Adsorptive Stripping Voltammetric Determination of Traces of Molybdenum in Natural Water in the Presence of α-Benzoinoxime

Abstract

The electrochemical behavior of the molybdenum complex of α-benzoinoxime was investigated using cyclic voltammetry and linear scan voltammetry, after adsorptive accumulation of the complex onto a hanging mercury drop electrode (HMDE). The signal corresponds to the reduction of molybdenum in the complex adsorbed at the HMDE surface. Under optimal conditions, the adsorptive stripping voltammetric procedure gave an extremely low detection limit of 0.1 nM (9.6 ng/1) Mo(VI) following stirred accumulation for 5 min at 0.0 V (vs. Ag/AgC1). The reduction current-[Mo(VI)] relationships were linear up to 25 and 100 nM. Repetitive determinations of 10 nM solutions gave relative standard deviations of 2.2 and 3.5%, for 1 and 5-min accumulation periods, respectively. Most of the ions investigated did not interfere with the determination of molybdenum, except for tungsten. Excellent selectivity against copper was observed. The proposed procedure was applied to the direct determination of molybdenum in natural water.