SU883713A1 - Phenobarbital quantitative determination method - Google Patents

Description

one

The invention relates to analytical chemistry, and more specifically to methods for the quantitative determination of phenobarbital.

The known method for the quantitative determination of phenobarbital, I conclude (diis in the spectrophotometry of the sample being analyzed in a medium of 0.1 sodium hydroxide solution P.

Hex; the selection method is low selectivity - the determination is hampered, for example, caffeine or nicotinic acid.

The closest to the proposed invention of the technical essence and the achieved result is a method for quantitative determination of phenobarbital, concluded in the spectrophotometry of the analyzed sample in the presence of alkali - ammonia solution relative to the comparison solution - ammonia solution t2.

The disadvantage of the method is low selectivity - nicotinic acid and caffeine sodium benzoate, for example, interfere with the determination.

The purpose of the invention is the determination of the selectivity.

The goal is achieved by the fact that according to the proposed method

Quantitative determination of phenobarbital, consisting in spectrophotometry of the analyzed sample in the presence of alkali relative to the phenobarbital solution, use the solution of phenobarbital as a comparison solution.

The method for determining phenobarbital and the drug is as follows.

ten

About 0.15 g of phenobarbital (exact weight) is introduced into a 1000 ml volumetric flask, dissolved by heating in water and, after cooling, brought to the mark with water. (A similar solution can be obtained by dissolving the indicated sample, using a 200 ml volumetric flask, and then 20 ml of the resulting solution is diluted in a 100 ml volumetric flask). Then in two flasks 1 ml of the solution was added. Water to 10 ml is added to the first flask, 1 ml of a buffer solution with a pH of 9.0 is added to the second and also

25 is made up to 10 ml with water (i.e. 9 and 8 ml of water are added, respectively). The optical density of the second solution is then determined at 240 nm in a cuvette with a layer thickness of 1 cm, using

30 ka, as the first comparison solution

solution (ie, the increase in optical density d 0).

The content of the preparation is found by the method using a standard solution or according to a calibration graph.

The standard solution is prepared by growing, turning out 0.1500 g of phenobarbital in 1000 MP of water, as specified. 2 MP flasks are added with 1 MP of the standard solution and then, similarly to the subject, the increase in the optical density of the standard solution (L DO) is determined.

The content of the drug in percent (XJ is determined by the formula

X APO 00015-1000-100 USD

DO - the increase in optical density

test solution D0 (5 - increase in optical density

standard solution; a - the sample of the investigated solution of the drug,

To build a calibration graph, 0.5, 1.0, 2.0, 3.0, and 4.0 ml of successively in small flasks or tubes are added in succession with exactly 0.01% phenobarbital solution and water is added to 10 ml (series 1) . The indicated quantities of the same phenobarbital solution and 1 ml of a buffer solution with a pH of 9.0 are also successively added to another series of the same vessels. Then the contents in the flasks are made up to 10 ml with water (series 2). The optical density of the solutions of series 2 is determined using, as a comparison solution, the corresponding solutions of series 1 under the conditions described above. Using the values of phenobarbital concentration and optical density, build a calibration graph.

Note. To obtain a buffer solution (pH 9.0), 50 ml of a 0.2 molar solution of boric acid with potassium chloride are mixed with 21.3 ml of a 0.2 molar solution of sodium hydroxide and brought to 200 l with water.

The results of the determination of phenobarbital in the preparation are given in Table. one.

Table

x) Standard solution 1:10

Example 1. Quantitative determination of phenobarbitgsh in drug mixtures. .Mix number 1.

Phenobarbital0,003

Nicotinic acid 0.001 Methionine 0.05

Glucose2,2

1, the powder (precise weight) was diluted with gentle heating in water in a 100 ml volumetric flask and, after cooling, brought to the mark with water. 5 ml of the resulting solution are added to a dry tube and water is added to 10 ml. 5 MPs of the same solution, 1 ml of a ferrous solution with a pH of 9.0 and also brought to 10 ml are also added to the second tube. Then, the optical density of the second solution is determined on a spectrophotometer at a wavelength of 240 nm in a cuvette with a layer thickness of 1 cm, using the first solution as a comparison solution. In the case of using a standard (0.015%) solution of phenobarbital, proceed in the same way as above, while taking

YO him in the amount of 1 ml. Content

phenobarbital in 1 powder (X) is calculated by the formula

DR- 0.00, 1QO-B

X DOO-5a Where 40 is the increase in optical density of the test dOD solution — the increase in optical density of the standard solution; B is the average weight of the powder, G} a is the sample, g. Mixture No. 2. Phenobarbital 0.02. Nicotinic acid 0.01 Methionine gluconate calcium at 0.25 1 powder (exact weight) is dissolved with a slight heating in water in a 200 ml volumetric flask and after oh. Liands are adjusted to the mark. 1.5 ml of the solution obtained are added to a dry tube and water is added to 10 ml. The second Test tube is also filled with ml of the test solution, 1 m of buffer solution with a pH of 9.0, and also adjusted to 10 MP. Then they proceed in the same way as in mixture No. 1, beginning with the words, then the optical density of the second solution is determined. The content of phenobarbitgsha in 1 porciac (X) is calculated by the formula Y yP 0.00015-200-X D Do-1, 5-a Where dO is the increase in optical density of the test solution, the increase in optical density of the standard solution; B is the average weight of the powder, g} a is the sample, g. Mixture 3. Phenobarbital 0.01. Caffeine sodium benzoate 0.002 Calcium gluconate 0.25 Sugar 0.2. 1 powder (weighed accurately) was stirred in a dry flask with 10 ml of ethanol (96 °) for 5 minutes and then filtered. 9 ml of water were added to 1 ml of clear filtrate (solution A, it was also used to determine sodium cofein benzoate), 1.5 ml of solution A were added to a dry tube, and water was added to 10 ml. 1.5 ml of Solution A and 1 ml of buffer solution with pH are also introduced into the second tube and also made up to 10 ml. Then, they proceed in a similar way as in mixture 1, beginning with the words, then determining the optical density of the second solution .... The content of phenobarbital in 1 powder (X) is calculated by the formula dD-0.00015-10-10-6. dOv- 1. 1.5.a where LO is the increase in the optical density of the test solution, d 0 (, is the increase in the optical density of the standard solution / V is the average weight of the powder, g and a is the weight, g. Caffeine sodium benzoate. The optical density of solution A (see the definition of phenobarbital at 270 in a 1 cm cuvette. As a comparison solution, an aqueous solution of phenobarbitol 1: pa is used at a concentration corresponding to that in solution A, taking into account the content of phenobarbital found. sodium caffeine content 1 Powder (X) is found as D-10-10-B. 220.1.100 -a, where O is the optical density of the test solution; 220.1 is the specific indicator of the optical density of caffeine-sodium benzoate .j B is the average weight of the powder, g, ° is the weight, g. If it is necessary to determine not by specific absorption indicator (for example, with insufficient resolution of the instrument), use a standard solution. For this purpose, along with the definition, as indicated above, the optical density of a standard 0.002% solution of caffeine-benzoite sodium at 270 nm is established, the cuvette is 1 cm, the comparison solution is water . The content of sodium caffeine-benzoate in 1 powder is found in the formula V D-0.002-10-10-B DO100-a where DQ is the optical density of a 0.002% solution of caffeine-benzoate (, sodium. The remaining designations are given above. Results of the determination of phenobarbital in medicinal mixtures (example) are given in Table 2.

Nicotinic acid 0.001

Methionine 0.05 Glucose 0.2

;

0.0015% standard phenobarbital solution

Nicotinic acid 0.01

Methionine gluconate calcium 0.25

Caffeine benzoate: sodium 0,002

Calcium gluconate 0.25

0.2

Sugar

Claims (2)

Table 2 8837 Thus, the proposed method for the quantitative determination of phenobarbital makes it possible to selectively, without separation of concomitant substances, readily and with a small amount of time to determine this preparation, g Formula of the invention. The method of quantitative determination. Neither phenobarbital by spectrophotometry of the analyzed sample in the presence of alkali relative to the comparison solution is distinguished by 310 n and that, in order to increase the selectivity of the determination, phenobarbital solution is used as the comparison solution. Sources of information taken into account during the examination : 1. Solovyova G. D., Nazarova V. G, and Gulimov E. E. Proceedings of the II All-Congress of Pharmacists, Riga, 1974, p. 142-143. 2. Timofeeva N.T. and Shemkin FM, Spectrophotometric determination in the ultraviolet region of mixtures containing barbiturates, Pharmacia, 1967, 1, p. 755-60 (prototype).