5-(2′-Carboxyphnyl) Azo-8-quinolinol as a Sensitive Reagent for Extractive Spectrophotometric Determination of Nickel

A new sensitive extractive spectrophotometric method for the determination of nickel in sub-microgram level is discussed. 5-(2′-carboxyphenyl) azo-8-quinolinol reats with nickel at pH 5.2 to 6.1 to produce a wine red complex extractable in isomayl alcohol. The complex is stable for 24 hrs. Beer's law is obeyed in the range 0.04 to 0.60 ug of nickel per ml. The molar absorptivity and Sandell's sensitivity of the method are 5.5 × 10 4 1. mol −1 cm −1 and 0.001 μg cm −2 , respectively, at wavelength of maximum absorption (λ max 540 nm). Effects of diverse ions and variables have been studied in detail. The method has been applied to the determination of nickel in alloys like manganin, constantan, german silver, bronze, steel and in geological samples. Features of the method include high sensitivity, excelllent reproducibility and reliability.