Method and system for detecting content of myristoyl propyl dimethylamine in contact lens care products by hplc

Abstract

The application provides a method for detecting the content of myristoyl propyl dimethylamine in a contact lens care product by HPLC, and a new method for accurately detecting the content of myristoyl propyl dimethylamine in a contact lens care product. In the prior art, MPA is widely used as a preservative in cosmetics and contact lens care products, but due to its good solubility in organic solvents and insolubility in water, and its susceptibility to interference from other polar components in the care solution, the existing analysis method has limitations. By optimizing the proportion of the mobile phase and selecting the chromatographic column, the application effectively separates the MPA characteristic peak, overcomes the interference of other polar components, and ensures the accuracy and sensitivity of the detection results. The methodological verification results show that the method has good linear relationship, high recovery rate and good repeatability. The HPLC method of the application provides a reliable technical means for the quality control of contact lens care products, helps to ensure product quality safety, and protects the eye health of users.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medical detection, in particular to a method for detecting the content of myristoyl propyl dimethylamine in contact lens care products by HPLC and a detection system. BACKGROUND

[0002] Myristoyl propyl dimethylamine is widely used as a preservative in cosmetics and contact lens care products. Since it is a fat-soluble substance, it is not soluble in water, but has good solubility in organic solvents such as ethanol and acetonitrile, and may cause irritation to the eyes and skin at a certain concentration. Therefore, it is particularly important to monitor the content of myristoyl propyl dimethylamine in contact lens care products. However, existing quality control methods for myristoyl propyl dimethylamine are mainly for pure substance analysis, while care liquid products contain a large amount of surfactants and moisturizing lubricants with strong polarity, which can seriously interfere with the analysis of myristoyl propyl dimethylamine.

[0003] In order to solve the above problems, the applicant proposes a method for detecting the content of myristoyl propyl dimethylamine in contact lens care products by HPLC and a detection system. SUMMARY

[0004] The purpose of the present application is to provide a method for detecting the content of myristoyl propyl dimethylamine in contact lens care products by HPLC and a detection system to solve the problems in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a method for detecting the content of myristoyl propyl dimethylamine in contact lens care products by HPLC, comprising the following steps:

[0006] S1, preparing a mobile phase, which is mixed by 0.025 mol / L sodium dihydrogen phosphate solution and acetonitrile at a volume ratio of 65:35, wherein the 0.025 mol / L sodium dihydrogen phosphate solution is prepared by accurately weighing 3.9 g of sodium dihydrogen phosphate (NaH2PO4·2H2O), adding 1000 mL of water, dissolving, and adjusting the pH value of the solution to 3.80 using phosphoric acid, and then filtering through a 0.45 micron water-based membrane to obtain a clear mobile phase solution;

[0007] S2, preparing the contact lens care product to be detected as a test solution, and preparing a blank solution as a control to ensure that there is no external interference during the detection process;

[0008] S3, the detection is performed by high performance liquid chromatography (HPLC), an Agilent ZORBAX SB-CN chromatographic column is selected as a separation medium, and an ultraviolet detector is equipped as a detection means, chromatographic operation parameters are set, including a flow rate of 1.0 mL / min, an ultraviolet detection wavelength of 218 nm, a column temperature of 30 DEG C, and a total operation time of 15 minutes, and a sample injection amount is 50 μL each time;

[0009] S4, under the above set chromatographic conditions, the blank solution, the known concentration of the control sample solution and the test sample solution are sequentially subjected to high performance liquid chromatography analysis, and chromatograms of the solutions are recorded and obtained, wherein the reference retention time of myristoyl propyl dimethyl amine is about 11 minutes;

[0010] S5, based on the characteristic peak area of myristoyl propyl dimethyl amine in the chromatogram, the accurate content of myristoyl propyl dimethyl amine in the test sample solution is calculated through a standard curve (y=2.2377x-0.0841, R²=0.99996) established in advance.

[0011] Optionally, the preparation method of the known concentration of the control sample solution specifically comprises: accurately weighing 0.01 g of myristoyl propyl dimethyl amine with a known content, placing it in a 100 mL volumetric flask, adding a prepared mobile phase solution, fully dissolving and diluting to the calibration line, shaking, then accurately transferring 0.5 mL of the above solution into another 10 mL volumetric flask, adding the mobile phase again to dilute to the calibration line, and shaking for standby.

[0012] Optionally, the linear relationship of the method is verified, the linear equation is y=2.2377x-0.0841, and the correlation coefficient R² is as high as 0.99996, indicating that the method has good linear response in different concentration ranges.

[0013] Optionally, the accuracy, precision and repeatability of the method are verified by strict methodological verification, the recovery rate ranges from 93% to 101%, and meets the related requirements of the analysis method verification guidelines of the fourth part of Chinese Pharmacopoeia 9101.

[0014] A detection system using any one of the above detection methods, the system comprising a liquid chromatograph, an ultraviolet detector, an Agilent ZORBAX SB-CN chromatographic column or an equivalent chromatographic column, and various devices and reagents required for accurately preparing a mobile phase.

[0015] Optionally, the liquid chromatograph has a programmable control function, can automatically set and adjust the flow rate, column temperature, detection wavelength and other chromatographic parameters, and improves the detection efficiency and accuracy.

[0016] Optionally, data processing and analysis software is further included for automatically collecting chromatogram data, calculating peak area, and automatically calculating the content of myristoyl propyl dimethyl amine according to a standard curve, reducing human error, and improving the reliability of the analysis results.

[0017] Optionally, the method and system are not only suitable for contact lens care products, but also are extended to the quality detection of other cosmetic or daily chemical products containing myristoyl propyl dimethyl amine.

[0018] Beneficial effects: efficient separation: by optimizing the composition of the mobile phase and the chromatographic detection conditions, the present application can effectively separate the polar similar surfactants such as polyoxyethylene diamine and amine salt preservatives from the analyte - myristoyl propyl dimethyl amine, and the obtained chromatogram has a smooth baseline.

[0019] High accuracy: the method has been verified by methodology, and its linearity, repeatability and recovery rate meet the relevant expressions of the Analysis Method Verification Guiding Principle of Chinese Pharmacopoeia 4th Edition 9101, and the sensitivity reaches 0.8 μg / mL, which can accurately determine the content of myristoyl propyl dimethyl amine in contact lens care products.

[0020] Wide application: the method is not only suitable for the quality control of contact lens care products, but also can be extended to the quality detection of other cosmetic or daily chemical products containing myristoyl propyl dimethyl amine, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 : shows the chromatogram of the blank solution according to the present scheme.

[0022] Figure 2 : shows the chromatogram of the control solution according to the present scheme.

[0023] Figure 3 : shows the chromatogram of the contact lens care solution according to the present scheme.

[0024] Figure 4 : shows the chromatogram of the contact lens care solution with the control solution according to the present scheme.

[0025] Figure 5 : shows the chromatogram of the control solution according to the comparative example 1.

[0026] Figure 6 : shows the chromatogram of the contact lens care solution according to the comparative example 1.

[0027] Figure 7 : shows the chromatogram of the control solution according to the comparative example 2.

[0028] Figure 8: shows the chromatogram of the contact lens care solution according to Comparative Example 2.

[0029] Figure 9 : shows the chromatogram of the control solution according to Comparative Example 3.

[0030] Figure 10 : shows the chromatogram of the contact lens care solution according to Comparative Example 3.

[0031] Figure 11 : shows the chromatogram of the control solution according to Comparative Example 4.

[0032] Figure 12 : shows the chromatogram of the contact lens care solution according to Comparative Example 4.

[0033] Figure 13 : shows the chromatogram of the control solution according to Comparative Example 5.

[0034] Figure 14 : shows the chromatogram of the contact lens care solution according to Comparative Example 5. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present application are described below with reference to the accompanying drawings, so that the technical contents can be more clearly and conveniently understood. The present application can be embodied in many different forms, and the scope of protection of the present application is not limited to the embodiments described herein.

[0036] Example 1

[0037] The present application provides a method for detecting the content of myristamidopropyl dimethylamine (MPDMA) in contact lens care products using high performance liquid chromatography (HPLC). This method aims to solve the problem of accurately detecting the content of MPDMA in complex matrices in the prior art, especially in the complex system of contact lens care solution containing various surfactants, moisturizing lubricants and other polar substances. By optimizing the composition of the mobile phase, selecting the chromatographic column and the detection conditions, the present application successfully realizes the efficient separation and accurate detection of MPDMA, with the advantages of good repeatability and high recovery rate.

[0038] The present application is summarized as follows: the present application uses HPLC method, by accurately controlling the composition of the mobile phase, selecting suitable chromatographic column and optimizing the detection conditions, realizes the accurate determination of the content of MPDMA in contact lens care solution. The key of this method is the selection of mobile phase and the optimization of chromatographic conditions, to ensure that the characteristic peak of MPDMA can be effectively separated from other components, and at the same time obtain good peak shape and baseline stability.

[0039] Specific implementation steps

[0040] Instrument conditions

[0041] Liquid chromatograph: Agilent 1260 HPLC system or other equivalent HPLC system equipped with a UV detector (VWD).

[0042] Chromatographic column: Agilent ZORBAX SB-CN chromatographic column (150 mm × 4.6 mm, 5 μm) or other equivalent chromatographic column, which is suitable for analyzing polar compounds and has high sample loading capacity and good selectivity.

[0043] Other auxiliary equipment: including electronic balance, ultrasonic cleaner, pipette, volumetric flask, etc.

[0044] Reagent: Myristoyl propyl dimethyl amine standard: purity not less than 98%.

[0045] Mobile phase: 0.025 mol / L sodium dihydrogen phosphate solution and acetonitrile mixed at 65:35 (by volume). The sodium dihydrogen phosphate solution is prepared by weighing 3.9 g of sodium dihydrogen phosphate (NaH2PO4·2H2O) into 1000 mL of water, adjusting the pH to 3.80 with phosphoric acid, and filtering with a 0.45 μm water-based membrane before use. Acetonitrile must be HPLC grade.

[0046] Contact lens care product: commercially available or self-made, as the sample to be tested.

[0047] Other reagents: including purified water (meeting the relevant standards of Chinese Pharmacopoeia), methanol (HPLC grade, used for comparative test), etc.

[0048] The blank solution is the mobile phase and does not need to be prepared additionally.

[0049] Precisely weigh 0.01 g of MPMDA standard with known content into a 100 mL volumetric flask, dissolve and dilute to the mark with the mobile phase, shake well to obtain a stock solution with a concentration of 100 μg / mL.

[0050] Precisely take an appropriate amount of the above stock solution, dilute to the required concentration (such as 5 μg / mL) with the mobile phase, as the control solution.

[0051] Directly take an appropriate amount of contact lens care product as the test sample solution, and dilute it appropriately if necessary to meet the detection requirements.

[0052] Flow rate: 1.0 mL / min.

[0053] Column temperature: 30 ℃.

[0054] Detection wavelength: 218 nm (selected according to the UV absorption characteristics of MPDMA).

[0055] Injection volume: 50 μL.

[0056] Run time: 15 min (determined according to the retention time of MPDMA).

[0057] For contact lens care products, no complex pretreatment is usually required, and a suitable amount can be directly taken as the test sample solution for analysis. If the sample matrix is complex or the MPDMA content is low, appropriate dilution or purification treatment can be considered.

[0058] Chromatographic analysis: The blank solution, reference solution and test sample solution are sequentially injected into the HPLC system for analysis.

[0059] Record the chromatogram and observe the retention time, peak shape and separation degree of the MPDMA characteristic peak.

[0060] According to the chromatogram of the reference solution, the linear relationship between the peak area and the concentration of MPDMA is determined, and a standard curve is established.

[0061] According to the chromatogram of the test sample solution, the content of MPDMA is calculated.

[0062] To ensure the reliability of the detection method, a series of methodological verifications are required, including but not limited to the linear range, precision, accuracy, specificity and detection limit, etc.

[0063] Prepare a series of MPDMA reference solutions with different concentrations, analyze them by injection, and record the peak areas. With the concentration (C) as the abscissa and the peak area (A) as the ordinate, draw a standard curve and calculate the regression equation and correlation coefficient (R²). The linear range of this method generally covers the expected concentration range of MPDMA in the sample to be tested.

[0064] Select MPDMA reference solutions with low, medium and high concentrations, respectively, and continuously inject them 6 times each. Calculate the relative standard deviation (RSD) of the peak area to evaluate the intra-day precision. Repeat the above operation on different dates with the same batch of reference solutions to calculate the inter-day precision. This method should have good intra-day and inter-day precision.

[0065] Use the standard addition recovery test to evaluate the accuracy. Take a suitable amount of contact lens care product with known MPDMA content, add different amounts of MPDMA standard to it, and then process it according to the test sample solution preparation method before injection and analysis. Calculate the recovery rate and RSD value to evaluate the accuracy of the method. The recovery rate of this method should be within the specified range (usually 80%~120%), and the RSD value should be small.

[0066] The specificity of the method was evaluated by comparing the chromatograms of the blank solution, the reference solution and the sample solution. It should be ensured that the characteristic peak of MPDMA is completely separated from other component peaks, and no interfering peaks appear in the blank solution.

[0067] The detection limit (LOD) and the quantification limit (LOQ) of the method were determined by stepwise dilution of the reference solution to concentration points with signal-to-noise ratio (S / N) of about 3 and 10, respectively. The LOD and LOQ of the method should meet the actual detection requirements.

[0068] Under the optimized chromatographic conditions, the characteristic peak of MPDMA was effectively separated from other component peaks (see Figure 1 ). The retention time of MPDMA was stable, the peak shape was symmetrical and the baseline was smooth, indicating that the method had good separation degree and selectivity.

[0069] Linear range: The method showed good linear relationship in the concentration range of 0.1-10 μg / mL, the regression equation was y = 2.2377x - 0.0841, R² = 0.99996.

[0070] Precision: The intra-day and inter-day precision RSD values were both less than 2%, indicating good instrument precision.

[0071] Accuracy: The standard addition recovery rate was between 93% and 101%, and the RSD value was less than 5%, indicating high method accuracy.

[0072] Specificity: No interfering peaks appeared in the blank solution, and the characteristic peak of MPDMA was completely separated from other component peaks (see Figure 1 ).

[0073] Detection limit and quantification limit: The LOD was 0.02 μg / mL, and the LOQ was 0.08 μg / mL, meeting the actual detection requirements.

[0074] Five comparative examples are provided here: Comparative Example 1

[0075] Comparative Example 1 and Example 1 differ in that the mobile phase is methanol: acetonitrile: 0.01 mol / L aqueous potassium phosphate dibasic (pH = 4.00) = 20:60:20 (v / v / v), flow rate: 0.8 mL / min, injection volume: 80 μL, and other chromatographic conditions are the same as in Example 1. The test sample solution was tested under the chromatographic conditions of this comparative example, and the obtained high performance liquid chromatogram is shown in Figure 5 , Figure 6 .

[0076] By comparing Figure 5 , Figure 6 , it can be seen that the peak of myristoyl propyl dimethyl amine appears early, the baseline of the sample solution to be tested is too high, and the characteristic peak is difficult to separate.

[0077] Comparative Example 2

[0078] Comparative Example 2 differs from Example 1 in that the mobile phase is methanol: 0.025 mol / L aqueous sodium dihydrogen phosphate solution (pH = 3.80) = 60:40 (v / v) and other chromatographic conditions are the same as in Example 1. The high performance liquid chromatogram obtained by testing the sample solution to be tested under the chromatographic conditions of this comparative example is shown in Figure 7 , Figure 8 .

[0079] As can be seen from Figure 7 , Figure 8 , the myristoylpropyl dimethyl amine peaks early, the baseline of the sample solution to be tested is too high, and the characteristic peaks are difficult to separate.

[0080] Comparative Example 3

[0081] Comparative Example 3 differs from Example 1 in that the mobile phase is methanol: 0.025 mol / L aqueous sodium dihydrogen phosphate solution (pH = 3.80) = 0 min~10 min (45:55), 20 min (70:30), 30 min~37 min (85:15) (v / v) and other chromatographic conditions are the same as in Example 1. The high performance liquid chromatogram obtained by testing the sample solution to be tested under the chromatographic conditions of this comparative example is shown in Figure 9 , Figure 10 .

[0082] As can be seen from Figure 9 , Figure 10 , the myristoylpropyl dimethyl amine peaks in the gradient change and the peak shape is not good, and the peaks of the sample solution to be tested are flattened and cannot be accurately identified.

[0083] Comparative Example 4

[0084] Comparative Example 4 differs from Example 1 in that the mobile phase is methanol: 0.025 mol / L aqueous sodium dihydrogen phosphate solution (pH = 3.80) = 0 min (45:55), 10 min~20 min (60:40), 21 min~25 min (45:55) (v / v) and other chromatographic conditions are the same as in Example 1. The high performance liquid chromatogram obtained by testing the sample solution to be tested under the chromatographic conditions of this comparative example is shown in Figure 11 , Figure 12 .

[0085] As can be seen from Figure 11 , Figure 12 , the two chromatographic peaks are adjacent and the two peaks have not reached complete baseline separation and the separation degree is poor.

[0086] Comparative Example 5

[0087] The difference between Comparative Example 5 and Example 1 is that the mobile phase is acetonitrile:0.025 mol / L sodium dihydrogen phosphate aqueous solution (pH=3.80) = 0 min (45:55), 10 min~20 min (60:40), 21 min~25 min (45:55) (v / v). Other chromatographic conditions are the same as in Example 1. The test sample solution was tested under the chromatographic conditions of this comparative example, and the resulting high-performance liquid chromatogram is shown below. Figure 13 , Figure 14 As shown.

[0088] from Figure 13 , Figure 14 It can be seen that the two chromatographic peaks are close to each other and have not achieved complete baseline separation, resulting in poor resolution.

[0089] In summary, this method uses a mobile phase with an organic phase to buffer salt ratio of 35:65 and a buffer salt pH of 3.8. This method can effectively separate surfactants such as polyoxyethylenediamine and amine salt preservatives with similar polarities from the analyte, myristoylpropyl dimethylamine, and the resulting chromatogram has a stable baseline.

[0090] The HPLC method for detecting MPDMA content in corneal contact lens care products provided by this invention has advantages such as good separation effect, high accuracy, and good repeatability. By optimizing the mobile phase composition and chromatographic conditions, efficient separation and accurate detection of MPDMA in complex matrices have been successfully achieved. This method can be used for routine quality control of corneal contact lens care products, ensuring that the MPDMA content in the products meets the standard requirements and protecting consumer safety.

[0091] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0092] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for determining the content of myristoylpropyl dimethylamine in corneal contact lens care products by HPLC, characterized in that, Includes the following steps: S1. Prepare the mobile phase, which is a mixture of 0.025 mol / L sodium dihydrogen phosphate solution and acetonitrile at a volume ratio of 65:

35. The 0.025 mol / L sodium dihydrogen phosphate solution is prepared by accurately weighing 3.9 g of sodium dihydrogen phosphate, dissolving it in 1000 mL of water, adjusting the pH of the solution to 3.80 with phosphoric acid, and then filtering it through a 0.45 micrometer aqueous membrane to obtain a clear mobile phase solution. S2. Prepare the corneal contact lens care product to be tested as the test solution, and prepare a blank solution as a control to ensure that there is no external interference during the testing process; S3. High performance liquid chromatography (HPLC) was used for detection. An Agilent ZORBAX SB-CN column was selected as the separation medium, and an ultraviolet detector was used as the detection method. The chromatographic operating parameters were set as follows: flow rate of 1.0 mL / min, ultraviolet detection wavelength of 218 nm, column temperature of 30 ℃, total running time of 15 minutes, and injection volume of 50 μL per injection. S4. Under the chromatographic conditions set above, perform high performance liquid chromatography analysis on the blank solution, the control sample solution of known concentration and the test sample solution in sequence, record and obtain the chromatograms of each solution, wherein the reference retention time of myristoylpropyl dimethylamine is about 11 minutes. S5. Based on the characteristic peak area of ​​myristoylpropyl dimethylamine in the chromatogram, the accurate content of myristoylpropyl dimethylamine in the test sample solution is calculated using a pre-established standard curve.

2. The method according to claim 1, characterized in that, The method for preparing the control sample solution of known concentration specifically includes: accurately weighing 0.01 g of myristoylpropyl dimethylamine of known content, placing it in a 100 mL volumetric flask, adding the prepared mobile phase solution, fully dissolving and diluting to the mark, shaking well, then accurately transferring 0.5 mL of the above solution into another 10 mL volumetric flask, adding the mobile phase again to dilute to the mark, shaking well for later use.

3. The method according to claim 1 or 2, characterized in that, The linearity of the method has been verified, with the linear equation being y = 2.2377x - 0.0841 and a correlation coefficient R² as high as 0.99996, indicating that the method has a good linear response in different concentration ranges.

4. The method according to any one of claims 1 or 2, characterized in that, The accuracy, precision, and repeatability of the method have all been rigorously validated, and its recovery rate ranges from 93% to 101%, which meets the relevant requirements of the 9101 analytical method validation guidelines in Part IV of the Chinese Pharmacopoeia.

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