SU1559275A1 - Method of quantitative determination of oxyethylated surface-active substances - Google Patents

Abstract

This invention relates to analytical chemistry, in particular to the quantitative determination of cationic surfactants. The goal is to increase the detection sensitivity. The determination is carried out by treating an aqueous solution of the analyzed sample with bromophenol blue and monooctylphenyl ether of polyethylene glycol -30 with a molar ratio of bromophenol blue to monooctylphenyl ether of polyethylene glycol -30 1: (10 ÷ 20). The process is carried out with subsequent photometry of the resulting solution. 3 tab.

Description

The invention relates to the analytical chemistry of organic compounds, in particular to methods for the determination of cationic surfactants (CLAW), and can be used to quantitatively determine long chain salts of quaternary ammonium bases such as alkyl pyridinium halides, alkyl benzyl dimethyl, alkyl trimethyl and al halides. - kiltriethylammonium, used as detergents, pharmaceutical agents, pharmaceuticals.

The purpose of the invention is to increase the sensitivity of determining KLAV.

Example 1. Definition of a KLAB type of alkyl pyridinium, alkyl benzyl dimethyl, alkyl trimethyl and alkyl triethylammonium.

In a 25 ml volumetric flask, 5 ml of acetate buffer solution with a pH of 3.95, 5 ml of 2 solution of bromophene blue (BFS), 1 ml of polyethylene glycol-30 mopooctylphenol ether (MOPEP-30) and an aliquot part of the analyzed solution are placed. containing KLAV. The solution is brought to the mark with water and the decrease in light absorption of the resulting solution is measured at L 595 nm in a cuvette with 1,2 cm of the comparative solution not containing CPAS. The content of CLAV in the analyzed solution is determined by the gradient graph-P

SP CO No.

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ku The construction of the calibration curve is carried out in a similar way using a standard solution determined by KLAB. The content of CLAV in the final volume when building the calibration curve should be 5-140 µg.

The results of quantitative determination of various types of KLAV are given in Table 1.

The results presented in Table 1 show that it is possible for the proposed method to carry out the determination of different CLAVES at their content of 5–140 μg in 25 ml of the final volume with a relative error of 0.5–4.0%. EXAMPLE 2 A decrease in the light absorption of a colored compound during the processing of detectable CLAH VFS in the presence of MOPHEP-30 is observed in the pH range 3.9-4.0. The data presented in table 1, show the possibility of implementing the proposed method at a pH of 3.95.

Table 2 shows the results of the determination of CLAV at different pH values of the claimed range, as well as at pH values beyond the claimed range. The determination is carried out as in Example 1 using acetate buffer solutions with the desired pH value.

Thus, the determination of KLAV by the proposed method in the pH range 3.9-4.0 allows one to achieve the purpose of the invention. When the pH of the solution is less than 3.9, no colored compound is formed. When the pH of the solution is more than 4.0, the nature of the processes in the BFS-MOFEP-30-CPAS system changes. The consequence of this is the fact that the implementation of the proposed method with pH values beyond the interval 3.9-4.0 does not lead to the achievement of the objective of the invention.

Example 3: Justification of the claimed range of the ratio of concentrations of BFS and OFE-30.

The data presented in Tables 1 and 2 illustrate the possibility of determining

laziness KLAV the proposed method with the ratio of the concentrations of BFS: IEFEP-30 -1: 10.

Table 3 shows the results of the determination of the KLHW at different values of the ratio of the BFS and OFEL 30 concentrations of the claimed interval, as well as at the values of the BFS: MOFEP-30, which are beyond the claimed interval. The determination is carried out analogously to Example 1 using a constant concentration of BFS and a variable concentration of MOFEP-30.

Thus, the implementation of the proposed method of determining the KLAV using the BFS and OFE-30, taken in a ratio of 1: (10-20), allows to achieve the purpose of the invention. Going beyond the claimed interval to achieve the objective of the invention does not. So, with an increase in the relative content of IEFEP-30 more than BFS: IEFEP-30 1:20, the sensitivity of the proposed method decreases. With a decrease in the relative content of MOFEP-30 below BFS: IEFEP-30, 1:10, the formation of insoluble precipitates is observed, which makes it impossible in principle to implement the method.

Claims (1)

Invention Formula The method of quantitative determination of cationic surfactants by treating an aqueous solution of the analyzed sample with bromophenol blue followed by photometry of the resulting solution, which is characterized in that, to increase the sensitivity of the determination, the solution of the analyzed sample is additionally treated with mono-octylphenyl ether polyethylene - glycol -30 at the molar ratio of bromophenol blue to mono-octylphenyl ether of polythylene glycol -30, equal to 1: (10-20), and the treatment is carried out at pH 3.9-4.0. - Table Cetylpyridine bromide (CPB) Cetyltrimethylammonium bromide (CTAB) Tetradecyltri-etipammonium bromide (TTEAB) Dimethylbenzyl tetradecylammonium chloride 5.14 30.5 70.7 99.4 141 4.0 2.5 1.3 0.9 1.9 4987 30.3 69.9 101 142 3.8 2.4 0.5 2.0 2.1 100 140: 305 50 . 100,140 55 50 100 Undecided Not defined 140- -