© 2018 JETIR December 2018, Volume 5, Issue 12 www.jetir.org (ISSN-2349-5162) JETIR1812503 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 15 Voltammetric resolution of Adenosine at Pretreated/Graphite pencil electrode: A Cyclic Voltammetric Study K. R. Mahanthesha 1 , B.E. Kumara Swamy 1 * and S. R. Priyanka 2 1 Department of P.G. Studies and Research in Industrial Chemistry, Jnana Sahyadri, Kuvempu University, Shankaraghatta-577 451, Shimoga, Karnataka (S), INDIA 2 Department of P.G. Studies and Research in Chemistry, Sahyadri Science College (Autonomous), Constituent College of Kuvempu University, Shimoga-577203, Karnataka (S), INDIA ABSTRACT The surface of graphite pencil electrode (GPE) was modified by electrochemical pretreatment method and has been employed for the cyclic voltammetric determination of adenosine in the presence of adenine in 0.2M phosphate buffer solution (pH 7.4) with scan rate 0.05 Vs -1 . The electrochemical oxidation of adenosine and adenine was investigated by cyclic voltammetry (CV) method at pretreated/graphite pencil electrode (PGPE). The PGPE showed excellent electrocatalytic activity towards adenosine and adenine determination. The parameters such as effect of scan rate, concentration, and interference study were investigated at PGPE. The electrode phenomenon was found to be discussed at PGPE. Furthermore, the modified electrode exhibited good limit of detection for adenosine and adenine. Hence, the PGPE shows good electrocatalytic properties and can be applied for the determination of adenosine and adenine individually and simultaneously. Keywords: Pretreated/Graphite pencil electrode, Adenosine, Adenine, Simultaneous. * 1 Corresponding Author: 1. INTRODUCTION Nowadays, carbon based electrodes are frequently used for electrochemical determination of purine nucleosides [1]. It is known that electrochemical determination of drugs and biological compounds is often difficult with bare electrodes due to their poor responses and high over-potentials. Modification of electrode surfaces using different approaches is often performed to overcome these limitations. The fabrication of modified electrode is one of the key parameter for the electrocatalytic activity of a carbon based electrode. There are several methods for the fabrication of the electrode which improves catalytic activity of an electrode. For carbon electrodes, a typical procedure is the electrochemical treatment which relies on the electrochemical oxidation or reduction at certain conditions [2]. Carbon electrodes, graphite pencil receive increasing interest as electrode material due to favorable electrochemical performances, low cost and disposability. Among them, the development of reagentless biosensor plays an important role in the research field. Electrochemical pretreatment method is one which increases the rate of the electron transfer at the electrode surface in order to improve the kinetics of electrode processes. There are few literature were reported on pretreated carbon based electrode for electrochemical determination of organic compounds [3-6]. Present study describes the electrochemical pretreatment of graphite pencil electrode for electrochemical determinations of adenosine and adenine. Purine nucleosides are well-known for their metabolic and biological effects in human system. Their detection and determination has become increasingly important in the field of biomedical research owing to their importance in normal cellular functions. The importance of such a determination stems from the fact that changes in the concentration of these nucleosides in body fluids have been used to indicate the presence of various diseases [7, 8] and hence, their analysis is highly desirable. Adenosine modulates physiological functions in heart and brain, and regulates oxygen supply during cell stress [9] and has also been suggested to be useful in the regulation of renal function [10]. The amounts of adenosine in the urine and plasma samples can also be the marker of some diseases such as carcinoma or liver diseases [11]. So it is important to determine adenosine concentration in different body fluids samples. Different analytical methods have been proposed for the determination of adenosine and most of them are based on the chromatography, which is sensitive and accurate with some pretreatment procedures [12, 13]. The electrooxidation of adenosine on the common working electrode showed high oxidation potential and limited sensitivity. So the chemically modified electrodes were used to overcome the disadvantages and improve the sensitivity [14, 15]. On the other hand, adenine is a vital constituent of deoxyribonucleic acids. It is very important in storing genetic information. Measuring the levels of adenine is important in bioscience and clinical diagnosis, because their amount of concentration can act as important indicators for the diagnosis of various illnesses [16-21]. In view of the importance of adenosine and adenine in human physiology, attempts have been made to determine them simultaneously in body fluids, since both occur together in biological system, by various techniques. In the present research, the development of reagentless biosensor was a great challenge for researchers. we have used the GPE which was activated in 0.1 N sulfuric acid (H2SO4) under potential between 0.6 to 2.0V at scan rate of 0.1 Vs -1 for a 10 cycles in an unstirred solution by using