Spectrophotometric Determination of Fe(III), V(V) and Cu(II) Using Some Hydroxamic acid Derivatives

Abstract

New, simple, rapid and accurate methods for the spectro- photometric

determination of Fe(III), V(V) and Cu(II) using N-benzoyl-N-phenylhydroxamic

acid and four of its derivatives and N-furoyl-N-phenyl-hydroxamic

acid are described. The optimum conditions favouring the

formation of coloured complexes are extensively studied. The

stoichiometric ratios of the formed complexes were 1 : 1, 1 : 3 (M : L) for

Fe(III), 1 : 3 (M : L) for V(V) and 1 : 1, 1 : 2 (M : L) for Cu(II). The

stability constants were determined applying spectrophotometric methods.

Beer's law was found to be obeyed up to 4.48, 4.49 and 5.67 μg/mL for

Fe(III)-(1a–1f), V(V)-(1a–1f), and Cu(II)-( 1a–1f) complexes, respectively.

The molar absorptivity, specific absorptivity, Sandell sensitivity and

Ringbom optimum range are given. Spectrophotometric and direct titration

methods using EDTA are suggested and the named hydroxamic acid derivatives

as indicators. The applicability of using ligand (III) for the detrmination

of Fe and V in crude oils has been evalutated.