SU1539640A1 - Method of determining concentration of timecaine and analogues thereof in aqueous solutions - Google Patents

Abstract

This invention relates to analytical chemistry and can be applied in the pharmaceutical industry. The aim of the invention is to expand the scope of application of the method for quantitative determination of trimecaine and its analogues in aqueous solutions. In the method, the calcium-selective electrode EM CA-01 in a solution with a PH from 4 to 6 is used as the ion-selective electrode. Unlike the known method, it allows, due to its sensitivity to trimekain and its analogs, to increase the class of analytes and simplify the analysis procedure. 3 tab.

Description

The invention relates to analytical chemistry, more precisely to methods for the quantitative determination of organic compounds in aqueous solutions, namely the quantitative determination of trimecaine and its analogues (in particular, lidocaine), and can be used in the pharmaceutical industry.

The purpose of the invention is to expand the scope, i.e. the ability to determine not only lidocaine, but also mecaine and analogs, is achieved by the fact that the calcium selective electrode EM Ca-01 in a solution with pH from C until 6,

which is significantly more selective for trimecain and its analogues than the previously used electrode, the selectivity coefficients of trimekain and its analogs with respect to the calcium ion are 4-107. Since the selectivity of the calcium electrode with respect to other ions is known, this indicates a high selectivity of the electrode. The presence of calcium ions in solution does not interfere with the determination of trimecaine and its analogues. Moreover, the determination is recommended against the background of chlorides of metal cations with a constant concentration (or 10–2 mol / l).

A significant advantage of the proposed method is its versatility.

00

with

SE Ј

31

greasiness. The calcium electrode is proposed to be used in the calcium form, not to translate it in advance into the form of a detectable ion (trimecaine or any of its analogs). This allows the electrode to be used to determine trimekain or its analogue immediately, without prior preparation, which simplifies and speeds up the determination.

The dependence of the EMF (mV) on the concentration of trimekain in aqueous solution is given in table. 1. Measurement of EMF is performed using ion meter M-115i

Table 1

Dependence of EMF (mV) on the concentration of trimekain in aqueous solution (von mol / l CaCl)

1 2 3

s

5 6

2

5 1 2 5 1

105

y-5 yu-4 y-4

123.5, 5 15M 170.0 185.0 20

thirty

Example 1. Weigh the stock solution at a concentration of C (weighed Trimecainum 1.138 ry in 200 ml of water) and dilute the solution with (C mol / L, pH 6.0 solution. Prepare custom solutions ( See this one in 1 volumetric flasks, one of the solutions listed in the table of solution I or II and 10 mx mol / l of the Ca solution measure the electromotive voltage of a galvanic compound composed of an EM electrode of Ca-01 and a р electrode measured in these solutions, Is solution is prepared by withdrawing a pool with trimecain 1 ml of a 100 ml volumetric flask with also 10 ml M / l Ca for this purpose thief measure standard solutions. The measurements are given in Table

10s

Table

Quantitative determination of an aqueous solution of trimekain by

graduation schedule

0

five

0

five

0

Example 1. Preparing a stock solution of trimekain at a concentration of C mol / l (weight of trimecainum 1.138 g dissolved in 200 ml of water - solution I) according to an exact weight, then the solution is diluted 10 times (mol / l, solution II), pH 6.0. By diluting the last solution, seven standard solutions were prepared (see Table 2). For this, a volume of solution I or II and 10 ml of 1 x x mol / l CaCl solution is added to 100 ml volumetric flasks. The emf of a galvanic cell composed of a calcium selective electrode EM Ca-01 and a chlorine-silver reference electrode immersed in these solutions is then measured. The test solution is prepared by taking 1 ml of solution from a vial of trimecaine in a 100 ml volumetric flask Also add 10 ml of M / l CaClg. The emf for this solution is measured in a series of standard solutions. The measurement results are shown in Table 2.

PRI mme R 2. Definition of lidocaine.

Prepared two standard solutions of lidocaine concentration

1.0-Yu-s Mol / L (pC 3.00) and 5.0 x X 10 mol / L (pC 3.30). Solutions prepared on the background of 0.001 mol / l, pH 6.0.

The pH meter was adjusted to pH 2b2 for these two standard solutions (pH value 5.00 is taken as the value of the pC 3.00 scale). The adjustment was carried out after sequential immersion of the calcium electrode EMC-01 in a standard solution with a PC value of 3.00, then in a standard solution with a pC value of 3.30.

For the measurement, 1 ml of lidocaine was taken from the ampoule mg per 2 ml), placed in a 100 ml measuring flask, 10 ml of 0.01 mol / l CaClj, water was added to the mark and the pC value corresponding to this solution was measured. , on a scale of pH meter. The results of several measurements are presented in Table. 3

Table3 The definition of lidocaine in the ampoule

15396 0

0

As a result of applying the method, a number of advantages are achieved: the time of one determination is several minutes (min), the concentrations of trimecaine and its analogues are reliably determined (5 mg / l and above), the reproducibility of the analysis results is 5%.

All measurements were carried out while controlling the pH of the test solution, since it was found that when going beyond the interval A-6, the electrode reading deteriorates. This phenomenon is associated with the selective operation interval of the electrode itself and with the formation of complex complexes of the studied organic substances with metal cations present in the solution.

The proposed method of measurement allows, in comparison with the existing method, to expand the scope of application of the direct potentiometric method of analysis not only for lidocaine, but also for trimecain and its analogues, while reducing the laboriousness of preparing solutions, and consequently, the analysis time is reduced.

five

Claims (1)

Invention Formula The method of determining the concentration of trimekain and its analogs in aqueous solutions using an ion-selective electrode, characterized in that, in order to expand the field of application, the determination is carried out using a calcium ion-selective electrode in the pH range from Tsdob.