Highly Sensitive Electrochemical Detection of Tyramine Using a Poly(Toluidine Blue)-Modified Carbon Screen-Printed Electrode

Abstract

Tyramine (4-hydroxyphenethylamine) is a biogenic amine commonly found in alcoholic beverages or fermented and dried foods. A healthy person can consume about 200–800 mg per single oral intake. Increased tyramine consumption can lead to serious health problems, especially in people with food allergies. Therefore, measurements of tyramine levels are an immediate concern. In this study, the electroactive dye polymer toluidine blue was used as a new sensor material for the rapid determination of tyramine, for which it was immobilized on carbon screen printing electrodes (SPEs). Toluidine blue (TB) 0.5 mM was electrochemically polymerized on the screen-printed electrode surface by the cyclic voltammetric method. Under optimal conditions, the poly-TB modified carbon SPE showed the tyramine oxidation peak at 0.67 V, while the bare carbon SPE showed the same tyramine oxidation peak at 0.9 V. With the modified one, tyramine can be detected over a wide linear range from $0.02~ \mu \text{M}$ to $270.5~ \mu \text{M}$ , with a low detection limit of $0.007~ \mu \text{M}$ (S/N = 3) and a sensitivity of $1.78~ \mu \text{A}$ nM ⁻¹ cm ⁻² found. A tyramine concentration of at least $0.02~ \mu \text{M}$ is recommended for real sample analysis. Our developed sensor showed good selectivity to tyramine in the presence of other biogenic amines such as dopamine (DA), L-cystine (L-CY), putrescine (PU), and histamine (HIS), which are commonly found in real samples. The sensor described offers unique advantages such as low manufacturing cost, ease of use, reusability, good sensitivity and high selectivity over other biogenic amines.