Method for analyzing eight surfactants in hair and skin cleaning cosmetics

Abstract

The invention relates to a method for analyzing eight surfactants in hair and skin cleaning cosmetics. The method comprises the following steps: S1, pretreating a sample to be detected; s2, pretreatment of a mixed standard product of eight surfactants; s3, spectrum measurement working conditions are set; s4, analyzing and detecting by a high performance liquid chromatography-mass spectrometry instrument. According to the analysis method for the eight surfactants in the hair and skin cleaning cosmetics, the content of the eight surfactants in the hair and skin cleaning cosmetics can be effectively, qualitatively and quantitatively analyzed, the quantification line and the detection limit are low, and the method is simple, easy to implement and high in detection efficiency and accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of cosmetics detection, and more specifically to an analysis method for 8 surfactants in hair and skin cleansing cosmetics. Background Art

[0002] Surfactants are important ingredients in cosmetics, and have a series of functions such as dispersion, decontamination, solubilization and penetration. Surfactants can be divided into anionic, cationic, zwitterionic and nonionic surfactants according to whether they can dissociate in aqueous solution and the type of charge they carry after dissociation. Usually, a small amount of surfactants will not irritate the skin, but most types of surfactants are more or less toxic to a certain extent. Since the composition of cosmetic formulas is diverse and complex, in addition to oil and water raw materials, there are also various functional surfactants, preservatives, flavors and pigments, etc., which belong to multiphase dispersion systems. With the increasing number of cosmetic dosage forms and functional requirements, the variety of surfactants used in cosmetics is also increasing. Composite surfactants composed of multiple surfactants have become an inevitable choice. Therefore, the correct determination of multiple surfactants in cosmetics is very important, which also provides an important guarantee for the safety of cosmetics.

[0003] The existing patent CN104502465B discloses a gel filtration chromatography analysis method for the components of alkyl glycoside surfactant products. The alkyl glycoside surfactant is mainly determined by gel filtration chromatography, but there are many types of surfactants in cosmetics, which will reduce the test accuracy during actual application. This method cannot measure different types of surfactants, reducing the determination efficiency.

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

[0005] In order to solve the problems in the prior art, the first aspect of the present invention provides an analysis method for 8 surfactants in hair and skin cleansing cosmetics, comprising the following steps: S1: pretreatment of the sample to be tested; S2: pretreatment of a mixed standard of 8 surfactants; S3: setting of spectrum measurement working conditions; S4: high performance liquid chromatography-mass spectrometry instrument analysis and detection.

[0006] As a preferred technical solution, the present invention provides a method for analyzing 8 surfactants in hair and skin cleansing cosmetics, wherein the 8 surfactants include sodium lauryl polyoxyethylene ether sulfate, sodium dodecyl sulfate, sodium α-olefin sulfonate, alkyl glucoside, cocamidopropyl betaine, triethanolamine cocoyl glutamate, potassium cocoyl glycinate and sodium lauroyl sarcosinate.

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

[0008] As a preferred technical solution, the pretreatment step of the 8 surfactant mixed standard products includes: preparing 8 surfactant standard solutions; mixing the 8 surfactant standard solutions so that the concentration of each substance is 100 mg / L, using this as the mother liquor and diluting it with a dilution solvent in multiples of 1:5:10:20:50:100 to prepare 6 standard solutions to obtain a mixed standard solution.

[0009] As a preferred technical solution, the dilution solvent is acetonitrile: aqueous solution in a volume ratio of (2-4):(1-3).

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

[0011] As a preferred technical solution, the spectrum measurement working condition setting includes chromatographic condition setting and mass spectrometry condition setting.

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

[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 ammonium acetate.

[0015] Since it is necessary to pay attention to the peaks of 8 surfactants in positive and negative ion modes at the same time, the applicant found through a large number of experiments that selecting 3-6 mmol / L ammonium acetate aqueous solution as the mobile phase can avoid the unstable peaks caused by different addition modes of compounds in positive ion mode. The main reason is that ammonium acetate, as a low-concentration ammonium salt, can also be used as a buffer ion to avoid the interaction between the silica surface and the compound in some chromatographic columns, and ultimately improve the stability of the peaks.

[0016] As a preferred technical solution, the chromatographic conditions include: using porous silica gel as filler; 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°C.

[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 solution, the mass spectrometry conditions include: the ion source is ESI; the scanning ion mode is MRM; the capillary voltage is 2500-3500V for positive ions and 2000-3000V for negative ions.

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

[0021] Another aspect of the present invention provides an application of a method for analyzing eight surfactants in hair and skin cleansing cosmetics, wherein the method is applied in the analysis method of hair and skin cleansing cosmetics.

[0022] Beneficial Effects

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

[0024] 2. The present invention provides an analytical method for 8 surfactants in hair and skin cleansing cosmetics. By using a 3-6 mmol / L ammonium acetate aqueous solution as the mobile phase, the unstable peaks caused by different addition modes of the compounds in the positive ion mode can be avoided, thereby improving the detection accuracy.

[0025] 3. The present invention provides an analysis method for 8 surfactants in hair and skin cleansing cosmetics. By optimizing various parameters of the LCMS instrument, the 8 surfactants do not interfere with each other during the detection process, thereby ensuring the accuracy of the detection results. The method is simple and easy to implement, and has high detection efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1Comparison of LC-MS spectra of sodium lauryl polyoxyethylene ether sulfate solvent peak and 1 mg / L standard

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

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

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

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

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

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

[0033] Figure 8 Comparison of LC-MS spectra of sodium lauroyl sarcosinate solvent peak and 1 mg / L standard

[0034] Fig. 9 LC-MS spectra of instrument detection limits of 0.1 mg / L (K12, LS-30), 0.5 mg / L (CAB, triethanolamine cocoyl glutamate, AES, potassium cocoyl glycinate, AOS) and 1.0 mg / L (APG) DETAILED DESCRIPTION

[0035] The experimental methods in the following examples of the present invention, where no specific conditions are specified, are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0036] 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] Embodiment 1 A first aspect provides a method for analyzing 8 surfactants in hair and skin cleansing cosmetics, comprising the following steps:

[0039] S1: Pretreatment of samples to be tested;

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

[0041] S12: Use a gas-tight syringe to accurately draw 1 mL of sample solution, remove the needle, replace it with a 0.22 μm organic phase filter membrane, and filter the solution into an automatic sample bottle. Use a pipette to accurately transfer 0.1 mL of sample solution to another automatic injection bottle, and accurately add 0.9 mL of acetonitrile:water solution with a volume ratio of 3:2. At this time, the sample solution is diluted 10 times, seal the lid tightly, attach a label, and wait for testing.

[0042] S2: pretreatment of 8 surfactant mixed standard products;

[0043] S21: Weigh 0.1 g (accurate to 0.0001 g) of each of 8 surfactant standards, including sodium lauryl polyoxyethylene ether sulfate, sodium dodecyl sulfate, sodium α-olefin sulfonate, alkyl glucoside, cocamidopropyl betaine, triethanolamine cocoyl glutamate, potassium cocoyl glycinate and sodium lauroyl sarcosinate, into a 100 mL volumetric flask, dilute to volume with methanol, prepare 1000 mg / L standard stock solutions, and store at 4-8°C;

[0044] S22: Use a pipette to accurately transfer 0.1 mL of the 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. Use this as the mother solution, and then dilute with dilution solvent in multiples of 1:5:10:20:50:100 to prepare 6 standard solutions to obtain a mixed standard solution, which is prepared and used immediately. The dilution solvent is acetonitrile:water solution with a volume ratio of 3:2.

[0045] S3: Setting of spectrum measurement working conditions;

[0046] Table 1 Liquid chromatography-mass spectrometry working conditions

[0047]

[0048] Table 2 Instrument elution program

[0049]

[0050] Table 3 Mass spectrometry method settings

[0051]

[0052]

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

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

[0055] The second aspect of the embodiment provides an analysis method for 8 surfactants in hair and skin cleansing cosmetics, which is used in the analysis method of hair and skin cleansing cosmetics.

[0056] Performance Testing

[0057] 1. Selectivity

[0058] Compare the 8 surfactant solvent peaks and standard LC-MS spectra, the results are as follows: Figures 1 to 8 As can be seen from the figure, the solvent peaks of the eight surfactants have certain peaks, but the responses are all below the detection limit, and the method has good selectivity.

[0059] 2. Linear

[0060] Draw a standard curve with the concentration of the mixed standard solution as the horizontal axis and the peak area as the vertical axis. Calculate and report the fitting 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 of the eight surfactants all meet the R 2 >0.998, indicating that the standard curve has a good fit.

[0065] 3. Method detection limit and quantification limit

[0066] The concentration of the sample with 5 times the signal-to-noise ratio was defined as the instrument detection limit, and 3 times the instrument detection limit was defined as the quantification limit, as shown in Table 2. The concentrations were 0.1 mg / L (K12, LS-30), 0.5 mg / L (CAB, triethanolamine cocoyl glutamate, AES, potassium cocoyl glycinate, AOS) and 1.0 mg / L (APG) instrument detection limit LC-MS spectra are shown in Fig. 9 .

[0067] Table 2 Detection limit and quantification limit

[0068]

[0069]

[0070] Note: MDL = IDL × fixed volume × dilution factor / sampling volume; MQL = IQL × fixed volume × dilution factor / sampling volume.

[0071] Conclusion: The quantification limits of the eight surfactants were no greater than the linear low point.

[0072] 4. Recovery rate

[0073] The sample was prepared in parallel for 3 times and tested in turn. The recovery rate in this method is the ratio of the sample measured value to the true value, and the results are shown in Table 3.

[0074] Table 3 Recovery test results

[0075]

[0076] Conclusion: Sodium dodecyl sulfate was quantitatively determined by subtraction method, which had many influencing factors and poor stability of the result deviation. The recoveries of the other seven surfactants were all between 80% and 120%.

[0077] 5. Repeatability

[0078] The three test sample solutions prepared in parallel were introduced into the liquid chromatography-mass spectrometer for determination, and the peak area of ​​each substance was recorded. The specific results are shown in Table 4.

[0079] Table 4 Repeatability test results

[0080]

[0081] Conclusion: Sodium dodecyl sulfate was quantitatively determined by subtraction method, which had many influencing factors and poor stability of the result deviation. The RSD of the results of the other 7 surfactants were all less than 10%.

Claims

1. A method for analyzing 8 surfactants in hair and skin cleansing cosmetics, characterized in that: The following steps are involved: S1: Pretreatment of samples to be tested; S2: pretreatment of 8 surfactant mixed standard products; S3: Setting of spectrum measurement working conditions; S4: High performance liquid chromatography-mass spectrometry instrument analysis and detection.

2. The method for analyzing eight surfactants in hair and skin cleansing cosmetics according to claim 1, characterized in that: The eight surfactants include sodium lauryl polyoxyethylene ether sulfate, sodium dodecyl sulfate, sodium α-olefin sulfonate, alkyl glucoside, cocamidopropyl betaine, triethanolamine cocoyl glutamate, potassium cocoyl glycinate and sodium lauroyl sarcosinate.

3. The method for analyzing eight surfactants in hair and skin cleansing cosmetics according to claim 1, characterized in that: The sample pretreatment step includes: weighing the sample, adding methanol to mix well, filtering with an organic phase filter membrane with a pore size of 0.1 to 0.3 μm, adding a diluent solvent to the filtrate to dilute it, and shaking it well to obtain the sample.

4. The method for analyzing eight surfactants in hair and skin cleansing cosmetics according to claim 1, characterized in that: The pretreatment steps of the 8 surfactant mixed standard products include: preparing 8 surfactant standard solutions; mixing the 8 surfactant standard solutions to make the concentration of each substance 100 mg / L, using the 8 surfactant standard solutions as the mother liquor to dilute and prepare 6 standard solutions with a dilution solvent in multiples of 1:5:10:20:50:100 to obtain a mixed standard solution.

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

6. The method for analyzing eight surfactants in hair and skin cleansing cosmetics according to claim 1, characterized in that: The spectrum measurement working condition setting includes chromatographic condition setting and mass spectrometry condition setting.

7. The method for analyzing eight surfactants in hair and skin cleansing cosmetics according to claim 6, characterized in that: The chromatographic conditions include: using porous silica gel as filler; 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° C.

8. The method for analyzing eight surfactants in hair and skin cleansing cosmetics according to claim 7, characterized in that: The organic acid salt includes at least one of ammonium formate, ammonium acetate, sodium phosphate and potassium phosphate.

9. The method for analyzing eight surfactants in hair and skin cleansing cosmetics according to claim 7, characterized in that: The gradient elution method includes: from 0 to 3 minutes, the volume ratio of mobile phase A to mobile phase B is 15-25:75-85; from 3 to 8.5 minutes, the volume ratio of mobile phase A to mobile phase B is 90-100:0-10; from 8.5 to 15 minutes, the volume ratio of mobile phase A to mobile phase B is 15-25:75-85.

10. Use of the method for analyzing eight surfactants in hair and skin cleansing cosmetics according to claims 1 to 9, characterized in that: This method is used in the analysis of hair and skin cleansing cosmetics.

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