Development of highly sensitive extractive spectrophotometric determination of nickel(II) in medicinal leaves, soil, industrial effluents and standard alloy samples using pyridoxal-4-phenyl-3-thiosemicarbazone

Pyridoxal-4-phenyl-3-thiosemicarbazone (PPT) is proposed as a new sensitive reagent for the extractive spectrophotometric determination of nickel(II). PPT reacts with nickel(II) in the pH range 4.0–6.0 to form a reddish brown colored complex, which was well-extracted into n-butanol. The absorbance value of the Ni(II)–PPT complex was measured at different time intervals at 430 nm, to ascertain the stability of the complex. The system obeyed Beerʹs law up to 0.5–5.0 μg mL−1 of nickel(II), with an excellent linearity in terms of the correlation coefficient value of 0.99. The molar absorptivity and Sandellʹs sensitivity of the extracted species are 1.92×104 L mol−1 cm−1 and 0.003057 μg cm−2 respectively at 430 nm. The detection limit of the method is 0.069 μg mL−1. To assess precision and accuracy of the developed method, determinations were carried out at different concentrations. The relative standard deviation of all measurements does not exceed 2.62%. The developed method has been satisfactorily applied for the determination of nickel(II), when present alone or in the presence of diverse ions, which are usually associated with nickel(II) in medicinal leaves, soil and industrial effluent samples. Various standard and certified reference materials (CM 247 LC, IN 718, BCS 233, 266, 253 and 251) have also been tested for the determination of nickel for the purpose of validation of the present method. The results of the proposed method are compared with those obtained from an atomic absorption spectrometer (AAS).