Poly(xylenol blue) modified multiwall carbon nanotubes-glassy carbon electrode for simultaneous determination of ascorbic acid, epinephrine, and uric acid by differential pulse voltammetry

Carbon nanotubes (CNTs) have received considerable attention in electrochemistry for a long time [1]. Epinephrine (EP) is an important catecholamine neurotransmitter in the mammalian central nervous system and biological body fluids [2]. It has been used for the treatment of myocardial infarction, hypertension, bronchial asthma, cardiac arrest, and cardiac surgery in clinics. Therefore, a simple, fast, and sensitive method is necessary for its determination in both biological fluids and pharmaceutical preparations. Uric acid (UA) and ascorbic acid (AA) commonly coexist in such biological fluids as blood and urine. However, a major obstacle usually encountered in the detection of EP is the interference of UA and AA, which are usually present at high concentrations and can be oxidized at a potential close to that of EP. Thus, their simultaneous determinations have always been considered as a serious challenge in these studies.