Voltammetric Determination of Orange II by Using Carboxyl Functionalized Multi-walled Carbon Nanotubes Modified Platinum Disk Microelectrode

Orange II is one of the azo dyes, which is widely used as coloring agent in a variety of products, such as textile, paper, foodstuffs, hair dye and leather. Many countries have regulated the use of some of azo dyes in foodstuffs because they pose a potential risk to human health and are even carcinogenic [1, 2].In this work, a method for electrochemical determination of low concentration of Orange II is described. Thereby motivated, the electrochemical behavior of Orange II was evaluated in this study by using a carboxyl functionalized multi-walled carbon nanotubes on platinum disk microelectrode (MWCNTs-COOH/Pt). Orange II analyzed by differential pulse voltammetry (DPV) when Orange II is electrochemically oxidized on MWCNTs-COOH/Pt. Optimization of condition was performed to attain the maximum sensitivity for the determination of Orange II. Compared to the bare platinum disk microelectrode, the electrochemical responses of Orange II was greatly increased by MWCNTs-COOH/Pt. The surface of the modified electrode was characterized by different methods including XPS, XRD and SEM. Calibration curves were constructed that showed two linear ranges of 0.02-0.3 and 2-10 μmol L-1. The relative standard deviation and recovery for determination of Orange II (0.1 μmol L-1) were 4.3 and 105.0 as percent, respectively. Limit of detection for Orange II determination was also evaluated (0.014 μmol L-1). The method was applied for the determination of Orange II in various environmental water samples. This approach showed advantages on simplicity, sensitivity and selectivity of Orange II determination when was compared with the other related analytical methods.