A kinetic spectrophotometric method for vanadium(v) determination in food samples using a Janus Green-bromate system

Abstract

This paper describes a new, simple, sensitive and selective catalytic kinetic spectrophotometric method for trace amount determination of vanadium(V) in food samples. The method is based upon the catalytic effect of vanadium(V) on the oxidation of Janus Green by bromate in sulfuric acid media. The reaction was followed spectrophotometrically by measuring the decrease in absorbance of Janus Green at 618 nm. The dependence of sensitivity on the reaction variables was studied and discussed. Under optimum experimental conditions, the fixed time procedure was used to obtain a calibration curve over the range of 0.5–150.0 ng mL⁻¹ of vanadium(V). The calculated detection limit (3S_b/m) was 0.11 ng mL⁻¹ for twelve replicate measurement of blank signal. The relative standard deviations for six replicate determinations of 10.0, 50.0 and 100.0 ng mL⁻¹ of vanadium(V) were 1.22, 0.96 and 0.80%, respectively. The effect of various species commonly associated with vanadium(V) in real samples was also investigated. The proposed method was successfully applied for the determination of vanadium(V) in food samples and the results were in excellent agreement with those of atomic absorption spectrometry.