A rapid batch detection method for p-hydroxyacetophenone in cosmetics

Abstract

The present invention relates to a rapid batch detection method for p-hydroxyacetophenone in cosmetics, and belongs to the technical field of cosmetics analysis. The detection method provided by the present invention comprises the following steps: (1) adding ultrapure water to the cosmetics to be tested, vortexing and ultrasonicating to obtain a dispersion; (2) adding aldehyde-free ethanol to the dispersion, ultrasonicating twice to obtain a mixed extract, and centrifuging to obtain a supernatant; (3) taking the supernatant, adding hydrochloric acid and dinitrophenylhydrazine, heating reaction, cooling and adding potassium hydroxide to color to obtain a liquid to be tested; (4) using spectrophotometry to detect and obtain the content of p-hydroxyacetophenone in the cosmetics to be tested. The present invention optimizes the extraction step of p-hydroxyacetophenone in cosmetics, combined with the dinitrophenylhydrazine colorimetric method, to provide a fast, efficient, simple to operate, low-cost, high-accuracy, and good-precision detection method for p-hydroxyacetophenone in cosmetics.

Description

Technical Field

[0001] The invention relates to the technical field of cosmetic analysis, and in particular to a rapid batch detection method for p-hydroxyacetophenone in cosmetics. Background Art

[0002] Preservatives are an indispensable raw material in cosmetics. Their main function is to prevent the growth of microorganisms in cosmetics under different environments, which may lead to the deterioration of cosmetics. Parahydroxyacetophenone is a common preservative. It has certain antioxidant properties and is usually used as an antioxidant. However, due to its strong preservative effect, it is also often used as a preservative synergist. The detection of parahydroxyacetophenone is crucial to ensure the quality and safety of cosmetics.

[0003] The existing detection method for p-hydroxyacetophenone in cosmetics is mainly the high performance liquid chromatography-diode array detector method. This method needs to be measured using a high performance liquid chromatograph. Although the content of p-hydroxyacetophenone can be accurately measured, the instrumentation is expensive, the operation is complicated, the maintenance cost is high, and the operation is difficult. Therefore, this method is not suitable for enterprises or laboratories with limited conditions to detect, and the detection cost is high. In addition, when the high performance liquid chromatography method is processed in large quantities, the required elution and detection time are long, and the high performance liquid chromatography step alone requires at least several hours to obtain the final result, which is not conducive to the demand for batch rapid detection. The existing p-hydroxyacetophenone detection method has certain limitations.

[0004] Therefore, it is urgent to optimize the steps and develop a new, simple, low-cost test method with shorter detection time to reduce the cost of detecting p-hydroxyacetophenone in cosmetics and achieve rapid detection, making it more suitable for enterprises or laboratories with limited conditions to carry out detection, while ensuring the reliability of the test results, which is valuable in cosmetics production and quality monitoring, testing and other applications. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a rapid batch detection method for p-hydroxyacetophenone in cosmetics. The method has good extraction effect of p-hydroxyacetophenone in cosmetics, high detection accuracy, good precision, and shorter time consumption, and is suitable for batch rapid testing of cosmetic samples.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a rapid batch detection method for p-hydroxyacetophenone in cosmetics, comprising the following steps:

[0008] (1) adding ultrapure water to the cosmetic to be tested, vortexing and ultrasonicating once to obtain a dispersion; the vortexing time is 12-18 minutes, and the ultrasonicating time is 27-33 minutes;

[0009] (2) adding aldehyde-free ethanol to the dispersion, performing a second ultrasonic treatment to obtain a mixed extract, and then centrifuging to obtain a supernatant; the volume ratio of the ultrapure water to the mixed extract is (0.8-1.2):(1.8-2.2);

[0010] (3) taking the supernatant, adding hydrochloric acid and dinitrophenylhydrazine, heating to react, and adding potassium hydroxide to develop color after cooling to obtain a test solution;

[0011] (4) Detecting the test liquid by spectrophotometry to obtain the content of p-hydroxyacetophenone in the test cosmetic.

[0012] The rapid batch detection method for p-hydroxyacetophenone in cosmetics provided by the present invention optimizes the pre-treatment extraction steps, is applicable to the detection of a variety of different matrices, has high accuracy, and good precision. The spectrophotometric detection and analysis using dinitrophenylhydrazine (i.e., 2,4-dinitrophenylhydrazine) color development can significantly improve the test efficiency; wherein the spectrophotometric detection can use the standard curve method (external standard method) to quantify the sample, which is convenient for batch processing and rapid detection of a large number of cosmetic samples.

[0013] During the pretreatment process, the present invention uses ultrapure water and aldehyde-free ethanol to disperse and extract in sequence, avoiding the influence of impurities in the solvent on the test results; at the same time, first using a specific proportion of water to disperse the cosmetics to be tested is conducive to improving the detection accuracy of the method for parahydroxyacetophenone, so that the spiked recovery rate is increased to more than 90%. If an inappropriate ratio of ultrapure water and aldehyde-free ethanol is used, the spiked recovery rate decreases and the accuracy of the test results decreases; if the order of adding the solvent is changed, the extraction recovery rate is reduced to about 50%, and the effect is significantly deteriorated.

[0014] In addition, the degree of dispersion of the tested cosmetics after vortexing and ultrasonic treatment also has a significant impact on the extraction recovery rate. Under the above-mentioned specific vortexing and ultrasonic conditions, it is beneficial to improve the detection accuracy. If the vortexing and ultrasonic time is too short, the spiked recovery rate cannot reach more than 90%; if the vortexing and ultrasonic time is continued to increase, the spiked recovery rate will no longer increase.

[0015] The detection method of the present invention is used to detect the common cosmetic product matrices on the market, and the recovery rate of p-hydroxyacetophenone added is greater than 90%, the detection accuracy is high, and the RSD is below 3%, the detection precision is good, and the test requirements are also met. In contrast, the detection method for p-hydroxyacetophenone in cosmetics provided by the present invention meets the requirements of detection accuracy and precision, has good specificity, and has lower cost, high efficiency, can realize rapid batch detection, and has low requirements for operators, and has certain application value in the quality monitoring and detection of cosmetics in enterprises or laboratories.

[0016] More preferably, the vortex oscillation time is 15 min, and the ultrasound time is 30 min.

[0017] Further preferably, the volume ratio of the ultrapure water to the mixed extract is 1:2.

[0018] Preferably, the vortex oscillation has a power of 55-65 W and a rotation speed of 1800-2200 rpm.

[0019] Further preferably, the power of the vortex oscillation is 60W and the rotation speed is 2000rpm.

[0020] Preferably, in step (1), the volume ratio of the mass of the cosmetic to be tested to ultrapure water is (0.5-1.5) g: (20-30) ml.

[0021] Preferably, in the steps (1) and (2), the frequency of the first ultrasound and the second ultrasound is 38-42 kHz, and the temperature is 25-35° C.; and the time of the second ultrasound is 25-35 min.

[0022] Further preferably, in the step (1), the temperature of the first ultrasound is 30°C.

[0023] Further preferably, in the step (2), the temperature of the secondary ultrasound is 30° C., and the time of the secondary ultrasound is 30 min.

[0024] By strictly controlling the above dispersion and extraction conditions, p-hydroxyacetophenone in cosmetics can be fully extracted and the test accuracy can be improved.

[0025] Preferably, in step (2), the centrifugal speed is 5500-6500 r / min, and the centrifugal time is 4-6 min.

[0026] Preferably, in step (3), the heating reaction temperature is 60-70° C. and the reaction time is 35-45 min.

[0027] More preferably, in step (3), the heating reaction temperature is 65° C. and the reaction time is 40 min.

[0028] Preferably, in step (3), the cooling is performed in an ice water bath, and the cooling time is 4-6 minutes.

[0029] Preferably, in step (3), the color development time is 9-11 minutes.

[0030] As a preferred embodiment, step (3) is specifically as follows: take 1 ml of the supernatant, add 1.5 ml of concentrated hydrochloric acid and 1 ml of 5 mmol / L dinitrophenylhydrazine, mix well, place in a 65°C water bath and heat for 40 min to react; after heating, cool in an ice water bath for 5 min, and then add 1.5 mol / L potassium hydroxide solution for color development for 10 min.

[0031] Preferably, in step (4), the detection wavelength of the spectrophotometry is 320-325 nm.

[0032] Further preferably, in step (4), the detection wavelength of the spectrophotometry is 324 nm.

[0033] Preferably, the detection limit of the rapid batch detection method for p-hydroxyacetophenone in cosmetics is 0.129 g / kg, and the quantification limit is 0.387 g / kg.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. Simple operation: The present invention uses a specific solvent to extract p-hydroxyacetophenone in cosmetics, and then uses dinitrophenylhydrazine as a color developer to detect at a specific wavelength to quantitatively measure the content of p-hydroxyacetophenone. The whole process is simple to operate, does not require complex instruments and professional technicians, and is suitable for enterprises or laboratories with limited conditions to carry out detection.

[0036] 2. Low cost: Compared with the existing high performance liquid chromatography-diode array detector method, the present invention does not need to use expensive high performance liquid chromatographs, which greatly reduces the detection cost. At the same time, the reagents of the present invention are all conventional reagents with low prices, which further reduces the detection cost.

[0037] 3. Fast detection speed: The detection process of the present invention only takes a few minutes to complete, and the pre-treatment and detection are separated from large-scale analytical instruments, which can be quickly detected in batches, greatly improving the detection speed; it can also be combined with photometric colorimetry to meet the needs of faster detection.

[0038] 4. High accuracy and good precision: After the optimized pre-treatment extraction steps, the results of the determination of p-hydroxyacetophenone in various cosmetic matrices all meet the requirements of a recovery rate greater than 90% and an RSD less than 3%. In general, compared with the prior art, the present invention has the advantages of simple operation, low cost, fast detection speed and high accuracy, and is an ideal method for detecting p-hydroxyacetophenone. DETAILED DESCRIPTION

[0039] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with specific examples. The test methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0040] Example 1

[0041] The present invention is directed to an embodiment of a rapid batch detection method for p-hydroxyacetophenone in cosmetics. The cosmetics to be tested in this embodiment are three facial cream products with different p-hydroxyacetophenone contents. The p-hydroxyacetophenone detection method in this embodiment is:

[0042] (1) Precisely weigh two portions of 1 g of the cream sample to be tested into a 50 ml colorimetric tube in parallel, add 25 ml of ultrapure water, vortex and oscillate for 15 min to disperse, and then place in an ultrasonic cleaner at 30° C. for 30 min to obtain a dispersion;

[0043] (2) Take out the colorimetric tube, add aldehyde-free ethanol, make the volume to 50 ml, and place it in an ultrasonic cleaner at 30°C for extraction for 30 min to obtain an extract; take 10 ml of the extract into a centrifuge tube, centrifuge it in a high-speed centrifuge at 6000 r / min for 5 min to obtain a supernatant;

[0044] (3) Take 1 ml of the supernatant in a 50 mL colorimetric tube, add 1.5 ml of concentrated hydrochloric acid and 1 ml of 5 mmol / L dinitrophenylhydrazine, mix well, and place in a 65°C water bath for 40 min to react; after the water bath is completed, place the colorimetric tube in an ice water bath to cool for 5 min, then add 1.5 mol / L potassium hydroxide solution for color development for 10 min, dilute to the scale with aldehyde-free ethanol, mix well, and the solution to be tested is obtained;

[0045] (4) Using aldehyde-free ethanol to adjust the zero value, using a spectrophotometer, measure the absorbance of the test solution in a 1 cm quartz cuvette at a wavelength of 324 nm;

[0046] (5) preparing a series of p-hydroxyacetophenone standard solutions with a concentration gradient, performing a color reaction and measuring absorbance in the same manner as in steps (3) and (4) above, and plotting a standard curve with concentration as the abscissa and absorbance as the ordinate. The results are shown in Table 1;

[0047] It can be seen that the standard curve of p-hydroxyacetophenone has good linearity in the concentration range of 0.003~0.015mmol / L, R 2 is 0.999.

[0048] (6) The content of p-hydroxyacetophenone in the tested cream sample was calculated based on the standard curve, the absorbance of the tested solution, and the dilution multiple. The results are shown in Table 2.

[0049] It can be seen that the above-mentioned detection method for p-hydroxyacetophenone can achieve a high recovery rate and good extraction effect when measuring different facial cream samples.

[0050] Table 1-1 Standard curve of p-hydroxyacetophenone

[0051]

[0052] Table 1-2 Determination results of p-hydroxyacetophenone content in three facial cream products

[0053]

[0054] Effect Example 1

[0055] In order to explore the precision of the rapid batch detection method for p-hydroxyacetophenone in cosmetics provided by the present invention, a facial cream sample was measured 10 times using the method in Example 1. The results are shown in Table 2 below.

[0056] As shown in Table 2, the method of the present invention is used to repeatedly determine the p-hydroxyacetophenone in cosmetics 10 times, and the RSD value of the obtained results is less than 3%, with high precision, which meets the detection requirements.

[0057] Table 2 Precision results

[0058]

[0059] Effect Example 2

[0060] In order to explore the accuracy of the rapid batch detection method for p-hydroxyacetophenone in cosmetics provided by the present invention, the blank matrix sample of the cream sample was subjected to a spiked recovery experiment at low, medium and high levels using the detection method in Example 1. The results are shown in Table 3 below.

[0061] As shown in Table 3, by using the detection method of p-hydroxyacetophenone of the present invention, low, medium and high level spike experiments were carried out, and the recovery rates were all above 94%, with high accuracy, meeting the testing requirements of cosmetics.

[0062] Table 3 Results of spike recovery experiments at low, medium and high levels

[0063]

[0064] Effect Example 3

[0065] In order to explore the applicability of the rapid batch detection method for p-hydroxyacetophenone in cosmetics provided by the present invention to cosmetics with different matrices, the detection method in Example 1 was used to carry out a spike recovery experiment on several common cosmetic blank matrix samples. The results are shown in Table 4 below.

[0066] As can be seen from Table 4, the test method provided by the present invention is used to determine the content of p-hydroxyacetophenone in water, lotion, cream and gel. From the results, it can be seen that the recovery effect of the lotion matrix is ​​the best, and the recovery rate of the emulsion matrix is ​​lower. However, the test method of the present invention has a spiked recovery rate of p-hydroxyacetophenone content in different cosmetic matrices greater than 94%, which is suitable for a variety of matrices, has high accuracy, and meets the testing needs of cosmetics.

[0067] Table 4 Results of spike recovery experiments for different cosmetic blank matrices

[0068]

[0069] Effect Example 4

[0070] In order to explore the detection limit and quantification limit of the rapid batch detection method for p-hydroxyacetophenone in cosmetics provided by the present invention, according to the "Technical Specifications for Safety of Cosmetics", 0.005A is used as the detection limit and 0.015A is used as the quantification limit, and the results are shown in Table 5. It can be seen that the detection limit of the method is 0.129g / kg and the quantification limit is 0.387g / kg.

[0071] Table 5 Results of detection limit and quantification limit

[0072]

[0073] Comparative Example 1

[0074] The difference between Comparative Example 1 and Example 1 is that in steps (1)-(2), the added dispersion / extraction solvents and the proportions are different. Three cream products with different p-hydroxyacetophenone contents were extracted and tested respectively, and the different treatment methods and recovery rate results are shown in Tables 6-1 to 6-5 below.

[0075] Comparing the results of Tables 6-1 to 5 with those of Example 1, it can be seen that:

[0076] Using only ultrapure water for dispersion and extraction cannot effectively extract parahydroxyacetophenone in cosmetics; using only aldehyde-free ethanol for dispersion and extraction, the extraction recovery rate is also not ideal, only about 70%; changing the ratio of ultrapure water added in the dispersion step to aldehyde-free ethanol added during extraction: too little ultrapure water and too much aldehyde-free ethanol (Table 6-3), or too much ultrapure water and too little aldehyde-free ethanol (Table 6-4), will lead to a significant decrease in the recovery rate and fail to achieve the effect of accurate determination.

[0077] Changing the order of adding aldehyde-free ethanol and ultrapure water (Table 6-5), that is, using aldehyde-free ethanol for vortex oscillation and ultrasonic treatment, and then adding water for ultrasonic treatment, the test recovery rate is only about 50%, which cannot effectively realize the extraction and determination of parahydroxyacetophenone in cosmetics.

[0078] Only by using ultrapure water dispersion and aldehyde-free ethanol extraction, and at a specific ratio of ultrapure water to aldehyde-free ethanol, can a better extraction effect be achieved and the recovery rate be significantly improved, thereby ensuring the accuracy of this method in detecting p-hydroxyacetophenone in cosmetics.

[0079] Table 6-1 Recovery results of dispersion and extraction using only ultrapure water

[0080]

[0081]

[0082] Table 6-2 Recovery results of dispersion and extraction using only aldehyde-free ethanol

[0083]

[0084] Table 6-3 Recovery results of changing the ratio of ultrapure water and aldehyde-free ethanol 1

[0085]

[0086] Table 6-4 Recovery results of changing the ratio of ultrapure water and aldehyde-free ethanol 2

[0087]

[0088] Table 6-5 Recovery results of changing the order of adding aldehyde-free ethanol and ultrapure water

[0089]

[0090] Comparative Example 2

[0091] The difference between Comparative Example 2 and Example 1 is that in step (1), the conditions of vortex oscillation and ultrasound are different. Three cream products with different p-hydroxyacetophenone contents are extracted and tested respectively. The specific operations and recovery rate results are shown in Tables 7-1 and 7-2 below.

[0092] Comparing the results of Table 7-1 to 2 with those of Example 1, it can be seen that vortex oscillation and ultrasound determine the degree of dispersion of the sample in water, which directly affects the subsequent extraction and detection recovery results of parahydroxyacetophenone. If the vortex and ultrasound treatment time is too short, it will lead to incomplete dispersion, poor extraction effect, and significantly reduced recovery, and the purpose of accurate determination cannot be achieved. The dispersion conditions defined in the present invention are moderate, which is conducive to the extraction and accurate detection of parahydroxyacetophenone in cosmetics, while improving the test efficiency.

[0093] Table 7-1 Recovery results after vortexing for 5 minutes and ultrasonication for 10 minutes

[0094]

[0095] Table 7-2 Recovery results after vortexing for 10 minutes and ultrasonication for 20 minutes

[0096]

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A rapid batch detection method for p-hydroxyacetophenone in cosmetics, characterized in that: The following steps are involved: (1) adding ultrapure water to the cosmetic to be tested, vortexing and ultrasonicating once to obtain a dispersion; the vortexing time is 12-18 minutes, and the ultrasonicating time is 27-33 minutes; (2) adding aldehyde-free ethanol to the dispersion, performing a second ultrasonic treatment to obtain a mixed extract, and then centrifuging to obtain a supernatant; the volume ratio of the ultrapure water to the mixed extract is (0.8-1.2):(1.8-2.2); (3) taking the supernatant, adding hydrochloric acid and dinitrophenylhydrazine, heating to react, and adding potassium hydroxide to develop color after cooling to obtain a test solution; (4) Detecting the test liquid by spectrophotometry to obtain the content of p-hydroxyacetophenone in the test cosmetic.

2. The rapid batch detection method for parahydroxyacetophenone in cosmetics according to claim 1, characterized in that: In the step (1), the volume ratio of the mass of the cosmetic to be tested to ultrapure water is (0.5-1.5) g: (20-30) ml.

3. The rapid batch detection method for parahydroxyacetophenone in cosmetics according to claim 1, characterized in that: In the step (1), the power of the vortex oscillation is 55-65W, and the rotation speed is 1800-2200rpm.

4. The rapid batch detection method for parahydroxyacetophenone in cosmetics according to claim 1, characterized in that: In the steps (1) and (2), the frequency of the first ultrasound and the second ultrasound is 38-42 kHz, and the temperature is 25-35° C.; the time of the second ultrasound is 25-35 min.

5. The rapid batch detection method for parahydroxyacetophenone in cosmetics according to claim 1, characterized in that: In the step (2), the centrifugal speed is 5500-6500 r / min, and the centrifugal time is 4-6 min.

6. The rapid batch detection method for parahydroxyacetophenone in cosmetics according to claim 1, characterized in that: In the step (3), the heating reaction temperature is 60-70° C. and the reaction time is 35-45 min.

7. The rapid batch detection method for parahydroxyacetophenone in cosmetics according to claim 1, characterized in that: In the step (3), the cooling is performed in an ice water bath, and the cooling time is 4-6 minutes.

8. The rapid batch detection method for parahydroxyacetophenone in cosmetics according to claim 1, characterized in that: In the step (3), the color development time is 9-11 minutes.

9. The rapid batch detection method for parahydroxyacetophenone in cosmetics according to claim 1, characterized in that: In the step (4), the detection wavelength of the spectrophotometer is 320-325 nm.

10. The rapid batch detection method for p-hydroxyacetophenone in cosmetics according to claim 1, characterized in that: The detection limit was 0.129 g / kg and the quantification limit was 0.387 g / kg.

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