RU2396549C1 - Method of spectrophotometry analysis of asparcam for determination of potassium - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: at first, total potassium asparaginate and magnesium asparaginate is determined by a spectrophotometric method when measuring optical density of a coloured reaction product of asparaginate-ions and ninhydrin at wave length 568 nm; amount of magnesium asparaginate is determined by chelatometry titration. To calculate amount of potassium asparaginate in preparation Asparcam, the content of magnesium asparaginate is subtracted.

EFFECT: method provides exact results; it is sensitive, easy-to-implement, and profit-proved; it does not require toxic reagents.

2 ex, 6 tbl

Description

The invention relates to the field of pharmacy, and in particular to a method for the quantitative determination of potassium asparaginate in the drug Asparkam, and can be used in laboratories for standardization and quality control of medicines containing potassium asparaginate.

The closest analogues are methods for determining potassium asparaginate: emission spectrophotometry and acidimetric titration in a protogenic solvent medium [FS 42-1701-97 Asparkam tablets, FS 42-1600-91 Potassium asparaginate]. The principle of determination by emission spectrophotometry is as follows: a solution of the drug is sprayed in the form of an aerosol in a burner flame; a characteristic emission of potassium atoms arises, the intensity of which is measured on a flame photometer. Acidimetric titration in a protogenic solvent (acetic anhydride) in the presence of benzene is carried out with a solution of perchloric acid after preliminary acetylation of the amino group; the equivalence point is determined potentiometrically, graphically. One determination takes about two hours; the method requires the use of toxic reagents. Both methods give poorly reproducible results.

The aim of the present invention is to develop a simpler, economical, sensitive and accurate method for determining potassium asparaginate in the preparation "Asparkam". The goal is achieved using spectrophotometric methods. First, the sum of the potassium asparaginate and magnesium asparaginate is determined by measuring the optical density of the colored reaction product of the asparaginate ions with ninhydrin at a wavelength of 568 nm, using only potassium asparaginate as a standard sample; the amount of magnesium asparaginate is determined by complexometric titration [3]. When calculating the potassium content of asparaginate in the Asparkam preparation, the magnesium content of asparaginate in it is subtracted.

To achieve this goal, the following tasks were solved:

the absorption spectra of the reaction products of aspartic acid, potassium asparaginate and magnesium asparaginate with ninhydrin were taken, the analytical wavelength was selected;

optimal conditions for the reaction of aspartic acid with ninhydrin have been established;

the effect of magnesium ions on the absorption of the reaction product of aspartic acid with ninhydrin was studied;

verified compliance with the basic law of light absorption of the reaction products of aspartic acid, potassium asparaginate and magnesium asparaginate with ninhydrin;

Methods have been developed for the determination of aspartic acid, potassium asparaginate and magnesium asparaginate by a spectrophotometric method based on the reaction with ninhydrin.

A theoretical calculation of the individual components in potassium and magnesium asparaginate showed that the amount of asparaginate ion in them is almost the same (73.3%). Therefore, their reaction products with ninhydrin should have equal or very close optical density (Table 1). The values of specific and molar absorption indices indicate a high sensitivity of the procedure (Table 2).

Example 1. Determination of the potassium content of asparaginate in a mixture with magnesium asparaginate (1: 1 ratio, model mixture).

0.1750 g of potassium asparaginate and 0.1750 g of magnesium asparaginate (accurately weighed) are placed in a 100 ml volumetric flask, 50 ml of water heated to a temperature of 50-60 ° C are added, the contents of the flask are mixed for 5 minutes, cooled to 20 ° C, bring the volume of the flask with water to the mark and mix (solution A). 5 ml of solution A is placed in a volumetric flask with a capacity of 100 ml, the volume of the flask is adjusted to the mark with water and stirred (solution B). 2 ml of solution B is placed in a volumetric flask with a capacity of 100 ml, 4 ml of phosphate buffer solution with a pH of 6.4, 2 ml of a 1% solution of ninhydrin in ethyl alcohol 95%, 2 ml of a 0.05% aqueous solution of ascorbic acid are added, heated to boiling water bath for 30 min, quickly cooled to 20 ° C, bring the volume of the flask with water to the mark and mix. In parallel, an experiment is conducted with 2 ml of a 0.0175% solution of a working standard sample (RSO) of potassium asparaginate (magnesium asparaginate) and a control (2 ml of water). The optical density of the colored solutions was measured against a background of control on a spectrophotometer at 568 nm in a cuvette with a layer thickness of 1 cm.

The potassium content of asparaginate in the mixture in percent (X) is calculated by the formula:

,

,

where D ₁ is the optical density of the reaction product of a mixture of potassium asparaginate and magnesium asparaginate;

D ₂ is the optical density corresponding to the absorption of the reaction product of magnesium aspartate. Calculated by the formula:

D _{o (K)} is the optical density of the reaction product potassium asparaginate (OCO);

D _{o (Mg)} is the optical density of the reaction product of magnesium asparaginate (RSO);

a _{o (K)} - a sample of OCO potassium asparaginate, g;

a _{o (Mg)} —weighed portion of magnesium oxide aspartate, g;

a ₁ - the total sample of a mixture of potassium and magnesium asparaginate (0.3500 g);

Y is the magnesium content of asparaginate in the mixture (50%).

Analyzing the data of Table 3, we can conclude that the absorption of the reaction products of potassium asparaginate and magnesium asparaginate is almost the same, therefore, we can limit ourselves to measuring the optical density of only the reaction product of a solution of potassium phosphate asparaginate. Then the calculation formula is simplified:

Example 2. Determination of potassium content of asparaginate in tablets "Asparkam" composition:

potassium asparaginate (C ₄ H ₆ KNO ₄ * 1 / 2H ₂ O) 0.175 g,

magnesium asparaginate (C ₈ H ₁₂ MgN ₂ O ₈ * 4H ₂ O) 0.175 g,

excipients to obtain a tablet weighing 0.5 g.

An exact weighed powder of ground tablets in the range of 0.055-0.070 g is placed in a 250 ml volumetric flask, 50 ml of water heated to a temperature of 50-60 ° C are added, the contents of the flask are mixed for 5 min, cooled to 20 ° C, the volume of the flask is adjusted water to the mark and mix. The contents of the flask are filtered through a blue ribbon paper filter, discarding the first 10-15 ml of the filtrate. 2 ml of the filtrate will be placed in a 100 ml volumetric flask, 4 ml of a phosphate buffer solution with a pH of 6.4, 2 ml of a 1% solution of ninhydrin in ethyl alcohol 95%, 2 ml of a 0.05% aqueous solution of ascorbic acid are added, and heated in boiling water the bath for 30 minutes, quickly cooled to 20 ° C, bring the volume of the flask with water to the mark and mix. In parallel, an experiment is carried out with 2 ml of a solution of a working standard sample (RSO) of potassium asparaginate (0.045 g in 250 ml of water) and a control (2 ml of water). The optical density of the colored solutions was measured against a background of control on a spectrophotometer at 568 nm in a cuvette with a layer thickness of 1 cm.

The magnesium content of asparaginate in tablets is determined by the complexometric method (method FS 42-1598-98).

The potassium content of asparaginate in one tablet in grams (X) is calculated by the formula:

,

,

where D ₁ is the optical density of the test solution (the reaction product of a mixture of potassium asparaginate and magnesium asparaginate);

D _{o the} optical density of the reaction product of potassium asparaginate (RSO);

and _about - a hinge of OCO potassium asparaginate, g;

a ₁ - a portion of the powder of powdered tablets, g;

P is the average weight of one tablet, g;

U - the magnesium content of asparaginate in one tablet, determined by the complexometric method,

The results of the quantitative determination of potassium asparaginate in a model mixture of Asparkam tablets (in one tablet) are shown in Table 4, in various series of Asparkam tablets, in Table 5.

Comparative characteristics of the proposed method with the known (acidimetric titration in a protogenic solvent medium) are presented in table 6.

Table 1 The content of individual components in potassium and magnesium asparaginates The name of the substance and its formula M.m. Theoretically calculated content,% Is defined, % Asparaginate ion Mg ²⁺ (K ⁺ ) H ₂ O Asparaginate ion Magnesium Asparaginate Hydrate (C ₈ H ₁₂ MgN ₂ O ₈ * 4H ₂ O) 360.59 73,269 6,742 19,989 73.50 ± 0.85 Potassium Asparaginate Hydrate (C ₄ H ₆ KNO ₄ * 1 / 2H ₂ O) 180.21 73,303 21,697 5,000 73.54 ± 0.97

table 2 Detection limits of potassium asparaginate and magnesium asparaginate by spectrophotometric method by reaction with ninhydrin Substance Absorption rates Detection limit The concentration of the substance in the photometric solution, μg / ml E ^1% 1 cm ε mcg / ml μmol / l Magnesium asparaginate 1200 43300 0.208 0.577 0.875-7,000 (r = 0.999) Potassium asparaginate 1200 21600 0.208 1.16 0.875-7,000 (r = 1,000)

Table 4 The results of the determination of potassium asparaginate in the model mixture of Asparkam tablets A portion of the model mixture (a ₁ ), g D ₁ D _o (a _o ) Y X, g Metrological data [4] 0,0557 0.370 0.430 0.178 0.168

0,0607 0.408 0.172 S = 0.00303 0.0625 0.418 0.170

0,0663 0.435 (0.0448) 0.164

0,0688 0.460 0.170

Table 5 The results of determination of potassium asparaginate in various series of Asparkam tablets Series FS requirement 42-1701-97 Is defined

(при n=5)Magnesium asparaginate, g

(with n = 5) Potassium asparaginate, g

(with n = 5) one Magnesium Asparaginate 0.168-0.184 g 0.180 0.183 2 0.182 0.184 3 Potassium asparaginate 0.168-0.192 g 0.183 0.183

Table 6 Comparative characteristics of the proposed method with a known method of titration in a protogenic solvent medium Way A portion of the powder of powdered tablets, g Analysis time, min Toxic Reagents Used Metrological characteristic (at n = 5) Protogen solvent titration 2.5 120 Anhydride
vinegar - 10 ml; benzene-10 ml

S = 0.00572

Proposed 0,055-0,070 80 No

S = 0.00303

Information sources

1. FS 42-1701-97 Tablets "Asparkam".

2. FS 42-1600-91 Potassium asparaginate.

3. FS 42-1598-98 Magnesium asparaginate.

4. The State Pharmacopoeia of the USSR: issue 1. General methods of analysis. / Ministry of Health of the USSR. - 11th ed., Ext. - M .: Medicine, 1987.

Claims (1)

A method for the quantitative determination of potassium asparaginate in an Asparkam preparation, characterized in that the potassium asparaginate content in an Asparkam preparation is calculated by subtracting the magnesium asparaginate content determined by complexometric titration from the sum of potassium and magnesium asparaginates, the content of which is determined spectrophotometrically, by measuring the optical density of the colored the reaction product of asparaginate ions with ninhydrin at a wavelength of 568 nm, using only aspartate Ia.