Development of a highly sensitive extractive spectrophotometric method for the determination of nickel(II) from environmental matrices using N-ethyl-3-carbazolecarboxaldehyde-3-thiosemicarbazone

Nickel(II) reacts with N-ethyl-3-carbazolecarboxaldehyde-3-thiosemicarbazone (ECCT) and forms a yellow colored complex, which was extracted into n-butanol from sodium acetate and acetic acid buffer at pH 6.0. The absorbance value of the Ni(II)–ECCT complex was measured at different intervals of time at 400 nm, to ascertain the time stability of the complex. The extraction of the complex into the solvent was instantaneous and stable for more than 72 h. The system obeyed Beerʹs law in the concentration range of 1.2–5.6 μg ml−1 of nickel(II), with an excellent linearity and a correlation coefficient of 0.999. The molar absorptivity and Sandellʹs sensitivity of the extracted species were found to be 1.114×104 L mol−1 cm−1 and 5.29×10−3 μg cm−2 at 400 nm, respectively. Hence, a detailed study of the extraction of nickel(II) with ECCT has been undertaken with a view to developing a rapid and sensitive extractive spectrophotometric method for the determination of nickel(II) when present alone or in the presence of diverse ions which are usually associated with nickel(II) in environmental matrices like soil and industrial effluents. Various standard alloy samples (CM 247 LC, IN 718, BCS 233, 266, 253 and 251) have been tested for the determination of nickel for the purpose of validation of the present method. The results of the proposed method are comparable with those from atomic absorption spectrometry and were found to be in good agreement.