Synthesis and chromogenic properties of phthalazinohydrazones and spectrophotometric and analogue derivative spectrophotometric determination of micro-amounts of nickel with 5-methylfurfural-1-phthalazinohydrazone

Abstract

The synthesis of two new hydrazones is described together with the results of spectrophotometric studies of their chromogenic reactions. One of them, 5-methylfurfural-1-phthalazinohydrazone (MFPH), has been utilised for the spectrophotometric determination of nickel at the parts per million level. On the basis that nickel(II) reacts with MFPH to form a stable 1 : 2 (metal: ligand) complex, having absorption maxima at 470 and 503 nm in 2.4% Triton X-100 solution and the solution of the complex gives a constant absorbance in the pH range 7.2–10.4, a sensitive and practical method for the determination of nickel has been proposed. The molar absorptivity and the sensitivity for an absorbance of 0.001 are 3.7 × 10⁴ l mol^–1 cm^–1 and 1.6 ng cm^–2, respectively, the relative standard deviation for 15.3 µg of nickel (15 replicates) being 0.7%. Application of the proposed method to the determination of nickel in standard iron and steel samples and in chemicals and further sensitisation of the method by employing analogue derivative spectrophotometry are also described.