Application of Pyrogallol Azo Derivative as a Mediator for Simultaneous Voltammetric Sensing of Ascorbic Acid, Epinephrine, Acetaminophen, and Tryptophan

An electroactive film of poly 4-(2-p-methyl-phenyldiazenyl)-1,2,3-tri hydroxybenzene modified glassy carbon electrode was fabricated for the simultaneous determination of ascorbic acid (AA), epinephrine (EP), acetaminophen (AC), and Tryptophan (Trp). Bare glassy carbon exhibited merged oxidation currents for these quaternary mixtures. The modified film electrode not only behaves as a strong electron mediating for separation of the oxidation signals of AA, EP, AC, and Trp with the potential differences of 210, 140, and 250 mV between AA-EP, EP-AC, and AC-Trp, respectively, but it remarkably enhance the electro-oxidation signals of AA, EP, AC, and Trp compared with the bare electrode. The diffusion coefficients and the catalytic rate constants, $\text{k}_{\mathrm {h}}$ , of these compounds on the modified electrode surface were evaluated. The detection limits of AA, EP, AC, and Trp were calculated as 0.1, 0.02, 0.05, and $0.08~\mu $ mol $\text{L}^{-1}$ , respectively. The proposed sensor provides application in biochemical compounds analysis in human plasma samples.