High performance liquid chromatography and mass spectrometry detection method for polyethylene glycol impurities in AES

Abstract

The invention discloses a high performance liquid chromatography and mass spectrometry combined detection method for polyethylene glycol impurities in AES. The high performance liquid chromatography and mass spectrometry combined detection method comprises the following steps: step 1, pre-treating a sample; step 2, high performance liquid chromatography separation; step 3, mass spectrum detection; 4, drawing a standard curve; and 5, sample determination and result calculation. According to the method, a high performance liquid chromatography and mass spectrometry combined technology is adopted, and an optimized sample pretreatment method and detection conditions are combined, so that rapid and accurate detection of the polyethylene glycol impurities in the AES can be realized. The method has high sensitivity and can detect trace polyethylene glycol impurities, and the detection limit is as low as 0.1 mu g / mL. The method is good in accuracy and repeatability, and the reliability of a detection result can be ensured through standard curve drawing and strict experimental operation.

Description

Technical Field

[0001] The present invention relates to the technical field of polyethylene glycol impurity detection in AES, and specifically to a high performance liquid chromatography-mass spectrometry method for detecting polyethylene glycol impurities in AES. Background Art

[0002] AES, an important anionic surfactant, is widely used in industries such as detergents and cosmetics. However, during the AES production process, polyethylene glycol (PEG) impurities are inevitably generated. The presence of PEG impurities can affect the quality and performance of AES products, such as reduced surface activity and poor foaming properties. In certain applications, PEG impurities can even cause adverse reactions with other ingredients, affecting product stability and performance. Therefore, accurately measuring the PEG impurity content in AES is crucial to ensuring AES product quality.

[0003] Currently, the main methods for detecting polyethylene glycol impurities in AES include gas chromatography and spectrophotometry. Patent CN115047128A (A method for determining residual acetaldehyde in polyethylene glycol bulk drugs) uses gas chromatography for determination; the specific chromatographic parameters are: 100% dimethylpolysiloxane as the stationary phase, an inlet temperature of 180°C, a hydrogen flame ionization detector temperature of 250°C, and a headspace equilibrium temperature of 70°C. Gas chromatography requires sample derivatization, which is complex and can introduce errors. Patent CN109030396A (A method for rapid determination of nitrate in aquaculture water) uses spectrophotometry, but spectrophotometry has low sensitivity and is difficult to detect trace amounts of polyethylene glycol impurities. High-performance liquid chromatography-mass spectrometry (HPLC-MS) has the advantages of high separation efficiency, high sensitivity, and accurate qualitative and quantitative analysis. However, there is currently no mature HPLC-MS detection method for polyethylene glycol impurities in AES. Therefore, there is an urgent need to develop an accurate and efficient detection method. Summary of the Invention

[0004] The object of the present invention is to provide a method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry, comprising the following steps:

[0006] Step 1: Sample pretreatment: Accurately weigh a certain mass of AES sample, dissolve the sample, centrifuge and filter to remove impurities to obtain the sample solution to be tested;

[0007] Step 2: HPLC separation: Select a suitable chromatographic column and mobile phase, and inject the sample solution into the HPLC for separation;

[0008] Step 3: Mass spectrometry detection: By selecting the ion source and mode, setting the scan range, and setting the mass spectrometry parameters, the multiple reaction monitoring mode is used to select the characteristic ion pairs of polyethylene glycol impurities for monitoring. By monitoring the characteristic ion pairs, the polyethylene glycol impurities can be accurately identified and quantified;

[0009] Step 4: Plotting a standard curve: Accurately weigh different masses of polyethylene glycol standard products, place them in multiple volumetric flasks, add an acetonitrile-water mixed solution, and prepare a series of polyethylene glycol standard solutions; according to the conditions of steps 2 and 3 above, perform high performance liquid chromatography-mass spectrometry on the polyethylene glycol standard solutions of different concentrations, and record the peak area of the characteristic ion of the polyethylene glycol impurity in the standard solution of each concentration; plot a standard curve with the concentration of the polyethylene glycol standard solution as the abscissa and the peak area of the characteristic ion as the ordinate to obtain a linear regression equation;

[0010] Step 5. Sample determination and result calculation: Substitute the peak area of the characteristic ion of the polyethylene glycol impurity in the sample solution to be tested into the linear regression equation of the standard curve to calculate the concentration of the polyethylene glycol impurity in the sample solution to be tested; calculate the content of the polyethylene glycol impurity in the AES sample based on the weighed mass and constant volume parameters of the sample.

[0011] Preferably, the sample dissolution in step 1 is specifically as follows: accurately weighing a certain mass of the AES sample into a centrifuge tube, adding an appropriate amount of acetonitrile-water mixed solution, the volume ratio of acetonitrile to water is 6:4, and vortexing for 5 minutes to fully dissolve the sample; the acetonitrile-water mixed solution can effectively dissolve the AES sample and has good solubility for polyethylene glycol impurities, laying the foundation for subsequent detection.

[0012] Preferably, the centrifugal separation in step 1 is specifically as follows: centrifuging the fully dissolved solution at 4°C and 12,000 r / min for 10 minutes, and transferring the supernatant to a new centrifuge tube; the centrifugation operation can precipitate insoluble impurities, thereby obtaining a relatively pure sample solution and avoiding interference of impurities on the test results.

[0013] Preferably, the filtration and impurity removal in step 1 specifically includes: adding a 0.2 μm organic filter membrane to the supernatant to filter and further remove tiny particle impurities to obtain a sample solution to be tested.

[0014] Preferably, in step 2, selecting a suitable chromatographic column and mobile phase is specifically as follows:

[0015] Chromatographic column selection: A C18 column was used, which has excellent separation effect on polyethylene glycol impurities and can effectively separate polyethylene glycol impurities from other components in the AES sample. The length and inner diameter of the C18 column are 250 mm × 4.6 mm, and the particle size of the packing material is 5 μm.

[0016] Mobile phase selection: Acetonitrile-water was used as the mobile phase, and the acetonitrile-water volume ratio gradient was changed as follows: from 0 to 10 minutes, the acetonitrile volume fraction increased linearly from 30% to 70%; from 10 to 15 minutes, the acetonitrile volume fraction was maintained at 70%; from 15 to 20 minutes, the acetonitrile volume fraction was linearly decreased from 70% to 30%, with a flow rate of 0.8 mL / min. By setting a reasonable mobile phase gradient, efficient separation can be achieved at different time periods according to the properties of polyethylene glycol impurities;

[0017] The column temperature of the C18 column was set at 35°C. At this temperature, the separation performance of the column was relatively stable, ensuring the repeatability and accuracy of the separation effect. The injection volume of the mobile phase was 10 μL.

[0018] Preferably, the selection of the ion source and mode in step 3 is as follows: the ion source is an electrospray ion source, and the positive ion mode is adopted; the electrospray ion source can effectively ionize the polyethylene glycol impurities in the sample solution, and the positive ion mode is suitable for the detection of polyethylene glycol impurities;

[0019] The scanning range is specifically set to m / z 100-1000, which can cover the main ion peaks of polyethylene glycol impurities, ensuring that the presence of polyethylene glycol impurities can be accurately detected;

[0020] The mass spectrometry parameters were set as follows: the drying gas temperature was set to 350°C, the drying gas flow rate was set to 10 L / min, and the nebulizing gas pressure was set to 40 psi. Reasonable setting of these mass spectrometry parameters can ensure the effective transmission and detection of ions and improve the sensitivity and accuracy of detection.

[0021] Preferably, in step 4, the volume ratio of acetonitrile to water in the acetonitrile-water mixed solution is 6:4; and the concentration range of the polyethylene glycol standard solution is 0.1 μg / mL-100 μg / mL.

[0022] Preferably, the linear regression equation in step 4 is specifically:

[0023] With the concentration of polyethylene glycol standard solution as the horizontal axis and the peak area of characteristic ions as the vertical axis, a standard curve was drawn to obtain the linear regression equation:

[0024] y=1537.25x+86.31

[0025] Where y is the peak area of the characteristic ion and x is the concentration of the polyethylene glycol standard solution.

[0026] Preferably, the specific calculation formula for the polyethylene glycol impurity content in the AES sample in step 5 is:

[0027]

[0028] Among them, C PEG is the content of polyethylene glycol impurities in mg / kg; A PEG is the peak area of polyethylene glycol impurities in the sample; C std is the concentration of polyethylene glycol in the standard solution in mg / L; V is the constant volume of the sample solution in L; A std is the peak area of polyethylene glycol in the standard solution; m is the weighed mass of the sample in kg.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention utilizes high-performance liquid chromatography-mass spectrometry (HPLC-MS / MS) coupled with optimized sample pretreatment methods and detection conditions to enable rapid and accurate detection of polyethylene glycol impurities in AES. This method exhibits high sensitivity and can detect trace amounts of polyethylene glycol impurities with a detection limit as low as 0.1 μg / mL. The method demonstrates excellent accuracy and reproducibility, and the reliability of the test results is ensured through standard curve development and rigorous experimental procedures. The method is simple to operate, employs simple sample pretreatment procedures, and offers a high degree of automation in the detection process, making it suitable for routine testing of AES product quality control. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of the detection method of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] See also Figure 1 The present invention provides a method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry, comprising the following steps:

[0034] Step 1. Sample pretreatment: Accurately weigh a certain mass of AES sample, and perform sample dissolution, centrifugation and filtration to remove impurities in sequence to obtain a sample solution to be tested; Sample dissolution is specifically as follows: Accurately weigh a certain mass of AES sample in a centrifuge tube, add an appropriate amount of acetonitrile-water mixed solution, the volume ratio of acetonitrile to water is 6:4, and vortex oscillation for 5 minutes to fully dissolve the sample; The acetonitrile-water mixed solution can effectively dissolve the AES sample and has good solubility for polyethylene glycol impurities, laying the foundation for subsequent detection; Centrifugal separation is specifically as follows: Centrifuge the fully dissolved solution at 4°C and 12000r / min for 10 minutes, and transfer the supernatant to a new centrifuge tube; Centrifugation can precipitate insoluble impurities, thereby obtaining a relatively pure sample solution and avoiding interference of impurities on the test results; Filtration and impurity removal is specifically as follows: Add a 0.2μm organic filter membrane to the supernatant for filtration to further remove tiny particle impurities to obtain a sample solution to be tested;

[0035] Step 2: HPLC separation: Select a suitable chromatographic column and mobile phase, and inject the sample solution into the HPLC for separation. The specific steps for selecting a suitable chromatographic column and mobile phase are as follows:

[0036] Chromatographic column selection: A C18 column was used, which has excellent separation effect on polyethylene glycol impurities and can effectively separate polyethylene glycol impurities from other components in the AES sample. The length and inner diameter of the C18 column are 250 mm × 4.6 mm, and the particle size of the packing material is 5 μm.

[0037] Mobile phase selection: Acetonitrile-water was used as the mobile phase, and the acetonitrile-water volume ratio gradient was changed as follows: from 0 to 10 minutes, the acetonitrile volume fraction increased linearly from 30% to 70%; from 10 to 15 minutes, the acetonitrile volume fraction was maintained at 70%; from 15 to 20 minutes, the acetonitrile volume fraction was linearly decreased from 70% to 30%, with a flow rate of 0.8 mL / min. By setting a reasonable mobile phase gradient, efficient separation can be achieved at different time periods according to the properties of polyethylene glycol impurities;

[0038] The column temperature of the C18 column was set at 35°C. At this temperature, the separation performance of the column was relatively stable, which could ensure the repeatability and accuracy of the separation effect. The injection volume of the mobile phase was 10 μL;

[0039] Step 3: Mass spectrometry detection: By selecting the ion source and mode, setting the scan range, and setting the mass spectrometry parameters, the multiple reaction monitoring mode is adopted, and the characteristic ion pairs of the polyethylene glycol impurities are selected for monitoring. By monitoring the characteristic ion pairs, the polyethylene glycol impurities can be accurately identified and quantified. The ion source and mode are selected as follows: the ion source is an electrospray ionization source, and the positive ion mode is adopted. The electrospray ionization source can effectively ionize the polyethylene glycol impurities in the sample solution, and the positive ion mode is suitable for the detection of polyethylene glycol impurities.

[0040] The scanning range is specifically set to m / z 100-1000, which can cover the main ion peaks of polyethylene glycol impurities, ensuring that the presence of polyethylene glycol impurities can be accurately detected;

[0041] The mass spectrometry parameters were set as follows: the drying gas temperature was set to 350°C, the drying gas flow rate was set to 10 L / min, and the nebulizing gas pressure was set to 40 psi. Reasonable setting of these mass spectrometry parameters can ensure the effective transmission and detection of ions and improve the sensitivity and accuracy of detection.

[0042] In step 4, the volume ratio of acetonitrile to water in the acetonitrile-water mixed solution is 6:4; the concentration range of the polyethylene glycol standard solution is 0.1 μg / mL-100 μg / mL;

[0043] Step 4: Plotting a standard curve: Accurately weigh different masses of polyethylene glycol standard products, place them in multiple volumetric flasks, add acetonitrile-water mixed solution, and prepare a series of polyethylene glycol standard solutions; according to the conditions of steps 2 and 3 above, perform high performance liquid chromatography-mass spectrometry on the polyethylene glycol standard solutions of different concentrations, and record the peak area of the characteristic ion of polyethylene glycol impurities in the standard solution of each concentration; plot a standard curve with the concentration of the polyethylene glycol standard solution as the abscissa and the peak area of the characteristic ion as the ordinate to obtain a linear regression equation; the linear regression equation is specifically:

[0044] With the concentration of polyethylene glycol standard solution as the horizontal axis and the peak area of characteristic ions as the vertical axis, a standard curve was drawn to obtain the linear regression equation:

[0045] y=1537.25x+86.31

[0046] Where y is the peak area of the characteristic ion, and x is the concentration of the polyethylene glycol standard solution;

[0047] Step 5. Sample determination and result calculation: Substitute the peak area of the characteristic ion of polyethylene glycol impurity in the sample solution to be tested into the linear regression equation of the standard curve to calculate the concentration of polyethylene glycol impurity in the sample solution to be tested; calculate the content of polyethylene glycol impurity in the AES sample based on the weighed mass and constant volume parameters of the sample; the specific calculation formula for the content of polyethylene glycol impurity in the AES sample is:

[0048]

[0049] Among them, C PEG is the content of polyethylene glycol impurities in mg / kg; A PEG is the peak area of polyethylene glycol impurities in the sample; C std is the concentration of polyethylene glycol in the standard solution in mg / L; V is the constant volume of the sample solution in L; A std is the peak area of polyethylene glycol in the standard solution; m is the weighed mass of the sample in kg.

[0050] Example 1:

[0051] Sample preparation: Accurately weigh 1.0000g of AES sample into a 50mL centrifuge tube. Add 20mL of acetonitrile-water mixture (acetonitrile:water volume ratio of 6:4) and vortex for 5 minutes to fully dissolve the sample. Centrifuge the solution at 4°C, 12,000 rpm for 10 minutes. Transfer the supernatant to a new 50mL centrifuge tube and filter through a 0.2μm organic filter to obtain the sample solution.

[0052] High performance liquid chromatography separation: A C18 column (250 mm × 4.6 mm, 5 μm) was used with acetonitrile-water (volume ratio gradient change: 0-10 min, acetonitrile volume fraction linearly increased from 30% to 70%; 10-15 min, acetonitrile volume fraction maintained at 70%; 15-20 min, acetonitrile volume fraction linearly decreased from 70% to 30%) as the mobile phase at a flow rate of 0.8 mL / min, the column temperature was set at 35°C, and the injection volume was 10 μL. The sample solution to be tested was injected into the high performance liquid chromatograph for separation.

[0053] Mass spectrometry detection: The ion source was selected as electrospray ion source (ESI), the positive ion mode was adopted, the scanning range was m / z 100-1000, the drying gas temperature was set to 350°C, the drying gas flow rate was 10 L / min, the nebulizing gas pressure was 40 psi, and the multiple reaction monitoring (MRM) mode was adopted to select the characteristic ion pairs of polyethylene glycol impurities for monitoring.

[0054] To prepare the standard curve, accurately weigh 0.0010 g, 0.0100 g, 0.1000 g, and 1.0000 g of polyethylene glycol standard into 100 mL volumetric flasks. Add acetonitrile-water mixture (acetonitrile:water volume ratio of 6:4) to prepare polyethylene glycol standard stock solutions with concentrations of 10 μg / mL, 100 μg / mL, 1000 μg / mL, and 10,000 μg / mL, respectively. Take appropriate amounts of these standard stock solutions and dilute them with acetonitrile-water mixture (acetonitrile:water volume ratio of 6:4) to prepare polyethylene glycol standard solutions with concentrations of 0.1 μg / mL, 1 μg / mL, 10 μg / mL, 50 μg / mL, and 100 μg / mL. Analyze polyethylene glycol standard solutions of varying concentrations using the HPLC and mass spectrometry detection conditions described above, and record the peak area of the characteristic polyethylene glycol impurity ion in each standard solution. The standard curve was drawn with the concentration of the polyethylene glycol standard solution as the abscissa and the peak area of the characteristic ion as the ordinate, and the linear regression equation was obtained: y=1537.25x+86.31, with a correlation coefficient r=0.9995.

[0055] Sample Assay and Calculation: The sample solution was tested using the HPLC and mass spectrometry conditions described above. The peak area of the characteristic polyethylene glycol impurity ion in the sample solution was recorded as 25,000. Substituting the peak area into the linear regression equation of the standard curve, the concentration of the polyethylene glycol impurity in the sample solution was calculated to be 1.99 μg / mL. Based on the sample mass and the constant volume, the polyethylene glycol impurity content in the AES sample was calculated to be 0.0398%.

[0056] Example 2:

[0057] Sample preparation: Accurately weigh 0.5000g of AES sample into a 25mL centrifuge tube. Add 10mL of acetonitrile-water mixture (acetonitrile:water volume ratio of 6:4) and vortex for 5 minutes to fully dissolve the sample. Centrifuge the solution at 4°C, 12,000 rpm for 10 minutes. Transfer the supernatant to a new 25mL centrifuge tube and filter through a 0.2μm organic filter to obtain the sample solution.

[0058] High performance liquid chromatography separation: A C18 column (250 mm × 4.6 mm, 5 μm) was used with acetonitrile-water (volume ratio gradient change: 0-10 min, acetonitrile volume fraction linearly increased from 30% to 70%; 10-15 min, acetonitrile volume fraction maintained at 70%; 15-20 min, acetonitrile volume fraction linearly decreased from 70% to 30%) as the mobile phase at a flow rate of 0.8 mL / min, the column temperature was set at 35°C, and the injection volume was 10 μL. The sample solution to be tested was injected into the high performance liquid chromatograph for separation.

[0059] Mass spectrometry detection: The ion source was selected as electrospray ion source (ESI), the positive ion mode was adopted, the scanning range was m / z 100-1000, the drying gas temperature was set to 350°C, the drying gas flow rate was 10 L / min, the nebulizing gas pressure was 40 psi, and the multiple reaction monitoring (MRM) mode was adopted to select the characteristic ion pairs of polyethylene glycol impurities for monitoring.

[0060] To prepare the standard curve, accurately weigh 0.0010 g, 0.0100 g, 0.1000 g, and 1.0000 g of polyethylene glycol standard into 100 mL volumetric flasks. Add acetonitrile-water mixture (acetonitrile:water volume ratio of 6:4) to prepare polyethylene glycol standard stock solutions with concentrations of 10 μg / mL, 100 μg / mL, 1000 μg / mL, and 10,000 μg / mL, respectively. Take appropriate amounts of these standard stock solutions and dilute them with acetonitrile-water mixture (acetonitrile:water volume ratio of 6:4) to prepare polyethylene glycol standard solutions with concentrations of 0.1 μg / mL, 1 μg / mL, 10 μg / mL, 50 μg / mL, and 100 μg / mL. Analyze polyethylene glycol standard solutions of varying concentrations using the HPLC and mass spectrometry detection conditions described above, and record the peak area of the characteristic polyethylene glycol impurity ion in each standard solution. The standard curve was drawn with the concentration of the polyethylene glycol standard solution as the abscissa and the peak area of the characteristic ion as the ordinate, and the linear regression equation was obtained: y=1537.25x+86.31, with a correlation coefficient r=0.9995.

[0061] Sample Assay and Calculation: The sample solution was tested using the HPLC and mass spectrometry conditions described above. The peak area of the characteristic polyethylene glycol impurity ion in the sample solution was recorded as 12,000. Substituting the peak area into the linear regression equation of the standard curve, the concentration of the polyethylene glycol impurity in the sample solution was calculated to be 0.93 μg / mL. Based on the sample mass and the constant volume, the polyethylene glycol impurity content in the AES sample was calculated to be 0.0186%.

[0062] It can be seen from Examples 1 and 2 that the detection method of the present invention has good accuracy and repeatability, and can accurately detect the content of polyethylene glycol impurities in AES.

[0063] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry, characterized by: The following steps are involved: Step 1: Sample pretreatment: Accurately weigh a certain mass of AES sample, dissolve the sample, centrifuge and filter to remove impurities to obtain the sample solution to be tested; Step 2: HPLC separation: Select a suitable chromatographic column and mobile phase, and inject the sample solution into the HPLC for separation; Step 3: Mass spectrometry detection: By selecting the ion source and mode, setting the scan range, and setting the mass spectrometry parameters, the multiple reaction monitoring mode is used to select the characteristic ion pairs of polyethylene glycol impurities for monitoring. By monitoring the characteristic ion pairs, the polyethylene glycol impurities can be accurately identified and quantified; Step 4: Plotting a standard curve: Accurately weigh different masses of polyethylene glycol standard products, place them in multiple volumetric flasks, add an acetonitrile-water mixed solution, and prepare a series of polyethylene glycol standard solutions; according to the conditions of steps 2 and 3 above, perform high performance liquid chromatography-mass spectrometry on the polyethylene glycol standard solutions of different concentrations, and record the peak area of the characteristic ion of the polyethylene glycol impurity in the standard solution of each concentration; plot a standard curve with the concentration of the polyethylene glycol standard solution as the abscissa and the peak area of the characteristic ion as the ordinate to obtain a linear regression equation; Step 5. Sample determination and result calculation: Substitute the peak area of the characteristic ion of the polyethylene glycol impurity in the sample solution to be tested into the linear regression equation of the standard curve to calculate the concentration of the polyethylene glycol impurity in the sample solution to be tested; calculate the content of the polyethylene glycol impurity in the AES sample based on the weighed mass and constant volume parameters of the sample.

2. The method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that: The sample dissolution in step 1 is specifically as follows: accurately weigh a certain mass of AES sample into a centrifuge tube, add an appropriate amount of acetonitrile-water mixed solution, the volume ratio of acetonitrile to water is 6:4, and vortex for 5 minutes to fully dissolve the sample.

3. The method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry according to claim 2, characterized in that: The centrifugal separation in step 1 is specifically as follows: the fully dissolved solution is centrifuged at 4° C. and 12,000 rpm for 10 minutes, and the supernatant is transferred to a new centrifuge tube.

4. The method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry according to claim 3, characterized in that: The filtering and impurity removal in step 1 specifically includes: adding a 0.2 μm organic filter membrane to the supernatant to filter and further remove tiny particle impurities to obtain a sample solution to be tested.

5. The method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that: In step 2, selecting a suitable chromatographic column and mobile phase is specifically as follows: Chromatographic column selection: A C18 chromatographic column was used, wherein the length and inner diameter of the C18 chromatographic column were 250 mm × 4.6 mm, and the particle size of the filling material was 5 μm; Mobile phase selection: Acetonitrile-water was used as the mobile phase, and the acetonitrile-water volume ratio gradient was changed as follows: 0-10 min, the acetonitrile volume fraction was linearly increased from 30% to 70%; 10-15 min, the acetonitrile volume fraction was maintained at 70%; 15-20 min, the acetonitrile volume fraction was linearly decreased from 70% to 30%, and the flow rate was 0.8 mL / min; The column temperature of the C18 column was set at 35 °C, and the injection volume of the mobile phase was 10 μL.

6. The method for detecting polyethylene glycol impurities in AES by high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that: The selection of the ion source and mode in step 3 is specifically as follows: the ion source is an electrospray ion source, and the positive ion mode is used; the electrospray ion source can effectively ionize the polyethylene glycol impurities in the sample solution, and the positive ion mode is suitable for the detection of polyethylene glycol impurities; The scanning range was specifically set to m / z 100-1000; The mass spectrometry parameters were set as follows: the drying gas temperature was set to 350°C, the drying gas flow rate was set to 10 L / min, and the nebulizing gas pressure was set to 40 psi.

7. The method for preparing the high performance liquid chromatography-mass spectrometry detection method for polyethylene glycol impurities in AES according to claim 1, characterized in that: In the step 4, the volume ratio of acetonitrile to water in the acetonitrile-water mixed solution is 6:4; the concentration range of the polyethylene glycol standard solution is 0.1 μg / mL-100 μg / mL.

8. The method for preparing the high performance liquid chromatography-mass spectrometry detection method for polyethylene glycol impurities in AES according to claim 1, characterized in that: The linear regression equation in step 4 is specifically: With the concentration of polyethylene glycol standard solution as the horizontal axis and the peak area of characteristic ions as the vertical axis, a standard curve was drawn to obtain the linear regression equation: y=1537.25x+86.31 Where y is the peak area of the characteristic ion and x is the concentration of the polyethylene glycol standard solution.

9. The method for preparing the high performance liquid chromatography-mass spectrometry detection method for polyethylene glycol impurities in AES according to claim 1, characterized in that: The specific calculation formula for the polyethylene glycol impurity content in the AES sample in step 5 is: Among them, C PEG is the content of polyethylene glycol impurities in mg / kg; A PEG is the peak area of polyethylene glycol impurities in the sample; C std is the concentration of polyethylene glycol in the standard solution in mg / L; V is the constant volume of the sample solution in L; A std is the peak area of polyethylene glycol in the standard solution; m is the weighed mass of the sample in kg.

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