Synthesis and Chromogenic Properties of Some Phthalazinylhydrazones and Extractive Spectrophotometric and Analogue-Derivative Speotrophotometric Determination of Trace Amounts of Nickel with Di-2-pyridylmethanone 1-Phthalazinylhydrazone

Abstract

Abstract Four kinds of 1-phthalazinylhydrazones have been synthesized and their chromogenic properties and reactivities with metal ions investigated. Of the synthesized hydrazones, di-2-pyridylmethanone 1-phthalazinylhydrazone (DPPhH) proved to be the best chromogenic reagent for nickel. It reacts with nickel(II) at pH above 2.5 to form a 1:2 (nickel–ligand) complex extractable into various organic solvents. The extracted species into benzene has an absorption maximum at 500 nm and gives a maximum and constant absorbance in the pH range 4.3–10.7. Beer’s law is obeyed over the range 0.1–1.0 μg cm−3 of nickel. The molar absorptivity (ε) and the sensitivity for an absorbance of 0.001 are 5.4×104 dm3 mol−1 cm−1 and 1.08 ng cm−2 at 500 nm, respectively. A sensitive and selective extraction-spectrophotometric method for the determination of nickel at μg cm−3 levels is proposed and has been applied successfully to the analysis of iron and steel samples. The proposed method can be made more sensitive by the introduction of an analogue-derivative spectrophotometric technique.