Improving Electrochemical Performance of Polypyrrole Coating by Graphene Oxide-Carbon Nanotube and Zinc Oxide Nanorods in the Role of a Sensor for the Simultaneous Measurement of Morphine and Methadone

Document Type : Research Paper


1 Department of Chemistry, Payame Noor University, 19395-4697, Tehran, Iran

2 Shenyang National Lab for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, China


The current research examines the designation of an electrochemical sensor for the simultaneous measurement of morphine and methadone using graphene oxide /multi-walled carbon nanotube/zinc oxide nanorods/polypyrrolenanocomposite, coated on the surface of the graphite electrode reinforced by a hollow fiber.Its performance was investigated by voltammetry methods while the nanocomposite structure was confirmed by FTIR, EDX, XRD, and SEM techniques.To optimize the effectual factors, the Taguchi test designing method with L27(3x7) orthogonal array was applied. Thevoltammetricanalysisshowed that two irreversible oxidation peaks appeared at the potentials of 0.81 V and 0.41 V for methadone and morphine, respectively. Furthermore, the electrochemical investigations showed that the oxidation process of morphine and methadone wasunder the control of the diffusion phenomenon and two electrons and two protons had been exchanged on the surface of the electrode for bothanalytes. Chronoamperometry was used to measure the diffusion coefficients of drugs which were found for morphine and methadone to be 5.31×10-6 cm2s-1 and 1.19×10-6 cm2 s-1. Under optimal conditions, for morphine, two linear concentration ranges of 0.04-10 μM and 10.0-100 μM and a detection limit of 0.01 μM were noted whereas for methadone, two linear ranges were observed in 0.06-8.0 μM and 8.0-100 μM and the detection limit was 0.02 μM. The designed sensor can be well used for the simultaneous measurement of the drugs with relative recovery percentages in the range of 98.80-100.22%for morphine and in the range of 98.14-100.58% for methadone.