Determination of Nickel in Alkaline Salts by Inductively Coupled Plasma Atomic Emission Spectroscopy Using 1-(2-Thiazolylazo)-p-Cresol for Preconcentration and Separation

Abstract

The present paper describes the use of 1-(2-thiazolylazo)-p-cresol (TAC) for separation, preconcentration and determination of nickel (ng g−1) in alkaline salts using Inductively Coupled Plasma Atomic Emission Spectroscopy technique (ICP-AES). The method proposed is based on the liquid-liquid extraction of the complex formed between nickel(II) cation and 1-(2-thiazolylazo)-p-cresol (TAC). Parameters such as: TAC concentration, effect of pH, influence of the organic solvent on the extraction, back extraction and mineralisation of the organic phase were studied. The results demonstrated that nickel in the form of nickel(II)-TAC complex, in the pH range of 5.0 to 12.0, can be quantitatively extracted from saline solutions (up to 30% NaCl) using the following solvents: isoamyl alcohol, carbon tetrachloride, chloroform, xylene, hexane, butyl acetate or methyl isobutyl ketone. The solution for the nickel determination can be obtained by a back extraction using 5 ml of a 1M hydrochloric acid solution or also by the mineralisation of organic phase with evaporation of the organic solvent and digestion of the residue with concentrated nitric acid. The procedure was used for nickel determination in alkaline salts of analytical grade and food salts. The standard addition technique was used and the recoveries obtained revealed that the proposed procedure shows good accuracy and precision.