Synthesis and analytical application of a novel tetradentate N2O2 Schiff base as a chromogenic reagent for determination of nickel in some natural food samples

A novel sensitive chromogenic reagent, N,N′-bis(3-methylsalicylidene)-ortho-phenylene diamine (MSOPD), has been synthesized and used in the spectrophotometric determination of nickel. At pH 8, MSOPD can react with nickel ion at room temperature to form a 1:1 complex. The apparent molar absorptivity is 9.5 × 104 l mol−1 cm−1 at 430 nm. Beerʹs low is obeyed over the range 0–1.0 × 10−5 M of nickel with a detection limit of 1.36 × 10−8 M. The relative standard deviation for measurement of 3.41 × 10−6 M nickel is 1.3% (n = 10). The method has successfully been applied to determination of trace amounts of nickel in some natural food samples.