Method for analyzing antioxidants in cosmetics

Abstract

The invention relates to a method for analyzing an antioxidant in cosmetics, the antioxidant is VE acetate, and the method comprises the following steps: (1) preparing a standard solution; (2) preparing a sample solution; (3) detecting by using a liquid chromatography-mass spectrometry method; and (4) result analysis: establishing a standard curve and verifying the method. The method for analyzing the antioxidants in the cosmetics, established by the invention, is good in separation degree and strong in specificity, and can be used for quickly and accurately realizing the analysis and determination of VE acetate.

Description

Technical Field

[0001] The present invention relates to the technical field of cosmetic ingredient detection, and more specifically to an analysis method for antioxidants in cosmetics. Background Art

[0002] Most of the cosmetics currently on the market contain antioxidants with biological effects. Reasonable use of the different functions of antioxidants and long-term use can effectively slow down the aging of the skin and achieve the effects of anti-aging (anti-glycation), whitening and freckle removal, skin repair, anti-allergy and anti-inflammatory. Antioxidants have become an indispensable additive in cosmetic formulas. They can not only effectively delay the oxidation of products, but also enhance consumers' natural antioxidant defense system. VE acetate, also known as tocopherol acetate or vitamin E acetate, is an important compound that can directly provide hydrogen atoms to superoxide radicals, combine with free radicals in the body, reduce oxidative damage caused by superoxide radicals, prevent cells from being oxidized, and thus help resist aging. Because of its good antioxidant, moisturizing and skin conditioning functions, it is widely used in cosmetics. Although the use of VE acetate in cosmetics and skin care products is considered safe, long-term contact or excessive use may cause certain irritation to the skin.

[0003] The existing patent CN112684046 A discloses a method for determining the composition of oils in cosmetics. The gas chromatography / mass spectrometry detection method is mainly used to detect 12 kinds of oils including VE acetate, but different oils will affect each other, the detection time is long, and the test accuracy is reduced.

[0004] Therefore, it is very important to develop an analytical method for antioxidants in cosmetics. Summary of the invention

[0005] In order to solve the problems in the prior art, the present invention provides an analysis method for antioxidants in cosmetics, wherein the antioxidant is VE acetate, comprising the following steps:

[0006] (1) Preparation of standard solution: weigh the standard of VE acetate antioxidant, dilute to volume with organic solvent, prepare 7 kinds of VE acetate standard working solutions, and store at 4-8°C for future use;

[0007] (2) preparing a sample solution: weighing a cosmetic sample, adding chloroform, shaking well, adding a small molecule polyol, extracting by vortex oscillation, standing to obtain a supernatant, filtering the supernatant through an organic phase filter membrane, adding a diluent to the filtrate to dilute it to obtain a sample solution for later use;

[0008] (3) Liquid chromatography-mass spectrometry detection: The standard working solution and the sample solution are eluted using a liquid chromatography-mass spectrometer to obtain chromatograms of the standard solution and the sample solution for analysis and detection;

[0009] (4) Result analysis: Establish standard curve and verify the method.

[0010] As a preferred technical solution, the organic solvent includes: one or more of acetonitrile, methanol or ethanol.

[0011] As a preferred technical solution, the organic is methanol.

[0012] As a preferred technical solution, the concentrations of the seven VE acetate standard working solutions are 0.1 mg / L, 0.5 mg / L, 1 mg / L, 2 mg / L, 5 mg / L, 10 mg / L, and 20 mg / L, respectively.

[0013] As a preferred technical solution, the small molecule polyol includes one or more of methanol, ethanol, and isopropanol.

[0014] As a preferred technical solution, the small molecule polyol is methanol.

[0015] As a preferred technical solution, the organic phase filter membrane is an organic filter membrane with a pore size of 0.22 μm.

[0016] As a preferred technical solution, the diluent is one or more of methanol, chloroform, and acetonitrile.

[0017] As a preferred technical solution, the diluent is methanol.

[0018] As a preferred technical solution, the chromatographic conditions of the liquid chromatography include: chromatographic column: ACQUITY UPLCBEH C18, specifications are 1.7μm×2.1mm×50mm; mobile phase A is methanol, mobile phase B is 0.1-0.3% formic acid aqueous solution; column temperature is 35-45°C; injection volume is 2-5μL; flow rate: 0.3-0.5mL / min.

[0019] As a preferred technical solution, the chromatographic conditions of the liquid chromatography include: chromatographic column: ACQUITY UPLCBEH C18 (1.7μm×2.1mm×50mm); mobile phase A is methanol, and mobile phase B is 0.1% formic acid aqueous solution; column temperature is 35°C; injection volume is 2μL; flow rate: 0.3mL / min.

[0020] As a preferred technical solution, the volume ratio of the mobile phase A to the mobile phase B is (97-98): (2-3).

[0021] As a preferred technical solution, the volume ratio of the mobile phase A to the mobile phase B is 98:2.

[0022] VE acetate has a small molecular weight and a long chain structure, and is strongly retained on the stationary phase. The applicant has found through research that using a methanol and formic acid aqueous solution with a volume ratio of 98:2 as the mobile phase can improve its peak shape in the chromatogram and make the detection results more accurate.

[0023] As a preferred technical solution, the mass spectrometry conditions include: the ion source is ESI; the scanning ion mode is MRM; the ion source temperature is 150°C; and the capillary voltage is 3000-5000V.

[0024] As a preferred technical solution, the mass spectrometry conditions include: the ion source is ESI; the scanning ion mode is MRM; the ion source temperature is 150°C; and the capillary voltage is 3000V.

[0025] Beneficial Effects

[0026] 1. The present invention provides an analytical method for antioxidants in cosmetics, which can achieve qualitative and quantitative detection of VE acetate, with a detection limit as low as 0.2 ppm and a linear correlation coefficient greater than 0.99, and has good application prospects.

[0027] 2. The analytical method for antioxidants in cosmetics provided by the present invention has a good recovery rate, an RSD of less than 10%, and good repeatability.

[0028] 3. The analytical method for antioxidants in cosmetics provided by the present invention has a short testing time and completes the separation and qualitative and quantitative detection of VE acetate within 5 minutes.

[0029] 4. The present invention provides an analytical method for antioxidants in cosmetics, which has good separation and strong specificity, and can quickly and accurately realize the analytical determination of VE acetate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 LC-MS spectra comparing blank test and standard solution test

[0031] Figure 2 LC-MS spectrum of VE acetate at the instrument detection limit of 0.2 mg / L DETAILED DESCRIPTION

[0032] 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.

[0033] 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.

[0034] Example

[0035] Example 1

[0036] Example 1 of the present invention specifically provides a method for analyzing antioxidants in cosmetics, wherein the antioxidant is VE acetate, comprising the following steps:

[0037] 1. Information on standards and samples

[0038] 1.1. Standard substance: VE acetate, CAS: 52225-20-4, purity 100%;

[0039] 1.2. Develop sample formula, as shown in Table 1:

[0040] Table 1

[0041]

[0042] 2. Solution preparation

[0043] 2.1. Preparation of standard solution

[0044] Weigh 0.1 g (accurate to 0.0001 g) of the standard product of VE acetate antioxidant into a 100 mL volumetric flask, dissolve it in methanol to the mark to prepare a 1000 mg / L standard stock solution, and store it at 4-8°C.

[0045] Use a gas-tight syringe to accurately transfer 0.1 mL of the 1000 mg / L standard stock solution to the autosampler bottle, and accurately add 0.9 mL of methanol. The concentration is now 100 mg / L. Use this as the mother solution, and then use methanol to dilute it step by step to prepare 7 series of mixed standard solutions, see Table 2.

[0046] Table 2

[0047]

[0048] 2.2. Preparation of sample solution

[0049] Weigh 0.2g of cosmetic sample (accurate to 0.0001g) and add it to a 100mL volumetric flask that has been rinsed with chloroform. Add about 10mL of chloroform. At this time, the sample is light yellow and turbid. Add about 60mL of methanol. After the sample is dissolved, add methanol to the scale, shake well, and let it stand.

[0050] Use a syringe to draw 1mL of sample solution, remove the needle, replace it with a 0.22μm organic phase filter membrane, and filter the solution into an automatic sample bottle. Use a pipette to accurately transfer 0.1mL of sample solution to another automatic injection bottle, accurately add 0.9mL of water, at this time the sample solution is diluted 10 times, seal the lid tightly, attach a label, and wait for testing.

[0051] 2.3 Liquid chromatography-mass spectrometry detection

[0052] The VE acetate standard working solution and the sample solution were eluted by liquid chromatography-mass spectrometry to obtain the chromatograms of the standard solution and the sample solution for analysis and detection. The liquid chromatography-mass spectrometry working condition settings are shown in Table 3, the instrument elution program is shown in Table 4, and the mass spectrometry method settings are shown in Table 5.

[0053] Table 3

[0054]

[0055] Table 4

[0056]

[0057]

[0058] Table 5 Mass spectrometry method settings

[0059]

[0060] 2.4. Result analysis: establishing standard curve and method verification

[0061] Among them, the formula for sample test results is:

[0062]

[0063] Where:

[0064] Xi——the content of the substance to be tested in the sample, in %;

[0065] C——The concentration of the substance to be tested in the test solution obtained according to the standard curve, in mg / L;

[0066] C 0 ——The concentration of the substance to be tested in the blank solution obtained according to the standard curve, in mg / L;

[0067] V——test solution volume, in mL;

[0068] f——dilution multiple of test solution;

[0069] m – mass of the sample, in g.

[0070] Performance Testing

[0071] 1. Selectivity

[0072] 1.1 Blank test: Except for not adding samples, the remaining steps are the same as above for blank test.

[0073] 1.2. Standard solution test: Perform the standard working solution test according to the above steps.

[0074] The LC-MS spectra of blank test and standard solution test are as follows: Figure 1 shown.

[0075] Conclusion: Figure 1 It can be seen that there is no impurity peak in the blank test, the response and separation of VE acetate standard are good, and the method has good selectivity.

[0076] 2. Linear

[0077] According to the standard solutions of the series of concentrations prepared in the above Example 1, according to the instrument test conditions in Example 1, the LCMS test analysis was performed, the chromatogram and the corresponding peak area were recorded, and the standard curve was drawn with the concentration of the mixed standard solution as the abscissa and the peak area as the ordinate. The fitting equation, range, and correlation coefficient were calculated and reported. The data results are shown in Table 6.

[0078] Table 6

[0079]

[0080] Conclusion: The correlation coefficients of the standard curves of VE acetate and VE acetate both meet the R 2 ≥0.998, indicating that the standard curve has a good fit.

[0081] 3. Method detection limit and quantification limit

[0082] The sample concentration at 5 times the signal-to-noise ratio is defined as the instrument detection limit, and 3 times the instrument detection limit is defined as the instrument quantification limit. See Table 7 for details. The LC-MS chromatogram of the instrument detection limit of VE acetate at a concentration of 0.2 mg / L is shown in Figure 2 .

[0083] Table 7

[0084]

[0085] 4. Recovery rate

[0086] The cosmetic sample solution 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 8.

[0087] Table 8

[0088]

[0089] Conclusion: The recovery rate of VE acetate is between 80% and 120%, which meets the requirements.

[0090] 5. Repeatability

[0091] According to the determination conditions of Example 1, three cosmetic 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 9.

[0092] Table 9 Repeatability test results

[0093]

[0094] Conclusion: The RSD of VE acetate was less than 10%, and the repeatability was good.

[0095] 6. Reproducibility

[0096] Different people used the same method to process and test the same sample to examine the reproducibility. The specific results are shown in Table 10.

[0097] Table 10

[0098]

[0099] Conclusion: The relative deviation of VE acetate between individuals was less than 10%, and the reproducibility was good.

Claims

1. A method for analyzing antioxidants in cosmetics, characterized in that: The antioxidant is VE acetate, comprising the following steps: (1) Preparation of standard solution: weigh the standard of VE acetate antioxidant, dilute to volume with organic solvent, prepare 7 kinds of VE acetate standard working solutions, and store at 4-8°C for future use; (2) preparing a sample solution: weighing a cosmetic sample, adding chloroform, shaking well, adding a small molecule polyol, extracting by vortex oscillation, standing to obtain a supernatant, filtering the supernatant through an organic phase filter membrane, adding a diluent to the filtrate to dilute it to obtain a sample solution for later use; (3) Liquid chromatography-mass spectrometry detection: The standard working solution and the sample solution are eluted using a liquid chromatography-mass spectrometer to obtain chromatograms of the standard solution and the sample solution for analysis and detection; (4) Result analysis: Establish standard curve and verify the method.

2. The method for analyzing antioxidants in cosmetics according to claim 1, characterized in that: The organic solvent includes: one or more of acetonitrile, methanol or ethanol.

3. The method for analyzing antioxidants in cosmetics according to claim 1, characterized in that: The concentrations of the seven VE acetate standard working solutions are 0.1 mg / L, 0.5 mg / L, 1 mg / L, 2 mg / L, 5 mg / L, 10 mg / L, and 20 mg / L, respectively.

4. The method for analyzing antioxidants in cosmetics according to claim 1, characterized in that: The small molecule polyol includes one or more of methanol, ethanol and isopropanol.

5. The method for analyzing antioxidants in cosmetics according to claim 4, characterized in that: The small molecule polyol is methanol.

6. The method for analyzing antioxidants in cosmetics according to claim 1, characterized in that: The organic phase filter membrane is an organic filter membrane with a pore size of 0.22 μm.

7. The method for analyzing antioxidants in cosmetics according to claim 1, characterized in that: The diluent is one or more of methanol, chloroform and acetonitrile.

8. The method for analyzing antioxidants in cosmetics according to claim 1, characterized in that: The chromatographic conditions of the liquid chromatography include: chromatographic column: ACQUITY UPLC BEH C18, specification: 1.7μm×2.1mm×50mm; mobile phase A is methanol, mobile phase B is 0.1-0.3% formic acid aqueous solution; column temperature is 35-45°C; injection volume is 2-5μL; flow rate: 0.3-0.5mL / min.

9. The method for analyzing antioxidants in cosmetics according to claim 5, characterized in that: The volume ratio of the mobile phase A to the mobile phase B is (97-98): (2-3).

10. The method for analyzing antioxidants in cosmetics according to claim 1, characterized in that: The mass spectrometry conditions include: the ion source is ESI; the scanning ion mode is MRM; the ion source temperature is 150° C.; and the capillary voltage is 3000-5000V.

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