Kaveh Molaei - Center of Excellence in Electrochemistry, Faculty of Chemistry, Tehran University, Tehran, Iran
Hadi Beitollahi - Environment Department, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran
Hassan Karimi Maleh - Department of Chemistry, Graduate University of Advanced Technology, Kerman, Iran
Mohammad Reza Ganjali - Department of Chemistry, Graduate University of Advanced Technology, Kerman, Iran

Isoproterenol is a sympathomimetic beta adrenergic agonistmedication. It had been used for bradycardia or heart block. By activating 1-receptors on the heart, it induces positivechronotropic, dromotropic, and inotropic effects [1]. Isoproterenol has positive inotropic and chronotropic effects on the heart. Acetaminophen is a widely used analgesic anti-pyretic drug. It is a suitable alternative for the patients who are sensitive to aspirin. However, overdoses willcause liver and kidney damage [1]. L-Tryptophan is one of the essential amino acids in protein biosynthesis of living organisms. Tryptophan concentration is a sensitive parameter to monitor the biochemical balance of the brain. It is very essential for people with sleep deprivation,anxiety and mood enhancement due to its ability to increase brain levels of serotonin and melatonin [2]. Theophylline is a kind of methyl xanthine derivatives which exists widely in nature. It has beenreported that theophylline can cause various physiological effects, such as relaxation of bronchialmuscle, gastric acid secretion and stimulation of the central nervous system. Theophylline is one of the most commonly used medications for the treatment of the symptomsof chronicasthma [1]. Carbon paste electrodes (CPEs) are widely utilized to perform the electrochemicaldeterminations of a variety of biological and pharmaceutical species owing to their low residual current and noise, ease of fabrication, wide anodic and cathodic potential ranges, rapid surfacerenewal, and low cost. Moreover, chemically modified electrodes (CMEs) can be easily prepared by adding different substances to the bulk of CPEs in order to increase sensitivity, selectivity, and rapidity of determinations [1].In the present work, a novel carbon paste electrode modified with graphene oxide nanosheets and a novel ferrocene derivative was fabricated. The electrochemical study of the modified electrode,as well as its efficiency for voltammetric oxidation of isoperoterenol, is described. It has been found that under optimum condition (pH 7.0) in cyclic voltammetry, the oxidation of isoperoterenol occurs at a potential about 120 mV less positive than that of an unmodified carbon paste electrode. The prepared modified electrode exhibits a very good resolution between the voltammetric peaks of isoperoterenol, acetaminophen, L-tryptophan and theophylline which makes it suitable for the detection of isoperoterenol in the presence of acetaminophen, Ltryptophan and theophylline in real samples.

Isoperoterenol, Acetaminophe, L-Tryptophan, Theophylline, Graphene, Modified electrode