Simultaneous determination of epinephrine and ascorbic acid at the electrochemical sensor of triazole SAM modified gold electrode

The electrochemical sensor of triazole (TA) self-assembled monolayer (SAM) modified gold electrode (TA SAM/Au) was fabricated. The electrochemical behaviors of epinephrine (EP) at TA SAM/Au have been studied,The TA SAM/Au shows an excellent electrocatalytic activity for the oxidation of EP and accelerates electron transfer rate. The diffusion coefficient is 1.135 x 10(-6) cm(2) s(1). Under the optimum experiment conditions (i.e. 0.1 mol (L-)1, pH 4.4, sodium borate buffer, accumulation time: 180 s. accumulation potential: 0.6 V, scan rate: 0.1 Vs(-1)), the cathodic peak current of EP versus its concentration has a good linear relation in the ranges of 1.0 x 10(-7) to 1.0 x 10(-5) mol L-1 and 1.0 x 10(-5) to 6.0 x 10(-4) mol L-1 by square wave adsorptive stripping voltammetry (SWASV), with the correlation coefficient or 0.9985 and 0.9996, respectively. Detection limit is down to 1.0 x 10(-8) mol L-1. The TA SAM/Au :an be used for the determination of EP in practical injection. Meantime, the oxidative peak potentials of EP and ascorbic acid (AA) are well separated about 200 +/- 10 mV at TA SAM/Au. the oxidation peak current increases approximately linearly with increasing concentration of both EP and AA in the concentration range of 2.0 x 10-5 to 1.6 x 10(-4) mol L-1. It can be used for simultaneous determination of EP and AA. (c) 2005 Elsevier B.V. All rights reserved.