Synthesis and analytical application of a novel tetradentate N(2)O(2) 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. Beer's 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.