RU1793341C - Method of 5-nitrofurfurol semicarbon determination - Google Patents

Abstract

SUMMARY OF THE INVENTION: the test sample is treated with potassium nitrate in concentrated sulfuric acid, the reaction mixture is diluted with water, alkalized with sodium hydroxide solution to pH 10-12, then the pH of the medium is adjusted to 5, treated with a solution of N, N, N, N chloride, N,. N-hexamethyl-p-rosaniline, the reaction product is extracted with methylbenzene, and the extract is photometric at a wavelength of 590 nm. 1 tab.

Description

The invention relates to analytical chemistry, and in particular to methods for the determination of 5-nmtrofurfural hemicarbazone. and can be applied in the practice of central factory laboratories, control laboratories of chemical enterprises, and chemical and toxicological laboratories.

A known method for the determination of furatsilin (semicarbazone 5-nitrofurfurol) is available in the processing of the analyzed sample with a sodium hydroxide solution, followed by photometric measurement of the resulting colored solution.

The method is not sufficiently accurate due to the rapid destruction of the colored product.

A known method for the photometric determination of furatsilin based on mercury (II) nitrate.

i.

The method is complex, involves the use of a toxic reagent and is not selective in the presence of chlorine ions.

Closest to the invention is a method for the determination of semicarbazone 5-nitrofurfurol (furatsilina) by treating the analyzed sample with a solution of diazotized novocaine in an aqueous alkaline medium, followed by photometry of the resulting colored solution.

The method is not sufficiently sensitive.

The aim of the invention is to increase the sensitivity of the method.

The goal is achieved in that in the method for determining semicarbazone 5-nitrofurfural. in which the analyzed sample is pretreated with a color reagent followed by photometry of the resulting colored solution, the analyzed sample is preliminarily |

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They are thoroughly treated with potassium nitrate in concentrated sulfuric acid, the reaction mixture is diluted with water, alkalized with sodium hydroxide solution to pH 10-12, then the pH of the medium is adjusted to 5, a solution of N, N, N1, N1, N chloride, m -hexamethyl-p-rosaniline, before photometry, the colored reaction product is extracted with methylbenzene, and the optical density is measured at a wavelength of 590

nm ...; .

The method is carried out as follows. . ; ..-, .., -. :.

The analyzed sample is treated with a 10% solution of potassium nitrate in concentrated sulfuric acid, the reaction mixture is diluted with water, alkalized with sodium hydroxide solution to pH 10-12, then the pH of the medium is adjusted to 5, treated with a solution of chloride N, N, N,: N, N, N-reK-Sametyl-p-rosaniline, the reaction product is extracted with methylbenzene L, the extract is separated and photometric at a wavelength of 590 nm. : - rf :: -; .- ;;; - -;

When Me p 1. Qualitative determination of semicarbazone 5-nitrofurfur.

 About 2 mg of 5-nitrofurfural semicarbazone is placed in an evaporation cup, and 0.5 ml of a 10% solution of potassium nitrate in concentrated sulfuric acid is added thereto. After 5 minutes, 1 ml of water was added to the reaction mixture, a 10% sodium hydroxide solution was added to an alkaline reaction (pH 10-12), the medium was adjusted to pH 5 by the addition of a 0.1 N hydrochloric acid solution. To the resulting solution was added 1 ml of a 0.01% solution of N, N, N1, N1, N, N-hexamethyl-p-rosaniline chloride, 10 ml of methylbenzene and extracted for 3 Min. The methylbenzene layer then turns purple. The sensitivity of the reaction is 0.1 μg / ml.

Example 2. Quantitative determination of semicarbazone 5-nitrofurfural.

Calibration plotting

0.25.0.50, 1.00, 1.50, 2.00, 2.50 ml of a standard (0.0016%) solution of semicarbazone 5-nitrofurfural in a mixture of ethanol and trichloromethane taken in volume 1: 1 ratio. The solvent was evaporated, 0.5 ml of a 10% solution of potassium nitrate in concentrated sulfuric acid was added to the dry residue, and the reaction solutions were kept for 5 min with periodic stirring. After the specified time, each solution is diluted with 1 ml

water, add a 10% solution of sodium hydroxide to an alkaline reaction (pH 10-12), and then, under the control of a potentiometer, adjust the pH of the medium to 5 by adding a 0.1 N solution of hydrochloric acid. TO

1 ml of a 0.01% solution of N, N, N1, N1, N, N-hexamethyl-p-rosaniline chloride was added to the resulting solution, and extracted with 10 ml of methylbenzene over 3 minutes. The stained extract was separated and photometric using a KFK-2 instrument with an Nfc 7 light filter (I 590 um) in a cuvette with a working layer thickness of 20 mm against the background of the extract obtained in the control experiment. Least squares method

the equation of the calibration graph, which in this case has the form:

0 0.0727-0 + 0.1156, where D is the optical density;

C is the concentration of semicarbazone, 5 nitrofurfural in a photometric solution, µg / mp.

Submission to the basic law of light absorption is observed in the concentration range of 0.4-4.0 μg / ml,

Quantification Method.

About 0.02 g (accurately weighed) of 5-nitrofurfurol semicarbazone is dissolved in a mixture of ethanol and trichloromethane taken in

volumetric ratio 1: 1. in a volumetric flask with a capacity of 50 ml (solution A). 1 ml of solution A was added to a 25 ml volumetric flask and the mixture was adjusted with ethanol-trichloromethane (1: 1) to the mark (solution B). 1,5

ml of solution B was placed in an evaporation cup and the solvent was evaporated. 0.5 ml of a 10% solution of potassium nitrate in concentrated sulfuric acid was added to the dry residue and further operations

carried out according to the scheme described for constructing a calibration graph. The quantitative content of 5-nitrofurfural semicarbaeone is determined by the equation of the calibration graph and converted to a weighed portion. The results of quantification and metrological characteristics are presented in table. 1.

Claims (1)

I Formula of the invention A method for determining emicarbazone 5-β-hydrofurfurol by treating an analyzed sample with a color reagent followed by photometric analysis of the resulting colored solution, in particular, and in order to increase the detection sensitivity, the analyzed sample is pre-treated with potassium nitrate in concentrated sulfuric acid, the reaction mixture was diluted with water, alkalized with sodium hydroxide solution to pH 10-12, the pH of the medium was adjusted to 5, a solution of Florida N, N, N1, N1, N, m hexamethyl p zanilin, before photometric measurements, the colored reaction product is extracted with methylbenzolm, and the optical density is measured at a wavelength of 590 nm.