Determination of molybdenum(VI) via adsorptive stripping voltammetry using an ex‒situ bismuth screen‒printed carbon electrode

Abstract

The development of a method for molybdenum(VI) determination in the presence of quercetin‒5′‒sulfonic acid (QSA) using a mercury‒free electrode is presented. Adsorptive stripping voltammetry is the electroanalytical technique used and an ex‒situ bismuth screen‒printed carbon electrode (BiSPCE) is the working electrode. The conditions for the bismuth film deposition were optimized and the different films were compared using field emission scanning electron microscopy. Different experimental parameters were optimized to obtain a sensitive, selective, and reproducible method. The best experimental parameters were: pH 5.8, ligand concentration: 30.0 µmol L−1; accumulation potential: −0.4 V, and accumulation time: 10 s. The detection and quantification limits obtained were 0.7 and 2.1 µg L−1, respectively. The linearity of the method was maintained in the range of 2.1 to 90.0 µg L−1. The possible interference of 36 foreign ions was studied. The method was validated with two certified water reference materials and synthetic seawater spiked with Mo(VI). The method was applied to determine the Mo(VI) concentration in tap water, groundwater, bottled mineral water, and seawater samples. The results were compared with measurements performed by an external analysis laboratory via ICP‒OES. The present work is an alternative method for molybdenum determination by an electroanalytical method, avoiding the use of mercury as electrode material. Additionally, the time required for sample analysis is fast due to the application of only 10 s in the accumulation step.