Carbon screen-printed electrode coated with poly (Toluidine blue) as an electrochemical sensor for the detection of tyramine

In the present work, the surface modification of a carbon screen-printed electrode by electrochemical polymerization of Toluidine blue (TB) for determination of tyramine is described. The electrochemical polymerization of the electrode with TB was done by cyclic voltammetry at a scan rate of 50 mV/s and a potential sweep between ‒0.7 V to 1.0V in presence of 0.5 mM TB in an electrolyte solution. At each cycle, the polymer film started to deposit on the carbon screen-printed electrode which was repeated 20 times. For parameter optimization the electrochemical behaviour of the modified electrode was analysed by amperometric methods such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A phosphate buffer solution (PBS) was used as an electrolyte for all the amperometric experiments. The electrochemically modified poly-TB coated carbon screen printed electrode showed an oxidation peak potential of tyramine at 0.67 V. The unmodified carbon screen printed electrode showed the tyramine peak potential at 0.9 V. Based on the voltammetric results, it was found that the poly-TB modified carbon screen printed electrode showed higher sensitivity (1.78 µA nM^-1 cm^-2) than a bare carbon electrode towards tyramine detection. Tyramine in 0.1 M PBS (pH 7.4) was analysed by cyclic voltammetry from the potential of ‒ 0.7 to 1.0 V at a scan rate of 50 mV/s. Poly-TB modified carbon screen printed electrode exhibited a linear response between catalytic peak current and tyramine concentration from 0.02 µM to 270.5 µM with a lower detection limit 0.007 µM (S/N=3).