RU2517160C1 - Method of determining bendazole - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: solutions of an analyte (bendazole) and a comparison sample are prepared. The solvent used to prepare the test solutions is 0.1M hydrochloric acid solution. The comparison sample used is benzoic acid or phenolphthalein. Optical density of the analyte (bendazole) solution and the comparison sample is measured on a spectrophotometer with analytical wavelength of 270 nm. The results are calculated using a formula by entering a calculation factor of 0.181 into said formula when determining using benzoic acid and 0.293 when determining using phenolphthalein.

EFFECT: method increases reproducibility of measurement results, reduces cost, labour input, analytical error and enables unification of the analysis method.

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Description

The present invention relates to medicine and can be used in the Centers for quality control and certification of medicines for standardization and quality control of medicines.

The current drug quality control system requires pharmaceutical science to continuously improve the effectiveness of existing methods of analysis.

Among modern methods of pharmaceutical analysis, optical control methods occupy an important place, which are widely used both for the purposes of quantitative determination and for the control of purity and identification of drugs.

There are various methods for the determination of bendazole, which is used in medical practice as an antispasmodic, antihypertensive and immunomodulating agent.

There is a method of acidimetric quantitative determination of bendazole (dibazole) in a substance, which consists in preparing a solution of dibazole in glacial acetic acid, adding a solution of mercury oxide acetate, followed by titration with a 0.1 M solution of perchloric acid using crystalline violet as an indicator (FS 42-1548- 97 "Dibazole", C 3). The titrimetric method for the quantitative determination of dibazole recommended by regulatory documents is highly toxic, insensitive, and time-consuming.

The closest and adopted by us for the prototype is a method for determining bendazole by preparing solutions of the test substance and a solution of a working standard sample (RSO) of the analyte using a solution of hydrochloric acid as a solvent, 0.01 M, followed by spectrophotometry at wavelengths 267, 270, 273 , 276, 279 nm and calculation of the results according to the formula (Vergeichik et al. "Quantitative determination of dibazole in dosage forms by the method of derivative spectrophotometry" // Pharmacy, M., Medicine, 1 988, No. 5, C.41-43). In this work, a spectrophotometric method for the determination of bendazole using a derivative spectrophotometry is proposed, the solvent is a 0.01 M solution of hydrochloric acid. This method leads to both an increase in time and an increase in the error of quantification.

The use of the spectrophotometric method for the analysis of the substance of bendazole is difficult due to the lack of a state standard sample for this drug. The production of such a standard sample is expensive, since it finds application only in pharmaceutical analysis. Therefore, the method of determination using state standard samples will be inaccessible to many laboratories.

In the proposed method, the authors proposed to use a 0.1 M solution of hydrochloric acid as a solvent. The optimal solvent provides stabilization of the test solution, which increases the reproducibility of the determination results and reduces the error of analysis. The use of a 0.1 M hydrochloric acid solution as a solvent increases the stability of the test solution and increases the analysis sensitivity by a factor of 2, which is 0.0001 g / ml. The use of optimal optical density values and the use of a 0.1 M hydrochloric acid solution as a solvent reduces the analysis error, which confirms the comparison of the determination errors of E = 0.27% for the proposed method and E = 2.3% for a close analogue, therefore, the proposed method allows reduce the accuracy of the analysis compared to the prototype. In addition, the reproducibility of the determination results is increased, which confirms the comparison of the variances of two sample sets using the F-distribution with f ₁ = f ₂ = 10, p = 99% for the proposed method and a close analogue. It was established F _ex = 10.72 with F _tab = 8.47, therefore, the proposed method has higher reproducibility.

The use of benzoic acid and phenolphthalein as a standard sample in the proposed method reduces the error and cost of analysis. An important role in the analysis of external comparison samples is played by the specific value of the conversion factor, which allows conversion to the test substance. The accuracy of determining the conversion factor significantly affects the achievement of a technical result. The experimental studies conducted by the authors proved that the conversion factor of 0.181 when determined by benzoic acid and 0.293 when determined by phenolphthalein results in reproducible and accurate results, which leads to a determination error of 0.27%. The value of the conversion factor must be indicated in the calculation formula. The conversion factor is found from the expression:

, $${\mathrm{TO}}_{PeR}=\frac{E_{\mathrm{at}\mathrm{about}\mathrm{from}}}{E_{\mathrm{about}\mathrm{from}}}$$

,

wherein E _Sun - specific absorption rate comparison sample benzoic acid or phenolphthalein with analytical wavelength;

E _OS - the specific absorption rate of the working sample comparing the determined (investigated) substance at the analytical wavelength (determined during the development of the method).

The method proposed by the authors allows the analysis both in tablets and in substance, i.e. is unified.

The technical result of the proposed method is to increase the reproducibility of the determination results, reducing the analysis error, unifying the analysis methods, reducing the cost of analysis.

The technical result is achieved by preparing a solution of the analyte and a standard reference sample, followed by spectrophotometry and calculation of the results by the formula.

New in achieving the technical result is that a 0.1 M hydrochloric acid solution is used as a solvent for the preparation of the solution to be determined, and benzoic acid or phenolphthalein is used as a standard reference sample, the optical density of solutions is measured at an analytical wavelength of 270 nm, in the calculation formula the results enter the value of the conversion factor of 0.181 when determined by benzoic acid and 0.293 when determined by phenolphthalein.

The studied substance changes the absorption spectrum depending on the pH of the medium. Based on the experimental data and the properties of bendazole, the authors proved that a 0.1 M solution of hydrochloric acid is the optimal solvent for spectrophotometric determination. The optimal solvent provides stabilization of the test solution, which increases the reproducibility of the determination results and reduces the error of analysis.

The absorption spectrum of bendazole in a 0.1 M solution of hydrochloric acid (pH 1.1) is characterized by two absorption maximums at wavelengths of 270 ± 1 nm and 275 ± 1 nm and a minimum absorption at 245 ± 1 nm. A further increase in pH to 12.5 leads to a bathochromic shift of the absorption maxima by 4 nm with a simultaneous hypsochrome shift, as well as the appearance of another maximum at a wavelength of 244 ± 1 nm. Storage of bendazole solutions for three days showed that during this time no significant changes occurred with the solutions. The most stable solutions of bendazole at pH 1.1 - 3.0, therefore, as an optimal solvent for spectrophotometric determination of bendazole, you can offer a 0.1 M solution of hydrochloric acid (pH 1.1).

A wavelength of 270 nm was chosen as analytical for the quantitative determination of bendazole. At this wavelength, there is a minimal error in the measurement of the optical density, since this wavelength is the maximum absorption of the analyte in a 0.1 M hydrochloric acid solution.

Based on the dependence established by the authors, according to which, substances for which the interval between the analytical wavelength and the maximum (or minimum) absorption of these comparison samples does not exceed half the half-width of their absorption band can be used as comparison samples in the proposed method, the authors use benzoic acid and phenolphthalein, since the optimal absorption region in which they can be used is 266-280 nm and 268-282 nm, respectively. Benzoic acid and phenolphthalein are mass-produced by the hc category industry, they have GOSTs (GOST 10521-78 and 5850-72) that regulate their quality. A solution of benzoic acid and phenolphthalein in a 0.1 M hydrochloric acid solution is stable during storage for a long time. The use of benzoic acid and phenolphthalein in the proposed method reduces the error of analysis.

Comparative analysis with the prototype shows that the claimed technical solution is characterized in that a 0.1 M solution of hydrochloric acid is used as a solvent for the preparation of the test solution, and benzoic acid or phenolphthalein is used as a comparison sample, spectrophotometry is carried out at an analytical wavelength of 270 nm and introduced in the formula for calculating the results, the value of the conversion factor is 0.181 when determined by benzoic acid and 0.293 when determined by phenolphthalein, which corresponds to cr the novelty of the invention.

A new set of features provides an increase in the reproducibility of the determination results, a decrease in the analysis error, reduces the cost and analysis time, unifies the analysis methods, which meets the criterion of "industrial applicability".

In the analysis of known solutions, it was revealed that they lack information on the influence of distinguishing features on the achievement of the technical solution, therefore, the invention meets the criterion of "inventive step".

The method is as follows. Prepare a solution of a benzoic or phenolphthalein acid comparison sample for the analysis of bendazole. For this, the exact mass of benzoic or phenolphthalein acid 0.1000 g or 0.0700 g, respectively, is placed in a volumetric flask with a capacity of 50 ml, dissolved in 20 ml of ethyl alcohol, the volume of the solution is brought up to the mark with alcohol and stirred. 2 ml of a solution of benzoic acid or phenolphthalein is placed in a 50 ml volumetric flask, the solution volume is adjusted with a 0.1 M hydrochloric acid solution to the mark and stirred.

Then a quantitative determination of bendazole in the substance is carried out. For this, the exact mass of bendazole (0.2000 g) is placed in a 100 ml volumetric flask, dissolved in 20 ml of ethyl alcohol, the volume of the solution with this alcohol is adjusted to the mark, and stirred. 1 ml of the resulting solution was placed in a volumetric flask with a capacity of 100 ml, the volume of the solution was adjusted with a 0.1M solution of hydrochloric acid to the mark and stirred. The optical density of the test solution and the solution of the external reference sample is measured on a spectrophotometer at a wavelength of 270 nm in cuvettes with a working layer length of 10 mm. As a comparison solution, a 0.1 M hydrochloric acid solution is used.

The calculation of the results of the quantitative determination of bendazole is carried out according to the formula

$$X\%=\frac{D_x\cdot a_{\mathrm{at}\mathrm{about}\mathrm{from}}\cdot V_{\mathrm{one}}\cdot V_2\cdot V_3^{/}\cdot {\mathrm{TO}}_{PeR}\cdot \mathrm{one\; hundred}\cdot \mathrm{one\; hundred}}{D_{\mathrm{at}\mathrm{about}\mathrm{from}}\cdot a_x\cdot V_3\cdot V_{\mathrm{one}}^{/}\cdot V_2^{/}\left(\mathrm{one\; hundred}-W\right)},$$

where D _x and D _VOS are the optical densities of the analyte and reference sample, respectively;

a _x and a are the _eastern weights of the analyte and the reference sample, respectively;

V ₁ and V ₂ - the volumes of the prepared solution of the analyte;

V ₃ - the volume of an aliquot of the analyte;

- объемы приготовленного раствора образца сравнения; $$V_{\mathrm{one}}^{/}\mathrm{and}{V}_2^{/}$$

- volumes of the prepared solution of the reference sample;

- объем аликвоты образца сравнения; $$V_3^{/}$$

- the volume of an aliquot of the reference sample;

100 - coefficient for conversion to percent;

W - humidity,%;

To _per - 0.181 - the value of the conversion factor for benzoic acid and 0.293 the value of the conversion factor for phenolphthalein in a 0.1 M hydrochloric acid solution.

The content of bendazole should be at least 99.0% in terms of dry matter.

The proposed method is illustrated by the following examples.

Example 1. Prepare solutions of the analyte and the reference sample as described above. Optical densities of the prepared solutions are measured on a spectrophotometer. Next, they calculate the results according to the formula, using the corresponding value of the conversion factor.

When determining bendazole by benzoic acid, the following results were obtained:

D _x = 0.9393; _Sun D = 0.6799; and _x = 0.0998; and _Boc = 0.1998; humidity 0.5%; X = 99.97%. The results are statistically processed and presented as follows:

=99,91; S²=0,1459; S=0,3819; $$S_{\overline{x}}$$

=0,1208; ΔХ=0,2729; Е%=0,273; S_r=0,004.When n = 10; $$\overline{X}$$

= 99.91; S ² = 0.1459; S = 0.3819; $$S_{\overline{x}}$$

= 0.1208; ΔX = 0.2729; E% = 0.273; S _r = 0.004.

This example confirms that the content of bendazole meets the requirements of the regulatory document (FS 42-1548-97).

When determining bendazole by phenolphthalein, the following results were obtained:

D _x = 0.9208; _Sun D = 0.7545; and _x = 0.2010; and _vos = 0.0701 humidity 0.5%; X = 99.82%. The results are statistically processed and presented as follows:

=99,90; S²=0,0836; S=0,2891; $$S_{\overline{x}}$$

=0,0914; ΔХ=0,2066; Е%=0,207; S_r=0,003.When n = 10; $$\overline{X}$$

= 99.90; S ² = 0.0836; S = 0.2891; $$S_{\overline{x}}$$

= 0.0914; ΔX = 0.2066; E% = 0.207; S _r = 0.003.

This example confirms that the content of bendazole meets the requirements of the regulatory document (FS 42-1548-97).

The proposed method using samples of comparison of benzoic acid and phenolphthalein proved to be optimal for the quantitative determination of bendazole in tablets of 0.02 g, and also allows for the determination of dosage uniformity and control of the test of “dissolution” of bendazole tablets.

The method of quantitative determination of bendazole in the dosage form differs from the method of quantitative determination of bendazole in a substance only by the preparation of the test solution.

Example 2. For the quantitative determination of bendazole in tablets of 0.02 g, take the exact mass of powder of ground tablets 0.25 g and placed in a volumetric flask with a capacity of 100 ml, dissolved in 20 ml of alcohol, shaken for 5 minutes. Bring the volume of the solution with alcohol to the mark and mix. The solution is filtered, the first 10-15 ml of the filtrate is discarded, and 10 ml of the resulting solution is placed in a 100 ml volumetric flask, the volume of the solution is adjusted with a 0.1 M hydrochloric acid solution to the mark and stirred.

The content of bendazole in tablets of 0.02 g should be 0.018-0.022 g, based on the average weight of one tablet.

When analyzing bendazole tablets of 0.02 g for benzoic acid, the results are as follows:

D _x = 0.7447; _Sun D = 0.5528; and _x = 0.2573; and _Boc = 0.1014; P _cf. = 0.2618; X = 0.0201 g. The results are statistically processed and presented as follows:

=102,76; S²=4,8377; S=2,1995; $$S_{\overline{x}}$$

=0,6955; ΔХ=1,5719; Е%=1,530; S_r=0,021.When n = 10; $$\overline{X}$$

= 102.76; S ² = 4.8377; S = 2.1995; $$S_{\overline{x}}$$

= 0.6955; ΔX = 1.5719; E% = 1.530; S _r = 0.021.

The content of bendazole in dosage forms meets the requirements of the regulatory document.

When analyzing bendazole tablets of 0.02 g for phenolphthalein, the results are as follows:

D _x = 0.7328; _Sun D = 0.7447; and _x = 0.2524; and _Boc = 0.0829; P _cf. = 0.2618; X = 0.0198 g. The results are statistically processed and presented as follows:

=95,16; S²=5,0351; S=2,2439; $$S_{\overline{x}}$$

=0,7096; ΔХ=1,6037; Е%=1,685; S_r=0,024.When n = 10; $$\overline{X}$$

= 95.16; S ² = 5.0351; S = 2.2439; $$S_{\overline{x}}$$

= 0.7096; ΔX = 1.6037; E% = 1,685; S _r = 0.024.

The content of bendazole in dosage forms meets the requirements of the regulatory document.

Example 3. To determine the uniformity of dosage of bendazole tablets of 0.02 g, one tablet is placed in a volumetric flask with a capacity of 100 ml and dissolved in 20 ml of alcohol, shaken for 5 minutes. Bring the volume of the solution with alcohol to the mark and mix. The solution is filtered, the first 10-15 ml of the filtrate is discarded and 10 ml of the resulting solution is placed in a 100 ml volumetric flask, the solution volume is adjusted to the mark with a 0.1 M hydrochloric acid solution and stirred.

The optical density of the resulting solution is measured on a spectrophotometer at a wavelength of 270 nm in a cuvette with a working layer length of 10 mm. As a comparison solution, a 0.1 M hydrochloric acid solution is used. At the same time, the optical density of the solution of an external reference sample of benzoic acid or phenolphthalein is measured.

The permissible deviation from the nominal value is not more than 15% for ten analyzed tablets.

When analyzing ten tablets of bendazole of 0.02 g each, a maximum deviation from the nominal content of +5.94 and -9.35% was obtained.

Example 4. To control the test of "dissolution" of bendazole tablets, a unified methodology was taken as the basis (GFHI ed., C.159-160). A 0.1 M hydrochloric acid solution was used as a dissolution medium, a dissolution time of 30 minutes, a volume of dissolution medium of 1000 ml, a rotation speed of 100 rpm, and a temperature of (37 ± 1) ° C.

When analyzing bendazole tablets of 0.02 g, one tablet is placed in a basket, after 30 minutes of rotation a sample is taken. The solution is filtered. The optical density of the test solution is measured on a spectrophotometer at a wavelength of 270 nm in cuvettes with a working layer length of 10 mm. As a comparison solution, a 0.1 M hydrochloric acid solution is used. At the same time, the optical density of the solution of the benzoic acid or phenolphthalein acid comparison sample is measured.

According to (GFXI ed. S.159-160), at least 75% of the active substance from the content in the dosage form within 30 minutes must pass into the dissolution medium.

When analyzing bendazole tablets of 0.02 g, the release of the substance was: 99%, 98%, 100%, 99%, 98%, 100%, 99%, 98%, 99%, 99% for ten tablets, respectively.

The proposed method for the determination of bendazole using a benzoic acid or phenolphthalein acid comparison sample allows to increase the reproducibility of the analysis, reduce the analysis error, reduce its cost, eliminate the use of toxic reagents and unify the analysis methods.

Claims (1)

A method for the quantitative determination of bendazole by spectrophotometry of the analyte and a standard reference sample, characterized in that a 0.1 M solution of hydrochloric acid is used as a solvent for the preparation of the determined solution, spectrophotometry is carried out at an analytical wavelength of 270 nm, and benzoic acid or phenolphthalein is used as the reference sample and the calculation of the results is carried out according to the formula:

,
where D _x and D _VOS are the optical densities of the analyte and the reference sample, respectively;
a _x and a are the _eastern samples of the substance being determined and the reference sample, respectively;
V ₁ and V ₂ - the volumes of the prepared solution of the analyte;
V ₃ - the volume of an aliquot of the analyte;

and

- volumes of the prepared solution of the reference sample;

- the volume of an aliquot of the reference sample;
100 - coefficient for conversion to percent;
W - humidity,%;
To _per . - 0.181 - the value of the conversion coefficient for benzoic acid and 0.293 the value of the conversion coefficient for phenolphthalein in a 0.1 M hydrochloric acid solution.