A method for detecting the purity of lactobionic acid in the preparation process of erythromycin lactobionate

Abstract

The present application discloses a method for detecting the purity of lactobionic acid in the preparation process of erythromycin lactobionate, comprising the following steps: establishing a linear regression equation between conductivity and the concentration of sodium lactobionate solution, and deriving the relationship between the theoretical concentration of lactobionic acid and conductivity; detecting the actual concentration of lactobionic acid using titration; measuring the conductivity of the solution after titration, and calculating the theoretical concentration of lactobionic acid according to the relationship; the ratio of the actual concentration to the theoretical concentration is the purity. This detection method can detect the purity of lactobionic acid after cation exchange in real time, ensuring that its value is above the standard, which is conducive to the preparation of erythromycin lactobionate with stable quality and ensuring the safety of patients' medication. The above detection method is simple and easy to control, low cost and strong stability.

Description

Technical Field

[0001] The present application relates to the technical field of purity detection, and in particular to a method for detecting the purity of lactobionic acid in the preparation process of erythromycin lactobionate. Background Art

[0002] Erythromycin lactobionate is an inhibitor, but at high concentrations it also has bactericidal effects against certain bacteria. It has a wide range of indications, including clinical use in the treatment of acute tonsillitis and pharyngitis caused by hemolytic Streptococci and Streptococcus pneumoniae in patients allergic to penicillin; scarlet fever and cellulitis caused by hemolytic Streptococci; diphtheria and diphtheria carriers; gas gangrene, anthrax, and tetanus. Erythromycin lactobionate for injection is produced by salting erythromycin with lactobionic acid. The intermediate lactobionic acid is prepared using sodium lactobionic acid as the raw material, through exchange and separation of sodium ions on a cation exchange resin column. The quality of the lactobionic acid directly affects the quality of the erythromycin lactobionate product. If the sodium lactobionic acid is not fully exchanged during the preparation process, the resulting lactobionic acid will be of insufficient purity, affecting the salt formation process between erythromycin and lactobionic acid. Therefore, the content and purity of the lactobionic acid solution produced after the ion exchange is ensured.

[0003] Currently, the content of lactobionic acid intermediates in the preparation of erythromycin lactobionate in China can only be determined through a simple sodium ion content determination method, and the accurate purity range cannot be identified. However, a single test of lactobionic acid content cannot ensure whether the exchange process between sodium lactobionate and the cationic resin exchange column during the production process is normal. Abnormal conditions cannot be fed back in a timely manner, and thus the stability of the production process cannot be judged. The normality of the ion exchange process can only be judged based on experience in producing lactobionic acid or the results of the finished product of erythromycin lactobionate for injection. The stability of product quality cannot be guaranteed, which affects the safety of patients' medication. Summary of the Invention

[0004] The invention provides a method for detecting the purity of lactobionic acid in the preparation process of erythromycin lactobionate, so as to solve the technical problem in the prior art that the purity range of lactobionic acid cannot be accurately determined during the preparation process of erythromycin lactobionate, thereby failing to ensure the quality stability of the erythromycin lactobionate product.

[0005] To achieve the above object, the technical solution provided by the present invention is as follows:

[0006] A first aspect of the present invention provides a method for detecting the purity of lactobionic acid in the preparation process of erythromycin lactobionate, comprising the following steps:

[0007] S1. preparing sodium lactobionate solutions of different concentrations and measuring their conductivity respectively, establishing a linear regression equation between the conductivity and the concentration of the sodium lactobionate solution, and deriving a relationship between the theoretical concentration of lactobionic acid and the conductivity;

[0008] S2. Taking the lactobionic acid solution obtained during the preparation of erythromycin lactobionic acid, and detecting the actual concentration of lactobionic acid therein by titration;

[0009] S3, measuring the conductivity of the solution after titration in step S2, and calculating the theoretical concentration of lactobionic acid according to the relationship formula in step S1;

[0010] S4. The ratio of the actual concentration of the lactobionic acid obtained in step S2 to the theoretical concentration of the lactobionic acid obtained in step S3 is the purity of the lactobionic acid in the lactobionic acid solution.

[0011] Furthermore, in step S1, the concentration range of the prepared sodium lactobionate solution is 9.55 mg / mL to 33.42 mg / mL.

[0012] Furthermore, in step S1, there is a linear relationship between the conductivity and the concentration of the sodium lactobionate solution, and the linear equation is y=8.7692x-2.4712, wherein y is the concentration of sodium lactobionate and x is the conductivity.

[0013] Furthermore, in the step S1, the relationship between the theoretical concentration of lactobionic acid and the conductivity is z=(8.7692x-2.4712)*(molecular weight of lactobionic acid / molecular weight of sodium lactobionate).

[0014] Furthermore, the step S3 specifically includes: diluting the titrated solution in the step S2 to n times the volume of the lactobionic acid solution, and measuring its conductivity. The relationship between the theoretical concentration of lactobionic acid and the conductivity is a=n*(8.7692x-2.4712)*(lactobionic acid molecular weight / sodium lactobionic acid molecular weight).

[0015] The present invention provides a method for detecting the purity of lactobionic acid during the preparation of erythromycin lactobionate. Based on the linear relationship between the conductivity and concentration of a strong electrolyte solution at low concentrations, a conductivity method is used to find the linear relationship between the concentration of sodium lactobionate and its conductivity. The relationship between the theoretical concentration of lactobionic acid and the conductivity is further derived, thereby determining the purity of lactobionic acid in the solution after cation exchange. This ensures that the purity of lactobionic acid during the production of erythromycin lactobionate is above the standard, facilitates the preparation of erythromycin lactobionate with stable quality, and ensures the safety of medication for patients. The above-mentioned detection method is simple and easy to control, low in cost, and highly stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 1 is a graph showing the relationship between conductivity and concentration of the sodium lactobionate solution in Example 1 of the present invention;

[0018] Figure 2 This is a trend diagram of lactobionic acid purity data in Example 2 of the present invention. DETAILED DESCRIPTION

[0019] In order to help those skilled in the art better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of this application.

[0020] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the efficacy and purpose that can be achieved by this application.

[0021] The present invention provides a method for detecting the purity of lactobionic acid in the preparation process of erythromycin lactobionate, comprising the following steps:

[0022] S1. preparing sodium lactobionate solutions of different concentrations and measuring their conductivity respectively, establishing a linear regression equation between the conductivity and the concentration of the sodium lactobionate solution, and deriving a relationship between the theoretical concentration of lactobionic acid and the conductivity;

[0023] S2. Taking the lactobionic acid solution obtained during the preparation of erythromycin lactobionic acid, and detecting the actual concentration of lactobionic acid therein by titration;

[0024] S3, measuring the conductivity of the solution after titration in step S2, and calculating the theoretical concentration of lactobionic acid according to the relationship formula in step S1;

[0025] S4. The ratio of the actual concentration of lactobionic acid obtained in step S2 to the theoretical concentration of lactobionic acid obtained in step S3 is the purity of lactobionic acid in the lactobionic acid solution.

[0026] During the preparation of erythromycin lactobionate, the quality of the intermediate lactobionic acid significantly impacts the final product. To a certain extent, the higher the purity of the lactobionic acid, the more stable the prepared erythromycin lactobionate, resulting in higher product quality. However, since lactobionic acid is a monoprotic weak acid with no conjugated system and no UV absorption, its purity cannot be tested by liquid chromatography. Furthermore, lactobionic acid readily polymerizes at high temperatures, making its purity impossible to test by gas chromatography.

[0027] The present invention uses a conductivity method to determine the linear relationship between the conductivity and the concentration of a strong electrolyte solution at low concentrations. This method further derives the relationship between the theoretical concentration of lactobionic acid and its conductivity, thereby determining the purity of lactobionic acid in the solution after cation exchange. This ensures that the purity of lactobionic acid in the erythromycin lactobionate production process is above the standard, thereby facilitating the preparation of erythromycin lactobionate with stable quality and ensuring the safety of the drug for patients. The above-mentioned detection method is simple, easy to control, low-cost, and highly stable.

[0028] It can be understood that the theoretical concentration of lactobionic acid in step S1 refers to the assumption that the lactobionic acid solution removed in step S2 contains only lactobionic acid but no sodium lactobionate. Therefore, the linear relationship between the theoretical concentration of lactobionic acid and conductivity can be derived from the linear equation between the concentration of sodium lactobionate and conductivity.

[0029] The above steps specifically include:

[0030] 1. Determine the conductivity of sodium lactobionate solution at different concentrations.

[0031] (1) Take a blank purified water sample, control the temperature at 25°C, and measure its conductivity; (2) Prepare sodium lactobionate solutions of different concentrations, control the temperature at 25°C, and measure their conductivity.

[0032] 2. Establish a linear regression equation between conductivity and concentration of sodium lactobionate solution.

[0033] According to the measured data, a linear regression equation was established with conductivity as the X-axis and sodium lactobionate concentration as the Y-axis, and the correlation was determined to obtain a linear equation of sodium lactobionate concentration and conductivity.

[0034] 3. Determine the actual concentration of lactobionic acid in the lactobionic acid solution during the preparation of erythromycin lactobionate.

[0035] Use a pipette with a volume of V1 to accurately transfer the lactobionic acid solution and place it in a 250mL conical flask. Then add methyl red solution and titrate to the endpoint with a calibrated 0.1mol / L NaOH standard solution. Calculate the lactobionic acid concentration C based on the NaOH standard solution. The calculation formula is as follows: C = [C NaOH *V NaOH *M(lactobionic acid)] / V1, where M(lactobionic acid) is the molecular weight of lactobionic acid.

[0036] 4. Calculation of the theoretical concentration of lactobionic acid.

[0037] To establish a fixed concentration conversion relationship, regardless of the amount of NaOH standard solution added for titration, the titrated solution is diluted to n times the volume of the original lactobionic acid solution, and then the conductivity is measured. Assuming that the lactobionic acid solution removed in step 3 contains only lactobionic acid and no sodium lactobionate, the linear relationship between the theoretical concentration of lactobionic acid and conductivity is derived from the linear equation between sodium lactobionate concentration and conductivity, and the theoretical concentration of lactobionic acid is calculated.

[0038] 5. Calculation of the purity of lactobionic acid solution.

[0039] The purity of the lactobionic acid solution is obtained by the ratio of the actual lactobionic acid concentration measured by titration to the theoretical lactobionic acid concentration calculated by conductivity, thereby judging the exchange of lactobionic acid during the preparation of erythromycin lactobionic acid and improving the exchange efficiency of lactobionic acid in real time.

[0040] Example 1

[0041] 1. Determine the conductivity of sodium lactobionate solution at different concentrations.

[0042] (1) Measure the temperature, conductivity, and pH of the blank water sample and control the temperature at around 25°C.

[0043] (2) Weigh each batch of sodium lactobionate from batch A as shown in Table 1, dissolve it in approximately 50 mL of purified water, and transfer it to a 100 mL volumetric flask. Rinse with a small amount of purified water and adjust the volume to 100 mL. Stir until completely dissolved, and measure the temperature, conductivity, and pH of the sodium lactobionate solution.

[0044] Table 1 Preparation and measurement data of sodium lactobionate solution

[0045]

[0046] 2. Establish a linear regression equation between conductivity and sodium lactobionate solution concentration. Based on the data in Table 1, establish a linear regression equation with conductivity as the X axis and sodium lactobionate concentration as the Y axis. Figure 1 , judge its correlation and obtain the linear equation of sodium lactobionate concentration and conductivity.

[0047] Depend on Figure 1 It can be found that when the concentration of sodium lactobionate is in the range of 9.55 mg / mL to 33.42 mg / mL, there is a linear relationship with the conductivity. The linear equation is y=8.7692x-2.4712, where y is the concentration of sodium lactobionate and x is the conductivity. The square of the correlation coefficient is R 2 =0.9977, indicating that there is a good linear relationship between the concentration of sodium lactobionate and the conductivity of its solution.

[0048] Example 2

[0049] Use a 10 mL pipette to accurately pipette the lactobionic acid solution. During the preparation of erythromycin lactobionic acid, a total of 10 groups were taken from different batches. The lactobionic acid solution was placed in a 250 mL conical flask, and then methyl red solution was added dropwise. Titrate to the endpoint with a calibrated 0.1 mol / L NaOH standard solution. Calculate the lactobionic acid concentration C based on the NaOH standard solution using the following formula: C = [C NaOH *V NaOH = M(lactobionic acid) / 10, where M(lactobionic acid) is the molecular weight of lactobionic acid. The titrated solution was diluted to 100 mL and the conductivity of the solution was measured. See Table 2 for the data.

[0050] Table 2 10 groups of lactobionic acid solution titration experimental data

[0051]

[0052] Based on the linear relationship between the sodium lactobionic acid concentration and the conductivity of its solution in Example 1, the relationship between the theoretical lactobionic acid concentration and the above conductivity was derived as follows: z = 10 * (8.7692x - 2.4712) * (lactobionic acid molecular weight / sodium lactobionic acid molecular weight), i.e., z = 10 * (8.2623x - 2.3284), where z is the theoretical concentration of lactobionic acid and x is the conductivity. Substituting the conductivity of the titrated and diluted solution (see Table 2) into the above relationship yields the theoretical concentration of lactobionic acid. The results are shown in Table 2.

[0053] The purity of lactobionic acid can be calculated by comparing the actual concentration and theoretical concentration of lactobionic acid in the solution in Table 2 (actual concentration of lactobionic acid / theoretical concentration of lactobionic acid).

[0054] The purity data calculated in Example 2 were processed by 3σ in the form of a chart. The purity of lactobionic acid corresponding to the qualified preparation product was calculated according to the titration concentration / theoretical concentration, and the purity was plotted as a trend chart. Figure 2 .Depend on Figure 2From the purity trend chart of lactobionic acid, we can see that the upper control line (UCL) is 100.44% and the lower control line (LCL) is 97.65%. This indicates the purity range of lactobionic acid. During the production process, a provisional lactobionic acid standard can be set to detect abnormalities in a timely manner and take corresponding measures to ensure that the purity of the intermediate lactobionic acid remains above the standard and the potency of erythromycin lactobionic acid produced by the salt formation process of erythromycin and lactobionic acid is guaranteed.

[0055] Example 3

[0056] Statistical analysis was performed to verify the applicability of the linear equation. If the linear regression equation showed good correlation, standard solutions of sodium lactobionate from batches B and C were prepared at concentrations of approximately 20 mg / mL and 25 mg / mL, respectively. The conductivity was measured and the conductivity was substituted into the formula y = 8.7692x - 2.4712 to calculate the conductivity-converted concentration. The test deviation was then calculated to verify its applicability. Test deviation = [(converted conductivity concentration - prepared concentration) / prepared concentration)] * 100%. The test deviation results are shown in Table 3.

[0057] Table 3 Detection bias

[0058]

[0059] By measuring the conductivity of sodium lactobionate at different concentrations, a linear relationship between sodium lactobionate and conductivity was established within the concentration range of 9.55 mg / mL to 33.42 mg / mL. Once this linear relationship was established, the applicability of the linear equation was verified using standard solutions prepared from batches B and C of sodium lactobionate. The data in Table 3 show that the detection deviation is less than 2%, demonstrating the good applicability of this method.

[0060] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting the purity of lactobionic acid in the preparation process of erythromycin lactobionate, characterized in that: The following steps are involved: S1. preparing sodium lactobionate solutions of different concentrations and measuring their conductivity respectively, establishing a linear regression equation between the conductivity and the concentration of the sodium lactobionate solution, and deriving a relationship between the theoretical concentration of lactobionic acid and the conductivity; S2. Taking the lactobionic acid solution obtained during the preparation of erythromycin lactobionic acid, and detecting the actual concentration of lactobionic acid therein by titration; S3, measuring the conductivity of the solution after titration in step S2, and calculating the theoretical concentration of lactobionic acid according to the relationship formula in step S1; S4. The ratio of the actual concentration of the lactobionic acid obtained in step S2 to the theoretical concentration of the lactobionic acid obtained in step S3 is the purity of the lactobionic acid in the lactobionic acid solution.

2. The detection method according to claim 1, wherein In the step S1, the concentration of the prepared sodium lactobionate solution is in the range of 9.55 mg / mL to 33.42 mg / mL.

3. The detection method according to claim 2, characterized in that In step S1, there is a linear relationship between the conductivity and the concentration of the sodium lactobionate solution, and the linear equation is y=8.7692x-2.4712, wherein y is the concentration of sodium lactobionate and x is the conductivity.

4. The detection method according to claim 2, characterized in that In the step S1, the relationship between the theoretical concentration of lactobionic acid and the conductivity is z=(8.7692x-2.4712)*(molecular weight of lactobionic acid / molecular weight of sodium lactobionate).

5. The detection method according to any one of claims 2 to 4, characterized in that The step S3 specifically includes: diluting the titrated solution in the step S2 to n times the volume of the lactobionic acid solution, and measuring its conductivity. The relationship between the theoretical concentration of lactobionic acid and the conductivity is a=n*(8.7692x-2.4712)*(lactobionic acid molecular weight / sodium lactobionic acid molecular weight).

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