SU763360A1 - Method of determining polyethylenepolyamine - Google Patents

Description

one

The invention relates to the field of the chemistry of high molecular weight compounds, specifically to methods for the quantitative determination of polyethylene polyamine (PEPA).

A known method for determining polyethylene polyamine by photometry of a complex of polyethylene polyamine with copper ions (H) l.

However, the method does not allow the determination of PEP in the presence of caustic soda / because of the formation of copper hydroxide ions, which precipitate and distort the photometric results. In addition, this method involves measuring the optical density in the infrared region of the spectrum at a wavelength of 860 nm, which requires the use of more complex than photocolorimeter instruments, such as a spectrophotometer. This complicates the analysis. The specified method involves the use of an organic solvent - absolute alcohol.

The purpose of the invention is to simplify the process, which would allow the determination of polyethylene polys1Min without the use of organic solvents, extraction and complex equipment and the possibility of determination in the presence of caustic alkalis and zinc ions.

The goal is achieved

5 by preliminary neutralization of the sample with a strong acid, to a pH of 3.23, 5 and. creating in the sample using an acetate buffer solution of the medium with a pH range of 3.09-6.1, preferably 5.2, and photometry of the blue complex in the visible part of the spectrum at L 590-640 nm. The principle difference of the proposed method is that the influence of caustic alkalis on the formation of

complex of copper ions with polyethylene polyamine. In the absence of such neutralization, copper ions, forming hydroxide with one alkali, precipitate

20 and interfere with photometric measurement of the partially formed complex. In addition, without such neutralization or at neutralization to a pH value of 3.5, zinc ions are hydrolyzed, which also form a hydroxide, precipitate and interfere with photometry, increasing the optical density of the solution. Neutralization of the sample to a pH of 3.2-3.5 allows

30 using acetate buffer solution, create conditions when the color of the complex formed obeys the Bouguer – Lambert – Beer law in the visible part of the spectrum at a wavelength of 597 1sh. The proposed method allows the determination of polyethylene polyamides at a concentration of up to 10,000 µg / ml in the presence of all the components of the electrolyte of the galvanized zinc, eliminates the extraction process, the use of organic solvents, which simplifies and accelerates the determination procedure. Example 1. Quantitative determination of polystyrene polyamine is carried out in an alkaline electrolyte. Zinc of the following composition, g / l: Necessary reagents and devices. A solution of copper sulphate, 1%. Sodium acetic acid solution, 1N Hydrochloric acid solution, 1 u ,,, (fi sanal), Acetate buffer solution, pH 5.2. Methylorane solution, 0.1% hydrochloric acid solution, 0.1 n. PEPA standard solution containing 5 g / l. A photocolorimeter. A determination method. Transfer 5 ml of filtered electrolyte into a 100 ml volumetric flask, dilute to the mark with distilled water and mix thoroughly. 10 ml of diluted electrolyte is transferred to a 250 ml conical flask, 50-70 Ni of distilled water are added, 2-3 drops of methyl orange solution and titrated with 0.1% hydrochloric acid solution until a pink color appears. Another aliquot of the diluted electrolyte is transferred into a 50 ml volumetric flask, the amount of hydrochloric acid solution that is titrated by methyl orange, 5-10 ml, acetate buffer solution, 2 ml of copper sulphate solution is added and the solution is allowed to stand for 10 min After that, the contents of the flask are diluted with buffer / solution to the mark and stirred. I At the same time, a blank is prepared containing a buffer solution and 2 ml of copper sulphate solution in a 50 ml volumetric flask. Photometric measurements are carried out in a 50 ml cuvette, with a red light filter (5 8 (597 nm)), setting up an FEK56M instrument according to the sample and reading on the left drum according to the blank sample. in an aliquot. The calculation is carried out according to the formula: n-in lOOOD- «-PEPag -cG concentration de a - the content of PEPD in an aliquot, found from the calibration curve. yy - the amount of undiluted electrolyte in milliliters taken for analysis. Construction of a calibration curve. Calibration curve A standard solution containing 5 g / l of polyethylene polyamine (PEPD) is built in. For this purpose, 1.25 g of PEPA is weighed by analytical weights, quantitatively transferred to a 250 ml volumetric flask, filled with water to the mark and thoroughly mixed. ml of the prepared basic standard PEP transfer, transfer to a 100 ml volumetric flask, make up to the mark with water and stir. To collect 50 ml. black flasks with a capacity of 50 ml, select 4.8.10 ... 20 ml of the diluted solution, which corresponds to PEPA 0.002.0.004 ... 0.01 g (10,000 μg), 5-10 ml of buffer solution are added, 2 ml of r copper sulphate solution and allow to stand for 10 min. Next, do as described in the method of determination. . According to the measurement data, a calibration curve is plotted, plotting the content of PEPA in grams on the abscissa axis and the optical density on the ordinate axis. The results of the definitions are given in the table.

Claims (1)

1. Korenman I.M. Photometric, analysis and methods for the determination of organic compounds. M., Himi, 1975, p. 280 (prototype).