Extraction and preconcentration of vanadium from food samples using aqueous two-phase systems by a multivariate study

Abstract

Vanadium plays essential and toxic roles in humans and in nature, depending on its concentration. Therefore, monitoring its concentration in food samples is important, as this analyte is usually found in trace amounts in these samples. In this context, this work proposes a new methodology for the determination of vanadium in food samples using an aqueous two-phase system formed by (NH4)2SO4 + PEG400 + H2O with the complexing agent Br-PADAP to extract and pre-concentrate the analyte in the top-phase with detection by atomic absorption spectrometry. Multivariate analysis using fractional factorial design was applied to define the significant variables and a Box-Behnken matrix was used to find the critical points for these variables, which defined as pH 3.60, an ultra-thermostatted bath time of 2.12 h and complexing agent concentration of 0.00810 100w. Under optimised extraction conditions, the method presented limits of detection and quantification of 0.0220 μg⸳kg-1 and 0.665 μg.kg-1, respectively; accuracy of 2.51% and enrichment factor of 19.1. The methodology was applied to certified reference samples of apple leaves (NIST1515) and food samples with recovery percentages values of 94.1% and 93.8-108%, respectively. Therefore, a novel, efficient and organic solvent-free methodology was developed for the determination of vanadium in food samples.