SPECTROPHOTOMETRIC DETERMINATION OF COPPER (II) AFTER DISPERSIVE LIQUID-LIQUID EXTRACTION OF ITS COMPLEX WITH 6,7-DIHYDROXY-4-METHYL-2-PHENYLBENZOPYRYLIUM CHLORIDE

The specificity of the dispersive liquid-liquid semi-microextraction of Copper (II) complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyryl chloride has been studied. It is noted that the transition to semi-microextraction technology can significantly reduce the toxic organic solvents consumption, and the use of dispersion solvent can intensify the complex extraction of Сopper (II) complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyryl chloride. Optimal conditions for spectrophotometric determination of Сopper (II) after dispersive liquid-liquid semi-microextraction of its complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyrylium chloride were found to be: 1.5 mL of chloroform, 1.5 mL of methanol, pH 4.5, λmax = 535 nm, l = 1 cm. The main analytical characteristics of the developed dispersive liquid-liquid semi-microextraction-spectrophotometric method are calculated: the calibration graph is linear in the wide range of concentrations of 17-480 μg/L, and the limit of detection and limit of determination are 5 and 17 μg/L, respectively. The molar ratios Copper (II) : interferer, in which there is no effect on the quantitative determination of Copper(II) by the proposed dispersive liquid-liquid semi-microextraction-spectrophotometric method have been established. The proposed method for Copper (II) spectrophotometric quantification after preconcentration via dispersive liquid-liquid semi-microextraction as a complex with 6,7-dihydroxy-4-methyl-2-phenylbenzopyrilium chloride was tested in the analysis of model solutions and water samples. The accuracy of the developed dispersive liquid-liquid semi-microextraction-spectrophotometric method was checked by the "spiked-found" method and the relative standard deviation does not exceed 3.9%. The proposed technique is simple, sensitive and environmentally friendly.