RU1800331C - Method for o-, m-, p-phenylenediamine quantitative determination - Google Patents

Abstract

Usage: in analytical chemistry. The inventive sample is treated with an alcoholic solution of dimethylaminocinnamic aldehyde in an amount of 4.57-10 5 -4.57-110 4 M in the presence of sodium dodecyl sulfate with a concentration in the reaction mixture of 4.0 -10 3 -4, M in citrate buffer a solution with a pH of 2.0-4.0, followed by photometry of the resulting solution. 6 tab.

Description

The invention relates to analytical chemistry, in particular to methods for the quantitative photometric determination of o-, m-, p-phenylenediamines.

The purpose of the invention is to increase the sensitivity of the method for determining o-, m-, p-phenylenediamines.

The goal is achieved in that the analysis of the analyzed sample is carried out with an alcohol solution of p-dimethylaminocinnamic aldehyde in an amount of 4.56-10 5 - 4.56-10 4 M in the presence of sodium dodecyl sulfate with a concentration in the reaction mixture of M in a citrate buffer solution at pH 2.0-4.0.

The invention is illustrated by the following examples.

EXAMPLE 1. Construction of a calibration characteristic for the photometric determination of large quantities of-, m-, p-phenylenediamines.

. An accurately weighed sample of dry matter, e.g. m-phenylenediamine (0.025 g), was placed in a 25 ml volumetric flask and dissolved in distilled water. The standard solution contains 1 μg / ml m-phenylenediamine.

In order to construct a calibration curve, in eight volumetric flasks with a capacity of 25 ml, 7-10 ml of citrate buffer solution (pH 3.0) is measured, then 1 ml (0.04 μg / ml), 2 ml (0.08 μg / ml). 3 ml (0.12 μg / ml), 4 ml (0.16 μg / ml), 5 ml (0.20 μg / ml), 10 ml (0.40 μg / ml) of working solution of m-phenylenediamine with a concentration 10 μg / ml, 0.1 ml of a 0.2% solution of p-dimethylaminocinnamic aldehyde (p-DMACA), 1 ml (M sodium dodecyl sulfate solution (DSN)) are added to each flask and adjusted to the mark with citrate buffer solution (pH 3.0). The optical density of the resulting solutions was measured at K FC-2 in cuvettes with an absorbing layer thickness of I 1 cm at I max 590 nm relative

 H

Yo

00

oh oh

(A CL)

should be 4

 - 4

a comparison solution containing 0.1 ml of a 0.2% solution of p-DMACA, 1 ml of a M solution of DSN and a buffer solution with a pH of 3.0, V 25 ml. From the obtained optical density values, the dependence A f (C) is plotted. The Bouguer-Lambert-Beer Act is valid at a concentration of m-phenylenediamine of 0.06-0.8 µg / ml.

Example 2. Construction of a calibration characteristic for the photometric determination of small amounts of o-, m-, p-phenylenediamines.

To construct the calibration characteristic, a working solution of m-phenylenediamine with a concentration of 1 μg / ml is used. 7-8 ml of citrate buffer solution with a pH of 3.0, 0.5 ml (0.02 μg / ml) is poured into eight 25-ml volumetric flasks. 1 ml (0.04 μg / ml), 2 ml (0.08 μg / ml), 3 ml (0.12 μg / ml), 4 ml (0.1 μg / ml), 5 ml (0, 20 μg / ml), 10 ml (0.4 μg / ml), 15 ml (0.60 μg / ml) of a working solution of m-phenylenediamine with a concentration of 1 μg / ml, then 0.1 is added to each flask ml of a 0.2% solution of p-DMACA, 1 ml each of a solution of DS # and the volume was adjusted to the mark with citrate buffer solution at pH 3.0. The optical density of the resulting solutions was measured on KFK-2 at I max 590 nm in cuvettes with an absorbent layer thickness of 5 cm, relative to the reference solution containing 0.1 ml of a 0.2% solution of p-DMAC, 1 ml of M solution and citrate buffer solution with a pH of 3.0. From the obtained values of optical density, the dependence A f (C) is built. The Bouguer-Lambert-Beer law holds at a concentration of m-phenylenediamine of 0.04-0.4 µg / ml.

The methods for determining small and large amounts of o-, p-phenylenediamines are similar.

It was found that for the determination of o-, m-, p-phenylenediamines, the optimal concentration of p-DMAC is 4.56-10 5 - 4.56-10 4 M, which is achieved by adding 0.1-1.0 ml of 0.2 % p-dimethyl-minocinnamic aldehyde solution. The error of determination increases at a concentration of p-Dmak C 4.56-10 M and C 4.56-104 M (Table 1).

It was found that the concentration of sodium dodecyl sulfate in the reaction mixture

 M what

achieved by adding a solution of DSMa in an amount of 1 ml M - 1 ml

1 M At a concentration of 4-10

from

10

fifteen

20 25

45

fifty

thirty

35

40

55

M and C M the error in the determination of phenylenediamines is increased (Table 2).

All further studies were carried out with solutions of the following concentrations of p-DMAC 1.14-KG2 M (0.2%), 0.1 ml was added to the reaction mixture, 10 ml sodium dodecyl sulfate was introduced 1 ml.

The compliance of the o-, m-, p-phenylenediamine-p-DMAKA-DS1Ma system with the Bouguer-Lambert-Behr law was studied, the range of variation in the concentration of phenylenediamines was 0.04-0.6 μg / ml. It has been found that by the proposed method for the determination of phenylenediamines, it is possible to find both large and low concentrations. Two ranges of the determined contents of o-, m-, p-phenylenediamines were found.

I. 0-phenylenediamine

1) 0.04-0.2 μg / ml, 5cm;

2) 0.08-0.8 μg / ml, I 1 cm

II. m-phenylenediamine

1) 0.04-0.4 μg / ml, I 5 cm

2) 0.06-0.80 mcg / ml, I 1 cm

III. p-phenylenediamine

1) 0.04-0.6 μg / ml, I 5 cm

2) 0.08-0.9 μg / ml, I 1 cm

Analytical signals were recorded on KFK-2, A max 590 nm for o-, m-phenylenediamines and 640 nm for p-phenylenediamine.

A relationship was established between the values of the detection limit of o-, m-, p-phenylenediamines (for example, o-phenylenediamine) and the concentration of p-DMACA, DSN and pH values of the medium (Tables 3-5).

Table 6 shows data showing the advantages of the claimed method for the determination of o-, m-, p-phenylenediamines.

Claims (1)

SUMMARY OF THE INVENTION A method for the quantitative determination of o-, m-, p-phenylenediamines by treating an analyzed sample with an organic reagent in the presence of a buffer solution and then metering the solution, characterized in that, in order to increase the sensitivity of the method, an alcohol solution of p-dimethylaminocinnamic aldehyde is used as a reagent in an amount of 4.57-10 5-4.57-10 4 M, a citrate buffer solution with a pH of 2.0-4.0 is used as a buffer solution and the treatment is carried out in the presence of dodecyl sulfate with a concentration in the reaction smesi4,0-10 03/04/10 2M. Table 1 Determination of phenylenediamine content (for example, p - phenylenediamine) at various concentrations of the reagent p - dimethylaminocinnamic aldehyde (M, KFK-2, I 1 cm U0bsch 25ml, Yamaks 630 nm) table 2 Determination of the content of o - phenylenediamine at various concentrations of dodecyl sulfate (Sp - DMAC 4.56 M, CPK - 2, I 1 cm, V06u, 25 ml, I max 590 nm) Table 3 Dependence of the value of the detection limit on the concentration of p-DMAKA reagent (Sdma 4.0, pH 3.0, KFK-2, I 5 cm, Yamax 590 nm) Dependence of the detection limit on the concentration of sodium dodecyl sulfate (Sp - DMAKA 4.56, pH 3.0, KFK-2, I max 590 nm, 5 cm) Dependence of the limit of detection on the pH of the medium (SdmAKA 4.56 Sds # 4.0, 5 cm, I max 590 nm, 25 ml) Comparison of the claimed method with the base object organic agents 1 1 cm m-PDA: 0 ,, mcg / ml I 5 cm 0.06-0.8 mcg / ml 1 1 cm p-PDA: 0.04-0.6 mcg / ml 1 5 cm 0.08-0.9 mcg / ml 1 1 cm -5-If 4.56-10 -4.56-10 K p-DMAC solution 4-10-s - / (. TO 2 M DSCa solution pH 2.0-4.0 citrate buffer solution .... Table 4 Table 5 , Prototype table and Salicylic aldehyde Heating to 70 ° C for 5 hours Alkaline (KaOH) pH 11