Extraction-spectrophotometric determination of nickel at microgram level in water and wastewater using 2-[(2-mercaptophenylimino)methyl]phenol

An extraction-spectrophotometric method for determination of nickel at sub ppm level using 2-[(2-mercaptophenylimino)methyl]phenol (MPMP) as the new extractant is described. The reagent reacts with nickel(II) at pH > 10 and form a 1:2 brown complex, which is extracted into chloroform. The complex has a maximum absorption at 421 nm with the molar absorptivity of 2.41 × 105 M-1 cm-1. Beer’s law is obeyed over the range of 0.011-0.30 μg mL-1. The Sandell’s sensitivity for 0.001 absorbance unit is 5.34 × 10-4 μg cm-2. The relative standard deviation at 0.018 μg mL-1 is 1.1 % (n = 8). The procedure was successfully applied to determination of nickel in wastewater and standard alloy and the accuracy was determined by recovery experiment, independent analysis by furnace-AAS, and analysis of a certified reference martial. KEY WORDS: Ni determination, Liquid-liquid extraction, Schiff bases, Spectrophotometry Bull. Chem. Soc. Ethiop. 2008, 22(3), 323-329.