Method for determining content of ferrous iron in ferric carboxymaltose injection

Abstract

The invention provides a method for determining the content of ferrous iron in a ferric carboxymaltose injection. The method comprises the following steps: (1) preparing an iron (II) standard solution; (2) preparing an electrolyte solution; and (3) determining the iron (II) concentration in the test sample by adopting a polarography method: carrying out differential pulse volt-ampere scanning by adopting a polarograph in the electrode potential range of-0.1 volt to-0.4 volt, recording a polarogram, determining the potential and peak height of an iron (II) peak, circularly adding the iron (II) standard solution for four times according to a standard addition method, recording the iron (II) peak detected at-250 + / -100 mV, and determining the iron (II) concentration in the test sample according to the iron (II) concentration detected at-250 + / -100 mV. And calculating the iron (II) concentration in the test solution according to a standard addition method. According to the method, the concentration of the divalent iron in the test sample can be measured by using the polarograph through a standard addition method, the content of the divalent iron in the test sample can be calculated through a formula, and the method has the advantages of simplicity and convenience in operation, high specificity, good sensitivity and good accuracy; the method can be used for content determination and quality control of ferrous iron in the ferric carboxymaltose injection, and has a great application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and detection, and in particular to a method for determining the content of divalent iron in ferric carboxymaltose injection. Background Art

[0002] Ferric carboxymaltose injection is a new type of intravenous iron preparation, suitable for iron deficiency anemia that is ineffective or cannot be treated orally. Compared with traditional intravenous iron preparations (such as iron dextran, iron sucrose, etc.), ferric carboxymaltose has no sensitization and antigenicity, and has better safety; it allows large-dose rapid administration, avoiding the problems of frequent punctures and time-consuming injections, and has a very broad market application prospect. Ferric carboxymaltose itself is a complex composed of iron (III) hydroxide and carboxymaltodextrin, in which the iron content and valence distribution are very important quality standards.

[0003] At present, the total iron content and valence distribution in carboxymaltose iron injection are mainly determined by titration, atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-OES) and voltammetric polarography. However, these existing methods have defects. The titration method is cumbersome and prone to valence changes; AAS and ICP-OES can only determine the total iron content, and cannot distinguish the valence state of the iron element; polarography was first included in the USP-NF Iron Sucrose Injection monograph quality standard, and the test result is the R value (ratio of divalent iron to trivalent iron signal), which needs to be combined with AAS or ICP-OES total iron content to calculate the divalent iron ratio. The operation is cumbersome and complicated, and is affected by many factors such as the instrument parameters of the polarograph. The reproducibility of the R value is poor, and the accuracy of the valence state distribution of the iron element is poor. Summary of the invention

[0004] In view of the shortcomings of the prior art described above, the object of the present invention is to provide a method for determining the content of divalent iron in carboxymaltose iron injection, using a polarograph and quantifying the content of divalent iron in the product by the standard addition method. The method has the advantages of simple operation, high specificity, good sensitivity and good accuracy, and can be used for the determination and quality control of divalent iron in carboxymaltose iron injection.

[0005] To achieve the above purpose and other related purposes, a method for determining the content of divalent iron in ferric carboxymaltose injection is provided, comprising the following steps: (1) Prepare iron (II) standard solution: dilute ammonium ferrous sulfate and ascorbic acid with water to prepare a 500 ppm iron (II) standard solution; (2) Prepare electrolyte solution: dilute sodium pyrophosphate with water and adjust the pH to 7.0 ± 0.05 with hydrochloric acid; (3) Determine the concentration of iron (II) in the sample by polarography: inject the electrolyte solution into a polarographic cell equipped with a dropping mercury electrode, insert the electrode into the liquid in the polarographic cell, and pass nitrogen into the liquid for 5 minutes. Take 30 μL of the sample solution and add it to the polarographic cell. Pass nitrogen for 30 seconds. Use a polarographic trace metal analyzer (i.e., polarograph) to perform differential pulse voltammetry scanning in the electrode potential range of -0.1 V to -0.4 V, record the polarogram, and determine the potential and peak height of the iron (II) peak. Repeat the standard addition method for 4 times, add 30 μL of the iron (II) standard solution, pass nitrogen for 30 seconds, and record the value at -250±100. A group of iron (II) peaks detected at mV are linearly plotted with the added concentration of the iron (II) standard solution and the iron (II) peak height, and the iron (II) concentration in the test solution is calculated by the standard addition method, that is, the concentration of the added iron (II) standard solution is used as the abscissa and the corresponding iron (II) peak height is used as the ordinate to draw a linear equation, and the iron (II) concentration in the test solution is deduced from the distance from the intersection of the extended line of the test point on the Y axis and the X axis to the origin through the linear equation; (4) Calculate the iron (II) content in the test sample according to the following formula:

[0006] In the formula C: Iron (II) concentration in the test sample, μg / mL; V: dilution volume of the test sample, mL; m: sample weight of the test sample, mg.

[0007] Note: The C value is automatically generated by the instrument.

[0008] Preferably, in step (1), 700 mg of ammonium ferrous sulfate and 100 mg of ascorbic acid are weighed into a 200 ml brown volumetric flask, and water is added to dissolve and dilute to obtain a 500 ppm iron (II) standard solution. The iron (II) standard solution is prepared and used immediately to avoid the change of the valence state of iron (II).

[0009] Preferably, in step (2), 11.15 g of sodium pyrophosphate is weighed, 200 mL of water is added to dissolve it, the pH value is adjusted to 7.0±0.05 with hydrochloric acid, and water is added to make the volume to 250 mL, thereby preparing an electrolyte solution.

[0010] Preferably, in step (3), the polarograph is a Metrohm 884 VA Computrace voltammetric polarograph or other instruments with equivalent functions.

[0011] More preferably, the main parameters of the polarograph are as follows: DME working electrode, stirrer speed of 2000 rpm, stirring start time of 5 seconds, equilibrium time of 5 seconds, voltage step of 0.015 volts, pulse amplitude of 0.05 volts, pulse time of 0.04 seconds, and voltage step time of 0.5 seconds.

[0012] Preferably, in step (3), the iron (II) peak height is detected at -250 mV.

[0013] As described above, a method for determining the content of ferrous iron in carboxymaltose ferric injection of the present invention has the following beneficial effects: the present invention uses a polarograph and the standard addition method to determine the concentration of ferrous iron in the test sample, and the content of ferrous iron in the test sample can be calculated by a formula. The method has the advantages of simple operation, high specificity, good sensitivity and good accuracy, and can be used for the determination and quality control of ferrous iron in carboxymaltose ferric injection, and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the polarogram of carboxymaltose iron injection in Example 1 of the present invention.

[0015] Figure 2 It is the linear regression equation of the standard addition method established in Example 1 of the present invention.

[0016] Figure 3 The potential and peak height data of the iron (II) peak measured in each cycle in Example 1 of the present invention. DETAILED DESCRIPTION

[0017] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0018] Example 1 A method for determining the content of divalent iron in ferric carboxymaltose injection comprises the following steps: Prepare the iron (II) standard solution: weigh 700 mg of ammonium ferrous sulfate and 100 mg of ascorbic acid into a 200 ml brown volumetric flask, add water to dissolve and dilute to volume to obtain a 500 ppm iron (II) standard solution; (2) Prepare the electrolyte solution: weigh 11.15 g of sodium pyrophosphate, add 200 ml of water to dissolve, adjust the pH to 7.0 ± 0.05 with hydrochloric acid, and add water to dilute to 250 ml; (3) Determine the iron (II) concentration in the sample by polarography: Take 9.97 mL of the electrolyte solution and inject it into a polarographic cell equipped with a dropping mercury electrode. Insert the electrode into the liquid in the polarographic cell and pass nitrogen gas into the liquid for 5 minutes. Take 30 μL of the sample solution (newly opened carboxymaltose iron injection) and add it into the polarographic cell. Pass nitrogen gas for 30 seconds. Use a polarograph (Metrohm884VA Computrace voltammetric polarograph, parameters: DME working electrode, stirrer speed 2000 rpm, stirring time 5 seconds, equilibrium time 5 seconds, voltage step 0.015 V, pulse amplitude 0.05 V, pulse time 0.04 seconds, voltage step time 0.5 seconds), differential pulse voltammetric scan in the electrode potential range of -0.1 V ~ -0.4 V, record polarogram, measure the potential and peak height of iron (II) peak, add 30 μL of iron (II) standard solution by standard addition method 4 times, test after nitrogen is passed for 30 seconds, record a group of iron (II) peaks detected at -250 mV, and calculate the iron (II) concentration in the test solution by standard addition method.

[0019] The polarogram of the carboxymaltose iron injection is shown in Figure 1 The potential and peak height data of the Fe(II) peak in each cycle are shown in Figure 3 .

[0020] The linear regression equation was established by using the concentration of iron (II) standard solution added and the peak height of iron (II). Figure 2 . Linear regression equation Y=3.392*10 -9 -6.557*10 -6 X, correlation coefficient R 2 =0.99058, satisfying R 2 The requirement is ≥0.990, and the linear relationship is good.

[0021] (4) Calculate the iron (II) content in the test sample according to the following formula:

[0022] In the formula C: Iron (II) concentration in the test sample, μg / mL; V: dilution volume of the test sample, mL; m: sample weight of the test sample, mg.

[0023] In summary, the present invention uses a polarograph and can determine the concentration of divalent iron in the test sample by the standard addition method, and can calculate the content of divalent iron in the test sample by the formula, and the method has the advantages of simple operation, high specificity, good sensitivity and good accuracy, and can be used for the determination and quality control of divalent iron in carboxymaltose iron injection, and has great application prospects. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0024] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for determining the content of divalent iron in carboxymaltose iron injection, characterized in that, The steps include: (1) Preparation of iron (II) standard solution: dilute ammonium ferrous sulfate and ascorbic acid with water to prepare a 500 ppm iron (II) standard solution; (2) Prepare electrolyte solution: dilute sodium pyrophosphate with water and adjust the pH to 7.0 ± 0.05 with hydrochloric acid; (3) Determine the concentration of iron (II) in the sample by polarography: inject the electrolyte solution into a polarographic cell equipped with a dropping mercury electrode, insert the electrode into the liquid in the polarographic cell, and pass nitrogen into the liquid for 5 minutes. Take 30 μL of the sample solution and add it to the polarographic cell. Pass nitrogen for 30 seconds. Use a polarograph to perform differential pulse voltammetry scanning in the electrode potential range of -0.1 V to -0.4 V. Record the polarogram and measure the potential and peak height of the iron (II) peak. Add 30 μL of the iron (II) standard solution by the standard addition method for 4 cycles. Pass nitrogen for 30 seconds and test. Record the iron (II) peak detected at -250±100 mV. Use the iron (II) standard solution concentration and the iron (II) peak height as a linear relationship. Calculate the iron (II) concentration in the sample solution by the standard addition method.

2. The method according to claim 1, characterized in that The method further comprises step (4): calculating the iron (II) content in the test sample according to the following formula: In the formula C: Iron (II) concentration in the test sample, μg / mL; V: dilution volume of the test sample, mL; m: sample weight of the test sample, mg.

3. The method according to claim 1 or 2, characterized in that: In step (1), weigh 700 mg of ammonium ferrous sulfate and 100 mg of ascorbic acid into a 200 ml brown volumetric flask, add water to dissolve and adjust the volume to obtain a 500 ppm iron (II) standard solution.

4. The method according to claim 1 or 2, characterized in that: In step (2), 11.15 g of sodium pyrophosphate was weighed, 200 mL of water was added to dissolve it, the pH value was adjusted to 7.0±0.05 with hydrochloric acid, and water was added to make the volume to 250 mL, thereby preparing an electrolyte solution.

5. The method according to claim 1 or 2, characterized in that: In step (3), the polarograph is a Metrohm 884 VA Computrace voltammetric polarograph or other instruments with equivalent functions.

6. The method according to claim 5, characterized in that The main parameters of the polarograph are as follows: DME working electrode, stirrer speed of 2000 rpm, stirring start time of 5 s, equilibrium time of 5 s, voltage step of 0.015 V, pulse amplitude of 0.05 V, pulse time of 0.04 s, and voltage step time of 0.5 s.

7. The method according to claim 1 or 2, characterized in that: In step (3), the iron (II) peak height is detected at -250 mV.

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