Method for detecting polyether antifoam agent in water-soluble pharmaceuticals

Abstract

The application discloses a method for detecting polyether defoaming agent in water-soluble medicine, which comprises the following steps: heating a mixture of water-soluble medicine and water, wherein the heating temperature is 90-100 DEG C, to obtain a water-soluble medicine solution; extracting the water-soluble medicine solution with an extractant to obtain a solution rich in polyether defoaming agent as a test solution; and determining the residual amount of the polyether defoaming agent in the test solution by using a combination of molecular exclusion chromatography and an evaporative light scattering detector or a combination of molecular exclusion chromatography and an electric mist detector. The method has good sensitivity, accuracy and repeatability by using a special pretreatment method combined with the detection method of SEC chromatography-ELSD.

Description

Technical Field

[0001] This invention relates to a method for detecting polyether defoamers in water-soluble drugs. Background Technology

[0002] Polyether defoamers are a common type of industrial defoamer, typically composed of polyoxyethylene (PEG) and polypropylene (PPG) block copolymers. They use polyols (such as glycerol, pentaerythritol, etc.) as initiators and form a block structure through ring-opening polymerization of ethylene oxide (EO) and propylene oxide (PO). The molecular weight is generally in the range of 4000 to 8000.

[0003] The active pharmaceutical ingredient glutamine is the most abundant non-essential amino acid in the human body. It plays a core role in nitrogen transport, acid-base balance maintenance, antioxidant defense, and immune cell function regulation. Its industrial production adopts a fermentation process using glutamate-producing bacteria, and polyoxyethylene polyoxypropylene pentaerythritol ether is used as an antifoaming agent during the fermentation process.

[0004] Based on ICH M7 "Assessing and controlling DNA-reactive (mutagenic) impurities in pharmaceuticals to limit potential carcinogenic risks" and the "Guideline for the Control of Genotoxic Impurities" in General Chapter 9306 of the 2025 edition of the Chinese Pharmacopoeia, using toxicological data, the permissible daily exposure (PDE) value for the polyether defoamer polyoxyethylene polyoxypropylene pentaerythritol ether is 3.78 mg / d. Therefore, establishing a method suitable for detecting polyether defoamer residues in complex matrices is of great significance for ensuring drug quality and reducing the risk of medication use for patients.

[0005] Currently, the main method for determining the residual amount of polyether defoamers is liquid chromatography. The main steps are to perform appropriate pretreatment (dissolution or extraction) on the test sample to extract the defoamer from the drug matrix, and then perform quantitative analysis using liquid chromatography with a corresponding detector. However, the existing liquid chromatography method has low detection accuracy. Summary of the Invention

[0006] This invention addresses the problem of low accuracy in existing methods for detecting polyether defoamers in water-soluble drugs, and proposes a new method for detecting polyether defoamers in water-soluble drugs. This method exhibits good sensitivity, accuracy, and repeatability.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides a method for detecting polyether defoamers in water-soluble drugs, comprising the following steps: (1) Heating a mixture of water-soluble drug and water at a temperature of 90°C to 100°C to obtain an aqueous solution of water-soluble drug; (2) The aqueous solution of the water-soluble drug is extracted with an extractant to obtain a solution enriched with polyether defoamer as the test solution; (3) The residual amount of polyether defoamer in the test solution was determined by size exclusion chromatography-evaporative light scattering detector.

[0008] In this invention, the size exclusion chromatography-evaporative light scattering detector (ESD) coupling method refers to a technique that uses size exclusion chromatography (SEC) combined with an evaporative light scattering detector (ELSD) for quantitative analysis. The size exclusion chromatography-electro-atomization detector (EAD) coupling method refers to a technique that uses size exclusion chromatography (SEC) combined with an electro-atomization detector (CAD) for quantitative analysis.

[0009] In this invention, the water-soluble drug refers to a drug that can dissolve in water to form a homogeneous and stable aqueous solution, such as any one of glutamine, ampicillin, amikacin and vancomycin, preferably glutamine.

[0010] In this invention, the polyether defoamer is a common polyether defoamer found in water-soluble drugs, such as polyoxyethylene polyoxypropylene pentaerythritol ether.

[0011] In this invention, in step (1), the heating method can be conventional in the art, preferably a water bath heating method or a plate heating method, and more preferably a water bath heating method, which provides more uniform heating.

[0012] In this invention, in step (1), the mass-volume ratio of the water-soluble drug to the water is preferably 1g:(2.5~8)mL, for example 1g:4mL.

[0013] In this invention, in step (2), the extractant is preferably one or more of toluene, dichloromethane and ethyl acetate, and more preferably toluene.

[0014] In this invention, in step (2), the mass-volume ratio of the water-soluble drug to the extractant is preferably 2g:(1~2)mL, for example 2g:1mL.

[0015] In this invention, in step (2), the volume ratio of the extractant to the water is preferably 1:(5~16), more preferably 1:(7~10), for example 1:8.

[0016] In this invention, in step (3), it is preferable to use size exclusion chromatography-evaporative light scattering detector coupled method to determine the residual amount of polyether defoamer in the test solution.

[0017] In the size exclusion chromatography-evaporative light scattering detector coupled method, the mobile phase of size exclusion chromatography is preferably tetrahydrofuran.

[0018] In the size exclusion chromatography-evaporative light scattering detector coupled method, the flow rate of the mobile phase in the size exclusion chromatography is preferably 0.2~0.6 mL / min.

[0019] In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the elution method is preferably isocratic elution.

[0020] In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the injection volume of the test solution is preferably 5~20 μL, for example 10 μL.

[0021] In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the column packing material is preferably ethyl-bridged hybrid spherical silica particles, and more preferably BEH particles.

[0022] In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the particle size of the chromatographic column packing is preferably 3 μm.

[0023] In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the micropore size of the chromatographic column packing is preferably 45~200 Å.

[0024] In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the column temperature of the chromatographic column is preferably 20~50℃, for example 30℃.

[0025] In the size exclusion chromatography-evaporative light scattering detector coupled method, the size exclusion limit of the chromatographic column is preferably 1,000 to 400,000, more preferably 3,000 to 70,000. In a preferred embodiment, the size exclusion chromatography column is preferably a Waters ACQUITY APC XT 200 column with a size exclusion limit of 3,000 to 70,000.

[0026] In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the evaporation temperature of the evaporative light scattering detector is preferably 90~110℃.

[0027] In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the gas flow rate of the evaporative light scattering detector is preferably 1.4~1.6 mL / min.

[0028] In the aforementioned size exclusion chromatography-evaporative light scattering detector (EPSD) method, the optimal gain of the EPSD detector is 2 to 4. Gain refers to the signal amplification factor; specifically, the signal amplification factor of the EPSD detector is 2 to 4.

[0029] The positive and progressive effects of this invention are as follows: (1) The present invention utilizes SEC chromatography technology to achieve effective separation of polyether defoamers and water-soluble drugs on the same chromatographic column, and the main matrix components do not interfere with the detection.

[0030] (2) The chromatographic detection method of the present invention uses ELSD or CAD as a mass detector, which does not depend on the optical characteristics of the target analyte and has a good response to polyether defoamers that lack ultraviolet absorption groups, thus filling the blind spot of UV detection.

[0031] (3) The present invention combines a special pretreatment method with the detection methods of SEC-ELSD or SEC-CAD, and has good sensitivity, accuracy and repeatability.

[0032] (4) The present invention further adopts a pretreatment method of water bath heating and dissolution combined with toluene extraction, which makes the recovery rate reach 90.4%, and solves the problem that aqueous solution cannot be directly introduced into SEC column (damaging the chromatographic column). Attached Figure Description

[0033] Figure 1 The figures shown are chromatograms of the blank solution, the test solution of Example 1-1, and the system suitability solution. The blank solution refers to toluene. Detailed Implementation

[0034] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0035] Instruments: Ultimate 3000 high-performance liquid chromatography system (including evaporative light scattering detector, Thermo Scientific, USA); electronic analytical balance BSA2202S (Mettler-Toledo, Switzerland); constant temperature water bath; refrigerated centrifuge.

[0036] Polyoxyethylene polyoxypropylene pentaerythritol ether reference standard (content ≥99%, batch number 20240528, purchased from Xinkai Pharmaceutical Chemical Intermediates (Shanghai) Co., Ltd.); toluene, tetrahydrofuran, n-hexane, methanol (all chromatographic grade); sodium hydroxide (analytical grade); ultrapure water (resistivity >18 MΩ·cm); 5 batches of glutamine samples (batch numbers GM20231216983X, GM20230120, GM2202023, GM20240120 and GM2110058) were all provided by Xinkai Pharmaceutical Chemical Intermediates (Shanghai) Co., Ltd.

[0037] Preparation of standard curve: Reference solutions of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer with concentrations of 5 μg / mL, 10 μg / mL, 15 μg / mL, 20 μg / mL, and 25 μg / mL were prepared. The defoamer reference solutions were injected into an Ultimate 3000 high-performance liquid chromatograph for detection.

[0038] Size exclusion chromatography conditions: The chromatographic column used was a Waters ACQUITY APC XT200 column (150×4.6 mm, 3 μm) with a size exclusion limit of 3000~70000 (column efficiency: theoretical plate number of 1114). The packing material was 3 μm spherical BEH particles with a micropore size of 200 Å. The mobile phase was tetrahydrofuran (THF), the flow rate was 0.6 mL / min, the injection volume was 10 μL, and isocratic elution was performed. The column temperature was 30℃.

[0039] ELSD parameters: evaporation temperature 110℃, gas flow rate 1.6 mL / min, gain 4.

[0040] A linear regression was performed with the logarithm of mass concentration (c) on the x-axis and the logarithm of peak area (A) on the y-axis to obtain the standard curve and correlation coefficient results, as shown in Table 1.

[0041] Table 1

[0042] Determination of the limit of detection and the limit of quantitation: A 10 μg / mL standard solution of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer was prepared and detected using an Ultimate 3000 high-performance liquid chromatograph. The detection parameters were the same as those in the aforementioned standard curve preparation example. The limit of detection was set at a signal-to-noise ratio (S / N) ≥ 3, and the limit of quantitation was set at an S / N ≥ 10.

[0043] Among them, the detection limit refers to the lowest concentration of the analyte in the sample that can be detected by the instrument, the quantitation limit refers to the lowest concentration of the analyte in the sample that can be accurately quantified, and the quantitation limit RSD refers to the RSD of the average peak area of ​​6 consecutive injections at the quantitation limit.

[0044] The results are shown in Table 2 below.

[0045] Table 2

[0046] As can be seen from the limits of quantitation in Table 2, the lowest concentration of the analyte in the sample that can be accurately quantified is 3.280 μg / mL. Generally, an RSD of less than 5% indicates good accuracy. The above results show that the detection method of this invention has good sensitivity.

[0047] Example 1: In this embodiment, glutamine samples from the aforementioned five different batches (batch numbers GM20231216983X, GM20230120, GM2202023, GM20240120 and GM2110058) were tested.

[0048] The detection method is as follows: At room temperature (25℃), 2.0 g of glutamine sample was added to 8 mL of water and heated in a water bath (90℃~100℃) for 15 min. 1 mL of toluene was added to the resulting solution, and the mixture was shaken for 2-3 min. After standing, the layers separated into an upper oil phase and a lower aqueous phase. The upper oil phase was used as the test solution and added to a liquid chromatograph. Size exclusion chromatography-evaporative light scattering detector (SEC-ELSD) was used for detection to obtain the amount of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer.

[0049] In size exclusion chromatography, a Waters ACQUITY APC XT200 column (150 × 4.6 mm, 3 μm) with size exclusion limits of 3000–70000 was used. The packing material consisted of 3 μm spherical BEH particles with a micropore size of 200 Å. The mobile phase was tetrahydrofuran (THF). Chromatographic conditions: column temperature 30℃, flow rate 0.6 mL / min, injection volume 10 μL, isocratic elution. ELSD parameters: evaporation temperature 110℃, gas flow rate 1.6 mL / min, gain 4.

[0050] The detection amounts of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer in 5 batches of glutamine samples are shown in Table 3 below.

[0051] Table 3

[0052] Note: Multiply each detection amount in Table 3 above by 2 to obtain the detection amount in μg / mL.

[0053] As can be seen from Table 3, except for Examples 1-3, the detection amounts of the other examples are all higher than the limit of quantitation (3.280 μg / mL), indicating that the method of the present invention can accurately detect the content of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer in these glutamine samples.

[0054] Comparative Example 1-1: The difference between this comparative example and Example 1 is that the water bath heating is replaced by the addition of 10 mL of 1 mol / L NaOH. The remaining steps and parameters are the same as in Example 1.

[0055] The results showed that the glutamine sample was completely dissolved.

[0056] Comparative Examples 1-2: The difference between this comparative example and Example 1 is that the water bath heating is replaced by the addition of 10 mL of acetic acid. The remaining steps and parameters are the same as in Example 1.

[0057] The results showed that the glutamine sample was not completely dissolved.

[0058] Effect of dissolution method on recovery rate

[0059] Example 2: At room temperature (25℃), 8 mL of water was heated in a water bath (90℃~100℃) for 15 min. 1 mL of toluene was added to the resulting solution to make the toluene-to-water volume ratio 1:8. Then, 2 μL of 5 mg / mL polyoxyethylene polyoxypropylene pentaerythritol ether defoamer standard was added, and the mixture was shaken for 2-3 min. After standing, the layers separated into an upper oil phase and a lower aqueous phase. The upper oil phase was added to a liquid chromatograph and detected using size exclusion chromatography-evaporative light scattering detector (SEC-ELSD) technology. The chromatographic column, mobile phase, chromatographic conditions, and ELSD parameters were the same as in Example 1.

[0060] The recovery rate results are shown in Table 4.

[0061] Recovery rate = Concentration of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer detected in the upper oil phase / Theoretical concentration of added polyoxyethylene polyoxypropylene pentaerythritol ether defoamer. The theoretical concentration of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer refers to the concentration of 2 μL of 5 mg / mL polyoxyethylene polyoxypropylene pentaerythritol ether in 1 mL of toluene, i.e., 10 μg / mL.

[0062] Comparative Example 2-1: The difference between this comparative example and Example 2 is that the water bath heating is replaced by the addition of 10 mL of 1 mol / L NaOH. The remaining steps and parameters are the same as in Example 1.

[0063] The recovery rate results are shown in Table 4.

[0064] Comparative Example 2-2: When acetic acid was used to promote dissolution, the glutamine sample was not completely dissolved, so its recovery rate could not be calculated.

[0065] Table 4

[0066] As can be seen from Tables 3 and 4, the water bath heating method can not only dissolve glutamine, but also maintain the chemical stability of the defoamer, resulting in a high recovery rate. In contrast, although Comparative Example 1 can dissolve glutamine, its recovery rate is only 27.8%.

[0067] Effect of extractant on recovery rate

[0068] Example 3-1: At room temperature (25℃), 8 mL of water was heated in a water bath (90℃~100℃) for 15 min. 1 mL of toluene was added to the resulting solution to make the extractant-to-water volume ratio 1:8. Then, 2 μL of 5 mg / mL polyoxyethylene polyoxypropylene pentaerythritol ether defoamer standard was added, and the mixture was shaken for 2-3 min. After standing, the layers separated into an upper oil phase and a lower aqueous phase. The upper oil phase was added to a liquid chromatograph and detected using size exclusion chromatography-evaporative light scattering detector (SEC-ELSD) technology. The chromatographic column, mobile phase, chromatographic conditions, and ELSD parameters were the same as in Example 1.

[0069] The recovery rate results are shown in Table 5. The recovery rate was calculated in the same way as in Example 2.

[0070] Example 3-2: The difference between this embodiment and Embodiment 3-1 is that toluene is replaced with dichloromethane. The remaining steps and parameters are the same as in Embodiment 3-1.

[0071] The recovery rate results are shown in Table 5. The recovery rate was calculated in the same way as in Example 2.

[0072] Table 5

[0073] It can be seen that the recovery rate is higher when toluene is used as the extractant.

[0074] The effect of the volume ratio of extractant to water on the recovery rate: Example 4-1: At room temperature (25℃), 8 mL of water was heated in a water bath (90℃~100℃) for 15 min. 1 mL of toluene was added to the resulting solution to make the toluene-to-water volume ratio 1:8. Then, 2 μL of 5 mg / mL polyoxyethylene polyoxypropylene pentaerythritol ether defoamer standard was added, and the mixture was shaken for 2-3 min. After standing, the layers separated into an upper oil phase and a lower aqueous phase. The spiked sample solution in the upper oil phase was added to a liquid chromatograph and detected using size exclusion chromatography-evaporative light scattering detector (SEC-ELSD) technology. The chromatographic column, mobile phase, chromatographic conditions, and ELSD parameters were the same as in Example 1.

[0075] The recovery rate results are shown in Table 6. The recovery rate was calculated in the same way as in Example 2.

[0076] Example 4-2: The difference between this embodiment and Embodiment 4-1 is that the amount of toluene added is adjusted so that the volume ratio of toluene to water is 1:5. The remaining steps and parameters are the same as in Embodiment 4-1.

[0077] The recovery rate results are shown in Table 6. The recovery rate was calculated in the same way as in Example 2.

[0078] Example 4-3: The difference between this embodiment and Embodiment 4-1 is that the amount of toluene added is adjusted so that the volume ratio of toluene to water is 1:16. The remaining steps and parameters are the same as in Embodiment 4-1.

[0079] The recovery rate results are shown in Table 6. The recovery rate was calculated in the same way as in Example 2.

[0080] Table 6

[0081] It can be seen that the recovery rate is relatively high when the volume ratio of toluene to water is 1:8.

[0082] Results review: The glutamine used below is the glutamine from Example 1-1 (batch number GM20231216983X).

[0083] (1) System applicability

[0084] Preparation of glutamine system suitability solution: Accurately weigh approximately 2.0 g of glutamine, add 8 ml of water, and heat in a water bath (90℃~100℃) for 15 min. Accurately add 1 mL of toluene solution and shake up and down for 3 min. Then add 2 μL of 5 mg / mL polyoxyethylene polyoxypropylene pentaerythritol ether defoamer reference solution, shake well, and allow to stand for separation. Take the upper layer as the system suitability solution.

[0085] The above-described glutamine system suitability solution was added to a liquid chromatograph and detected using size exclusion chromatography-evaporative light scattering detector (SEC-ELSD) technology. The chromatographic column, mobile phase, chromatographic conditions, and ELSD parameters were the same as in Example 1.

[0086] The results showed that the retention time of the polyoxyethylene polyoxypropylene pentaerythritol ether defoamer was 5.13 min. Neither toluene solvent nor glutamine interfered with the determination of the polyoxyethylene polyoxypropylene pentaerythritol ether defoamer. The peak-to-valley ratio was >2, which met the system suitability requirements of the 2025 edition of the Chinese Pharmacopoeia.

[0087] Figure 1 The chromatograms shown are those of the system suitability solution, the test solution from Example 1-1, and the blank solution (toluene). The symmetry factor of the chromatographic peak in the test solution from Example 1-1 is 1.12. It can be seen that the detection method of the present invention has good sensitivity, and the pretreatment method can effectively extract the polyoxyethylene polyoxypropylene pentaerythritol ether defoamer from glutamine without matrix interference.

[0088] (4) Precision

[0089] A reference solution of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer with a concentration of 10 μg / mL (solvent: toluene) was prepared and injected 6 times repeatedly using an Ultimate 3000 high performance liquid chromatography system.

[0090] The results showed that the peak area RSD (n=6) was 1.3%, which is less than 2.0%, indicating that the high performance liquid chromatography system of the present invention has good precision.

[0091] (5) Recovery rate (accuracy)

[0092] Glutamine was added to 8 mL of water and heated in a water bath for 15 min. Toluene was added to the resulting solution to make a toluene-to-water volume ratio of 1:8. Then, 2 μL (low level), 3 μL (medium level), and 4 μL (high level) of 5 mg / mL polyoxyethylene polyoxypropylene pentaerythritol ether reference standard were added, respectively. The mixture was shaken for 2-3 min, allowed to stand for separation, and the upper oil phase was collected, yielding a total of 9 fractions. These upper oil phases were used as spiked sample solutions in a liquid chromatograph, and detection was performed using size exclusion chromatography-evaporative light scattering detector (SEC-ELSD) technology. The chromatographic column, mobile phase, chromatographic conditions, and ELSD parameters were the same as in Example 1.

[0093] Calculate the recovery rate: Recovery rate = (A1 - A2) / A0.

[0094] Wherein, A1 represents the concentration of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer detected in the upper oil phase; A2 represents the original concentration of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer contained in glutamine, i.e., 2.05 ppm; A0 represents the theoretical concentration of added polyoxyethylene polyoxypropylene pentaerythritol ether defoamer, wherein the theoretical concentration of polyoxyethylene polyoxypropylene pentaerythritol ether defoamer refers to the concentration of 2 μL (or 3 μL or 4 μL) 5 mg / mL polyoxyethylene polyoxypropylene pentaerythritol ether in 1 mL toluene.

[0095] Table 7 shows the recovery rates of the nine spiked sample solutions.

[0096] Table 7

[0097] The results showed that the average recovery rate of the defoamer polyoxyethylene polyoxypropylene pentaerythritol ether in the above 9 spiked sample solutions was 90.4%, with an RSD of 2.3%. This indicates that the method of the present invention has good accuracy.

[0098] (6) Repeatability

[0099] Prepare six parallel spiking sample solutions: Accurately weigh approximately 2.0 g of glutamine, add 8 ml of water, and heat in a water bath for 15 min. Accurately add 1 mL of toluene solution, then add 2 μL of 5 mg / mL polyoxyethylene polyoxypropylene pentaerythritol ether defoamer reference standard, shake up and down for 2-3 min, then allow to stand for phase separation, and take the upper layer as the spiking sample solution. Add the above upper oil phase as the spiking sample solution to a liquid chromatograph, and detect using size exclusion chromatography-evaporative light scattering detector (SEC-ELSD) technology. The chromatographic column, mobile phase, chromatographic conditions, and ELSD parameters are the same as in Example 1.

[0100] The results showed that the RSD (n=6) of the polyoxyethylene polyoxypropylene pentaerythritol ether defoamer content determination was 1.39%, and the method had good repeatability.

Claims

1. A method for detecting polyether defoamers in water-soluble drugs, characterized in that, It includes the following steps: (1) Heating a mixture of water-soluble drug and water at a temperature of 90°C to 100°C to obtain an aqueous solution of water-soluble drug; (2) The aqueous solution of the water-soluble drug is extracted with an extractant to obtain a solution enriched with polyether defoamer as the test solution; (3) The residual amount of polyether defoamer in the test solution is determined by size exclusion chromatography-evaporative light scattering detector or size exclusion chromatography-electro-foaming detector.

2. The method for detecting polyether defoamers in water-soluble drugs as described in claim 1, characterized in that, In step (1), the heating method is either water bath heating or plate heating, preferably water bath heating.

3. The method for detecting polyether defoamers in water-soluble drugs as described in claim 1, characterized in that, In step (1), the mass-to-volume ratio of the water-soluble drug to the water is 1g:(2.5~8)mL, for example, 1g:4mL.

4. The method for detecting polyether defoamers in water-soluble drugs as described in claim 1, characterized in that, In step (2), the extractant is one or more of toluene, dichloromethane and ethyl acetate, preferably toluene.

5. The method for detecting polyether defoamers in water-soluble drugs as described in claim 1, characterized in that, In step (2), the mass-volume ratio of the water-soluble drug to the extractant is 2g:(1~2)mL, for example, 2g:1mL.

6. The method for detecting polyether defoamers in water-soluble drugs as described in claim 1, characterized in that, In step (2), the volume ratio of the extractant to the water is 1:(5~16), preferably 1:(7~10), for example 1:

8.

7. The method for detecting polyether defoamers in water-soluble drugs as described in claim 1, characterized in that, The polyether defoamer is polyoxyethylene polyoxypropylene pentaerythritol ether; And / or, the water-soluble drug is any one of glutamine, ampicillin, amikacin and vancomycin, preferably glutamine.

8. The method for detecting polyether defoamers in water-soluble drugs as described in claim 1, characterized in that, In step (3), the residual amount of polyether defoamer in the test solution is determined by size exclusion chromatography-evaporative light scattering detector.

9. The method for detecting polyether defoamers in water-soluble drugs as described in claim 8, characterized in that, The size exclusion chromatography-evaporative light scattering detector coupled method meets one or more of the following conditions: ①In the aforementioned size exclusion chromatography-evaporative light scattering detector coupled method, the mobile phase is tetrahydrofuran; ② In the size exclusion chromatography-evaporative light scattering detector coupled method, the flow rate of the mobile phase is 0.2~0.6 mL / min; ③ In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the elution method is isocratic elution; ④ In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the injection volume of the test solution is 5~20μL, for example 10 μL; ⑤ In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the chromatographic column packing is ethyl-bridged hybrid spherical silica particles, preferably BEH particles; ⑥ In the aforementioned size exclusion chromatography-evaporative light scattering detector coupled method, the particle size of the chromatographic column packing is 3 μm; ⑦ In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the micropore size of the chromatographic column packing is 45~200 Å; ⑧ In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the size exclusion limit of the chromatographic column is 1,000~400,000, preferably 3,000~70,000. For example, the chromatographic column used is a Waters ACQUITY APC XT 200 chromatographic column with a size exclusion limit of 3,000~70,000. In the molecular size exclusion chromatography-evaporative light scattering detector coupled method described in section ⑨, the column temperature of the chromatographic column is 20~50℃, for example 30℃.

10. The method for detecting polyether defoamers in water-soluble drugs as described in claim 8, characterized in that, The size exclusion chromatography-evaporative light scattering detector coupled method meets one or more of the following conditions: ①In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the evaporation temperature of the evaporative light scattering detector is 90~110℃; ② In the molecular size exclusion chromatography-evaporative light scattering detector coupled method, the gas flow rate of the evaporative light scattering detector is 1.4~1.6 mL / min; In the molecular size exclusion chromatography-evaporative light scattering detector coupled method described in ③, the gain of the evaporative light scattering detector is 2~4.

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