Electrochemically oxidized multiwalled carbon nanotube/glassy carbon electrode as a probe for simultaneous determination of dopamine and doxorubicin in biological samples

A facile and effective approach of fabricating oxidized multiwalled carbon nanotube/glassy carbon electrode (OMWCNT/GCE) is herein reported. The OMWCNT/GCE was prepared by electrochemical oxidation method in basic media (0.5 mol L-1 NaOH solution) and used as a sensor for simultaneous determination of dopamine (DA) and doxorubicin (DOX). Scanning electron microscopy, energy dispersive X-ray spectroscopy and cyclic voltammetry were used for characterization and performance study of the OMWCNT/GCE. The modified electrode exhibited good electrocatalytic properties toward the oxidation of DA and DOX. Peaks potential difference of 240 mV between DA and DOX was large enough to determine DA and DOX individually and simultaneously. Square wave voltammetry (SWV) was used for the simultaneous determination of DA and DOX in their binary mixture. Under the optimum conditions, the linear concentration dependences of SW peak current responses were observed for DA and DOX in the concentration ranges of 0.03-55 mu mol L-1 and 0.04-90 mu mol L-1, respectively. The detection limits (S/N = 3) were 8.5 x 10(-3) mu mol L-1, and 9.4 x 10(-3) mu mol L-1 for DA and DOX, respectively. The analytical utility of OMWCNT/GCE was also successfully demonstrated for the simultaneous determination of DA and DOX in human blood serum and urine samples.