A method for analyzing 8 surfactants in hair and skin cleansing cosmetic

Abstract

The application relates to an analysis method of eight surfactants in hair and skin cleaning cosmetics, which comprises the following steps: S1, pretreatment of a to-be-detected sample; S2, pretreatment of mixed standard samples of the eight surfactants; S3, setting of spectrum measurement working conditions; and S4, instrument analysis and detection by high performance liquid chromatography-mass spectrometry. The analysis method of the eight surfactants in the hair and skin cleaning cosmetics can effectively qualitatively and quantitatively analyze the content of the eight surfactants in the hair and skin cleaning cosmetics, the quantitative line and the detection limit are relatively low, the method is simple and easy to implement, and the detection efficiency and accuracy are relatively high.

Description

Technical Field

[0001] This invention relates to the field of cosmetic testing technology, and more specifically to an analytical method for eight surfactants in hair care and cleansing cosmetics. Background Technology

[0002] Surfactants are essential components in cosmetics, possessing a range of functions including dispersion, detergency, solubilization, and penetration. Based on their dissociation in aqueous solutions and the type of charge they carry after dissociation, surfactants are classified into anionic, cationic, amphoteric, and nonionic surfactants. While small amounts of surfactants generally do not irritate the skin, most types of surfactants exhibit some degree of toxicity. Cosmetic formulations are diverse and complex, including not only oils and water but also various functional surfactants, preservatives, fragrances, and pigments, forming a multiphase dispersion system. With the increasing variety of cosmetic dosage forms and functional requirements, the types of surfactants used in cosmetics are also increasing. Complex surfactants, composed of multiple surfactants, have become an inevitable choice. Therefore, the accurate determination of multiple surfactants in cosmetics is crucial, providing an important guarantee for cosmetic safety.

[0003] Existing patent CN104502465B discloses a gel filtration chromatography method for analyzing alkyl glycoside surfactant components. This method primarily uses gel filtration chromatography to determine alkyl glycoside surfactants. However, cosmetics contain a wide variety of surfactants, and in practical applications, this can lead to reduced testing accuracy. Furthermore, this method cannot determine different types of surfactants, thus reducing testing efficiency.

[0004] Therefore, it is very important to develop an analytical method for eight surfactants in hair and cleansing cosmetics. Summary of the Invention

[0005] To address the problems in the prior art, the first aspect of this invention provides an analytical method for eight surfactants in hair care and cleansing cosmetics, comprising the following steps: S1: sample pretreatment; S2: pretreatment of a mixed standard of eight surfactants; S3: setting of spectroscopic working conditions; S4: instrumental analysis and detection by high performance liquid chromatography-mass spectrometry.

[0006] As a preferred technical solution, the method for analyzing eight surfactants in hair care and cleansing cosmetics includes the following eight surfactants: sodium lauryl polyoxyethylene ether sulfate, sodium dodecyl sulfate, sodium α-olefin sulfonate, alkyl glycoside, cocamidopropyl betaine, cocoyl glutamate triethanolamine salt, cocoyl glycinate potassium, and sodium lauroyl sarcosinate.

[0007] As a preferred technical solution, the sample pretreatment step includes: weighing the sample, adding methanol and mixing thoroughly, filtering with an organic phase filter membrane with a pore size of 0.1 to 0.3 μm, adding a diluent to the filtrate for dilution, and shaking well to obtain the sample.

[0008] As a preferred technical solution, the pretreatment steps of the mixed standard of the eight surfactants include: preparing standard solutions of the eight surfactants; mixing the eight surfactant standard solutions to make the concentration of each substance 100 mg / L, and using this as the stock solution to dilute with a diluent in a ratio of 1:5:10:20:50:100 to prepare six standard solutions, thus obtaining a mixed standard solution.

[0009] As a preferred technical solution, the diluting solvent is an acetonitrile:water solution with a volume ratio of (2-4):(1-3).

[0010] As a preferred technical solution, the diluting solvent is an acetonitrile:water solution with a volume ratio of 3:2.

[0011] As a preferred technical solution, the spectral measurement working conditions settings include chromatographic conditions settings and mass spectrometry conditions settings.

[0012] As a preferred technical solution, the chromatographic conditions include: using porous silica gel as the packing material; using acetonitrile as mobile phase A and 3-6 mmol / L organic acid salt aqueous solution as mobile phase B for gradient elution; the flow rate is 0.2-0.6 mL per minute, and the column temperature is 25-50℃.

[0013] As a preferred technical solution, the organic acid salt includes at least one of ammonium formate, ammonium acetate, sodium phosphate, and potassium phosphate.

[0014] As a preferred technical solution, the organic acid salt is an ammonium acetate salt.

[0015] Because it was necessary to monitor the elution of eight surfactants in both positive and negative ion modes simultaneously, the applicant discovered through extensive experiments that using a 3–6 mmol / L ammonium acetate aqueous solution as the mobile phase could avoid peak instability caused by different addition mechanisms of compounds in the positive ion mode. The main reason is that ammonium acetate, as a low-concentration ammonium salt, can also act as a buffer ion, preventing the interaction between the silica surface in certain chromatographic columns and the compounds, ultimately improving peak stability.

[0016] As a preferred technical solution, the chromatographic conditions include: using porous silica gel as the packing material; using acetonitrile as mobile phase A and 5 mmol / L ammonium acetate aqueous solution as mobile phase B for gradient elution; the flow rate is 0.4 mL per minute, and the column temperature is 35℃.

[0017] As a preferred technical solution, the gradient elution method includes: from 0 to 3 min, the volume ratio of mobile phase A to mobile phase B is 15 to 25: 75 to 85; from 3 to 8.5 min, the volume ratio of mobile phase A to mobile phase B is 90 to 100: 0 to 10; from 8.5 to 15 min, the volume ratio of mobile phase A to mobile phase B is 15 to 25: 75 to 85.

[0018] As a preferred technical solution, the gradient elution method includes: from 0 to 3 min, the volume ratio of mobile phase A to mobile phase B is 20:80; from 3 to 8.5 min, the volume ratio of mobile phase A to mobile phase B is 95:5; from 8.5 to 15 min, the volume ratio of mobile phase A to mobile phase B is 20:80.

[0019] As a preferred embodiment, the mass spectrometry conditions include: an ESI ion source; an MRM scanning ion mode; and a capillary voltage of 2500–3500 V for positive ions and 2000–3000 V for negative ions.

[0020] As a preferred embodiment, the mass spectrometry conditions include: an ESI ion source; an MRM scanning ion mode; and a capillary voltage of 3000V for positive ions and 2500V for negative ions.

[0021] Another aspect of the present invention provides an application of an analytical method for eight surfactants in hair care and cleansing cosmetics. This method is applied in the analytical methods for hair care and cleansing cosmetics.

[0022] Beneficial effects

[0023] 1. The present invention provides an analytical method for eight surfactants in hair care and cleansing cosmetics, which can effectively analyze the content of eight surfactants in cosmetics qualitatively and quantitatively, and has low quantitative limits and detection limits.

[0024] 2. The present invention provides an analytical method for eight surfactants in hair care and cleansing cosmetics. By using a 3-6 mmol / L ammonium acetate aqueous solution as the mobile phase, the peak instability caused by different addition modes of compounds in positive ion mode can be avoided, thereby improving the detection accuracy.

[0025] 3. The present invention provides an analytical method for eight surfactants in hair care and cleansing cosmetics. By optimizing various parameters of the LCMS instrument, the eight surfactants do not interfere with each other during the detection process, thus ensuring the accuracy of the detection results. The method is simple and easy to implement, and has high detection efficiency and accuracy. Attached Figure Description

[0026] Figure 1Comparison of sodium lauryl ether sulfate solvent peak and 1 mg / L standard using liquid chromatography-mass spectrometry (LC-MS) spectroscopy.

[0027] Figure 2 Comparison of sodium dodecyl sulfate solvent peak and 0.5 mg / L standard LC-MS chromatogram

[0028] Figure 3 Comparison of sodium α-olefin sulfonate solvent peak and 2 mg / L standard LC-MS spectrum

[0029] Figure 4 Comparison of alkyl glycoside solvent peak and 5 mg / L standard LC-MS spectrum

[0030] Figure 5 Comparison of cocamidopropyl betaine solvent peak and 2 mg / L standard LC-MS spectrum

[0031] Figure 6 Comparison of the solvent peak of cocoyl glutamate triethanolamine salt and the LC-MS spectrum of 1 mg / L standard

[0032] Figure 7 Comparison of the solvent peak of potassium cocoyl glycinate and the LC-MS spectrum of 5 mg / L standard

[0033] Figure 8 Comparison of sodium lauroyl sarcosinate solvent peak and 1 mg / L standard using liquid chromatography-mass spectrometry (LC-MS) spectroscopy.

[0034] Figure 9 The instrument detection limits were measured using liquid chromatography-mass spectrometry (LC-MS) spectra at concentrations of 0.1 mg / L (K12, LS-30), 0.5 mg / L (CAB, cocoyl glutamate triethanolamine salt, AES, cocoyl glycinate potassium, AOS), and 1.0 mg / L (APG). Detailed Implementation

[0035] Unless otherwise specified, the experimental methods described in the following embodiments of the present invention are generally performed under conventional conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the embodiments are commercially available products.

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Example 1 provides a method for analyzing eight surfactants in hair care and cleansing cosmetics, comprising the following steps:

[0039] S1: Sample pretreatment;

[0040] S11: Weigh 0.5g of sample and place it in a 100mL volumetric flask. Dilute to the mark with methanol, shake well, and let stand.

[0041] S12: Accurately pipette 1 mL of sample solution using an airtight syringe, remove the needle, replace it with a 0.22 μm organic phase filter membrane, and filter the solution into an automated sample vial. Accurately pipette 0.1 mL of sample solution into another automated sample vial, and accurately add 0.9 mL of an acetonitrile:water solution with a volume ratio of 3:2. At this point, the sample solution is diluted 10 times. Seal the vial tightly, affix a label, and wait for testing.

[0042] S2: Pretreatment of a mixed standard of 8 surfactants;

[0043] S21: Weigh 0.1 g (accurate to 0.0001 g) each of the eight surfactant standards sodium lauryl polyoxyethylene ether sulfate, sodium dodecyl sulfate, sodium α-olefin sulfonate, alkyl glycoside, cocamidopropyl betaine, cocoyl glutamate triethanolamine salt, cocoyl glycinate potassium and lauroyl sarcosinate into 100 mL volumetric flasks, dilute to the mark with methanol, and prepare 1000 mg / L standard stock solutions respectively. Store at 4–8 °C.

[0044] S22: Accurately pipette 0.1 mL of each 1000 mg / L standard stock solution and dilute to 1 mL with methanol. At this point, the concentration of each surfactant is 100 mg / L. Using this as the stock solution, dilute with a diluent in a ratio of 1:5:10:20:50:100 to prepare six standard solutions, resulting in mixed standard solutions. Prepare and use immediately. The diluent is an acetonitrile:water solution with a volume ratio of 3:2.

[0045] S3: Spectrum measurement working conditions settings;

[0046] Table 1. Operating conditions for liquid chromatography-mass spectrometry

[0047]

[0048] Table 2 Instrument Elution Procedure

[0049]

[0050] Table 3 Mass Spectrometry Method Settings

[0051]

[0052]

[0053] S4: High performance liquid chromatography-mass spectrometry instrumental analysis and detection.

[0054] Accurately pipette 1 mL each of the standard solution and the sample solution, add 0.3 mL of water, mix well, filter, and collect the filtrate; accurately pipette 1–3 μL each of the filtrate of the matrix mixed control solution and the sample solution, inject them into the liquid chromatography-tandem mass spectrometry instrument, and calculate according to the external standard curve method to obtain the result.

[0055] The second aspect of the embodiment provides an analytical method for eight surfactants in hair care and cleansing cosmetics, which is applied in the analytical methods of hair care and cleansing cosmetics.

[0056] Performance testing

[0057] 1. Selectivity

[0058] The solvent peaks of the eight surfactants and the peaks of the standard were compared separately using liquid chromatography-mass spectra. The results are as follows: Figures 1-8 As can be seen from the figure, the solvent peaks of the eight surfactants show some elution, but the responses are all below the detection limit, indicating good method selectivity.

[0059] 2. Linear

[0060] Plot a standard curve with the concentration of the mixed standard solution on the x-axis and the peak area on the y-axis. Calculate and report the fitted equation, range, and correlation coefficient. The data results are shown in Table 1.

[0061] Table 1 Standard Curve and Range

[0062]

[0063]

[0064] Conclusion: The correlation coefficients of the standard curves for all eight surfactants satisfy R0. 2 A value >0.998 indicates a good fit to the standard curve.

[0065] 3. Limit of detection and limit of quantitation

[0066] The concentration of samples with a signal-to-noise ratio of 5 times was defined as the instrument detection limit, and the concentration of samples with a signal-to-noise ratio of 3 times was defined as the quantitation limit, as detailed in Table 2. The LC-MS chromatograms for the instrument detection limits of 0.1 mg / L (K12, LS-30), 0.5 mg / L (CAB, cocoyl glutamate triethanolamine salt, AES, cocoyl glycinate potassium, AOS), and 1.0 mg / L (APG) are shown in Table 2. Figure 9 .

[0067] Table 2 Limit of Detection and Limit of Quantification

[0068]

[0069]

[0070] Note: MDL = IDL × final volume × dilution factor / sample size; MQL = IQL × final volume × dilution factor / sample size.

[0071] Conclusion: The limits of quantitation for the eight surfactants were no greater than the low point of linearity.

[0072] 4. Recovery rate

[0073] Three parallel samples were prepared and tested sequentially. The recovery rate in this method is the ratio of the measured value to the true value of the sample, and the results are shown in Table 3.

[0074] Table 3 Results of the recovery rate test

[0075]

[0076] Conclusion: Sodium dodecyl sulfate was quantified by the difference method, which was affected by many factors, resulting in poor stability of the results. The recovery rates of the other seven surfactants were all between 80% and 120%.

[0077] 5. Repeatability

[0078] The three parallel test solutions were sequentially introduced into a liquid chromatography-mass spectrometry instrument for determination, and the peak areas of each substance were recorded. The specific results are shown in Table 4.

[0079] Table 4 Results of Repeatability Tests

[0080]

[0081] Conclusion: Sodium dodecyl sulfate is quantified by the difference method, which is affected by many factors, resulting in poor stability of the results. The RSD of the results for the other 7 surfactants is less than 10%.

Claims

1. A method for analyzing eight surfactants in hair and skin cleansing cosmetic products, characterized by, It comprises the following steps: S1: pretreatment of the sample to be tested; S2: pretreatment of 8 surfactant mixed standard samples; S3: setting of the spectrum working condition; S4: high performance liquid chromatography-mass spectrometry instrument analysis and detection; The 8 surfactants include sodium laureth sulfate, sodium dodecyl sulfate, sodium alpha-olefin sulfonate, alkyl polyglycoside, cocamidopropyl betaine, cocoyl glutamate triethanolamine salt, potassium cocoyl glycinate and sodium lauroyl methyl amino acid; The sample pretreatment step comprises the following steps: weighing the sample, adding methanol and mixing uniformly, filtering with an organic phase filter membrane with a pore size of 0.1-0.3 μm, adding a dilution solvent to the filtrate for dilution, and shaking uniformly to obtain the sample to be tested. The spectrum working condition setting comprises chromatographic condition setting and mass spectrometric condition setting. The chromatographic condition comprises the following steps: using porous silica gel as the filler, using acetonitrile as the mobile phase A and 3-6 mmol / L ammonium acetate aqueous solution as the mobile phase B for gradient elution, the flow rate is 0.2-0.6 mL / min, and the column temperature is 25-50℃. The gradient elution mode comprises the following steps: from 0 to 3 min, the volume ratio of the mobile phase A to the mobile phase B is 15-25:75-85; from 3 to 8.5 min, the volume ratio of the mobile phase A to the mobile phase B is 90-100:0-10; from 8.5 to 15 min, the volume ratio of the mobile phase A to the mobile phase B is 15-25:75-85.

2. The method for analyzing eight surfactants in a hair and skin cleansing cosmetic according to claim 1, characterized by, The 8 surfactant mixed standard sample pretreatment step comprises the following steps: preparing the standard solution of the 8 surfactants, mixing the 8 surfactant standard solutions to make the concentration of each substance 100 mg / L, and diluting the standard solution with the dilution solvent according to the dilution ratio 1:5:10:20:50:100 to prepare 6 standard solutions, thereby obtaining the mixed standard solution.

3. The method for analyzing eight surfactants in a hair and skin cleansing cosmetic according to claim 1 or 2, characterized by, The dilution solvent is acetonitrile:water solution with a volume ratio of (2-4):(1-3).

4. Use of the method for analyzing eight surfactants in a hair and skin cleansing cosmetic product according to any one of claims 1 to 3, characterized in that, The method is applied in the analysis method of hair care and skin care cosmetics.

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