Preparation process and quality inspection method of eczema cream

Abstract

The preparation process of the eczema cream comprises the following steps: S1, raw material pretreatment: coarsely crushing calcined calamine; removing impurities from cortex phellodendri, coarsely crushing, and removing impurities from indigo naturalis for later use; mixing the three components, performing superfine grinding, and sieving with a 100-mesh sieve to obtain a medicinal powder raw material; s2, substrate preparation: melting and stirring beeswax and sesame oil at 85-90 DEG C, and cooling to obtain a transparent substrate; s3, mixing and forming: mixing the medicinal powder raw materials and the transparent matrix according to the mass ratio of (2.07-1): 2.13, uniformly stirring at 85-90 DEG C, cooling, solidifying, sterilizing and packaging to obtain the eczema cream. According to the standardized preparation process and the quality inspection method of the eczema cream, by optimizing superfine grinding parameters, a matrix ratio and a quality control system, stable production and quality controllability of the eczema cream are achieved, and technical support is provided for preparation conversion.

Description

Technical Field

[0001] This invention relates to the field of traditional Chinese medicine ointment technology, specifically to a preparation process and quality inspection method for an eczema ointment. Background Technology

[0002] Eczema is a common inflammatory skin disease, mainly characterized by erythema and papules on the skin, possibly accompanied by oozing and itching. It is prone to recurrence, significantly impacting patients' quality of life. Currently, Western medicine treatments mostly rely on medications such as corticosteroids and antihistamines. These drugs can relieve symptoms in the short term, but long-term use can easily lead to adverse reactions, and the recurrence rate is relatively high. Clinical treatment needs have not yet been fully met.

[0003] Traditional Chinese medicine (TCM) has a long history of treating eczema. Relying on its unique advantages of "treatment based on syndrome differentiation, addressing both the root cause and symptoms," it demonstrates significant advantages in relieving symptoms, reducing recurrence rates, and ensuring safety. Therefore, topical TCM preparations have become an important option in clinical treatment. The eczema ointment originates from the "Clinical Experience Collection of Zhu Renkang" from the Guang'anmen Hospital of the Chinese Academy of Traditional Medicine. It is composed of indigo naturalis, phellodendron bark, and calcined calamine, working together to clear heat and dry dampness, cool the blood and detoxify, relieve itching and promote wound healing, aligning with the TCM pathogenesis of eczema as "wind, dampness, and heat obstructing the skin." This formula has been used clinically for many years, demonstrating advantages such as definite efficacy, moderate cost, and no significant adverse reactions. However, the original dosage form, a traditional powder, suffers from problems such as easy moisture absorption and deterioration, the need for immediate preparation and use, difficulty in controlling dosage, and inconvenience for patients. This not only wastes TCM resources but also limits its clinical application.

[0004] In recent years, the modernization of traditional Chinese medicine external preparations has become an important focus of innovation and development in traditional Chinese medicine. However, systematic research on eczema creams is currently lacking, and there is a lack of standardized preparation processes and scientific quality control systems, which has made it difficult to promote the transformation of these preparations. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a standardized preparation process and quality inspection method for eczema cream. By optimizing ultrafine grinding parameters, matrix ratio, and quality control system, stable production and quality control of eczema cream are achieved, providing technical support for formulation transformation.

[0006] A preparation process for an eczema cream includes the following steps:

[0007] S1. Raw material pretreatment: Calcined calamine is coarsely pulverized; Phellodendron bark is coarsely pulverized after removing impurities, and Indigo naturalis is set aside after removing impurities; the three are mixed and then ultra-finely pulverized, and passed through a 100-mesh sieve to obtain the medicinal powder raw material;

[0008] S2. Matrix preparation: Melt beeswax and sesame oil at 90℃ and stir for 10 minutes, then cool to obtain a transparent matrix;

[0009] S3. Mix the powdered raw material with the transparent matrix at a mass ratio of 1:2.07, stir evenly at 90°C, cool and solidify, sterilize and package to obtain the eczema cream.

[0010] Preferably, the particle size of the pharmaceutical raw material powder after ultra-fine pulverization in S1 is ≤150μm.

[0011] Preferably, the ultrafine grinding time after mixing the three components in S1 is 15 minutes.

[0012] Preferably, the mass ratio of calamine, phellodendron bark, and indigo in S1 after impurity removal is 10:1:1.

[0013] Preferably, the ratio of beeswax to sesame oil in S2 is beeswax (g): sesame oil (mL) = 6:20.

[0014] Preferably, after mixing S3, the mixture is stirred at 250-350 r / min for 20-40 min.

[0015] Preferably, sterilization in S3 is performed using ultraviolet sterilization with parameters of 30 μW / cm² for 30 min.

[0016] A quality inspection method for eczema cream includes the following steps:

[0017] T1. Qualitative Identification: Take 1g of the finished eczema cream, add 10ml of dichloromethane and 10ml of dilute hydrochloric acid, shake for 15 minutes, filter through filter paper, add potassium ferrocyanide test solution to the filtrate, shake to mix, and let stand for 5 minutes. If a white precipitate is formed or mixed with a trace amount of blue precipitate, it is a genuine product and meets the qualitative identification requirements for calcined calamine in eczema cream. If no precipitate is formed, or if obvious yellow or black precipitate appears, it is judged as unqualified.

[0018] T2. Quantitative determination: The determination was performed using the EDTA titration method. 1 g of eczema ointment was accurately weighed and placed in an Erlenmeyer flask. 10 ml of dichloromethane and 30 ml of dilute hydrochloric acid were added. The mixture was stirred continuously with a glass rod for 5 min. After standing for 10 min, the mixture was filtered through filter paper. The lower layer was collected and treated with 30 ml each of concentrated ammonia solution and ammonia-ammonium chloride buffer (pH 10.0). The mixture was shaken well, and 30 ml of disodium hydrogen phosphate solution (to stabilize the pH) was added. The mixture was sonicated for 2 min and then filtered again. The conical flask and residue were washed three times with a mixture of 1 part ammonia-ammonium chloride buffer (pH 10.0) and 4 parts water, 10 ml each time. The washings (the conical flask containing the lower layer) and filtrate were combined, 15 ml of 30% triethanolamine solution and a small amount of Eriochrome Black T indicator (approximately 0.1 g) were added, and the solution was titrated with EDTA titrant (0.05 mol / L) until the solution changed from purple-red to pure blue. The zinc oxide content in the eczema cream was calculated, and the zinc oxide content in the eczema cream was required to be ≥11.0%.

[0019] Record the volume of disodium ethylenediaminetetraacetate titrant consumed, and calculate the zinc oxide content in the eczema cream using the following formula:

[0020] ZnO content (%) = (T×V×F) / (m×1000)×100%

[0021] In the formula: T is the titer of disodium ethylenediaminetetraacetate titrant for zinc oxide (mg / mL); V is the volume of disodium ethylenediaminetetraacetate titrant consumed (mL); F is the concentration correction factor of disodium ethylenediaminetetraacetate titrant; and m is the sample amount (g).

[0022] Preferably, in the T2 quantitative determination, the titration endpoint is when the solution changes from purplish-red to pure blue and does not fade for 30 seconds.

[0023] Advantages of this invention:

[0024] Stable and controllable process: The parameters such as pulverization time and matrix ratio obtained through orthogonal experiments ensure the consistency of paste quality between batches, making it suitable for large-scale production;

[0025] The quality standards are clearly defined: the established qualitative identification and quantitative determination methods can effectively control the content of active ingredients in calamine and ensure stable efficacy.

[0026] Strong clinical applicability: The ointment dosage form solves the shortcomings of traditional powders, such as easy moisture absorption and inconvenience of use, resulting in higher patient compliance;

[0027] Its transformation value is outstanding: the process and quality control system fully meet the requirements of formulation production, providing technical support for standardization and promotion.

[0028] Instruction manual illustrations

[0029] Figure 1 Before and after comparison images for qualitative identification of eczema cream quality.

[0030] Figure 2 This is a comparison chart showing the quantitative determination of eczema cream quality before and after. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0032] 1 Experiment

[0033] 1.1 Instruments and Equipment

[0034] HH-8 electric thermostatic water bath (Shanghai Zuole Instrument Co., Ltd.); LWF-12A vibrating drug ultrafine pulverizer (Jinan Longwei Pharmaceutical Equipment Co., Ltd.); FA-2204B electronic balance (Shanghai Youke Instrument Co., Ltd., accuracy 0.0001g); FV-100 tilting jacketed concentration kettle (Fuzhou Sansheng Pharmaceutical Equipment Co., Ltd.); KQ-250B benchtop ultrasonic cleaner (Kunshan Ultrasonic Instrument Co., Ltd.); ZXC-Ⅱ type ultraviolet disinfection vehicle (Jiangyin Jianshifu Medical Equipment Co., Ltd.); WSN-R2-1000L purified water system (Changsha Woen Environmental Protection Technology Co., Ltd.); standard test sieve (100 mesh, Shangyu Daoxu Wusi Instrument Factory).

[0035] 1.2 Test Drugs

[0036] The raw materials and reagents used in this study all met the specifications, specifically as follows: Indigo naturalis (from Fujian), Phellodendron bark (from Fengjie, Chongqing), and calcined calamine (from Guangxi) were all identified as meeting the standards of the 2025 edition of the Chinese Pharmacopoeia (Part I); pharmaceutical-grade beeswax and edible-grade sesame oil were used as excipients; the reagents used included dilute hydrochloric acid (9.5%–10.5% (g / mL)), potassium ferrocyanide solution (10% (g / mL)), concentrated ammonia solution (25%–28% (mass fraction)), pH 10.0 ammonia (4.6–5.2 mol / L)-ammonium chloride (1.01 mol / L) buffer, disodium hydrogen phosphate solution (12% g / mL), 30% triethanolamine solution, Eriochrome Black T indicator, and 0.05 mol / L disodium ethylenediaminetetraacetate titrant, all of which were of analytical grade.

[0037] 2. Preparation method

[0038] 2.1 Process route design

[0039] Eczema cream preparation process: Raw material screening and impurity removal → coarse grinding → mixed ultrafine grinding → sieving → matrix melting → mixing of powder and matrix → stirring evenly → cooling and molding → sterilization → packaging → finished product.

[0040] 2.2 Raw material pretreatment

[0041] The mass ratio of calamine, phellodendron bark, and indigo is 10:1:1.

[0042] 2.2.1 Calcined Calamine Processing: First, remove impurities such as mud, sand and stones adhering to the surface, grind into coarse powder to obtain calcined calamine coarse powder for later use.

[0043] 2.2.2 Processing of other Chinese herbal raw materials: Take Phellodendron bark and place it on a clean workbench. Manually screen and remove impurities, mold, insect damage, mud, sand, and non-medicinal parts. Coarsely pulverize it using a Chinese herbal medicine pulverizer to obtain coarse Phellodendron bark powder (particle size approximately 5mm). Take Indigo naturalis and check its appearance to ensure there are no lumps or impurities. Set aside for later use.

[0044] 2.2.3 Mixing, Ultrafine Grinding and Sieving: Calcined calamine powder, coarse phellodendron bark powder, and indigo naturalis are mixed evenly according to the prescription ratio and put into an ultrafine pulverizer. The grinding parameters are adjusted. After grinding, the mixture is sieved through a 100-mesh standard inspection sieve. The powder that passes through the sieve is collected to ensure that the particle size is uniform and there are no obviously large particles. The remaining particles on the sieve are returned to the ultrafine pulverizer for further grinding until all of them pass through the 100-mesh sieve.

[0045] 2.3 Matrix Preparation: First, take the prescribed amounts of beeswax and sesame oil and place them in a clean distillation bowl (the ratio of beeswax (g): sesame oil (mL) = 6:20). Place the distillation bowl on a heating device and slowly heat it to 90℃, then continue heating for 10 minutes, stirring constantly to ensure the beeswax completely melts and fully blends with the sesame oil, forming a uniform and transparent liquid matrix. During heating, the temperature must be controlled to not exceed 90℃ to prevent oxidation and deterioration of the matrix.

[0046] 2.4 Mixing and Shaping: After the pretreatment of the medicinal powder is completed (calcined calamine, phellodendron bark, and indigo naturalis are mixed and ultra-finely pulverized for 15 minutes, then passed through a 100-mesh sieve), it is slowly added to the blended matrix, maintaining the matrix temperature at 85-90℃. An electric stirrer is turned on and set to a stirring speed of 300 rpm, stirring until the medicinal powder and matrix are completely blended, with no obvious particle sedimentation or stratification. Then, the heating device is turned off, stirring is stopped, and the mixture is allowed to cool and solidify naturally at room temperature (25℃±2℃) into a paste, thus obtaining the initial product of the eczema cream.

[0047] 2.5 Process Optimization

[0048] 2.5.1 Single-factor experiments used the uniformity of the paste's appearance (color uniformity, absence of graininess, and spreadability) as the evaluation index, employing a comprehensive score (appearance uniformity 30 points) to examine three key factors:

[0049] 1. Grinding time: Five levels were set: 5 min, 10 min, 15 min, 20 min, and 25 min. The results showed that the powder particle size was the most uniform (100% passed through a 100-mesh sieve) and the paste had the best fineness at 15 min.

[0050] 2. Drug-to-matrix ratio: Nine levels were set: 1:1.98, 1:2.38, 1:2.77, 1:2.07, 1:2.46, 1:2.85, 1:2.15, 1:2.54, and 1:2.93. The results showed that the paste had the best consistency and spreadability at a ratio of 1:2.07.

[0051] 2.5.2 Orthogonal Experiment Based on the results of single-factor experiments, three factors with the most significant impact on the quality of the ointment were selected: beeswax dosage (A), sesame oil dosage (B), and melting temperature (C). Each factor was set with three levels, and an L9 (3³) orthogonal experimental design was adopted. The comprehensive scoring system was set with reference to the ointment quality evaluation standard, and the comprehensive evaluation index was the comprehensive score of appearance uniformity (gloss 10 points, fineness 10 points, spreadability 10 points, full score 30 points).

[0052] 2.5.2.1 Factor Level Design

[0053] Table 1. Orthogonal experimental design of eczema cream preparation process.

[0054]

[0055] The table clearly defines the factors to be examined in the orthogonal experiment (beeswax dosage, sesame oil dosage, and melting temperature) and the three-level gradient of each factor, providing clear parameter basis for the subsequent design of the orthogonal experimental scheme and ensuring that the experiment can systematically examine the impact of key process parameters on the quality of the paste.

[0056] 2.5.2.2 Orthogonal Experimental Design and Results

[0057] Table 2. Orthogonal experimental design and results for the preparation process of eczema cream.

[0058]

[0059] This table records the complete schemes and results of 9 orthogonal experiments, covering the appearance scores (gloss, fineness, spreadability) of the paste under different combinations of process parameters. The results show that the fourth group of experiments (6g beeswax, 20ml sesame oil, temperature 90℃) had the highest comprehensive score (28 points). 2.5.2.3

[0061] Table 3. Visual Analysis of Orthogonal Experiments on Eczema Cream Preparation Process

[0062]

[0063] By calculating the total score (K), average value (k), and range (R) of each factor at different levels, the order of influence of key process parameters on the quality of the paste was determined to be C (temperature) > A (beeswax) > B (sesame oil), and the optimal combination of levels was determined to be A2B1C3 (6g beeswax, 20ml sesame oil, 90℃).

[0064] 3 Key Points for Quality Control in the Preparation Process

[0065] 3.1 Quality Control of Intermediate Products

[0066] 3.1.1 Quality of Calcinated Calamine: The coarse calamine powder should be white or light red, free of obvious impurities, and uniform in color. Take a small amount of calamine powder and test it according to the qualitative identification method. It should meet the identification characteristics of zinc oxide. Use EDTA titration method for preliminary testing. The content of zinc oxide (ZnO) in calamine should not be less than 40% to ensure that the process meets the standards.

[0067] 3.1.2 The quality of the mixed Chinese medicine powder should pass through a 100-mesh sieve, with a uniform color (light gray or grayish-green) and no moisture absorption or clumping. When examined by microscopic identification, indigo naturalis can be seen as blue powder, phellodendron bark can be seen as fiber bundles and stone cells, and calcined calamine can be seen as white powder, with no obvious impurities.

[0068] 3.1.3 In the intermediate quality stage, the paste should be uniform and transparent in the molten state, without turbidity or sediment; after cooling, the paste should be uniform light gray (or gray-green), with a fine texture, no grainy feel, good spreadability, and no stringing.

[0069] 3.2 Finished Product Quality Control

[0070] 3.2.1 Qualitative Identification (Specific Identification for Calamine) Referring to the identification method under Calamine in the 2025 edition of the Chinese Pharmacopoeia (Part I), and considering the characteristics of the eczema ointment preparation, the following detailed operating procedure was established: ① Sample Preparation: Take an appropriate amount of the finished eczema ointment and place it in a clean mortar. Accurately weigh 1.0000g using an electronic balance and place it in a 100mL stoppered conical flask. ② Reagent Addition: Accurately add 10mL of dichloromethane and 10mL of dilute hydrochloric acid to the conical flask. After tightening the stopper, place the flask in a shaker and shake at a frequency of 120 times / min for 15 minutes to allow the main component of calamine, zinc oxide, in the ointment to fully dissolve in the dilute hydrochloric acid, forming a zinc chloride solution. ③ Filtration: Filter the above mixture under reduced pressure using filter paper. Collect all the filtrate in another clean conical flask and discard the filter residue (containing insoluble components such as indigo naturalis and phellodendron bark). ④ Reaction and Observation: Pour 5 mL of filtrate into a test tube, slowly add 2 mL of potassium ferrocyanide solution using a pipette, gently shake to mix the two solutions thoroughly, let stand for 5 minutes, and then observe the color change of the precipitate in the test tube (e.g., ...). Figure 1(As shown). ⑤ Result judgment: If a white precipitate is formed in the test tube, or a trace amount of blue precipitate is mixed in, it is a genuine product and meets the qualitative identification requirements of calcined calamine in eczema cream; if no precipitate is formed, or obvious yellow, black or other abnormal precipitates appear, it is judged as unqualified. The principle of this identification method is: zinc oxide reacts with dilute hydrochloric acid to produce zinc chloride, and zinc chloride then reacts with potassium ferrocyanide to produce white zinc ferrocyanide precipitate (Zn2[Fe(CN)6]); if the raw material contains trace iron impurities, a trace amount of blue ferrocyanide precipitate may be formed, which are all normal characteristics of genuine products.

[0071] 3.2.2 Quantitative Determination (Zinc Oxide Content Determination) Three parallel samples were prepared for each batch of finished product, each weighing approximately 1.0000g. Each sample was then accurately weighed using an electronic balance (accurate to 0.0001g) and placed in a 100mL Erlenmeyer flask. 10mL of dichloromethane was added, followed by 30mL of dilute hydrochloric acid. The mixture was stirred continuously with a glass rod for 5 minutes to ensure complete dissolution of the zinc salt. After standing for 10 minutes, the sample was filtered through filter paper (the components of Phellodendron bark and Indigo naturalis remained in the aqueous layer, while zinc oxide dissolved in the upper layer). The upper layer was then placed in another 100mL Erlenmeyer flask, and 30mL each of concentrated ammonia solution and ammonia-ammonium chloride buffer (pH 10.0) were added. After shaking well, 30mL of disodium hydrogen phosphate solution was added, and the mixture was sonicated for 2 minutes before filtering again. The conical flask and residue were washed three times with a mixture of 1 part ammonia-ammonium chloride buffer (pH 10.0) and 4 parts water, 10 mL each time. All washings and filtrates were combined, and 15 mL of 30% triethanolamine solution was added. After mixing, a small amount of Eriochrome Black T indicator (approximately 0.1 g) was added. The solution immediately turned purple-red. The solution was placed on a titration rack and slowly titrated with disodium ethylenediaminetetraacetate titrant (0.05 mol / L), gently shaking the conical flask continuously during the titration until the solution changed from purple-red to pure blue (as shown in the image). Figure 2 The titration endpoint is reached when the color does not return to purple-red within 30 seconds.

[0072] Record the volume of disodium ethylenediaminetetraacetate titrant consumed, and calculate the oxidation using the following formula.

[0073]

[0074]

[0075]

[0076] In the formula:

[0077] : Mass (g) of medium-calcined calamine;

[0078] : Mass (g) of beeswax;

[0079] : Volume (mL) of sesame oil;

[0080] The density (g / mL) of sesame oil was fixed at 0.94 g / mL.

[0081] : Total mass (g) of all medicinal powders in the mixture;

[0082] : Actual weighed mass of the finished product sample (g);

[0083] 4.069: 1 mL of EDTA standard titrant (0.05 mol / L) is equivalent to the mass (mg) of ZnO;

[0084] Concentration correction factor for disodium ethylenediaminetetraacetate titrant. , F=0.964;

[0085] : Volume (mL) of disodium ethylenediaminetetraacetate (EDTA) titrant consumed in the titration;

[0086] Table 4. Data Report on Zinc Oxide Content Determination in Eczema Cream (including parameters, calculation process, and results)

[0087]

[0088] The limit stipulates that the zinc oxide (ZnO) content in the finished eczema cream shall not be less than 11.0%.

[0089] 4. Discussion: The preparation of eczema cream is based on traditional Chinese medicine theory, combined with modern pharmaceutical technology and orthogonal experimental optimization methods. Appropriate process parameters were systematically selected and detailed quality control standards were established, ultimately making the preparation of eczema cream more scientific and easier to control.

[0090] 4.1 Core Value of Orthogonal Experiment Through L9 (3³) orthogonal experiments, the key factors and optimal parameters affecting the quality of eczema cream were identified: The order of primary and secondary factors was: temperature (C) had the greatest impact on cream quality (R=5), followed by sesame oil dosage (B) (R=1.33), while beeswax dosage (A) had the least impact (R=1.67). Excessively high temperatures (>90℃) caused sesame oil to oxidize and deteriorate, producing an off-odor, and indigo to decompose or oxidize, resulting in poor stability; excessively low temperatures (<70℃) resulted in incomplete melting of beeswax and the appearance of particles in the cream; at 90℃, the matrix melted uniformly, exhibiting the best compatibility with the medicinal powder and optimal centrifugal stability. At 90℃, the optimal parameters were verified: a ratio of 6g beeswax + 20ml sesame oil resulted in a paste with moderate consistency, ensuring good spreadability (spreadability score of 9). Excessive sesame oil (>20ml) made the paste too thin and prone to dripping, causing slight layering; excessive beeswax (>6g) made the paste too thick and difficult to spread, reducing the appearance smoothness score. Process stability: the deviation of the three batches of samples in the verification test was <3%, indicating that the process parameters determined by the orthogonal experiment are stable and reliable, meeting the needs of large-scale production.

[0091] 4.2 Key Control Points for Core Process Steps

[0092] 4.21 Ultrafine grinding and sieving: 15 min ultrafine grinding controls the particle size of Chinese medicine powder to below 150 μm, increases the specific surface area of ​​active ingredients, which is conducive to the uniform dispersion of drugs in the matrix and penetration of the stratum corneum of the skin, and synergistically enhances the efficacy with the matrix melting process.

[0093] 4.22 Sterilization process: Ultraviolet sterilization (30μW / cm², 30min) can effectively control the microbial limit and avoid the destruction of drug components by high temperature sterilization, which meets the sterility requirements of topical ointments.

[0094] The above embodiments are only for illustrating the technical solutions and features of the present invention, and are intended to enable those skilled in the art to implement them better. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention are within the scope of protection of the present invention. The embodiments not described in detail are prior art.

Claims

1. A process for the preparation of eczema cream characterized in that, It comprises the following steps: S1, raw material pretreatment: calcined crude powder is crushed; after removing impurities, crude powder of cortex phellodendri is crushed, and indigo is removed for standby; after mixing, they are ultra-finely crushed, and the powder is obtained by passing through a 100-mesh sieve; S2, preparation of matrix: melt and stir the beeswax and sesame oil at 85-90°C, and cool to obtain a transparent matrix; S3, mixing and molding: mix the powder raw material and the transparent matrix at a mass ratio of 1: (2.07-2.13), stir uniformly at 85-90°C, cool and solidify, sterilize, package, and obtain the eczema paste.

2. A process for the preparation of eczema cream as claimed in claim 1 wherein, The particle size of the powder raw material after ultra-fine crushing in S1 is ≤150μm.

3. A process for the preparation of eczema cream as claimed in claim 1 wherein, The ultra-fine crushing time of the mixture of the three in S1 is 15min.

4. The process for the preparation of eczema cream as claimed in claim 1 wherein, The mass ratio of calcined, cortex phellodendri and indigo after removing impurities in S1 is 10:1:

1.

5. The process for the preparation of eczema cream as claimed in claim 1 wherein, The feeding ratio of beeswax and sesame oil in S2 is beeswax (g): sesame oil (mL) = 6:

20.

6. A process for the preparation of eczema cream as claimed in claim 1, wherein, The stirring speed in S3 is 250-350r / min, and the stirring time is 20-40min.

7. A process for the preparation of eczema cream as claimed in claim 1, wherein, The sterilization in S3 adopts ultraviolet sterilization, and the parameters are 30μW / cm² and 30min.

8. A method for quality control of eczema cream, characterized by, It comprises the following steps: T1, qualitative identification: take 1g of the eczema paste, add 10ml of dichloromethane and 10ml of dilute hydrochloric acid, shake for 15min, filter with filter paper, add potassium ferrocyanide test solution to the filtrate, shake well, and stand for 5min to form white precipitate or a small amount of blue precipitate, which is the genuine product, meeting the qualitative identification requirements of calcined in the eczema paste; if no precipitate is produced or obvious yellow or black precipitate is produced, it is determined to be unqualified; T2, quantitative determination: Determine by EDTA titration method, accurately weigh 1g of the eczema paste into a conical flask, add 10ml of dichloromethane and 30ml of dilute hydrochloric acid, continuously stir with a glass rod for 5min, stand for 10min, filter with filter paper, take the lower layer liquid, treat the filtrate with 30ml of concentrated ammonia solution and ammonia-ammonium chloride buffer (pH10.0) respectively, shake well, add 30ml of disodium hydrogen phosphate solution, ultrasonic vibration for 2min, filter again; wash the conical flask and residue with a mixture of 1 part of ammonia-ammonium chloride buffer (pH10.0) and 4 parts of water for 3 times, 10ml each time, combine the washing liquid and the filtrate, add 15ml of 30% triethanolamine solution and chrome black T indicator, titrate with 0.05mol / L EDTA titration solution until the solution changes from purple red to pure blue, calculate the content of zinc oxide in the eczema paste, and the content of zinc oxide in the eczema paste is ≥11.0%; Record the volume of EDTA titration solution consumed, and calculate the content of zinc oxide in the eczema paste according to the following formula: ZnO content (%) = (T×V×F) / (m×1000) ×100% In the formula: T is the titration degree of EDTA titration solution to zinc oxide (mg / mL); V is the volume of EDTA titration solution consumed (mL); F is the concentration correction factor of EDTA titration solution; m is the sample weight (g).

9. A method of quality testing of eczema cream as claimed in claim 8, wherein, In the quantitative determination of T2, the titration end point is that the solution changes from purple red to pure blue and does not fade for 30s.

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