LAUSR

Three tumor biomarkers (homovanillic acid (HVA), vanillylmandelic acid (VMA), and 5-hydroxyindole-3-acetic acid (5-HIAA)) have been determined by differential pulse voltammetry (DPV) at screen-printed carbon electrodes (SPCEs). As an optimum medium for all three analytes, Britton-Robinson buffer (0.04 mol ⋅ L−1, pH 3.0) was used. Dependencies of the peak current on the concentration of a biomarker were linear in the concentration range from 0.2 to 100 μmol ⋅ L−1 for all the tested compounds, with the limits of quantification 0.8 μmol ⋅ L−1 for homovanillic acid, 0.2 μmol ⋅ L−1 for vanillylmandelic acid, and 0.4 μmol ⋅ L−1 for 5-hydroxyindole-3-acetic acid. Moreover, it was verified that the newly developed methods can be used for simultaneous determination of HVA and VMA in mixture.