Spectrophotometric Determination of Nickel Using 2-[(5-Nitro-2-pyridyl)azo]-5-dimethylaminobenzoic Acid

Abstract

A new sensitive chromogenic reagent, 2-[(5-nitro-2-pyridyl)azo]-5-dimethylaminobenzoic acid (5-NO₂-PAMB), was synthesized and applied to the determination of nickel in aqueous solutions. This sensitive chromogenic reagent has a molar absorptivity (ε) of 1.64×10⁵l mol^-1 cm^-1 to nickel, and has excellent solubility in water. The reaction requires no heat or organic solvent. The reagent can react immediately with nickel at room temperature to form a blue complex with maximum wavelength of 631.2nm. The concentration of the linear range was 0.008-0.88μg/ml. Using this new reagent to determine nickel in a low-alloy steel sample, we obtained satisfactory results.