Electrochemical and catalytic investigations of epinephrine, acetaminophen and folic acid at the surface of titanium dioxide nanoparticle-modified carbon paste electrode

In the present paper, the use of a carbon paste electrode modified with 1-(4-(1, 3-dithiolan-2-yl)-6, 7-dihydroxy-2-methyl-6, 7-dihydrobenzofuran-3-yl)ethanone (DDE) and TiO2 nanoparticles prepared by a simple and rapid method was described. The modified electrode showed excellent properties for electrocatalytic oxidization of epinephrine (EP), acetaminophen (AC) and folic acid (FA). The apparent charge transfer rate constant, ks = 1.14 s−1, and transfer coefficient, α = 0.54, for electron transfer between the modifier and carbon paste electrode were calculated. It has been found that under optimum condition (pH = 7.0) in cyclic voltammetry, the oxidation of EP occurs at a potential about 280 mV less positive than that of an unmodified carbon paste electrode. The values of transfer coefficients (α = 0.46), catalytic rate constant (k = 1.2 × 104 M−1 s−1) and diffusion coefficient (D = 2.70 × 10−5 cm2 s−1) were calculated for EP. Differential pulse voltammetry (DPV) exhibited two linear dynamic ranges of 0.5 to 50.0 μM and 50.0 to 1,000 μM for EP. This modified electrode is quite effective not only for the detection of EP, AC and FA but also for the simultaneous determination of these species in a mixture. The limit of detection for EP, AC and FA is 0.10, 1.80 and 2.36 μM, respectively.