Photometric Extraction Detection of 2-Methyl-4-Chlorophenoxyacetic Acid in Water.

Autor: Zholt Kormosh, Shevchuk, Mykola, Kormosh, Natalia, Korolchuk, Svitlana, Savchuk, Tetiana, Suprunovich, Sergei
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Zdroj: Journal of Water Chemistry & Technology; Oct2022, Vol. 44 Issue 5, p362-368, 7p
Abstrakt: It has been shown that 2-methyl-4-chlorophenoxyacetic acid (MCPA) forms an ionic associate (IA) with the polymethine dye Astrafloxin FF (AF). The energy efficiency of IA formation is substantiated by the method of mathematical modeling. The molecular modeling of MCPA– + AF+ systems and related calculations are performed by using the HyperChem 8.0 software package in various initial variants for the mutual arrangement of counterions ("single point" procedure). The geometric optimization of ions is carried out by the molecular mechanics method MM+. The obtained IA is quite well extracted by various aromatic hydrocarbons. The maximum IA extraction from the aqueous phase is attained at pH = 6–12. The effect of the dye concentration on the optical density of the toluene extracts of MCPA–AF ionic associates is studied. The IA extraction attains a maximum at a dye concentration of (1.6–2.8) × 10–4 M. Extraction equilibrium is reached for 50–60 s. The stoichiometry of the MCPA–AF ionic associate is established by the spectrophotometric methods of isomolar series and equilibrium shift; the ratio of components is 1 : 1. The IA formation and extraction scheme is proposed. The conditional molar absorption coefficient of the ionic associate is 1.1 × 105. The calibration dependence of the optical density of extracts on the MCPA concentration is described by the linear equation a = 0.0116 + 0.0613 within the MCPA concentration range of 0.9–45.6 μg/cm3. The MCPA detection limit calculated by the 3s criterion (n = 5, P = 0.95) is 0.8 μg/cm3. The disperancy of the plotted calibration curve for the detection of 2-methyl-4-chlorophenoxyacetic acid is estimated by using the Cochran test G. The calculated Cochran criterion (n = 5, P = 0.95) is lower than its tabular value, i.e., Gcalcd = 0.25 < Gtab = 0.64 to evidence variance homogeneity. The method for the photometric extraction detection of 2-methyl-4-chlorophenoxyacetic acid in water and bottom sediments has been developed. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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