Synthesis and chromogenic properties of water-soluble substituted 2-pyridyl-3'-sulphophenylmethanone 2-pyridylhydrazones and spectrophotometric and analogue derivative spectrophotometric determination of trace amounts of cobalt with 2-pyridyl-3'-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone

Tsugikatsu Odashima, Takemitsu Kikuchi, Wataru Ohtani, Hajime Ishii

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    18 Citations (Scopus)

    Abstract

    Three water-soluble hydrazones, in which the 5-position of the pyridine ring in the hydrazine moiety of 2-pyridyl-3'-sulphophenylmethanone 2-pyridylhydrazone (PSPH) was substituted a methyl, chloro or nitro group, have been synthesised and their chromogenic properties and reactivities with metal ions investigated. The acid dissociation constants (Ka) of the synthesised hydrazones were determined spectrophotometrically. These values obeyed Hammett's law, the inductive effect of the substituents being found to reflect the pKa values. Of the synthesised hydrazones, 2-pyridyl-3'-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone (PSNPH) is the most sensitive for cobalt(II) determination. It reacts with cobalt(II) to form a 1:2 (metal to ligand) complex. This complex is rapidly oxidised above pH 2 to give a stable cobalt(III) complex with an absorption maximum at 496 nm. Beer's law is obeyed over the range 0.05-1.0 μg ml-1 of cobalt and the apparent molar absorptivity of the complex is 5.69 × 104 l mol -1 cm-1 at 496 nm. A sensitive and practical spectrophotometric method for the determination of trace amounts of cobalt with PSNPH is proposed and has been successfully applied to the determination of cobalt in steel samples. The method may be made more sensitive by employing an analogue derivative spectrophotometric technique.

    Original languageEnglish
    Pages (from-to)1383-1387
    Number of pages5
    JournalThe Analyst
    Volume111
    Issue number12
    DOIs
    Publication statusPublished - 1986 Jan 1

    Keywords

    • 2-pyridyl-3'-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone
    • Analogue derivative spectrophotometry
    • Cobalt determination
    • Spectrophotometry

    ASJC Scopus subject areas

    • Analytical Chemistry
    • Environmental Chemistry
    • Biochemistry
    • Spectroscopy
    • Electrochemistry

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