SU1559274A1 - 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 ethoxylated surfactants. The goal is to increase the sensitivity and accuracy of the determination. The determination is carried out by treating an aqueous solution of the analyzed sample with a color reagent — a mixture of bromophenol blue and decylpyridinium bromide, taken in a ratio of 1: (150 ÷ 250), at PH 4–10, followed by measuring the optical density of the resulting solution. The method provides a detection limit of 0.2 µg / ml, a relative determination error of 0.67-2.75%. It does not use highly toxic solvent-dichloroethane. 6 tab.

Description

This invention relates to the analytical chemistry of organic compounds, in particular to methods for determining surfactants, and can be used to quantify non-ionic surfactants (HIIAB) such as ethoxylated adducts of organic alcohols, phenols, amines, and their amides used as detergents, in the textile, leather, metalworking industry.

The purpose of the invention is to increase the sensitivity, accuracy and selectivity of the determination of nonionic surfactants.

Example 1. Determination of nonionic surfactants of the type of ethoxylated adducts of alcohols, acids, amines, amides and phenols.

In a 50 ml volumetric flask, 5 ml of phosphate buffer solution with pH 8.0, 2.3 ml of 2 × 10 4 M solution of bromophenol blue (BFS), 2.5 ml of 4 solution of bromide decylpyridine (BDP) (ratio of BFS concentrations: BJP 1: 200) and apiquot part of the analyzed solution containing nonionic surfactants. The solution is brought to the mark with water and its optical density is measured on a spectrophotometer (e.g., SF-4, SF-16), at nm in a cuvette with 1.5 cm relative to the reference solution, which does not contain nonionic surfactants. The content of nonionic surfactants in the analyzed solution is determined by the calibration curve. The construction of the calibration curve is performed in a similar way using a standard solution

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divided by the nonionic surfactants, the concentration of the nonionic surfactants in the construction of the calibration curve is 0.2-10 µg / ml.

The results of quantitative determination of ASWPs of the type of ethoxylated adducts of alcohols, acids, amines, amides, and phenols are given in.

Thus, the results presented in Table 1 show that by the proposed method it is possible to carry out the determination of different HI1AB with their content of 0.2-10.0 μg / ml with a relative error of 0.67-2.75%.

II p and m e r 2. Determination of polyethylene glycols.

Polyethylene glycol (PEG) - a common satellite NIAV in industrial wastewater - does not form the corresponding colored compound when processing BFS in the presence of LDP, which is confirmed by the data presented in Table 2. The determination is carried out analogously to example 1 using a standard solution of the corresponding PEG o

Thus, the data presented in Table 2 indicate the possibility of selective determination of nonionic surfactants by the proposed method in the presence of PEG.

II RIMER 3, Determination of nonionic surfactants of the type of ethoxylated adducts in the presence of PEG,

The determination is carried out analogously to example 1. Additionally, variable amounts of PEG-9, PEG-35, PEG-11 are introduced into the analyzed solution. The results of the quantitative determination of nonionic surfactants in the presence of NEG are presented in Table 3.

Thus, the proposed method can be used for the selective determination of nonionic surfactants of the type of ethoxylated addUnts in the presence of various PEGs with the content of the latter up to a concentration of 20 mg /

PRI me R 4. The rationale for the proposed range of pH.

The formation of a colored compound during the treatment of the determined BFA nonionic surfactants in the presence of BDP is observed in the range of pH 4-10. The data presented in Table 1 show the feasibility of implementing the proposed method at pH 8.0. Table 4 shows the results of the determination of nonionic surfactants different

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types at other pH values. The proposed range, as well as at pH values beyond the proposed pH range. The determination is carried out analogously to example 1 using appropriate buffer solutions with the desired pH value. Buffer solutions were prepared according to the method of Yu.Yu. Lurye.

Thus, the determination of nonionic surfactants by the proposed method in the range of pH 4-10 allows to achieve the objectives of the invention. When the pH of the solution is less than 4, the corresponding colored compound is not formed, which makes it impossible in principle to determine the nonionic surfactants at these pH values. When the pH of the solution is more than 10, a colored compound is formed; however, due to the enhancement of the photochemical oxidation of the dye, the relative determination error sharply increases. The consequence of this is the fact that the implementation of the proposed method, with RP values exceeding 4-10, does not achieve the objective of the invention.

Example 5 "Justification of the need to use the BDP in the determination of nonionic surfactants by the proposed method"

BST is a necessary component of the proposed color reagent, since the implementation of the proposed method in its absence does not lead to the formation of the corresponding colored compound. The results of the determination (as in Example 1) in the absence of BST are presented in Table 5.

Thus, the implementation of the proposed method in the absence of BST does not achieve the objective of the invention.

Example 6: Substantiation of the proposed range of the ratio of BLS and BJP concentrations.

The data presented in Table 1 illustrate the possibility of determining the nonionic surfactants by the proposed method with a ratio of BFS and BDP concentrations of 1: 200. Table 6 shows the results of determination of nonionic surfactants of various types for other values of the ratios of the BFS and BDP concentrations of the proposed interval, as well as for the BFS: BDP values that fall outside the proposed interval. The determination is carried out analogously to example 1 using a constant constant

the concentration of BFS and variable concentrations BD11,

Thus, the implementation of the proposed method for determining the nonionic surfactants using the BFS and BST, taken in a molar ratio of 1: (150-250), allows to achieve the purpose of the invention. Going beyond the proposed interval does not lead to the achievement of the objective of the invention. Thus, with an increase in the BDP content in the system, the formation of insoluble precipitates is observed, which makes it impossible in principle to implement the method. With a decrease in the relative content of BST, the sensitivity of the method decreases and, as a consequence, the detection limit increases and the relative determination error increases.

Using the proposed method for determining the nonionic surfactants gives the following positive effect compared with the known method: increasing the sensitivity of the method (detection limit 0.2 µg / ml instead of 2.0 µg / ml);

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improving the accuracy of the method (relative error of determination of 0.67-2.75% instead of 1.7-5.0%); increasing the selectivity of the method (it is possible to determine the nonionic surfactants in the presence of PEG at a concentration of up to 20 mg / ml); improvement of working conditions during mass determination (the highly toxic solvent dichloroethane is not used).

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Claims (1)

Invention Formula The method of quantitative determination of oxi- dated surface-active substances by treating an aqueous solution of the analyzed sample with a color reagent followed by measuring the optical density of the resulting solution, characterized in that, in order to increase the sensitivity and accuracy of determination, a mixture of bromophenol blue and bromine is used as a color reagent. Yes, decylpyridinium, taken in a molar ratio of 1: (150-250), and treated at a pH of 4-10 ° Ethoxylated alcohol adducts Syntanol DS-1 (monoalkyl ethers of polyethylene glycol based on primary fatty alcohols) c, () t (p 10-18,) Preparation OS-20 (monoalkyl ethers of polyethylene glycol based on primary fatty alcohols) SPNG-R (sgncho) tn (n 14-18,) ethoxylated acid adducts Table 1 2.76 2.60 1.34 0.67 8.12 0.19 0.59 1.82 5.96 10.03 2.63 2.51 2.10 1.08 1.67 Stearox-920 (glyuethylene glycol molestearate) с) 7нэ5соо (с1н4о) П1н (t "20) Laurox-9 (polyethylene glycol mo laurate) C (C2H40) tN (u 9) Oxyethylated adducts of amines Oxalits L-15 (apkyl-N, N-di-polyethylen glycol amine on new acids of coconut oil) CpHap + fN (C4H (f.O) lnH (C1H4 (p 10-12,) Ethoxylated adducts of phenols Preparation OP-10 (polyethylene glycol monoalkylphenyl ether) ) (p 8-10, t 10-12) Ethoxylated amide adducts. Sintamid-10 С N-mono (2-polyethylene col ethyl) amide of synthetic fatty acidsJ C pEg n ,, CONHCH ((p 10-16, t 10) Table2 50 Table 1  .e.I13 “1 0.21 2.40 2.03 1.53 1.20 2.55 1.98 1.20 1.02 0.49 2.75 2.10 1.08 2.52 0.41 2.53 1.50 1.27 1.89 0.59 2.75 2.15 1.19 2.67 Continuation of table 2 1b4 in T .i and i l and a 1  Table 5 5.0 10.0 Oh oh Sintanol DS-10 1: 150 Laurox-9 1: 250 Oxaline L-15 1: 280 Sintamide 10 1: 120 OP-101: 300 OS-20 1: 100 one Continuation of table 4 Continuation of table.5 Stearox 920 011-10 5.0 10.0 5.0 10.0 About About About About Table 0.19 2.96 7.11 10.13 0.19 2.99 7.13 9.90 Mutn.rr and Not defined 7.10 9.73 Mutn.rr and 2.72 2.19 2.59 2.01 2.68 2.33 2.33 2.09 3.14 5, 18 Not defined 10.37 5.48