Vanadium determination in water using alkaline phosphatase based screen-printed carbon electrodes modified with gold nanoparticles

A chronoamperometric assay for vanadium ions, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over riboflavin-5-monophosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The assay has a detection limit of 3.9 ± 0.4 μM, a repeatability of 7.6% (n = 4) and a reproducibility of 11.6% (n = 4). A study of the possible interferences shows that the presence of Mo (VI) may affect vanadium determination. The method was successfully applied to the determination of vanadium in tap water.