RU2027170C1 - Method of ethioneamide quantitative determination - Google Patents

Abstract

FIELD: analytical chemistry. SUBSTANCE: method of extraction-photometric assay involves the formation of ionic associate of ethioneamide and violet acidic anthraquinone dye, its extraction with chloroform from the acid medium, destruction with alkali solution following by measurement of optical density of released dye which is equivalent with ethioneamide quantitatively. Direct relationship between optical density value of solution to be examined and preparation quantity is at the range 30-150 mcg/ml. EFFECT: improved method of assay. 1 dwg, 4 tbl

Description

 The invention relates to analytical chemistry, and in particular to methods for the quantitative determination of ethionamide-2-ethyl-4-thiocarbanoyl-4-pyridine by the extraction-photometric method, and can be used in pharmaceutical analysis for the quantitative determination of a drug in a substance, in dosage forms and in objects biological origin.

 A known method for the determination of ethionamide [1] by reaction with nickel glyoximate and potassium thiocyanate. Its disadvantage is low sensitivity and low accuracy of determination.

 Closest to the invention is a method for the quantitative determination of ethionamide by the photometric method using 0.1% sodium pentacyanoaminoferroate (PCAF) [2], in which the analyzed sample is dissolved in methanol and processed by PCAF. The colored mixture is photometric at a wavelength of 550 nm.

 The disadvantage of this method is the low sensitivity, the use of a hard-to-reach, toxic and volatile solvent of methanol, as well as the fact that the method does not allow to determine ethionamide in biological fluids.

 The aim of the invention is to increase the accuracy and sensitivity of the determination of ethionamide, as well as expanding the scope.

 The goal is achieved in that in the method for the quantitative determination of ethionamide by dissolving the analyzed sample in water, processing the resulting solution with a color reagent in the presence of a universal buffer solution, followed by extraction with chloroform and photometry in the amount of a color reagent using a 0.04% aqueous solution of quantitative violet anthraquinone dye, processing they are carried out in the presence of a universal buffer solution at pH 2.5 with the ratio of the sample, the buffer solution of the color reagent and chlorofo Rma 1: 7: 2: 10 and photometer at a wavelength of 590 nm the aqueous layer.

 The method is as follows.

 For the quantitative determination of ethionamide, a standard aqueous solution containing 0.15 mg of this preparation in 1 ml is used. As a reagent, a 0.04% aqueous solution of acid violet anthraquinone dye 1-hydroxy-9,10-anthraquinone-4-amino (meta-tolyl sulfonic acid) [2] is used, in an acidic medium with ethionamide forming a colored ionic associate, which in the same medium is extracted with chloroform. A universal buffer mixture is used to create a specific pH of the medium. In a chloroform extract, when treated with a solution of alkali, the ionic associate of ethionamide and dye is destroyed. The liberated dye passes into the alkaline solution, the amount of which is equivalent to the amount of ethionamide that entered into its interaction.

 Data on the selection of optimal conditions for the quantitative determination of ethionamide are presented in table. 12.

 From the results given in table. 1, it follows that the ionic associate of ethionamide and reagent in large quantities is extracted with chloroform at pH 2.0-3.0. In further studies, a solution of universal buffer mixture with a pH of 2.5 was used.

 From the data given in table. 2, it follows that for the complete formation of the ionic associate between ethionamide and the reagent, it is necessary to add 1.8-2.2 ml of a 0.04% solution of acid violet anthraquinone dye. In further studies, 2 ml of a 0.04% solution of the indicated reagent were added.

 It was found that in order to achieve optimal conditions for the quantitative determination of ethionamide based on the interaction of the drug with an acid violet anthraquinone dye, it is necessary to take 1-2 ml of a solution of ethionamide containing in this volume from 0.03 to 0.15 mg of this drug, 7 ml of solution universal buffer mixture with a pH of 2.5, 2 ml of a 0.04% solution of reagent and 10 ml of chloroform.

 The drawing shows a graph of the optical density of the test solution on the amount of ethionamide in it, where the amount of ethionamide C is plotted horizontally, and the optical density D.

 EXAMPLE 1. Determination of ethionamide in a substance.

 1 ml of an aqueous solution of ethionamide (from 0.03 to 0.15 mg per sample) is added to the separatory funnel, 7 ml of a universal buffer mixture with a pH of 2.5, 2 ml of a 0.04% aqueous solution of the reagent and 10 ml of chloroform are added . The mixture is shaken for 3 minutes, then left to separate phases for 10 minutes. After phase separation, the chloroform layer is transferred to a separatory funnel containing 12 ml of 0.2 N. sodium hydroxide solution and shake for 10-15 seconds. After sedimentation of the phases, the colored alkaline solution is separated and the optical density of the colored alkaline solution is measured using a photoelectric colorimeter (using a filter that has an effective wavelength of 590 ± 10 nm, a cuvette of 20 mm). As a comparison solution, take 0.2 N. sodium hydroxide solution.

 Construction of a calibration graph. In the separatory funnels contribute 0.2; 0.4; 0.6; 0.8; 1.0 ml of a standard solution of ethionamide, 10 ml of which contains 0.15 mg of the drug. Then, in all the separatory funnels, a UBS solution (pH 2.5) is added up to 8 ml, 2 ml of a 0.04% solution of reagent, 10 ml of chloroform each and proceed as described above. Using the obtained values of optical density (table. 3), build a calibration graph (see drawing). Subordination to the Bouguer-Lambert-Beer law is observed in the range of ethionamide concentrations from 0.03 to 0.15 mg / ml.

 Using the calibration graph, determine the amount of the analyzed drug. This method can be used to quantify ethionamide in both substance and dragee.

 PRI me R 2. The quantitative determination of ethionamide in pills 0.25.

 For the quantitative determination of ethionamide in dragees, dragees were taken, weighed (accurate weighed) and ground. 0.02 (exact weighed) was taken from the crushed dragee, quantitatively transferred to a 100 ml volumetric flask, dissolved and adjusted to the mark with a universal pH 2.5 buffer mixture. For analysis, 1 ml of this solution was taken, 7 ml of universal buffer mixture and 2 ml of a 0.04% reagent solution were added. Then they acted analogously to example 1.

, где D_o - оптическая плотность стандартного раствора;
D_x - оптическая плотность исследуемого образца;
а_о - содержание этионамида в 1 мл стандартного раствора.The calculation of the concentration of ethionamide in dragees can be made not only according to the calibration schedule, but also according to the following formula:
a _x =

where D _o is the optical density of the standard solution;
D _x is the optical density of the test sample;
and _about - the content of ethionamide in 1 ml of a standard solution.

 Preparation of a standard solution.

 0.015 mg of ethionamide substance is placed in a 100 ml volumetric flask and dissolved in 50 ml of distilled water, the volume of the solution is adjusted to the mark with water. For analysis, take 1 ml of a standard solution.

 The assessment of the quantitative determination of ethionamide in substance and dragee is presented in table. 4.

 PRI me R 3. Determination of ethionamide in biological material.

 20 mg of ethionamide was added to 100 g of the finely divided corpse liver and left for a day with periodic stirring. The studied preparation was isolated from the liver three times with water acidified with oxalic acid to pH 2.0. The combined extracts were filtered through 4-5 layers of gauze and centrifuged. Ethionamide from extracts was extracted with chloroform from an alkaline medium (pH 8.0-9.0). Dry residues from acidic and alkaline extracts after distillation of chloroform were dissolved in 100 ml of universal buffer mixture (pH 2.5). For quantitative determination, 1-2 ml of this solution was taken and then acted as described in Example 1. After determining the optical density, the amount of ethionamide extracted from the biological material was calculated according to a calibration graph. Impurities isolated together with ethionamide from biological material do not interact with the reagent and do not interfere with the determination of ethionamide isolated from biological material.

Claims (1)

 METHOD FOR QUANTITATIVE DETERMINATION OF ETHIONAMIDE by dissolving the analyzed sample in water, processing the resulting solution with a color reagent in the presence of a universal buffer solution, followed by extraction with chloroform and photometry, characterized in that, in order to increase the accuracy and sensitivity of the determination and expansion of the scope of the method, 0 are used as a color reagent , 04% aqueous solution of acid violet anthraquinone dye, they are processed in the presence of a universal buffer th solution at pH 2,5 in a ratio of sample buffer tsvetoreagenta chloroform and 1: 7: 2: 10 and photometric at 590 nm the water layer.

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