pectrophotometric Determination of Copper(II) with Di-2-pyridyl Ketone [2-Furyl(thiocarbonyl)]hydrazone

Abstract

Di-2-pyridyl ketone [2-furyl(thiocarbonyl)]hydrazone (DPFTH) was used as a reagent for the extractive spectrophotometric determination of copper(II). The proton dissociation constants of the ligand determined spectrophotometrically were pK_a1=2.88 and pK_a2=6.70 at 25°C and, μ=0.1. Copper (II) can be quantitatively extracted with DPFTH in benzene from aqueous solution buffered to pH 5-11. The extracted species has absorption maxima at 364 and 457 nm and obeyed Beer's law over the range 0-38 μg of copper(II) in 10 ml at 457 nm. The molar absorptivity at this wavelength is 1.42 × 10⁴l·mol^-1·cm^-1 and the coefficient of variation (n=12) of this method was 0.53% for 25.4μg of copper. Nickel (II), zinc(II), palladium (II), mercury (II), bismuth (III) and EDTA interfered with the determination. The composition of the extracted species was also discussed.