SU1381401A1 - Method of determining polyethyleneoxide in aqueous solutions - Google Patents

Abstract

The invention relates to analytical chemistry, to methods for the quantitative determination of polyethylene oxide (PEO) in aqueous solutions, including those containing proteins; intended for the analysis of biological fluids. medical preparations, foodstuff, sewage and others, objects containing go. The purpose of the invention is to increase the sensitivity and simplify the method. For this, blood, plasma, urine and other aqueous solutions containing proteins are analyzed, the solutions are precipitated with 0.3 mol / l of trichloroacetic acid, followed by centrifugation or filtration. Then, PEO is reacted with iodine and potassium iodide in the presence of a concentrated solution of lithium chloride and the spectrophotometric determination of colored interaction products. The content of PEO in the test sample is found from a calibration curve based on the results of the analysis of samples with a known content of PEO. S (l

Description

The invention relates to analytical chemistry, namely to methods for the quantitative determination of polyethylene oxide (PEO) in aqueous solutions, including those containing proteins, and can be used in the analysis of biological fluids, drugs for medical purposes, food, wastewater and other objects containing polyethylene oxide.

The purpose of the invention is to increase the sensitivity of the method while simplifying it.

The invention permits determination of goh in samples containing proteins, since 0.3 mol / L trichloroacetic acid precipitating proteins is used to create an acidic environment. This allows them to be removed by simple centrifugation or filtration.

The method consists of the following

1. Preparation of the sample. In the analysis of blood, nlazma, urine and other aqueous solutions containing proteins, the preparation consists in precipitating the last 0.3 mol / l of trichloroacetic acid, followed by centrifugation or filtration. When analyzing aqueous solutions of non-protein-containing PEO, this step consists in adding 0.3 mol / l of trichloroacetic acid without centrifuging or filtering.

2. Reactions of PEO with iodine and potassium iodide in the presence of a concentrated solution of chlorine lithium and spectrophotometric determination of colored interaction products.

The content of PEO in the test sample is found from a calibration curve plotted based on the results of the analysis of samples with a known PEO content.

Example. Reagents: 0.3 mol / l trichloroacetic acid solution, 60% lithium chloride solution, iodine reagent (0.5 g of crystalline iodine and 1 g of potassium iodide per 00 ml of water).

Aiiajiii3 PEO in plasma: to 2 ml of plasma containing PEO is added

4 ml of 0.3 mol / l trichloroacetic acid, the mixture is kept in a thermostat at 37 ° C for 15 minutes. The precipitated proteins are filtered. To 2 ml of the filtrate was added 1 ml of a 60% lithium chloride solution,. the mixture is stirred, then added. 0.1 ml of iodine reagent, mix, and after 10 min. Determine the optical density of the reaction mixture at a wavelength of 530. The controls are samples analyzed without the use of PEO (plaem) analyzed by the described method. The results of the analysis of various amounts of PEO 1500 in blood plasma are presented in Table. one.

Table 1

Analysis of PEO in aqueous solutions: to 2 ml of the sample 4 ml of 0.3 mol / l of trichloroacetic acid, 3 ml of 60% lithium chloride solution are added and re-mastered, then 0.3 ml of iodine reagent is added and after 10 min the optical density of the reaction mixture at a wavelength of 530nm. As control use water.

The results of the analysis of PEO 1500, PEO 2000, PEO 4000, PEO 20000, PEO 40000 are presented in Table. 2

Table 2

The proposed method in comparison with the known provides an increase in sensitivity of 10 times (0.005 against 0.05 mg / ml), reducing the duration and complexity due to a smaller number of stages of analysis (1 -2 against 3-4 stages). The total duration of the analysis by the proposed method is no more than 40 minutes versus 3 hours when analyzed in a known manner, which is especially important for in-line analysis of samples containing PEO. In addition, in the analysis of the proposed method, highly toxic reagents, such as phenylhydrazine and barium salts, are not used, which significantly improves the sanitary and hygienic conditions of analytical work for determining PEO.

Claims (1)

Invention Formula The method of determining polyethylene oxide in aqueous solutions by treating the sample under study with a chemical reagent in acidic medium followed by spectrophotometry of the colored interaction product, characterized in that, in order to increase the sensitivity of the method while simplifying it, an aqueous solution of iodine in potassium iodide is used as a reagent, and the treatment is carried out in the presence of lithium chloride solution.