Extraction–Photometric Determination of Acetone Acylhydrazones in Aqueous Solutions

A procedure is developed for determining acetone acylhydrazones based on the formation of a colored complex with copper(II) ions of the composition Cu : reagent = 1 : 2 in ammonia solutions, its subsequent extraction with chloroform, and measurements of the absorbance of the extracts at 553 nm (ε = 128 L/(mol cm)); the analytical range is 80.0–590.0 mg/L; the relative error is <2.80%. Using acetone heptanoylhydrazone as an example, it was shown that the reagent in the complex compound is quantitatively extracted in the pH range 7−10 with a single extraction for 3 min; for its complete extraction, a twofold excess of copper(II) is sufficient. The spectra of the homologue complexes of the studied series of acetone acylhydrazones are similar. The high hydrolytic stability of the reagents in a narrow pH range of 9‒10 is established by the spectrophotometric method. The procedure is tested on solutions obtained in the study of the adsorption of reagents on chalcopyrite. The precision of the analysis results is verified by the addition method.