A method for detecting benzoic acid in Tanre Qing injection

Abstract

The application discloses a detection method of benzoic acid in Tanreqing injection, which comprises the following steps: taking test sample solution and control sample solution for detection, wherein the Tanreqing injection is composed of Huangqi, Xiongdan powder, Yangjiao, Jinyinhua, Lianhua and propylene glycol, the control sample is benzoic acid, the chromatographic conditions of the detection are as follows: a chromatographic column with octylsilane bonded silica gel as the filler is adopted, one or more of acetonitrile, methanol and tetrahydrofuran is selected as the mobile phase A, the mobile phase B is an acid aqueous solution, an alkali aqueous solution and / or a buffer salt aqueous solution, the gradient elution program is as follows: 0-22 min, 95% of the mobile phase B, the flow rate is 0.5-1.5 ml / min, the column temperature is 20-40 DEG C, and the detection wavelength is 180-300 nm; and the content information of benzoic acid in the Tanreqing injection is obtained according to the detection result. The method is simple, efficient and rapid, and the detection of the benzoic acid content provides a theoretical basis for the quality control and in-depth research of the pharmacodynamic material basis of the Tanreqing injection.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical technology, specifically to a method for detecting benzoic acid in Tanreqing injection. Background Technology

[0002] Tanreqing Injection is made from five medicinal herbs: Scutellaria baicalensis, bear bile powder, goat horn, honeysuckle, and forsythia. It has the effects of clearing heat, detoxifying, and resolving phlegm. It has significant efficacy in treating upper respiratory tract infections, acute bronchitis, pneumonia, pulmonary tuberculosis complicated with pulmonary infection, advanced lung cancer complicated with pulmonary infection, and severe asthma complicated with infection.

[0003] There are no existing reports on methods for determining the benzoic acid content in Tanreqing injection. Summary of the Invention

[0004] Based on this, the present invention provides a method for detecting benzoic acid in Tanreqing injection, the method comprising the following steps:

[0005] The test solution and the reference solution were tested. The Tanreqing injection was composed of Scutellaria baicalensis, bear bile powder, antelope horn, honeysuckle, forsythia, and propylene glycol. The reference standard was benzoic acid.

[0006] The chromatographic conditions for this detection are as follows: a chromatographic column packed with octylsilane-bonded silica gel is used; mobile phase A is selected from one or more of acetonitrile, methanol, and tetrahydrofuran; mobile phase B is an aqueous solution of acid, an aqueous solution of alkaline solution, and / or an aqueous solution of buffer salt; the gradient elution program is: 0–22 min, 95% mobile phase B, flow rate of 0.5–1.5 ml / min, column temperature of 20–40 °C, and detection wavelength of 180–300 nm.

[0007] Based on the test results, the content information of benzoic acid in the Tanreqing injection was obtained.

[0008] Furthermore, the test solution was Tanreqing injection.

[0009] Furthermore, the preparation method of the reference solution includes: weighing an appropriate amount of benzoic acid and adding a methanol solution with a volume percentage concentration of 10% to 100% to prepare a reference solution containing benzoic acid with a concentration of 1 to 1000 μg / ml.

[0010] Furthermore, the volume percentage concentration of the methanol solution is 10% or 100%.

[0011] Furthermore, the chromatographic column is either a PICKERING C8 column or a DIKMA Diamonsil Plus C8 column.

[0012] Furthermore, the chromatographic column is a PICKERING C8 column.

[0013] Furthermore, the specifications of the chromatographic column are as follows: column length is 25cm, inner diameter is 4.6mm, and particle size is 5μm.

[0014] Furthermore, the aqueous acid solution, aqueous alkaline solution, and / or aqueous buffer salt solution are selected from one or more weak acids and their salts, weak bases and their salts of different concentrations.

[0015] Furthermore, the aqueous acid solution, aqueous alkaline solution, and / or aqueous buffer solution are selected from different concentrations of formic acid, glacial acetic acid, phosphoric acid, trifluoroacetic acid, formic acid and ammonium formate, acetic acid and sodium acetate, acetic acid and ammonium acetate, disodium hydrogen phosphate and sodium dihydrogen phosphate, disodium hydrogen phosphate and potassium dihydrogen phosphate, disodium hydrogen phosphate and citric acid, citric acid and sodium citrate, glycine and hydrochloric acid, or phthalic acid and hydrochloric acid.

[0016] Furthermore, the acidic aqueous solution is an acidic aqueous solution with a concentration of 1–10 mmol / L.

[0017] Furthermore, the aqueous solution of the acid is an aqueous solution of formic acid at a concentration of 1–10 mmol / L.

[0018] Furthermore, the aqueous solution of the acid is an aqueous solution of formic acid at a concentration of approximately 2 mmol / L.

[0019] Furthermore, the mobile phase B is an aqueous solution of formic acid at a concentration of about 2 mmol / L, which contains about 20 mmol / L of ammonium acetate.

[0020] Furthermore, the buffer salt solution is an aqueous solution of phosphate and / or an aqueous solution of acetate.

[0021] Furthermore, the pH value of the buffer salt solution is no greater than 7.0.

[0022] Furthermore, the flow rate is 0.8–1.2 ml / min, for example 1.0 ml / min.

[0023] Furthermore, the column temperature is 20–40°C, for example, about 30°C.

[0024] Furthermore, the detection wavelength is 200–300 nm, for example, 220 nm.

[0025] Furthermore, the volume of the test solution added is 2 to 10 μl, for example, about 5 μl.

[0026] Furthermore, the amount of the reference solution added is 2 to 10 μl, for example, about 5 μl.

[0027] Furthermore, the peak purity of the chromatographic peak corresponding to this reference standard is greater than 995.

[0028] Furthermore, the theoretical plate number, calculated based on the benzoic acid peak, is no less than 8000.

[0029] Furthermore, the resolution of the chromatographic peak corresponding to this reference standard is greater than 2.0.

[0030] Furthermore, this information is based on the recorded peak areas in the chromatograms of the test solution and the reference solution, and the content of benzoic acid in the Tanreqing injection is calculated using the external standard method.

[0031] Furthermore, the standard curve for benzoic acid is y = 20.9528x + 18.4469.

[0032] According to another aspect of the present invention, the above-described detection method is provided for use in the quality detection and / or quality evaluation and / or quality control of benzoic acid in Tanreqing injection.

[0033] The beneficial effects of this invention are:

[0034] The method of this invention is simple, efficient and rapid. By detecting the benzoic acid content, it provides a theoretical basis for the quality control of Tanreqing injection and in-depth research on its pharmacodynamic material basis. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without exceeding the scope of protection claimed by the present invention.

[0036] Figure 1 This is a chromatogram of the reference solution of the present invention. Wherein, 1 represents benzoic acid.

[0037] Figure 2 This is a chromatogram of the test solution of the present invention (i.e., Tanreqing injection, batch number: 1803207). Wherein, 1 represents benzoic acid. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Unless otherwise stated, all technical and scientific terms and abbreviations used herein have the meanings commonly understood by one of ordinary skill in the field of this invention or the field of application of such terms. While any methods, conditions, substances, or materials similar to or equivalent to those disclosed herein may be used in the practice of this invention, preferred methods, conditions, substances, or materials are described herein.

[0040] This invention is intended to cover all options, variations, and equivalents that may be included in the field of prior art as defined in the claims. Those skilled in the art will recognize many similar or equivalent methods and substances described herein that can be applied in the practice of this invention. This invention is by no means limited to the description of methods and substances.

[0041] The singular forms “a,” “an,” and “the” used in the specification and appended claims include plural indicators unless the context clearly specifies otherwise.

[0042] In this invention, the term "comprising" and "including" are synonymous. The terms "comprising," "including," "having," "containing," or any other variations thereof as used herein are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus.

[0043] As described in the background section, there are no reports in the prior art regarding methods for determining the benzoic acid content in Tanreqing injection. To address the above problem, this invention provides a method for detecting benzoic acid in Tanreqing injection, which includes the following steps:

[0044] The test solution and the reference solution were tested. The Tanreqing injection was composed of Scutellaria baicalensis, bear bile powder, antelope horn, honeysuckle, forsythia, and propylene glycol. The reference standard was benzoic acid.

[0045] The chromatographic conditions for this detection are as follows: a chromatographic column packed with octylsilane-bonded silica gel is used; mobile phase A is selected from one or more of acetonitrile, methanol, and tetrahydrofuran; mobile phase B is an aqueous solution of acid, an aqueous solution of alkaline solution, and / or an aqueous solution of buffer salt; the gradient elution program is: 0–22 min, 95% mobile phase B, flow rate of 0.5–1.5 ml / min, column temperature of 20–40 °C, and detection wavelength of 180–300 nm.

[0046] Based on the test results, the content information of benzoic acid in the Tanreqing injection was obtained.

[0047] In this invention, when temperature, flow rate, wavelength, velocity, time, concentration, injection volume, equivalent, concentration, or other values ​​or parameters are expressed as ranges, preferred ranges, or a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “20–40” is disclosed, the described range should be interpreted as including ranges “20–40”, “20–38”, “20–35”, “20–33”, “20–30”, “20–25”, “20–23”, “25–40”, “25–38”, “25–35”, “25–30”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0048] In a preferred embodiment, the test solution is Tanreqing injection.

[0049] In a preferred embodiment, the method for preparing the reference solution includes: weighing an appropriate amount of benzoic acid and adding a methanol solution with a volume percentage concentration of 10% to 100% to prepare a reference solution containing benzoic acid with a concentration of 1 to 1000 μg / ml.

[0050] In a preferred embodiment, the volume percentage concentration of the methanol solution is 10% or 100%.

[0051] In a preferred embodiment, the chromatographic column is a PICKERING C8 column or a DIKMA DiamonsilPlus C8 column.

[0052] In a preferred embodiment, the chromatographic column is a PICKERING C8 column.

[0053] In a preferred embodiment, the chromatographic column has the following specifications: a column length of 25 cm, an inner diameter of 4.6 mm, and a particle size of 5 μm.

[0054] In a preferred embodiment, the acid aqueous solution, alkaline aqueous solution, and / or buffer salt aqueous solution are selected from one or more weak acids and their salts, and weak bases and their salts of different concentrations.

[0055] In a preferred embodiment, the acidic aqueous solution, alkaline aqueous solution, and / or buffer salt aqueous solution is selected from formic acid, glacial acetic acid, phosphoric acid, trifluoroacetic acid, formic acid and ammonium formate, acetic acid and sodium acetate, acetic acid and ammonium acetate, disodium hydrogen phosphate and sodium dihydrogen phosphate, disodium hydrogen phosphate and potassium dihydrogen phosphate, disodium hydrogen phosphate and citric acid, citric acid and sodium citrate, glycine and hydrochloric acid, or phthalic acid and hydrochloric acid.

[0056] In a preferred embodiment, the acidic aqueous solution is an acidic aqueous solution with a concentration of 1 to 10 mmol / L.

[0057] In a preferred embodiment, the acidic aqueous solution is a 1-10 mmol / L formic acid aqueous solution.

[0058] In a preferred embodiment, the acidic aqueous solution is an aqueous solution of formic acid at a concentration of about 2 mmol / L.

[0059] In a preferred embodiment, the mobile phase B is an aqueous solution of formic acid at a concentration of about 2 mmol / L, containing about 20 mmol / L of ammonium acetate.

[0060] In this invention, "about" refers to a value within a range of ±5% of a specific value. For example, "about 2" includes 2 ± 5%, or from 1.9 to 2.1; "about 20" includes 20 ± 5%, or from 19 to 21.

[0061] In a preferred embodiment, the buffer salt solution is an aqueous solution of phosphate and / or an aqueous solution of acetate.

[0062] In a preferred embodiment, the pH value of the buffer salt solution is not greater than 7.0.

[0063] In a preferred embodiment, the flow rate is 0.8 to 1.2 ml / min, for example 1.0 ml / min.

[0064] In a preferred embodiment, the column temperature is 20–40°C, for example, about 30°C.

[0065] In this invention, "about" refers to a value within a range of ±5% of a specific value. For example, "about 30" includes 30 ±5%, or from 28.5 to 31.5.

[0066] In a preferred embodiment, the detection wavelength is 200–300 nm, for example, 220 nm.

[0067] In a preferred embodiment, the amount of the test solution added is 2 to 10 μl, for example, about 5 μl.

[0068] In a preferred embodiment, the amount of the reference solution added is 2 to 10 μl, for example, about 5 μl.

[0069] In this invention, "about" refers to a value within a range of ±5% of a specific value. For example, "about 5" includes 5 ± 5%, or from 4.75 to 5.25.

[0070] In a preferred embodiment, the peak purity of the chromatographic peak corresponding to the reference standard is greater than 995.

[0071] In a preferred embodiment, the theoretical plate number, calculated based on the benzoic acid peak, is not less than 8000.

[0072] In a preferred embodiment, the resolution of the chromatographic peak corresponding to the reference standard is greater than 2.0.

[0073] In a preferred embodiment, the information is obtained by calculating the benzoic acid content of the Tanreqing injection solution using the external standard method based on the corresponding peak areas in the recorded chromatograms of the test solution and the reference solution.

[0074] In a preferred embodiment, the standard curve of the benzoic acid is y = 20.9528x + 18.4469.

[0075] According to another aspect of the present invention, the above-described detection method is provided for use in the quality detection and / or quality evaluation and / or quality control of benzoic acid in Tanreqing injection.

[0076] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or conditions recommended by the manufacturer.

[0077] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0078] The features mentioned above in this invention, or the features mentioned in the embodiments, can be combined arbitrarily. All features disclosed in this patent specification can be used in any compositional form, and each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0079] Example

[0080] 1. Instruments and reagents

[0081] Agilent 1260 series high performance liquid chromatograph; acetonitrile was chromatographic grade (Merck), water was ultrapure water (Milli-Q), formic acid was analytical grade (Shanghai Lingfeng Chemical Reagent Co., Ltd.), ammonium acetate was analytical grade (Pharmaceutical Group Chemical Reagent Co., Ltd.); benzoic acid reference standard (China National Institutes for Food and Drug Control, 100419-201703, 99.9%), Tanreqing injection (provided by Shanghai Kaibao Pharmaceutical Co., Ltd.).

[0082] 2. Chromatographic conditions and system suitability

[0083] 2.1 Chromatographic conditions

[0084] Octylsilane-bonded silica gel was used as the packing material (column length 25 cm, inner diameter 4.6 mm, particle size 5 μm); acetonitrile-2 mmol / L formic acid (containing 20 mmol / L ammonium acetate) solution (5:95) was used as the mobile phase; benzoic acid has maximum absorption at 224 nm, so the detection wavelength was set at 220 nm.

[0085] 2.2 Parallelism Test of Reference Standard

[0086] Five precise pipettes of benzoic acid reference solution with a concentration of 53.2467 μg / ml were injected and analyzed six times. The peak areas were recorded, and the results are shown in Table 1.

[0087] Table 1 Parallelism Test of Reference Solution

[0088]

[0089]

[0090] 2.3 Examination of Linear Relationships

[0091] Accurately weigh an appropriate amount of benzoic acid reference standard, and dilute to volume with methanol to prepare a stock solution containing 1 mg per ml. Then, accurately pipette an appropriate amount of the stock solution and dilute with water to prepare a series of reference standard solutions at concentration levels of 1, 5, 10, 20, 50, 100, and 200 μg / ml. Accurately pipette 5 μl of each solution and inject it into the liquid chromatograph, recording the peak area. Plot a standard curve with concentration (μg / ml) on the x-axis and peak area on the y-axis, and perform regression analysis. The results show that the linear relationship between benzoic acid concentration and peak area is good in the range of 1.064934–212.9868 μg / ml. The regression equation is: y = 20.9528x + 18.4469, and the correlation coefficient r = 0.99995.

[0092] 3. Durability assessment

[0093] 3.1 Investigation of the chromatographic column

[0094] Due to the differences in packing materials and performance of different models of chromatographic columns from different manufacturers, in order to investigate the feasibility and versatility of the method of the present invention, three chromatographic columns were investigated: (1) PICKERING C8 (0.46×25cm, 5μm), (2) DIKMA DiamonsilPlus C8 (0.46×25cm, 5μm), and (3) Agilent Poroshell HPH-C8 (0.46×10cm, 2.7μm).

[0095] The chromatograms of the test sample obtained from all three chromatographic columns showed peaks with retention times consistent with the reference standard. The peaks obtained from the 25cm column were more symmetrical and sharper, with a resolution >2, meeting the requirements. It is recommended to use a 25cm C8 column for benzoic acid determination, especially the PICKERING C8 (0.46×25cm, 5μm) column, which provides better separation. Specific symmetry factors and theoretical plate numbers are shown in Table 2. Based on the results, the theoretical plate number, calculated based on the benzoic acid peak, should be no less than 8000.

[0096] Table 2 Results of durability studies for different chromatographic columns

[0097]

[0098]

[0099] 3.2 Stability Test

[0100] Take 20 μg / ml of the reference solution and the sample solution (batch number: 1803207), accurately pipette each five times, and inject them for analysis at 0, 2, 4, 8, 12, 16, and 24 hours (as shown in the figures). Figure 1 and Figure 2 As shown in the figure, the peak area was recorded, and the results showed that the reference solution and the sample solution remained basically stable within 24 hours.

[0101] 4. Precision test

[0102] 4.1 Repeatability Test

[0103] The sample (batch number: 1803207) was measured 6 times according to the method of the present invention. The results are shown in Table 3. The repeatability of the method of the present invention is good.

[0104] Table 3. Results of repeatability tests (n=6)

[0105]

[0106] 4.2 Accuracy Test

[0107] Accurately pipette 5.0 ml of the sample (batch number: 1803207; benzoic acid content: 23.247 μg / ml) into a 10 ml volumetric flask. Accurately add 0.25 ml, 0.5 ml, and 1.0 ml of benzoic acid reference solution (concentration: 212.9868 μg / ml), respectively. Dilute to 10 ml with water, filter, discard the initial filtrate, and perform the same determination as the test solution. Calculations are then performed. The results show that the recovery rate of the method of this invention is good.

[0108] 4.3 Intermediate Precision Test

[0109] To investigate the effect of random variation factors on precision, the benzoic acid content of three batches of samples was determined by different analysts on different dates and with different instruments and equipment according to the method of this invention. The results showed that the determination results by different analysts on different dates and with different instruments and equipment were basically consistent, and the intermediate precision of the method was good.

[0110] 5. Sample determination

[0111] The content of benzoic acid in the collected samples was determined according to the method of the present invention, and the results are shown in Table 4.

[0112] Table 4. Results of Benzoic Acid Content Determination in Samples

[0113]

[0114]

[0115]

[0116] 6. Limited Edition

[0117] Benzoic acid is a common intermediate in the organic synthesis of pharmaceuticals, pesticides, and fragrances, and is also frequently used as a food preservative. Benzoic acid has low toxicity, with a median lethal dose (LD50) of 1700 mg / kg (rat, oral), and an acceptable daily intake (ADI) of 0–5 mg / kg (FDA / WHO, 1994). According to the GRAS (Generally Recognized As Safe) certification of the Flavor and Extract Manufacturers Association (USA), benzoic acid has virtually no genotoxicity in vivo and is classified as a safe food additive. China's National Food Safety Standard for the Use of Food Additives (GB2760-2014) also classifies benzoic acid as a permitted synthetic flavoring agent for food use, specifying limits ranging from 0.2 to 2.0 g / kg depending on the type of food.

[0118] The tests revealed that the benzoic acid content was low, far below the aforementioned limit. From a safety perspective, based on this limit, the benzoic acid limit for Tanreqing Injection is set as "the benzoic acid content per 1 ml of this product should not exceed 200 μg," which, calculated based on a mass of 1 g per milliliter of injection, is 0.2 g / kg. All 34 batches of samples tested met this limit.

[0119] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, any changes or modifications made by those skilled in the art based on the ideas of the present invention, its specific implementation methods, and its application scope, are all within the scope of protection of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for detecting benzoic acid in Tanreqing injection, characterized in that, The detection method includes the following steps: The test solution and the reference solution were tested. The Tanreqing injection was composed of Scutellaria baicalensis, bear bile powder, goat horn, honeysuckle, forsythia, and propylene glycol. The reference standard was benzoic acid. The chromatographic conditions for the detection are as follows: a chromatographic column packed with octylsilane-bonded silica gel is used; mobile phase A is selected from one or more of acetonitrile, methanol, and tetrahydrofuran; mobile phase B is an aqueous solution of acid, an aqueous solution of alkaline solution, and / or an aqueous solution of buffer salt; the gradient elution program is: 0–22 min, 95% mobile phase B, flow rate of 0.5–1.5 ml / min, column temperature of 20–40 °C, and detection wavelength of 180–300 nm. Based on the test results, the content information of benzoic acid in the Tanreqing injection was obtained.

2. The detection method according to claim 1, characterized in that, The test solution was Tanreqing injection.

3. The detection method according to claim 1, characterized in that, The method for preparing the reference solution includes: weighing an appropriate amount of benzoic acid and adding a methanol solution with a volume percentage concentration of 10% to 100% to prepare a reference solution containing benzoic acid with a concentration of 1 to 1000 μg / ml. Preferably, the volume percentage concentration of the methanol solution is 10% or 100%.

4. The detection method according to claim 1, characterized in that, The chromatographic column is either a PICKERING C8 column or a DIKMA DiamonsilPlus C8 column. Preferably, the chromatographic column is a PICKERING C8 column; More preferably, the chromatographic column has the following specifications: a column length of 25 cm, an inner diameter of 4.6 mm, and a particle size of 5 μm.

5. The detection method according to claim 1, characterized in that, The acid aqueous solution, alkaline aqueous solution and / or buffer salt aqueous solution are selected from one or more weak acids and their salts, weak bases and their salts of different concentrations; Preferably, the acidic aqueous solution, alkaline aqueous solution, and / or buffer salt aqueous solution are selected from formic acid, glacial acetic acid, phosphoric acid, trifluoroacetic acid, formic acid and ammonium formate, acetic acid and sodium acetate, acetic acid and ammonium acetate, disodium hydrogen phosphate and sodium dihydrogen phosphate, disodium hydrogen phosphate and potassium dihydrogen phosphate, disodium hydrogen phosphate and citric acid, citric acid and sodium citrate, glycine and hydrochloric acid, or phthalic acid and hydrochloric acid; More preferably, the acid aqueous solution is an acid aqueous solution with a concentration of 1 to 10 mmol / L; More preferably, the acidic aqueous solution is a 1-10 mmol / L formic acid aqueous solution; More preferably, the acidic aqueous solution is an aqueous solution of formic acid at a concentration of about 2 mmol / L; More preferably, the mobile phase B is an aqueous solution of formic acid at a concentration of about 2 mmol / L, which contains about 20 mmol / L of ammonium acetate; More preferably, the buffer salt aqueous solution is a phosphate aqueous solution and / or an acetate aqueous solution; More preferably, the pH value of the buffer salt solution is not greater than 7.

0.

6. The detection method according to claim 1, characterized in that, The flow rate is 0.8–1.2 ml / min, for example, 1.0 ml / min; Preferably, the column temperature is 20–40°C, for example, about 30°C; Preferably, the detection wavelength is 200–300 nm, for example, 220 nm; More preferably, the amount of the test solution added is 2 to 10 μl, for example, about 5 μl; More preferably, the amount of the reference solution added is 2 to 10 μl, for example, about 5 μl.

7. The detection method according to claim 1, characterized in that, The peak purity of the chromatographic peak corresponding to the reference standard is greater than 995. Particularly preferred, the theoretical plate number, calculated based on the benzoic acid peak, is not less than 8000; Particularly preferred is that the resolution of the chromatographic peak corresponding to the reference standard is greater than 2.

0.

8. The detection method according to claim 1, characterized in that, The information is obtained by calculating the benzoic acid content of the Tanreqing injection solution according to the external standard method based on the corresponding peak areas in the recorded chromatograms of the test solution and the reference solution.

9. The detection method according to claim 1, characterized in that, The standard curve for benzoic acid is y = 20.9528x + 18.4469.

10. Use of the detection method according to any one of claims 1 to 9 in the quality detection and / or quality evaluation and / or quality control of benzoic acid in Tanreqing Injection.

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