Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 4

The paper studied some regularities of extraction of dihydroxybenzenes (DHB) using toluene organic solutions of amine and phosphine oxides with the purpose of extraction concentration and determination of trace amounts in aqueous solutions. Distribution coefficients of DHB between toluene solutions of organic oxides and water versus the position of OH group in the molecule and the donor ability of oxides were determined. Pyrocatechin has higher extraction characteristics than resorcin and hydroquinone. The maximum distribution coefficients of DHB were reached, which provided their 95–97 % extraction from aqueous media at 50-fold concentration and single extraction. A method for determination of trace amounts of DHB (10^–7–10^–5 mol/dm³) in water samples with pre-concentration with toluene solutions of trioctylphosphine and trioctylamine oxides (0.5–0.7 mol/dm₃) followed by voltammetric detection in extract with a glassy carbon electrode (GCE) against acetonitrile and a solution of sodium perchlorate in isopropyl alcohol was developed. The current-voltage curves reflecting the kinetics of oxidation of analytes in a disk GCE at voltammetric detection of DHB in the organic phase were obtained. Calibration curve method was used for quantitative voltammetric determination of each isomer in individual solutions or binary mixtures of catechol, resorcin, and hydroquinone, resorcin, and also total DHB (in terms of pyrocatechin) in an extract. The level of reliable determination of DHB concentrations is 0.5–1 MPC; relative error does not exceed 5 %. A method for total determination of DHB, and also each isomer in individual samples or binary mixtures of pyrocatechin and resorcin, and hydroquinone and resorcin is recommended for use in analytical laboratories for monitoring the quality of natural and treated waste water.