Simultaneous Determination of Catecholamines and Serotonin on Poly(3,4-ethylene dioxythiophene) Modified Pt Electrode in Presence of Sodium Dodecyl Sulfate

A promising electrochemical sensor was developed using poly(3,4-ethylene dioxythiophene) modified platinum electrode in the presence of sodium dodecyl sulphate (SDS). This sensor is sensitive for the determination of catecholamine compounds, namely dopamine, epinephrine, L-norepinephrine, and L-DOPA, as well as serotonin (ST) in the presence of interference molecules such as uric acid, ascorbic acid (AA), and glucose. The presence of SDS in the medium plays a key role in the electrostatic attraction of these compounds toward the polymeric surface and causes repulsion toward the interfering ones. Cyclic voltammetry, linear sweep voltammetry, ultraviolet-visible (UV–vis), nuclear magnetic resonance and electrochemical impedance spectroscopy were used to verify the behavior of the studied compounds in micellar media. In the presence of an anionic surfactant, the presence of large excess of AA and glucose did not interfere with the voltammetric responses of catecholamine and ST. The linear response was obtained for serotonin in the range of 0.05–10 μmol l −1 and 20–100 μmol l −1 with correlation coefficients of 0.997 and 0.998 and detection limits 48 and 71 nmol l −1 , respectively. The utility of this modified electrode was demonstrated for the determination of ST in human urine.