SU893851A1 - Method of spectrophotometric determination of water in absolutized alcohol - Google Patents

Description

This invention relates to analytical chemistry, in particular to spectrophotometric methods, and may be used to quantify traces of water in an absolute alcohol.

Methods are known for quantifying traces of water based on the introduction of an active substance into a solution. By the change in the color of the solution or by the appearance of sediment occurring during the course of chemical reactions, the presence of moisture in the test solution is judged 1.

However, these methods do not allow for the quantitative determination of water in various media, based on direct measurement of the intensity of absorption at a wavelength corresponding to the absorption of water molecules L2J, or the intensity of absorption of the indicator containing metal ions on the carrier h.

These methods make it possible to determine the water content up to p-10 0-10%, however, they require complicated equipment, are long, laborious.

The closest to the proposed technical essence and the achieved result is the method of spectrophotometric determination of water in absolute alcohol, including the introduction of the reagent - chloride

10 cobalt and subsequent measurement of the intensity of absorption at 520 nm

P

The known method allows only high water content to be determined.

15 (1-11001). The low sensitivity of this method does not allow it to be used for the determination of trace amounts of water.

The purpose of the invention is to increase the sensitivity of the analysis.

This goal is achieved by the fact that in the method of spectrophotometric determination of water in absolothirophen alcohol, including the preliminary introduction of a reagent, rhodamine 6 J is used as a reagent.

A sample of the absolute alcohol after the introduction of the reagent is frozen.

The use of rhodamine 6 G is based on the dependence of its solubility on the water content in the absolute value; Mr. alcohol. When determining low water contents up to 0, the absolute alcohol sample is frozen after the introduction of the reagent, which makes it possible to detect a change in optical densities in the maxima of the long wavelength absorption band of rhodamine 6 F X 535 nm and ./2 500 nm. From the reference graph, the dependence of the ratio of these optical densities on the concentration of water determines its content in the alcohol being analyzed. When determining low water contents, especially in compounds that form hydrogen bonds, it is necessary to pre-temperature the cuvettes.

Example 1. A sample of rhodamine 6 W (9 mg) is dissolved in 1 ml of the alcohol to be analyzed and the optical density is measured at the maximum of the long wavelength absorption band in a 2 mm thick cuvette. The content of water in alcohol (0.15) is determined from the reference graph (1.38) from the reference graph.

Example 2. A portion of rhodamine 6 W (, 5 mg) was dissolved in 1 ml of the test alcohol. When this occurs, complete dissolution of rhodamine 6}, {with the establishment of a concentration of 10 mol / l. A sample of the analyzed solution is frozen at a temperature of -IISC in a 5 mm thick cuvette and the ratio of optical densities in the maxima of the long-wavelength absorption band is determined to be 2.69. On the reference curve, this ratio corresponds to 0.02 of water.

In comparison with the known ones, the proposed method is simpler and faster, does not require large amounts of a dye and a test alcohol, and reduces the limit of detectable water content from 1 to 0.01-0.003.

Claims (3)

1. A method for the spectrophotometric determination of water in absolute alcohol, including the preliminary introduction of a reagent, characterized in that, in order to increase the sensitivity of the analysis, rhodamine 6 G is used as a reagent, 2. Method pop. 1, I differ by the fact that a sample of absolute alcohol is frozen after injection of the reagent. Sources of information taken into account in the examination 1.Bermen A, Z. Technique of laboratory work in organic chemistry. M. Himi, 1978, p. 75-76. 2.Kin Kin L.V., Petrov A.V. Sat Modern methods of analysis. M.-L 1965, p. 185. 3. USSR author's certificate N °, class G 01 N 21/10, 1971. Ts. Terentev, VA, Strelchik L.C. Spectrophotometric determination of water in organic compounds using cobalt chloride. - ЖАХ, 1970, vol. 25, p. 382.