg), and based on the upper and lower detection limits, the detection method of this embodiment has the advantages of low detection limit and large linear range.

[0058] It should be noted that the double logarithmic coordinate system is used in this embodiment to obtain the upper and lower detection limits (1-10000 mg / kg), and based on the upper and lower detection limits, the detection method of this embodiment has the advantages of low detection limit and large linear range.

[0059] In step S2, the standard samples after the derivatization reaction are subjected to separation and detection by high performance liquid chromatography ultraviolet method; wherein the 2,3-dibromopropionamide generated by derivatization can be easily separated in high performance liquid chromatography, and can achieve the purpose of separation and detection by high performance liquid chromatography, so as to easily eliminate impurity interference and improve the accuracy of the detection result.

[0060] Meanwhile, based on the test results in step S2, a linear equation of the corresponding relationship between the mass x of acrylamide and the peak area y in the double logarithmic coordinate system can be obtained, and based on the linear equation, when the content of the sample to be tested is detected, the content of acrylamide in the water-in-oil polyacrylamide can be calculated according to the peak area of the sample to be tested.

[0061] It can be understood that the high performance liquid chromatography ultraviolet detection of this embodiment can be performed in a high performance liquid chromatograph. For example, an Agilent 1260 liquid chromatograph.

[0062] 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, and then taken out and cooled. Ferrous sulfate solution, anhydrous sodium sulfate and acetonitrile are added; extraction is performed, the acetonitrile layer is filtered to obtain the sample to be tested, including: A water-in-oil polyacrylamide emulsion is taken in a container, an acid reagent, a saturated potassium bromide solution and a potassium bromate solution are added, and the reaction is heated in a 60°C water bath; after the reaction is completed, a ferrous sulfate solution, anhydrous sodium sulfate and acetonitrile are added; extraction is performed, and after extraction, the acetonitrile layer is filtered through a filter membrane to obtain a sample to be tested.

[0063] In this embodiment, the container is preferably made of pp material, i.e. polypropylene material; the reason for choosing pp material in this embodiment is that pp material is more compatible with acetonitrile 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 the accuracy of the test results.

[0064] Generally, the heating time is 15 min to 240 min, preferably the heating time is 30 min to 240 min, more preferably the heating time is 2 h (120 min).

[0065] Specifically, the above steps can be: In a 15 mL round-bottom centrifuge tube, 0.5 g of water-in-oil polyacrylamide emulsion is weighed, 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] are added, sealed and shaken evenly.

[0066] It should be noted that after shaking, if the system is not yellow, potassium bromate solution needs to be added to make the system light yellow, because this step is to generate bromine elemental under acidic conditions by bromide and potassium bromate, and bromine elemental dissolved in water will form yellow bromine water, if the system is not yellow or light yellow, it means that the amount of bromine is not enough to completely react with acrylamide, i.e. the reaction is not complete, since the potassium bromide solution is a saturated potassium bromide solution, therefore the amount of potassium bromate is less in the initial reaction, therefore when the system is not yellow or light yellow, potassium bromate solution needs to be added.

[0067] After the above solution is light yellow, the round-bottom centrifuge tube is placed in a water bath for heating. Specifically, the heating time and the water bath temperature are consistent with step S1, heating for 2 h and the water bath temperature is 60°C.

[0068] After heating for 2 h, the system is cooled, 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate and 4 mL of acetonitrile are added, shaken up and down or vortexed for 1 min, placed in a centrifuge, centrifuged at 3000 rpm for 5 min, and the acetonitrile layer is filtered through a 0.45 μm filter membrane to obtain a sample to be tested.

[0069] The skilled in the art can know that, since the water-in-oil polyacrylamide emulsion is essentially a water-in-oil system, the hydrophilic polymer chains in the polymer extend to the internal water phase at the interface, and the system has good fluidity. When the water-in-oil polyacrylamide is placed in water, the water-in-oil droplets undergo phase inversion, the hydrophilic chains of the polymer interact to produce thickening effect (gel-like), making the whole system viscous, and the acrylamide is left in the viscous system, making it difficult to extract acrylamide in the water-in-oil polyacrylamide emulsion, that is, the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion is low, and the detection limit is relatively high.

[0070] In step S3, first, by adding saturated potassium bromide solution to the water-in-oil polyacrylamide emulsion, on the one hand, the high concentration of potassium bromide solution can effectively inhibit the phase inversion of the water-in-oil polyacrylamide emulsion, thereby effectively preventing the thickening effect of the emulsion, so that the system remains fluid, which is conducive to the derivatization reaction (better derivatization effect), and improves the accuracy of the detection result. On the other hand, under acidic conditions, based on the fluidity system maintained by the high concentration of potassium bromide solution, bromide and potassium bromate will first react to generate bromine, and then bromine will react with acrylamide to generate 2,3-dibromopropionamide. It can be understood that the 2,3-dibromopropionamide generated by derivatization is easily separated in the subsequent high performance liquid chromatography, and can achieve the purpose of separation and detection through high performance liquid chromatography.

[0071] In other words, the potassium bromide solution used in the present embodiment can not only effectively prevent the thickening effect of the emulsion and keep the system fluid, but also serve as one of the reaction raw materials of the derivatization reagent, together with potassium bromate, to convert acrylamide into 2,3-dibromopropionamide; therefore, the present embodiment not only facilitates the derivatization reaction, but also effectively avoids the introduction of new impurities to interfere with subsequent detection.

[0072] Secondly, after the derivatization reaction is completed, acetonitrile is added, on the one hand, after the derivatization reaction is completed, the mixture system (including saturated potassium bromide, potassium bromate, 2,3-dibromopropionamide, etc.) is still in a viscous fluid state, and the thickening of the system will affect the degree of extraction; in the present embodiment, acetonitrile is added to the mixture system after the derivatization reaction, acetonitrile as an extractant, extracts the derivatization product 2,3-dibromopropionamide in the mixture system into the acetonitrile phase, and avoids the dissolution of the oil phase in the emulsion, thereby better improving the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion in the pretreatment process; and when extracting, the whole is dispersed into small droplets by shaking, so that the contact area between acetonitrile and the mixture is larger, ensuring that enough components are extracted, thereby improving the accuracy and precision of the detection result.

[0073] In step S4, 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 mass of acrylamide in the sample to be tested, specifically including: The sample to be tested obtained in step S3 is injected into a high performance liquid chromatograph for high performance liquid ultraviolet 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.

[0074] Therefore, the sample to be tested after the above derivatization reaction is separated and detected by high performance liquid chromatography ultraviolet in the embodiment; the peak area of acrylamide in the sample to be tested is obtained. At the same time, based on the linear equation obtained in step S2, the content of acrylamide in the water-in-oil polyacrylamide can be calculated according to the peak area of the sample to be tested.

[0075] Therefore, the detection method of the embodiment has higher extraction efficiency in pretreatment, thereby improving the accuracy and precision of the test method of the embodiment.

[0076] It can be understood that in the test process of steps S2 and S4, the sample (standard sample or sample to be tested) is injected into a high performance liquid chromatograph for high performance liquid ultraviolet detection.

[0077] As an implementation mode, the chromatographic column used in the above high performance liquid chromatography ultraviolet detection is Agilent ZORBAX SB-C8, and the column temperature of the chromatographic column is 30°C.

[0078] As an implementation mode, the chromatographic conditions of the above high performance liquid chromatography ultraviolet detection include: The detection wavelength is 210-220 nm (for example, 214 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 (such as 85% mass concentration of phosphoric acid) in a volume ratio of 100:898:2.

[0079] In the embodiment, the gradient elution program of the mobile phase A and the mobile phase B is as follows: In 0-10 min, the volume ratio of the mobile phase A is increased from 0% to 30%, and the volume ratio of the mobile phase B is decreased from 100% to 70%; In 10-11 min, the volume ratio of the mobile phase A is increased from 30% to 80%, and the volume ratio of the mobile phase B is decreased from 70% to 20%; In 11-15 min, elute for 4 min with the mobile phase A in a volume ratio of 80% and the mobile phase B in a volume ratio of 20%; The volume ratio of the mobile phase A decreases from 80% to 0% and the volume ratio of the mobile phase B increases from 20% to 100% within 15-16 min; The mobile phase A with a volume ratio of 0% and the mobile phase B with a volume ratio of 100% are used to elute within 16-20 min for 4 min; The flow rate is 1.0 mL / min.

[0080] In summary, the detection method of the present embodiment can improve the extraction efficiency of acrylamide in the water-in-oil polyacrylamide emulsion during pretreatment, thereby reducing the detection limit. The existing detection method for acrylamide has a high detection limit, and the precision and accuracy are not high when detecting acrylamide in the water-in-oil polyacrylamide emulsion. Therefore, the detection method of the present embodiment can more efficiently extract acrylamide in the water-in-oil polyacrylamide emulsion during pretreatment according to the characteristics of the water-in-oil polyacrylamide emulsion, thereby improving the accuracy and precision of the detection results. At the same time, the detection method has a larger linear range (1-10000 mg / kg) and a lower detection limit, so it can be applied to more stringent and demanding application scenarios for acrylamide content detection.

[0081] Next, the use of the above detection method in the quality control of the water-in-oil polyacrylamide emulsion will be described.

[0082] Use It can be understood that since the water-in-oil polyacrylamide emulsion is generated by using acrylamide as a raw material, a certain amount of acrylamide will be left, and the water-in-oil polyacrylamide is usually used as an emulsifying thickener in daily chemicals, which can easily lead to direct or indirect contact of the residual acrylamide with the human body. Therefore, the production of water-in-oil polyacrylamide by using acrylamide as a raw material should limit the residual amount of acrylamide in the water-in-oil polyacrylamide.

[0083] As described above, the detection method provided by the present embodiment can more efficiently extract, thereby achieving low detection limit, accurate and rapid detection of the content of acrylamide in the water-in-oil polyacrylamide emulsion, and the detection method is efficient; therefore, it can meet the demand for safety risk screening of acrylamide in the water-in-oil polyacrylamide emulsion, and provide good technical support for the quality control and safety monitoring of the water-in-oil polyacrylamide emulsion, indicating that the detection method has better application prospect in the quality control of the water-in-oil polyacrylamide emulsion.

[0084] The present application will be further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate / explain the present application and not to limit the scope of the present application.

[0085] In the following examples, the materials, reagents and instruments used, if not specifically stated, are commercially available.

[0086] It should be noted that, in the following examples, if not specifically stated, the water used is distilled water; the following examples use high performance liquid chromatography for analysis (separation and detection) methods and conditions are shown as follows: The high performance liquid chromatograph uses Agilent 1260 liquid chromatograph, and the concentration of the phosphoric acid solution in the mobile phase B is 85%.

[0087] 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.

[0088] The gradient elution program is shown in Table 1 as follows: Table 1: Gradient elution program

[0089] Specifically, according to Table 1, within 0-10 min, the volume ratio of mobile phase A rises from 0% to 30%, and the volume ratio of mobile phase B drops from 100% to 70%; that is, the volume ratio of mobile phase A linearly rises from 0% at 0 min to 30% at 10 min; the volume of mobile phase B linearly drops from 100% at 0 min to 70% at 10 min.

[0090] Within 10-11 min, the volume ratio of mobile phase A rises from 30% to 80%, and the volume ratio of mobile phase B drops from 70% to 20%; that is, the volume ratio of mobile phase A linearly rises from 30% at 10 min to 80% at 11 min; the volume of mobile phase B linearly drops from 100% at 10 min to 20% at 11 min.

[0091] Within 11-15 min, elute with 80% volume ratio of mobile phase A and 20% volume ratio of mobile phase B for 4 min; that is, within 11-15 min, the volume ratio of mobile phase A and mobile phase B remains unchanged for elution.

[0092] Within 15-16 min, the volume ratio of mobile phase A drops from 80% to 0%, and the volume ratio of mobile phase B rises from 20% to 100%; that is, the volume ratio of mobile phase A linearly drops from 80% at 15 min to 0% at 16 min; the volume of mobile phase B linearly rises from 20% at 15 min to 100% at 16 min.

[0093] In 16-20 min, elute with 0% of mobile phase A and 100% of mobile phase B for 4 min; it can be understood that 16-20 min is eluted with 0% of mobile phase A and 100% of mobile phase B.

[0094] In this embodiment, the chromatographic column is selected from Agilent ZORBAX SB-C8, the length of the chromatographic column is 250 mm, the inner diameter of the chromatographic column is 4.6 mm, the particle diameter of the chromatographic column filler is 5 μm; the detection wavelength is set to 214 nm, the column temperature of the chromatographic column is 30℃, and the injection amount is 20 μL.

[0095] Example 1-10: Through related experiments, it is found in this embodiment that the derivative temperature and time of acrylamide are related to the peak area. Therefore, group experiments are set to verify the derivative conditions, which are as follows: Take 10 15 mL polypropylene round-bottom centrifuge tubes as the containers of the examples, and weigh about 0.5 g of the water-in-oil polyacrylamide emulsion sample in the centrifuge tubes of examples 2-5 and 7-10. Prepare an acrylamide standard solution with a concentration of 1728 mg / L, and add 100 μL of the solution into the centrifuge tubes of examples 1, 3-6 and 8-10, respectively. Then, 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] into examples 1-10, respectively, seal and shake well. Place examples 1-5 at room temperature (20℃), and place examples 6-10 in a water bath at 60℃. Take out examples 3 and 8 after 0.5 h, take out examples 4 and 9 after 1 h, and take out the remaining examples after 2 h. Cool all the examples to room temperature, and then add 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate and 4 mL of acetonitrile, shake up and down or vortex for 1 min, centrifuge at 3000 rpm for 5 min, take the upper organic phase through a 0.45 μm filter membrane into a sample bottle, and then inject the sample bottle into a high performance liquid chromatograph for separation and detection.

[0096] The recovery rate is calculated as follows (ignoring the influence of sample mass on peak area): ; Wherein: is the peak area of examples 3-5 and 8-10; is the peak area of examples 2 and 7 at the corresponding temperature; is the peak area of examples 1 and 6 at the corresponding temperature.

[0097] The experimental results are shown in Table 2: Table 2: Experimental results of Examples 1-10

[0098] Based on the test results of Table 2 and Figure 1 The peak area and recovery of acrylamide at a temperature of 60°C were better than at room temperature (20°C). Therefore, the reaction temperature was selected to be 60°C. Meanwhile, the recovery obtained by reacting for 0.5 h (30 min) at 60°C was less than the recovery obtained by reacting for 2 h, and therefore the reaction time was preferably 2 h (120 min).

[0099] Accuracy experiment: Examples 11-15 A 0.4742 g acrylamide standard was weighed into a 100 mL volumetric flask and diluted to volume with water to obtain a stock solution with a concentration of 4742 mg / L; 10.00 mL of the stock solution was transferred to another 100 mL volumetric flask and diluted to volume with water to obtain a first standard working solution with a concentration of 474.2 mg / L; 10.00 mL of the first standard working solution was taken into a new 100 mL volumetric flask and diluted to volume with water to obtain a second standard working solution with a concentration of 47.42 mg / L; 10 mL of the second standard working solution was taken into a new 100 mL volumetric flask and diluted to volume with water to obtain a third standard working solution with a concentration of 4.742 mg / L; 10 mL of the third standard working solution was taken into a new 100 mL volumetric flask and diluted to volume with water to obtain a fourth standard working solution with a concentration of 0.4742 mg / L.

[0100] 1.00 mL of the stock solution, the first standard working solution, the second standard working solution, the third standard working solution and the fourth standard working solution were respectively taken into five 15 mL polypropylene centrifuge tubes, 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, placed in a 60°C water bath for 2 h, taken out and 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, shaken up and down or vortexed for 1 min, centrifuged at 3000 rpm for 5 min, and the acetonitrile phase was taken through a 0.45 μm filter membrane into a sample bottle. The sample was injected into a high performance liquid chromatograph for detection, and the relationship between the chromatographic peak area and the mass of acrylamide was obtained, as shown in Table 3: Table 3: Relationship between chromatographic peak area and mass of acrylamide

[0101] Among them, Example 13 is taken as an example to obtain the chromatogram of Example 13, 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] Examples 16-18: 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. Table 4: Experimental Results of Examples 16-18

[0107] Examples 19-27: In 15 mL polypropylene round bottom centrifuge tubes, 9 portions of the aforementioned water-in-oil polyacrylamide emulsion were accurately weighed, the weights are shown in Table 5 (accurate to 1 mg), and 3 were taken as a group. 0.1 mL (parallel group 1), 0.3 mL (parallel group 2), and 0.6 mL (parallel group 3) of the 172.8 mg / L acrylamide working solution were added, respectively, 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, sealed and shaken well, and placed in a 60°C water bath for 2h. After cooling to room temperature, 1 mL of 20% ferrous sulfate solution, 0.5 g of anhydrous sodium sulfate and 4 mL of acetonitrile were added, shaken up and down or vortexed for 1 min, centrifuged at 3000 rpm for 5 min, and the upper organic phase was collected through a 0.45 μm filter membrane into a sample bottle. The obtained sample was injected into a high performance liquid chromatograph for detection to obtain the peak area of acrylamide, which was substituted into the linear equation calculated according to Examples 11-15 above to calculate the mass of acrylamide in the sample (μg).

[0108] Specifically, the acrylamide working solution can be prepared as follows: Take 10 mL of the acrylamide standard solution prepared in Examples 1-10 into a 100 mL volumetric flask, and dilute to volume.

[0109] Recovery rate calculation: ; In the formula: is the mass of the sample taken, g; is the concentration of the acrylamide working solution added (mg / L); is the volume of the acrylamide working solution added (mL).

[0110] Each concentration was prepared in triplicate, and three parallel experiments were performed. The recovery rate was determined according to the content determination item, and the results are shown in Table 5: Table 5: Experimental results of Examples 19-27

[0111] The results of Table 5 show that from the average recovery rate of the three parallel groups and the comprehensive RSD, the RSD is <3%, indicating good accuracy.

[0112] And, based on the conclusion that the acrylamide is linear in the mass range of 0.4742-4742 μg, and the sample weight of the water-in-oil polyacrylamide emulsion in Table 4, the detection limit of the detection method of the present example when the sample weight of the water-in-oil polyacrylamide emulsion in Table 4 is calculated; by calculation, the upper and lower limits of the detection method of the present example are 1-10000 mg / kg.

[0113] Therefore, the detection lower limit of the detection method of the present application can reach 1 mg / kg, which is lower than the required residual amount (2 mg / kg, calculated according to the addition amount of water-in-oil polyacrylamide and the maximum residual amount of acrylamide in the product) required in the "Cosmetic Safety Technology Specification (2015 Edition)"; thus, the detection method of the present example can meet the detection needs required by cosmetics, and has the advantage of low detection limit.

[0114] Precision experiment Examples 28-33: Take the sample solution of the above example 23, continuously sample 6 times, and record the precision of the peak area of acrylamide as shown in Table 6: Table 6: Precision experiment results

[0115] According to the experimental results in Table 6, it is shown that the detection method of the present example has excellent precision and repeatability.

[0116] Solution stability test Examples 34-38: Take the sample solution of the above example 23, respectively at room temperature for 4, 8, 12, 24, 48 hours, sample, and record the change of the peak area of the main component, the results are shown in Table 7: Table 7: Solution stability test results

[0117] According to the experimental results in Table 7, it is shown that the derivatized solution of the detection method of the present example has excellent stability within 48 hours at room temperature.

[0118] In summary, the detection method of the embodiment is aimed at the system of water-in-oil polyacrylamide emulsion. By adding saturated potassium bromide solution, the extraction efficiency of acrylamide in water-in-oil polyacrylamide emulsion can be improved during pretreatment, thereby reducing the detection limit. The problems of high detection limit of the existing acrylamide detection method and low precision and accuracy in detecting acrylamide in water-in-oil polyacrylamide emulsion are solved. At the same time, using acetonitrile as an extractant can better improve the extraction efficiency of acrylamide in water-in-oil polyacrylamide emulsion, further improving the accuracy and precision of the detection results. At the same time, the detection method of the embodiment has a larger linear range and a lower detection limit, so it can be applied to more stringent and higher requirement application scenarios for acrylamide content detection.

[0119] Therefore, the detection method of acrylamide provided in the embodiment can meet the demand of acrylamide safety risk screening in water-in-oil polyacrylamide emulsion, and provide good technical support for quality control and safety monitoring of water-in-oil polyacrylamide emulsion. It is suggested that the detection method has a better application prospect in the quality control of water-in-oil polyacrylamide emulsion.

[0120] The above describes the technical solutions provided by the embodiments of the present application in detail. The principles and implementation manners of the embodiments of the present application are described by applying specific examples. The above description of the embodiments is only applicable to help understand the principles of the embodiments of the present application; at the same time, for those skilled in the art, the specific implementation manners and application ranges of the embodiments of the present application will be changed, and the above description of the embodiments should not be understood as a limitation of the present 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 respectively 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 respectively added to different concentrations of acrylamide standard solution, 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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