RU2106617C1 - Method of quantitatively determining novocaine amide - Google Patents

Abstract

FIELD: analytical methods. SUBSTANCE: method includes measuring optical density of sample at 280 nm wavelength using reference Novocaine solution. Specific absorption value of reference solution is measured at 290 nm wavelength and Novocaine amide concentration in sample is calculated using formula: x = A₂₈₀•271,8•100/E $\genfrac{}{}{0ex}{}{\text{1\%}}{\text{1cm}}$ •272,7 where A₂₈₀ is optical density of the sample under investigation, E $\genfrac{}{}{0ex}{}{\text{1\%}}{\text{1cm}}$ specific absorption value of reference solution measured at 290 nm, 272.7 molar mass of Novocaine, and 271.8 molar mass of Novocaine amide. EFFECT: increased productivity and reliability of analysis due to using stable reference substance. 2 dwg, 2 tbl

Description

 The invention relates to the medical industry and the field of scientific research and can be used to control the quality of procainamide used as a pharmaceutical preparation.

 Known methods for the quantitative determination of nonokainamide based on the formation of Schiff bases with p-dimethylaminobenzaldehyde in an acidic medium, followed by photocolorimetric determination [1] and spectrophotometric determination using novocainamide as standard working standards (RSO) [2]. The literature describes methods for spectrophotometric determination of the molar masses of organic compounds of various classes. In this case, the following conditions must be met: in the absorption spectrum of the analyte and the standard substance, there should not be groups giving an absorption band that overlaps with the band of the chromophore common to them; for the compounds used, the Bouguer law [3] must be observed.

 The use of novocainamide as a working standard sample (RSO) for the quantitative determination of this drug in dosage forms is difficult due to its instability [4].

 The purpose of the invention is to increase the reproducibility and reliability of the results of the analysis of novocainamide, achieved by using its structural analogue, novocaine, as possessing greater stability. Registration of the results is carried out by a spectrophotometer.

 The essence of the invention is as follows, the study of the light absorption spectra of aqueous solutions of novocaine (1) and novocainamide (2) in the wavelength region of 270-300 nm showed that, despite the shift of the spectral curve, its shape and character do not change (Fig. 1). In addition, there is a linear relationship between the molar mass and the optical density of both aqueous solutions of these substances and their Schiff bases (Fig. 2). The data obtained allow the use of novocaine as an OCO for the determination of novocainamide.

 The method is illustrated by the following examples.

 Example 1. An exact weighed portion of novocainamide weighing 0.05 g is dissolved in water in a volumetric flask with a capacity of 200 ml, adjusted to the mark with water. To 2 ml of the solution add 2 ml of a 0.05% solution of p-dimethylaminobenzaldehyde in concentrated sulfuric acid and 6 ml of water. Similarly prepare a solution of novocaine, used as a standard. The optical density of the resulting solutions is measured at a wavelength of 440 nm. The results of determination of procainamide are shown in table 1.

где
A₂₈₀ - оптическая плотность исследуемого раствора новокаинамида;
E $\genfrac{}{}{0ex}{}{\text{1\%}}{\text{1см}}$ - удельный показатель поглощения новокаина при длине волны 290 нм
Результаты определения новокаинамида предложенным способом приведены в таблице 2.Example 2. 1 ml of a 10% solution of novocainamide is placed in a volumetric flask with a capacity of 100 ml and adjusted to the mark with water. 1 ml of the resulting solution was transferred to a 100 ml volumetric flask, adjusted to the mark with water and the absorbance was measured at a wavelength of 280 nm. In parallel, prepare a solution of the OCO novocaine. To do this, about 0.1 g of novocaine (accurately weighed) is dissolved in water in a 100 ml volumetric flask and adjusted to the mark with water. 1 ml of the resulting solution is transferred into a 100 ml volumetric flask, adjusted to the mark with water, the absorbance is measured at a wavelength of 290 nm, and the specific absorption rate of novocaine is calculated. Given that the molar masses of procainamide and procaine are respectively 271.8 and 272.7, the calculation of the content of procainamide (g / ml) was carried out according to the formula

Where
A ₂₈₀ - optical density of the studied solution of novocainamide;
E $\genfrac{}{}{0ex}{}{\text{one\%}}{\text{1cm}}$ - specific absorption rate of novocaine at a wavelength of 290 nm
The results of determination of procainamide by the proposed method are shown in table 2.

 Literature.

 1. Auto N 141486, class G 01 N 21/78, 1961.

 2. The United States Pharmacopeia. USP XXII. Official from January 1, 1990, p. 1145.

 3. Bershtein I.Ya., Kaminsky Yu.L. Spectrophotometric analysis in organic chemistry. L .: Chemistry, 1986.P. 154 - 155.

 4. International Pharmacopoeia. Ed. 11, WHO, Geneva, 1969, 984.

Claims (1)

A method for the quantitative determination of novocainamide by measuring the optical density of the studied solutions of novocainamide, characterized in that an aqueous solution of novocaine prepared by precise weighing is used as a working standard sample, the optical density of the studied solutions is recorded at a wavelength of 280 nm, a solution of a working standard sample at 290 nm, determine the specific absorption rate of novocaine, and the calculation of the content of novocainamide is carried out, given the ratio of the molar masses of novocaine and novocaine aninamide according to the formula

where A _{2 8 0} - the optical density of the investigated solution of procainamide;
E $\genfrac{}{}{0ex}{}{\text{one\%}}{\text{1cm}}$ - specific absorption rate of novocaine at a wavelength of 290 nm;
272.7 is the molar mass of novocaine;
271.8 - the molar mass of procainamide.

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