Structural Insight on Thiourea Doped Graphene: An Efficient Electrochemical Sensor for Voltammetric Detection of Morphine in Alcoholic and Non-Alcoholic Beverages

Morphine (MO) has been one of the most talked-about abused drug amongst all the opiates. In this context, the present work focuses on a facile and reliable method of morphine detection principled on electrochemical techniques. The excellent electronic properties of chemically synthesized nitrogen and sulphur doped graphene (NSG) have been utilized to detect MO in phosphate buffer solution (PBS) and beverages. The electrochemical property of the NSG with varying concentrations of the dopant (thiourea) and the un-doped graphene (G) material has been studied. All the materials have been characterized using Fourier transform infrared spectroscopy, X-ray diffraction , field emission scanning electron microscopy-energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. The electrochemical detection of MO has been carried out using DPV and CV. NSG material has been seen to proliferate the electron transfer of the oxidized MO and results in an enhanced current response. The detection response of MO has been noticed to be dependent on pH environments (2 to 11) and was found to be a proton-dependent mechanistic approach. The LDR, and LOD of MO, obtained using NSG 4 as the electrode, have been calculated as 294 µg/mL to 0.57 µg/mL, and 0.26 µg/mL, respectively. Furthermore, the electrode modifier showcased demonstrated fairly good stability and repeatability. The morphine detection results reported in this work show a reasonably good LOD in comparison to earlier reports. The detection of spiked MO in soft and hard drinks without any pre-treatment procedures has also been demonstrated.