SPECTROPHOTOMETRIC DETERMINATION OF NICKEL IONS IN NATURAL WATERS, SOLID COMPLEXES AND REAL SAMPLES USING 1-PHENYL -4- ETHYL THIOSEMICARBAZIDE

A very simple, highly sensitive and selective spectrophotometric procedure was developed for the determination of nickel(II). It is based on the reaction at pH ≈ 7 between the synthesized 1-phenyl-4-ethyl thiosemicarbazide (HPETS) and Ni(II) forming a violet complex, Ni(II): PETS (1:2),that floats quantitatively with oleic acid (HOL) surfactant. It exhibits a constant and maximum absorbance at 560 nm in both aqueous and surfactant layers. Beer s law is obeyed over the concentration 0.035 mg l^-1 with a detection limit of 0.0146 mg l^-1 for a standard aqueous solution of Ni(II). The molar absorpitivites in aqueous and surfactant are 0.2 × 10^6 and 0.73 × 10^6 mol l^-1 cm^-1 , respectively. The different analytical parameters affecting the floatation and determination processes were examined. The proposed procedure has been successfully applied to the analysis of Ni(II) in natural waters, solid complexes, simulated and real samples as steel and serpentine. The results obtained agree well with those samples analyzed by atomic absorption spectrophotometry (AAS). Moreover the flotation mechanism is suggested based on some physical and chemical studies on the solid complexes isolated from aqueous and surfactant layers.